// js/userBlocks.js
import {
  nostrClient,
  requestDefaultExtensionPermissions,
} from "./nostrClientFacade.js";
import { getActiveSigner } from "./nostr/index.js";
import { isSessionActor } from "./nostr/sessionActor.js";
import {
  buildBlockListEvent,
  buildMuteListEvent,
  BLOCK_LIST_IDENTIFIER,
  KIND_MUTE_LIST,
} from "./nostrEventSchemas.js";
import { devLogger, userLogger } from "./utils/logger.js";
import { STANDARD_TIMEOUT_MS, MAX_BLOCKLIST_ENTRIES } from "./constants.js";
import {
  publishEventToRelays,
  assertAnyRelayAccepted,
} from "./nostrPublish.js";
import { profileCache } from "./state/profileCache.js";
import { DEFAULT_RELAY_URLS } from "./nostr/toolkit.js";
import { relayManager } from "./relayManager.js";
import {
  DEFAULT_NIP07_ENCRYPTION_METHODS,
  runNip07WithRetry,
  NIP07_PRIORITY,
} from "./nostr/nip07Permissions.js";
import { relaySubscriptionService } from "./services/relaySubscriptionService.js";
import {
  getLastSuccessfulScheme,
  setLastSuccessfulScheme,
} from "./nostr/decryptionSchemeCache.js";
import {
  compareListEventsDesc,
  computeIncrementalSinceWithOverlap,
  selectNewestListEvent,
} from "./nostr/listEventOrdering.js";

class TinyEventEmitter {
  constructor() {
    this.listeners = new Map();
  }

  on(eventName, handler) {
    if (typeof eventName !== "string" || typeof handler !== "function") {
      return () => {};
    }

    if (!this.listeners.has(eventName)) {
      this.listeners.set(eventName, new Set());
    }

    const handlers = this.listeners.get(eventName);
    handlers.add(handler);

    return () => {
      handlers.delete(handler);
      if (!handlers.size) {
        this.listeners.delete(eventName);
      }
    };
  }

  emit(eventName, detail) {
    const handlers = this.listeners.get(eventName);
    if (!handlers || !handlers.size) {
      return;
    }

    for (const handler of Array.from(handlers)) {
      try {
        handler(detail);
      } catch (error) {
        userLogger.warn(
          `[UserBlockList] listener for "${eventName}" threw an error`,
          error,
        );
      }
    }
  }
}

export const USER_BLOCK_EVENTS = Object.freeze({
  CHANGE: "change",
  STATUS: "status",
});

const FAST_BLOCKLIST_RELAY_LIMIT = 3;
const FAST_BLOCKLIST_TIMEOUT_MS = 2500;
const BACKGROUND_BLOCKLIST_TIMEOUT_MS = 6000;
const MAX_BACKGROUND_BLOCKLIST_RELAY_LIMIT = 24;
// Keep interactive decrypt timeout above extension retry timeout window.
const DECRYPT_TIMEOUT_MS = Math.max(STANDARD_TIMEOUT_MS, 15000);
const BACKGROUND_DECRYPT_TIMEOUT_MS = 8000;
// PERF: Reduced from 10s to 3s for faster recovery during login.
const DECRYPT_RETRY_DELAY_MS = 3000;
const MAX_DECRYPT_RETRY_DELAY_MS = 30000;
function computeRetryDelay(baseDelayMs, attempt) {
  const normalizedAttempt = Number.isFinite(attempt) && attempt > 0 ? Math.floor(attempt) : 0;
  const multiplier = 2 ** normalizedAttempt;
  const nextDelay = Math.max(250, Math.floor(baseDelayMs * multiplier));
  return Math.min(MAX_DECRYPT_RETRY_DELAY_MS, nextDelay);
}

function sanitizeRelayList(candidate) {
  if (!Array.isArray(candidate)) return [];
  const seen = new Set();
  const relays = [];
  for (const value of candidate) {
    const normalized = typeof value === "string" ? value.trim() : "";
    if (!normalized || seen.has(normalized)) continue;
    seen.add(normalized);
    relays.push(normalized);
  }
  return relays;
}
function normalizeEncryptionToken(value) {
  if (typeof value !== "string") {
    return "";
  }
  return value
    .trim()
    .toLowerCase()
    .replace(/[^a-z0-9]/g, "");
}

function extractEncryptionHints(event) {
  if (!event || typeof event !== "object") {
    return [];
  }

  const tags = Array.isArray(event.tags) ? event.tags : [];
  const hints = [];

  const pushUnique = (scheme) => {
    if (!scheme || hints.includes(scheme)) {
      return;
    }
    hints.push(scheme);
  };

  for (const tag of tags) {
    if (!Array.isArray(tag) || tag.length < 2) {
      continue;
    }
    const name = typeof tag[0] === "string" ? tag[0].trim().toLowerCase() : "";
    if (name !== "encrypted" && name !== "encryption") {
      continue;
    }
    const rawValue = typeof tag[1] === "string" ? tag[1] : "";
    if (!rawValue) {
      continue;
    }
    const parts = rawValue
      .split(/[\s,]+/)
      .map((part) => normalizeEncryptionToken(part))
      .filter(Boolean);

    for (const part of parts) {
      if (part === "nip44v2" || part === "nip44v02") {
        pushUnique("nip44_v2");
        continue;
      }
      if (part === "nip44") {
        pushUnique("nip44");
        continue;
      }
      if (part === "nip04" || part === "nip4") {
        pushUnique("nip04");
      }
    }
  }

  return hints;
}

function determineDecryptionOrder(event, availableSchemes, cachedScheme = null) {
  const available = Array.isArray(availableSchemes) ? availableSchemes : [];
  const availableSet = new Set(available);
  const prioritized = [];

  if (cachedScheme && availableSet.has(cachedScheme)) {
    prioritized.push(cachedScheme);
  }

  const hints = extractEncryptionHints(event);
  const aliasMap = {
    nip04: ["nip04"],
    nip44: ["nip44", "nip44_v2"],
    nip44_v2: ["nip44_v2", "nip44"],
  };

  for (const hint of hints) {
    const candidates = Array.isArray(aliasMap[hint]) ? aliasMap[hint] : [hint];
    for (const candidate of candidates) {
      if (availableSet.has(candidate) && !prioritized.includes(candidate)) {
        prioritized.push(candidate);
        break;
      }
    }
  }

  for (const fallback of ["nip44_v2", "nip44", "nip04"]) {
    if (availableSet.has(fallback) && !prioritized.includes(fallback)) {
      prioritized.push(fallback);
    }
  }

  return prioritized.length ? prioritized : available;
}

function describeDiscardedEntry(entry) {
  if (typeof entry === "string") {
    return entry.trim();
  }

  if (entry === null) {
    return "null";
  }

  if (typeof entry === "undefined") {
    return "undefined";
  }

  if (Array.isArray(entry)) {
    try {
      return JSON.stringify(entry);
    } catch (_error) {
      return String(entry);
    }
  }

  if (typeof entry === "object") {
    try {
      return JSON.stringify(entry);
    } catch (_error) {
      return String(entry);
    }
  }

  return String(entry);
}

function sanitizeMuteTags(values, ownerPubkey, options = {}) {
  const logDiscarded = options?.logDiscarded !== false;
  const owner = normalizeHex(ownerPubkey);
  const sanitized = [];
  const seen = new Set();

  const iterable = Array.isArray(values)
    ? values
    : values instanceof Set
    ? Array.from(values)
    : values && typeof values[Symbol.iterator] === "function"
    ? Array.from(values)
    : [];

  const logDiscard = (entry, reason, extra) => {
    if (!logDiscarded) {
      return;
    }
    const detail = describeDiscardedEntry(entry);
    if (extra) {
      userLogger.warn(
        `[UserBlockList] Discarded block entry (${reason}).`,
        detail,
        extra,
      );
      return;
    }
    userLogger.warn(`[UserBlockList] Discarded block entry (${reason}).`, detail);
  };

  for (const entry of iterable) {
    let targetHex = null;

    if (Array.isArray(entry)) {
      if (entry.length < 2) {
        logDiscard(entry, "invalid-tuple");
        continue;
      }

      const label =
        typeof entry[0] === "string" ? entry[0].trim().toLowerCase() : "";
      if (label !== "p") {
        logDiscard(entry, "unsupported-tag");
        continue;
      }

      targetHex = normalizeHex(entry[1]);
      if (!targetHex) {
        logDiscard(entry, "invalid-target");
        continue;
      }
    } else if (typeof entry === "string") {
      targetHex = normalizeHex(entry);
      if (!targetHex) {
        logDiscard(entry, "invalid-string");
        continue;
      }
    } else if (entry && typeof entry === "object") {
      if (typeof entry.pubkey === "string") {
        targetHex = normalizeHex(entry.pubkey);
        if (!targetHex) {
          logDiscard(entry, "invalid-object-pubkey");
          continue;
        }
      } else {
        logDiscard(entry, "unsupported-entry");
        continue;
      }
    } else {
      logDiscard(entry, "unsupported-entry");
      continue;
    }

    if (owner && targetHex === owner) {
      logDiscard(entry, "self-target");
      continue;
    }

    if (seen.has(targetHex)) {
      logDiscard(entry, "duplicate", targetHex);
      continue;
    }

    seen.add(targetHex);
    sanitized.push(["p", targetHex]);
  }

  return sanitized;
}

function serializeBlockListTagMatrix(values, ownerPubkey, options = {}) {
  const tags = sanitizeMuteTags(values, ownerPubkey, options);
  return JSON.stringify(tags);
}

function extractPubkeysFromTags(tags, ownerPubkey = null, options = {}) {
  if (!Array.isArray(tags)) {
    return [];
  }
  const collected = [];
  const seen = new Set();
  const owner = ownerPubkey ? normalizeHex(ownerPubkey) : null;
  const limit = Number.isFinite(options?.limit)
    ? Math.max(0, Math.floor(options.limit))
    : null;

  for (const entry of tags) {
    if (!Array.isArray(entry) || entry.length < 2) {
      continue;
    }
    const label = typeof entry[0] === "string" ? entry[0].trim().toLowerCase() : "";
    if (label !== "p") {
      continue;
    }
    const normalized = normalizeHex(entry[1]);
    if (!normalized || (owner && normalized === owner) || seen.has(normalized)) {
      continue;
    }
    seen.add(normalized);
    collected.push(normalized);
    if (limit !== null && collected.length >= limit) {
      break;
    }
  }
  return collected;
}

function parseBlockListPlaintext(plaintext, ownerPubkey, options = {}) {
  if (typeof plaintext !== "string" || !plaintext) {
    return [];
  }

  let parsed;
  try {
    parsed = JSON.parse(plaintext);
  } catch (error) {
    userLogger.warn(
      "[UserBlockList] Failed to parse block list ciphertext as JSON; treating as empty.",
      error,
    );
    return [];
  }

  const owner = normalizeHex(ownerPubkey);
  const limit = Number.isFinite(options?.limit)
    ? Math.max(0, Math.floor(options.limit))
    : null;

  if (Array.isArray(parsed)) {
    if (limit !== null && parsed.length > limit) {
      devLogger.warn(
        "[UserBlockList] Block list payload exceeds entry limit; truncating.",
        { limit, payloadSize: parsed.length },
      );
    }
    return extractPubkeysFromTags(parsed, owner, { limit });
  }

  if (parsed && typeof parsed === "object") {
    if (Array.isArray(parsed.tags) && parsed.tags.length) {
      if (limit !== null && parsed.tags.length > limit) {
        devLogger.warn(
          "[UserBlockList] Block list tag payload exceeds entry limit; truncating.",
          { limit, payloadSize: parsed.tags.length },
        );
      }
      return extractPubkeysFromTags(parsed.tags, owner, { limit });
    }

    const legacy = Array.isArray(parsed.blockedPubkeys) ? parsed.blockedPubkeys : [];
    if (limit !== null && legacy.length > limit) {
      devLogger.warn(
        "[UserBlockList] Legacy block list payload exceeds entry limit; truncating.",
        { limit, payloadSize: legacy.length },
      );
    }
    const normalizedLegacy = legacy
      .map((value) => normalizeHex(value))
      .filter((value) => value && value !== owner);
    if (limit === null) {
      return normalizedLegacy;
    }
    return normalizedLegacy.slice(0, limit);
  }

  return [];
}

function isUserBlockListEvent(event) {
  if (!event || typeof event.kind !== "number") {
    return false;
  }

  if (event.kind === KIND_MUTE_LIST) {
    return true;
  }

  if (event.kind === 30002) {
    const tags = Array.isArray(event.tags) ? event.tags : [];
    return tags.some(
      (tag) =>
        Array.isArray(tag) &&
        typeof tag[0] === "string" &&
        tag[0].trim().toLowerCase() === "d" &&
        typeof tag[1] === "string" &&
        tag[1].trim() === BLOCK_LIST_IDENTIFIER,
    );
  }

  return false;
}

function isTaggedBlockListEvent(event) {
  if (!event || !Array.isArray(event.tags)) {
    return false;
  }
  return event.tags.some(
    (tag) =>
      Array.isArray(tag) &&
      tag.length >= 2 &&
      typeof tag[0] === "string" &&
      tag[0].trim().toLowerCase() === "d" &&
      typeof tag[1] === "string" &&
      tag[1].trim() === BLOCK_LIST_IDENTIFIER,
  );
}

const BECH32_CHARSET = "qpzry9x8gf2tvdw0s3jn54khce6mua7l";
const BECH32_CHARSET_MAP = (() => {
  const map = new Map();
  for (let index = 0; index < BECH32_CHARSET.length; index += 1) {
    map.set(BECH32_CHARSET[index], index);
  }
  return map;
})();

function bytesToHex(bytes) {
  if (!bytes || typeof bytes.length !== "number") {
    return "";
  }

  let hex = "";
  for (let index = 0; index < bytes.length; index += 1) {
    const value = bytes[index];
    if (typeof value !== "number") {
      return "";
    }
    const normalized = value & 0xff;
    hex += normalized.toString(16).padStart(2, "0");
  }
  return hex;
}

function bech32Polymod(values) {
  let chk = 1;
  const generators = [0x3b6a57b2, 0x26508e6d, 0x1ea119fa, 0x3d4233dd, 0x2a1462b3];

  for (const value of values) {
    const top = chk >>> 25;
    chk = ((chk & 0x1ffffff) << 5) ^ value;
    for (let bit = 0; bit < generators.length; bit += 1) {
      if ((top >>> bit) & 1) {
        chk ^= generators[bit];
      }
    }
  }

  return chk;
}

function bech32HrpExpand(hrp) {
  const expanded = [];
  for (let index = 0; index < hrp.length; index += 1) {
    const code = hrp.charCodeAt(index);
    expanded.push(code >>> 5);
  }
  expanded.push(0);
  for (let index = 0; index < hrp.length; index += 1) {
    const code = hrp.charCodeAt(index);
    expanded.push(code & 31);
  }
  return expanded;
}

function bech32VerifyChecksum(hrp, data) {
  return bech32Polymod(bech32HrpExpand(hrp).concat(data)) === 1;
}

function bech32Decode(value) {
  if (typeof value !== "string") {
    return null;
  }

  const trimmed = value.trim();
  if (!trimmed) {
    return null;
  }

  const lower = trimmed.toLowerCase();
  const upper = trimmed.toUpperCase();
  if (trimmed !== lower && trimmed !== upper) {
    return null;
  }

  const normalized = lower;
  const separatorIndex = normalized.lastIndexOf("1");
  if (separatorIndex < 1 || separatorIndex + 7 > normalized.length) {
    return null;
  }

  const hrp = normalized.slice(0, separatorIndex);
  const data = [];
  for (let index = separatorIndex + 1; index < normalized.length; index += 1) {
    const char = normalized[index];
    if (!BECH32_CHARSET_MAP.has(char)) {
      return null;
    }
    data.push(BECH32_CHARSET_MAP.get(char));
  }

  if (!bech32VerifyChecksum(hrp, data)) {
    return null;
  }

  return { hrp, words: data.slice(0, -6) };
}

function convertBits(data, fromBits, toBits, pad = true) {
  const result = [];
  let acc = 0;
  let bits = 0;
  const maxv = (1 << toBits) - 1;
  const maxAcc = (1 << (fromBits + toBits - 1)) - 1;

  for (const value of data) {
    if (value < 0 || value >> fromBits) {
      return null;
    }
    acc = ((acc << fromBits) | value) & maxAcc;
    bits += fromBits;
    while (bits >= toBits) {
      bits -= toBits;
      result.push((acc >>> bits) & maxv);
    }
  }

  if (pad) {
    if (bits) {
      result.push((acc << (toBits - bits)) & maxv);
    }
  } else if (bits >= fromBits || ((acc << (toBits - bits)) & maxv)) {
    return null;
  }

  return result;
}

function fallbackDecodeNpubToHex(value) {
  const decoded = bech32Decode(value);
  if (!decoded || decoded.hrp !== "npub") {
    return "";
  }

  const bytes = convertBits(decoded.words, 5, 8, false);
  if (!bytes || !bytes.length) {
    return "";
  }

  return bytesToHex(bytes);
}

function normalizeDecodedHex(value) {
  if (typeof value !== "string") {
    return null;
  }

  const trimmed = value.trim();
  if (!/^[0-9a-f]{64}$/i.test(trimmed)) {
    return null;
  }

  return trimmed.toLowerCase();
}

function normalizeNpubInput(value) {
  if (typeof value !== "string") {
    return "";
  }

  const trimmed = value.trim();
  if (!trimmed) {
    return "";
  }

  const lower = trimmed.toLowerCase();
  if (lower.startsWith("nostr:")) {
    return trimmed.slice(6).trim();
  }

  return trimmed;
}

function decodeNpubToHex(npub) {
  if (typeof npub !== "string") {
    return null;
  }

  const trimmed = normalizeNpubInput(npub);
  if (!trimmed) {
    return null;
  }

  if (/^[0-9a-f]{64}$/i.test(trimmed)) {
    return trimmed.toLowerCase();
  }

  const tools = typeof globalThis !== "undefined" ? globalThis?.NostrTools : null;
  const decoder = tools?.nip19?.decode;
  if (typeof decoder === "function") {
    try {
      const decoded = decoder(trimmed);
      if (!decoded || decoded.type !== "npub") {
        return normalizeDecodedHex(fallbackDecodeNpubToHex(trimmed));
      }
      if (typeof decoded.data === "string") {
        const normalized = normalizeDecodedHex(decoded.data);
        return normalized || normalizeDecodedHex(fallbackDecodeNpubToHex(trimmed));
      }
      return normalizeDecodedHex(bytesToHex(decoded.data));
    } catch (error) {
      return normalizeDecodedHex(fallbackDecodeNpubToHex(trimmed));
    }
  }

  return normalizeDecodedHex(fallbackDecodeNpubToHex(trimmed));
}

function normalizeHex(pubkey) {
  if (typeof pubkey !== "string") {
    return null;
  }

  const trimmed = pubkey.trim();
  if (!trimmed) {
    return null;
  }

  if (/^[0-9a-f]{64}$/i.test(trimmed)) {
    return trimmed.toLowerCase();
  }

  const decoded = decodeNpubToHex(trimmed);
  if (decoded) {
    return decoded;
  }

  return null;
}

class UserBlockListManager {
  constructor() {
    this.blockedPubkeys = new Set();
    this._privateBlocks = new Set();
    this._publicMutes = new Set();
    this.activePubkey = null;
    this.blockEventId = null;
    this.blockEventCreatedAt = null;
    this.lastPublishedCreatedAt = null;
    this.muteEventId = null;
    this.muteEventCreatedAt = null;
    this.loaded = false;
    this.emitter = new TinyEventEmitter();
    this.seedStateCache = new Map();
    this.decryptRetryTimeoutId = null;
    this.decryptRetryAttempt = 0;
    this.loadPromise = null;
    this.loadingPubkey = null;
    this.blockListSubscriptionKey = null;
    profileCache.subscribe((event, detail) => {
      if (event === "profileChanged") {
        this.reset();
      } else if (event === "runtimeCleared" && detail.pubkey === this.activePubkey) {
        this.reset();
        if (this.activePubkey) {
          this.loadBlocks(this.activePubkey);
        }
      }
    });
  }

  reset() {
    this.stopBlockListSubscription();
    this.blockedPubkeys.clear();
    this._privateBlocks.clear();
    this._publicMutes.clear();
    this.blockEventId = null;
    this.blockEventCreatedAt = null;
    this.lastPublishedCreatedAt = null;
    this.muteEventId = null;
    this.muteEventCreatedAt = null;
    this.loaded = false;
    if (this.decryptRetryTimeoutId) {
      clearTimeout(this.decryptRetryTimeoutId);
      this.decryptRetryTimeoutId = null;
    }
    this.decryptRetryAttempt = 0;
    this.loadPromise = null;
    this.loadingPubkey = null;
  }

  stopBlockListSubscription() {
    if (this.blockListSubscriptionHandle) {
      try {
        this.blockListSubscriptionHandle.close();
      } catch (error) {
        devLogger.warn("[UserBlockList] Failed to close block-list subscription handle", error);
      }
      this.blockListSubscriptionHandle = null;
    }
    if (this.blockListSubscriptionKey) {
      relaySubscriptionService.stopSubscription(
        this.blockListSubscriptionKey,
        "reset",
      );
      this.blockListSubscriptionKey = null;
    }
  }

  ensureBlockListSubscription(userPubkey, relays) {
    const normalized = normalizeHex(userPubkey);
    if (!normalized || !nostrClient?.pool) {
      return null;
    }

    const key = `block-list:${normalized}`;
    this.blockListSubscriptionKey = key;

    const filters = [
      { kinds: [KIND_MUTE_LIST], authors: [normalized] },
      { kinds: [30002], authors: [normalized], "#d": [BLOCK_LIST_IDENTIFIER] },
    ];

    // Route through the L1 SubscriptionManager when available (dedup + reconnect
    // re-issue); fall back to relaySubscriptionService in manager-less envs.
    const manager =
      typeof nostrClient.getSubscriptionManager === "function"
        ? nostrClient.getSubscriptionManager()
        : null;
    if (manager) {
      this.blockListSubscriptionHandle = manager.subscribe({
        key,
        relays,
        filters,
        label: "block-list",
        onEvent: (event) => this.handleBlockListEvent(event),
      });
      return this.blockListSubscriptionHandle;
    }

    return relaySubscriptionService.ensureSubscription({
      key,
      pool: nostrClient.pool,
      relays,
      filters,
      label: "block-list",
      onEvent: (event) => this.handleBlockListEvent(event),
    });
  }

  handleBlockListEvent(event) {
    const normalized = normalizeHex(event?.pubkey);
    if (!normalized || normalized !== this.activePubkey) {
      return;
    }
    if (!isUserBlockListEvent(event)) {
      return;
    }
    this.loadBlocks(normalized).catch((error) => {
      devLogger.warn("[UserBlockList] Failed to refresh after block list event", error);
    });
  }

  on(eventName, handler) {
    return this.emitter.on(eventName, handler);
  }

  getBlockedPubkeys() {
    return Array.from(this.blockedPubkeys);
  }

  getPublicMutes() {
    return Array.from(this._publicMutes);
  }

  getPrivateBlocks() {
    return Array.from(this._privateBlocks);
  }

  scheduleDecryptRetry(userPubkey, detail = {}) {
    if (!userPubkey) {
      return;
    }
    if (this.decryptRetryTimeoutId) {
      clearTimeout(this.decryptRetryTimeoutId);
    }
    const attempt = this.decryptRetryAttempt;
    const retryDelayMs = computeRetryDelay(DECRYPT_RETRY_DELAY_MS, attempt);
    this.decryptRetryAttempt = attempt + 1;
    const retryMeta = detail && typeof detail === "object" ? detail : {};
    const signerStatus = retryMeta.signerStatus || "unknown";
    this.decryptRetryTimeoutId = setTimeout(() => {
      this.decryptRetryTimeoutId = null;
      if (this.activePubkey !== userPubkey) {
        return;
      }
      const sinceValue = Number.isFinite(this.blockEventCreatedAt)
        ? Math.max(0, this.blockEventCreatedAt - 1)
        : undefined;
      this.loadBlocks(userPubkey, {
        since: sinceValue,
      }).catch((retryError) => {
        userLogger.warn("[UserBlockList] Decryption retry failed:", retryError);
      });
    }, retryDelayMs);
    devLogger.log(
      `[UserBlockList] Decryption stalled (${signerStatus}); retrying in ${retryDelayMs / 1000}s.`,
      retryMeta.error || retryMeta,
    );
  }

  isBlocked(pubkey) {
    const normalized = normalizeHex(pubkey);
    if (!normalized) {
      return false;
    }
    return this.blockedPubkeys.has(normalized);
  }

  async ensureLoaded(userPubkey) {
    if (this.loaded) {
      return;
    }

    const normalized = normalizeHex(userPubkey);
    if (!normalized) {
      return;
    }
    await this.loadBlocks(normalized);
  }

  async loadBlocks(userPubkey, options = {}) {
    const normalized = normalizeHex(userPubkey);

    if (this.loadPromise && this.loadingPubkey === normalized) {
      devLogger.log("[UserBlockList] Reusing in-flight block list load.", {
        pubkey: normalized,
      });
      return this.loadPromise;
    }
    if (this.loadPromise && this.loadingPubkey && this.loadingPubkey !== normalized) {
      devLogger.log("[UserBlockList] Waiting for existing block list load to settle.", {
        previous: this.loadingPubkey,
        next: normalized,
      });
      await this.loadPromise.catch(() => {});
    }

    const loadPromise = this.loadBlocksInternal(normalized, options);
    this.loadPromise = loadPromise;
    this.loadingPubkey = normalized;
    try {
      return await loadPromise;
    } finally {
      this.emitter.emit(USER_BLOCK_EVENTS.CHANGE, {
        action: "load-settled",
        blockedPubkeys: Array.from(this.blockedPubkeys),
        loaded: this.loaded === true,
        activePubkey: this.activePubkey || null,
      });
      if (this.loadPromise === loadPromise) {
        this.loadPromise = null;
        this.loadingPubkey = null;
      }
    }
  }

  async loadBlocksInternal(userPubkey, options = {}) {
    const normalized = normalizeHex(userPubkey);
    this.activePubkey = normalized;

    if (!normalized) {
      this.reset();
      this.loaded = true;
      return;
    }

    const since = Number.isFinite(options?.since)
      ? Math.max(0, Math.floor(options.since))
      : null;
    const statusCallback =
      typeof options?.statusCallback === "function"
        ? options.statusCallback
        : null;
    const loadMode =
      options?.mode === "background" ? "background" : "interactive";
    const allowPermissionPrompt =
      options?.allowPermissionPrompt !== false && loadMode !== "background";
    const decryptTimeoutMs = Number.isFinite(options?.decryptTimeoutMs)
      ? Math.max(0, Math.floor(options.decryptTimeoutMs))
      : allowPermissionPrompt
      ? DECRYPT_TIMEOUT_MS
      : BACKGROUND_DECRYPT_TIMEOUT_MS;
    // PERF: Previous 3s no-prompt timeout was too aggressive — extensions that
    // have already granted permission still need time to decrypt. 8s gives a
    // realistic window while still failing faster than the full 15s interactive
    // timeout.
    const nip07DecryptTimeoutMs = allowPermissionPrompt ? 15000 : 8000;
    const emitStatus = (detail) => {
      if (!detail || typeof detail !== "object") {
        return;
      }

      try {
        statusCallback?.(detail);
      } catch (callbackError) {
        userLogger.warn(
          "[UserBlockList] statusCallback threw while emitting status",
          callbackError,
        );
      }

      try {
        this.emitter.emit(USER_BLOCK_EVENTS.STATUS, detail);
      } catch (emitterError) {
        userLogger.warn(
          "[UserBlockList] Failed to dispatch status event",
          emitterError,
        );
      }
    };

    const readRelays = relayManager.getReadRelayUrls();
    const writeRelays = relayManager.getWriteRelayUrls();
    const relays = sanitizeRelayList([
      ...readRelays,
      ...writeRelays,
    ]);
    const effectiveRelays =
      relays.length > 0 ? relays : Array.from(DEFAULT_RELAY_URLS);
    emitStatus({ status: "loading", relays: effectiveRelays });
    if (!nostrClient?.pool && typeof nostrClient?.ensurePool === "function") {
      try {
        await nostrClient.ensurePool();
      } catch (error) {
        devLogger.warn("[UserBlockList] Failed to initialize relay pool for subscription", error);
      }
    }
    this.ensureBlockListSubscription(normalized, effectiveRelays);

    const localData = this._loadLocal(normalized);
    const hasLocalData = !!localData;

    if (localData) {
      this._privateBlocks = localData.privateBlocks || localData.blockedPubkeys || new Set();
      this._publicMutes = localData.publicMutes || new Set();
      this.blockedPubkeys = new Set([...this._privateBlocks, ...this._publicMutes]);

      if (Number.isFinite(localData.createdAt)) {
        this.blockEventCreatedAt = localData.createdAt;
      }
      this.loaded = true;
      this.emitter.emit(USER_BLOCK_EVENTS.CHANGE, {
        action: "sync",
        blockedPubkeys: Array.from(this.blockedPubkeys),
        source: "local",
      });
    }

    const applySets = (privateSet, publicSet, meta = {}) => {
      this._privateBlocks = privateSet;
      this._publicMutes = publicSet;
      this.blockedPubkeys = new Set([...privateSet, ...publicSet]);
      this.emitter.emit(USER_BLOCK_EVENTS.CHANGE, {
        action: "sync",
        blockedPubkeys: Array.from(this.blockedPubkeys),
        ...meta,
      });
    };

    const resolveDecryptors = async (event) => {
      let signer = getActiveSigner();

      const hints = extractEncryptionHints(event);
      const requiresNip44 = hints.includes("nip44") || hints.includes("nip44_v2");
      const requiresNip04 = !hints.length || hints.includes("nip04");

      const signerHasRequiredDecryptors = (candidate) => {
        const hasNip04 = typeof candidate?.nip04Decrypt === "function";
        const hasNip44 = typeof candidate?.nip44Decrypt === "function";
        return (!requiresNip44 || hasNip44) && (!requiresNip04 || hasNip04);
      };

      // FIX: Always attempt to resolve the signer if one isn't available,
      // regardless of allowPermissionPrompt. The previous guard meant that
      // background refreshes (allowPermissionPrompt=false) could never decrypt
      // because they skipped signer resolution entirely. ensureActiveSignerForPubkey
      // does not itself prompt the user — it only waits for an already-injected
      // extension or returns the existing signer.
      if (
        (!signer || !signerHasRequiredDecryptors(signer)) &&
        typeof nostrClient?.ensureActiveSignerForPubkey === "function"
      ) {
        signer = await nostrClient.ensureActiveSignerForPubkey(normalized);
      }

      // FIX: Check method existence only, not capabilities. NIP-07 adapters
      // always expose decrypt methods that check extension state at call time.
      // The capabilities getter dynamically queries window.nostr which may not
      // have injected nip04/nip44 modules yet (lazy injection), causing false
      // negatives that block decryption even when methods will work at call time.
      const signerHasNip04 = typeof signer?.nip04Decrypt === "function";
      const signerHasNip44 = typeof signer?.nip44Decrypt === "function";
      const signerAvailable = Boolean(signer);
      const signerHasDecryptors = signerHasNip04 || signerHasNip44;
      const signerStatus = signerAvailable
        ? signerHasDecryptors
          ? "present"
          : "present-missing-decryptor"
        : "missing";

      let permissionError = null;
      if ((!signerHasNip44 && requiresNip44) || (!signerHasNip04 && requiresNip04)) {
        if (!allowPermissionPrompt) {
          const error = new Error(
            "Encryption permissions are required to decrypt the block list.",
          );
          error.code = "user-blocklist-permission-required";
          error.permissionRequestDeferred = true;
          permissionError = error;
        } else {
          try {
            const permissionResult = await requestDefaultExtensionPermissions(
              DEFAULT_NIP07_ENCRYPTION_METHODS,
            );
            if (!permissionResult?.ok) {
              const error =
                permissionResult?.error instanceof Error
                  ? permissionResult.error
                  : new Error(
                      "Extension encryption permissions are required to use the browser decryptor.",
                    );
              error.code = "user-blocklist-permission-required";
              permissionError = error;
            }
          } catch (error) {
            const wrapped =
              error instanceof Error ? error : new Error(String(error));
            wrapped.code = "user-blocklist-permission-required";
            permissionError = wrapped;
          }
        }
      }

      const decryptors = new Map();
      const sources = new Map();
      const registerDecryptor = (scheme, handler, source) => {
        if (
          !scheme ||
          typeof handler !== "function" ||
          decryptors.has(scheme)
        ) {
          return;
        }
        decryptors.set(scheme, handler);
        sources.set(scheme, source || "unknown");
      };

      // Pass per-call timeouts to signer decrypt methods so they fail fast
      // during login (3s) instead of using the 60s default. This prevents a
      // single stalled extension call from blocking the entire decrypt pipeline.
      // Use HIGH priority for user blocks as they are critical for feed safety.
      const signerDecryptOptions = {
        priority: NIP07_PRIORITY.HIGH,
        timeoutMs: nip07DecryptTimeoutMs,
        retryMultiplier: 1,
      };

      if (signerHasNip44) {
        registerDecryptor(
          "nip44",
          (payload) =>
            signer.nip44Decrypt(normalized, payload, signerDecryptOptions),
          "active-signer",
        );
        registerDecryptor(
          "nip44_v2",
          (payload) =>
            signer.nip44Decrypt(normalized, payload, signerDecryptOptions),
          "active-signer",
        );
      }

      if (signerHasNip04) {
        registerDecryptor(
          "nip04",
          (payload) =>
            signer.nip04Decrypt(normalized, payload, signerDecryptOptions),
          "active-signer",
        );
      }

      const nostrApi = typeof window !== "undefined" ? window?.nostr : null;
      const decrypterOptions = {
        priority: NIP07_PRIORITY.HIGH,
        timeoutMs: nip07DecryptTimeoutMs,
        retryMultiplier: 1,
      };

      if (nostrApi) {
        if (typeof nostrApi.nip04?.decrypt === "function") {
          registerDecryptor(
            "nip04",
            (payload) =>
              runNip07WithRetry(
                () => nostrApi.nip04.decrypt(normalized, payload),
                { label: "nip04.decrypt", ...decrypterOptions },
              ),
            "extension",
          );
        }

        const nip44 =
          nostrApi.nip44 && typeof nostrApi.nip44 === "object"
            ? nostrApi.nip44
            : null;
        if (nip44) {
          if (typeof nip44.decrypt === "function") {
            registerDecryptor(
              "nip44",
              (payload) =>
                runNip07WithRetry(() => nip44.decrypt(normalized, payload), {
                  label: "nip44.decrypt",
                  ...decrypterOptions,
                }),
              "extension",
            );
          }

          const nip44v2 =
            nip44.v2 && typeof nip44.v2 === "object" ? nip44.v2 : null;
          if (nip44v2 && typeof nip44v2.decrypt === "function") {
            registerDecryptor(
              "nip44_v2",
              (payload) =>
                runNip07WithRetry(() => nip44v2.decrypt(normalized, payload), {
                  label: "nip44.v2.decrypt",
                  ...decrypterOptions,
                }),
              "extension",
            );
            if (!decryptors.has("nip44")) {
              registerDecryptor(
                "nip44",
                (payload) =>
                  runNip07WithRetry(
                    () => nip44v2.decrypt(normalized, payload),
                    { label: "nip44.v2.decrypt", ...decrypterOptions },
                  ),
                "extension",
              );
            }
          }
        }
      }

      if (permissionError) {
        permissionError.signerStatus = signerStatus;
      }

      // Use the shared cross-service cache so all list services benefit from
      // the first successful decrypt during login.
      const cachedScheme = getLastSuccessfulScheme(normalized);

      return {
        decryptors,
        sources,
        permissionError,
        order: determineDecryptionOrder(
          event,
          Array.from(decryptors.keys()),
          cachedScheme,
        ),
        signerStatus,
      };
    };

    try {
      if (!effectiveRelays.length) {
        // Only clear if truly no relays, though loadBlocks with no relays is weird.
        if (!this.loaded) {
          this.blockedPubkeys.clear();
          this.blockEventId = null;
          this.blockEventCreatedAt = null;
          this.loaded = true;
        }
        emitStatus({ status: "applied-empty" });
        emitStatus({ status: "settled" });
        return;
      }

        const applyEvents = async (
          events,
          { skipIfEmpty = false, source = "fast" } = {},
        ) => {
        const previousState = {
          blockedPubkeys: new Set(this.blockedPubkeys),
          privateBlocks: new Set(this._privateBlocks),
          publicMutes: new Set(this._publicMutes),
          blockEventId: this.blockEventId,
          blockEventCreatedAt: this.blockEventCreatedAt,
          loaded: this.loaded,
        };

        if (!Array.isArray(events) || !events.length) {
          if (skipIfEmpty) {
            return;
          }
          if (
            this.lastPublishedCreatedAt !== null ||
            this.blockEventCreatedAt !== null
          ) {
            emitStatus({ status: "stale", reason: "empty-result", source });
            return;
          }
          if (!this.loaded) {
             this.blockEventId = null;
             this.blockEventCreatedAt = null;
             applySets(new Set(), new Set(), { source, reason: "empty-result" });
          }
          emitStatus({ status: "applied-empty", source });
          return;
        }

        const validEvents = events.filter(
          (event) =>
            event && event.pubkey === normalized && isUserBlockListEvent(event),
        );

        if (!validEvents.length) {
          if (skipIfEmpty) {
            return;
          }
          if (
            this.lastPublishedCreatedAt !== null ||
            this.blockEventCreatedAt !== null
          ) {
            emitStatus({ status: "stale", reason: "empty-result", source });
            return;
          }
          if (!this.loaded) {
             this.blockEventId = null;
             this.blockEventCreatedAt = null;
             applySets(new Set(), new Set(), { source, reason: "empty-result" });
          }
          emitStatus({ status: "applied-empty", source });
          return;
        }

        // Separate by logic (Block vs Mute)
        // Legacy Block: Kind 10000 with d=user-blocks OR Kind 30002
        const legacyBlockEvents = validEvents
          .filter((e) => isTaggedBlockListEvent(e) || e.kind === 30002);

        // Standard Mute: Kind 10000 WITHOUT d=user-blocks
        const standardMuteEvents = validEvents
          .filter((e) => e.kind === KIND_MUTE_LIST && !isTaggedBlockListEvent(e));

        const newestLegacy = selectNewestListEvent(legacyBlockEvents, {
          preferredKinds: [KIND_MUTE_LIST, 30002],
        });
        const newestStandard = selectNewestListEvent(standardMuteEvents, {
          preferredKinds: [KIND_MUTE_LIST],
        });

        const newestStandardTime = Number.isFinite(newestStandard?.created_at)
          ? newestStandard.created_at
          : 0;
        const newestLegacyTime = Number.isFinite(newestLegacy?.created_at)
          ? newestLegacy.created_at
          : 0;

        // The "canonical" newest event for stale checks is simply the latest of either.
        const newestOverall =
          compareListEventsDesc(newestStandard, newestLegacy) <= 0
            ? newestStandard
            : newestLegacy;
        const newestCreatedAt = Math.max(newestStandardTime, newestLegacyTime);

        // We accept this state.
        this.blockEventId = newestOverall?.id || null;
        this.blockEventCreatedAt = newestCreatedAt;

        const looksLikeJsonPayload = (value) => {
          if (typeof value !== "string") {
            return false;
          }
          const trimmed = value.trim();
          if (!trimmed) {
            return false;
          }
          const first = trimmed[0];
          return first === "[" || first === "{";
        };

        // Helper to decrypt a single event
        const decryptEvent = async (ev, meta = {}) => {
          if (!ev) return [];
          const trimmedContent =
            typeof ev.content === "string" ? ev.content.trim() : "";
          const isContentEmpty = !trimmedContent;

          if (isContentEmpty) {
            return [];
          }

          const hasEncryptionHints = extractEncryptionHints(ev).length > 0;
          const isLegacyBlockFormat = isTaggedBlockListEvent(ev) || ev.kind === 30002;
          const optionalDecrypt = !hasEncryptionHints && !isLegacyBlockFormat;

          if (
            !hasEncryptionHints &&
            !isLegacyBlockFormat &&
            looksLikeJsonPayload(trimmedContent)
          ) {
            return parseBlockListPlaintext(trimmedContent, normalized, {
              limit: MAX_BLOCKLIST_ENTRIES,
            });
          }

          const { decryptors, order, sources, permissionError, signerStatus } =
            await resolveDecryptors(ev);
          meta.signerStatus = signerStatus;
          meta.decryptorSources = Array.from(sources.entries()).map(
            ([scheme, source]) => ({ scheme, source }),
          );

          if (!decryptors.size) {
            if (optionalDecrypt) {
              // NIP-51 allows descriptive plaintext in content for standard
              // mute lists. If decryptors are unavailable and encryption was
              // not explicitly indicated, keep public tags and continue.
              return [];
            }
            if (permissionError) {
              throw permissionError;
            }
            const error = new Error("No decryptor available for block list event.");
            error.code = "user-blocklist-no-decryptor";
            error.signerStatus = signerStatus;
            throw error;
          }

          // PERF: Fast path — if the shared cache already knows the correct
          // scheme (e.g. another list decrypted first), try ONLY that scheme
          // before falling back to the full parallel probe. This avoids
          // queuing redundant NIP-07 extension calls.
          let decryptedText = "";
          const sharedCachedScheme = getLastSuccessfulScheme(normalized);
          if (sharedCachedScheme && decryptors.has(sharedCachedScheme)) {
            try {
              const fastResult = await decryptors.get(sharedCachedScheme)(ev.content);
              if (typeof fastResult === "string" && fastResult) {
                decryptedText = fastResult;
                setLastSuccessfulScheme(normalized, sharedCachedScheme);
              }
            } catch {
              // Cached scheme failed — fall through to parallel probe.
            }
          }

          // PERF: Try all decryption schemes in parallel via Promise.any().
          // The first scheme to succeed wins, avoiding sequential 3-15s timeouts
          // per scheme that previously made worst-case decryption take 45s+.
          // Deduplicate schemes in the same family (nip44/nip44_v2 both call
          // the same underlying signer.nip44Decrypt) to avoid redundant calls.
          if (!decryptedText) {
            try {
              const getSchemeFamily = (s) =>
                s === "nip44" || s === "nip44_v2" ? "nip44" : s;
              const seenFamilies = new Set();
              const attempts = order
                .map((scheme) => {
                  const family = getSchemeFamily(scheme);
                  if (seenFamilies.has(family)) return null;
                  seenFamilies.add(family);
                  const handler = decryptors.get(scheme);
                  if (typeof handler !== "function") return null;
                  return handler(ev.content).then((plaintext) => {
                    if (typeof plaintext !== "string") {
                      throw new Error("non-string-result");
                    }
                    return { plaintext, scheme };
                  });
                })
                .filter(Boolean);
              if (attempts.length) {
                const result = await Promise.any(attempts);
                decryptedText = result.plaintext;
                setLastSuccessfulScheme(normalized, result.scheme);
              }
            } catch {
              // All schemes failed — decryptedText stays empty
            }
          }

          if (!decryptedText) {
            return [];
          }

          return parseBlockListPlaintext(decryptedText, normalized, {
            limit: MAX_BLOCKLIST_ENTRIES,
          });
        };

        const nextPrivateBlocks = new Set();
        const nextPublicMutes = new Set();
        let decryptionError = null;
        const decryptMeta = {
          standard: { eventId: newestStandard?.id || null },
          legacy: { eventId: newestLegacy?.id || null },
        };
        const resolveSignerStatus = () => {
          const statuses = [decryptMeta.standard.signerStatus, decryptMeta.legacy.signerStatus]
            .filter(Boolean);
          if (!statuses.length) {
            return "unknown";
          }
          if (statuses.every((status) => status === "missing")) {
            return "missing";
          }
          if (statuses.some((status) => status === "present-missing-decryptor")) {
            return "present-missing-decryptor";
          }
          return "present";
        };

        try {
          const decryptPromise = Promise.all([
            decryptEvent(newestStandard, decryptMeta.standard),
            decryptEvent(newestLegacy, decryptMeta.legacy),
          ]);
          const timeoutPromise = new Promise((_, reject) =>
            setTimeout(
              () => {
                const timeoutError = new Error(
                  `Decryption timed out after ${decryptTimeoutMs / 1000}s`,
                );
                timeoutError.code = "user-blocklist-decrypt-timeout";
                timeoutError.signerStatus = resolveSignerStatus();
                reject(timeoutError);
              },
              decryptTimeoutMs,
            ),
          );

          const [standardDecrypted, legacyDecrypted] = await Promise.race([
            decryptPromise,
            timeoutPromise,
          ]);

          // Merge the newest standard mute snapshot with legacy/private lists so
          // users retain full cross-client compatibility during migration.
          if (newestStandard) {
            const publicTags = extractPubkeysFromTags(newestStandard.tags, normalized, { limit: MAX_BLOCKLIST_ENTRIES });
            publicTags.forEach((pk) => nextPublicMutes.add(pk));
            standardDecrypted.forEach((pk) => nextPrivateBlocks.add(pk));
          }
          if (newestLegacy) {
            legacyDecrypted.forEach((pk) => nextPrivateBlocks.add(pk));
          }

        } catch (error) {
          // If permission denied or critical failure
          decryptionError = error;
        }

        if (decryptionError) {
          if (decryptionError.code === "user-blocklist-permission-required") {
            const signerStatus =
              decryptionError.signerStatus || resolveSignerStatus();
            this.blockedPubkeys = previousState.blockedPubkeys;
            this._privateBlocks = previousState.privateBlocks;
            this._publicMutes = previousState.publicMutes;
            this.blockEventId = previousState.blockEventId;
            this.blockEventCreatedAt = previousState.blockEventCreatedAt;
            this.loaded = true;
            emitStatus({
              status: "permission-required",
              signerStatus,
              source,
              reason: "decryptor-permission",
              allowPermissionPrompt,
              mode: loadMode,
              events: [newestStandard?.id, newestLegacy?.id].filter(Boolean),
              error: decryptionError,
            });
            emitStatus({ status: "settled" });
            return;
          }
          if (decryptionError.code === "user-blocklist-decrypt-timeout") {
            const signerStatus = decryptionError.signerStatus || resolveSignerStatus();
            const recoveredPrivateBlocks = new Set(previousState.privateBlocks);
            const recoveredPublicMutes = new Set([
              ...previousState.publicMutes,
              ...extractPubkeysFromTags(newestStandard?.tags, normalized, {
                limit: MAX_BLOCKLIST_ENTRIES,
              }),
            ]);
            this.blockEventId = newestOverall?.id || previousState.blockEventId;
            this.blockEventCreatedAt =
              Number.isFinite(newestCreatedAt) ? newestCreatedAt : previousState.blockEventCreatedAt;
            applySets(recoveredPrivateBlocks, recoveredPublicMutes, {
              source,
              reason: "decrypt-timeout-partial",
              events: [newestStandard?.id, newestLegacy?.id].filter(Boolean),
            });
            this.loaded = true;

            emitStatus({
              status: "stale",
              reason: "decrypt-timeout",
              signerStatus,
              source,
              blockedPubkeys: Array.from(this.blockedPubkeys),
            });
            emitStatus({ status: "settled" });

            userLogger.warn(
              "[UserBlockList] Decryption timed out; keeping stale list and retrying in background.",
              {
                signerStatus,
                events: [newestStandard?.id, newestLegacy?.id].filter(Boolean),
              },
            );
            this.scheduleDecryptRetry(normalized, {
              error: decryptionError,
              signerStatus,
            });
            return;
          }
          userLogger.warn(
            "[UserBlockList] Decryption failed during merge.",
            decryptionError,
          );
          this.blockedPubkeys = previousState.blockedPubkeys;
          this._privateBlocks = previousState.privateBlocks;
          this._publicMutes = previousState.publicMutes;
          this.blockEventId = previousState.blockEventId;
          this.blockEventCreatedAt = previousState.blockEventCreatedAt;
          this.loaded = true;
          const signerStatus =
            decryptionError.signerStatus || resolveSignerStatus();
          emitStatus({
            status: "error",
            error: decryptionError,
            decryptor: "mixed",
            signerStatus,
          });
          emitStatus({ status: "settled" });
          return;
        }

        const isStandardEffectiveEmpty = !newestStandard || ((!newestStandard.content || !newestStandard.content.trim()) && (!newestStandard.tags || !extractPubkeysFromTags(newestStandard.tags, normalized).length));
        const isLegacyEffectiveEmpty = !newestLegacy || ((!newestLegacy.content || !newestLegacy.content.trim()) && (!newestLegacy.tags || !extractPubkeysFromTags(newestLegacy.tags, normalized).length));

        const effectiveReason = (isStandardEffectiveEmpty && isLegacyEffectiveEmpty)
            ? "empty-events"
            : "applied-merge";

        applySets(nextPrivateBlocks, nextPublicMutes, {
          source,
          reason: effectiveReason,
          events: [newestStandard?.id, newestLegacy?.id].filter(Boolean),
        });
        this.decryptRetryAttempt = 0;

        if (effectiveReason === "empty-events") {
           emitStatus({ status: "applied-empty", event: newestOverall, source });
        } else {
           emitStatus({
             status: "applied",
             event: newestOverall,
             blockedPubkeys: Array.from(this.blockedPubkeys),
             source,
           });
        }
      };

      // Anchor the fetch to the service's current state to prevent desync.
      // If we have cached data, we ask for updates since that timestamp.
      // If we have no data, we force a full fetch (since=0).
      const fetchSince =
        hasLocalData && Number.isFinite(this.blockEventCreatedAt)
          ? computeIncrementalSinceWithOverlap(this.blockEventCreatedAt, 1)
          : 0;

      // Concurrent incremental fetch for all variants
      // We prioritize standard NIP-51 lists (Kind 10000) to ensure the UI loads quickly.
      // Legacy variants are fetched in parallel but processed separately to avoid blocking.

      const fastRelayLimit = Math.max(
        1,
        Math.min(FAST_BLOCKLIST_RELAY_LIMIT, relays.length || FAST_BLOCKLIST_RELAY_LIMIT),
      );
      const backgroundRelayLimit = Math.max(
        fastRelayLimit,
        Math.min(
          MAX_BACKGROUND_BLOCKLIST_RELAY_LIMIT,
          relays.length || MAX_BACKGROUND_BLOCKLIST_RELAY_LIMIT,
        ),
      );

      const standardFetchPromise = nostrClient.fetchListIncrementally({
        kind: KIND_MUTE_LIST,
        pubkey: normalized,
        relayUrls: effectiveRelays,
        since: fetchSince,
        timeoutMs: FAST_BLOCKLIST_TIMEOUT_MS,
        maxRelays: fastRelayLimit,
      });

      const legacyFetchPromise = Promise.all([
        nostrClient.fetchListIncrementally({
          kind: KIND_MUTE_LIST,
          pubkey: normalized,
          relayUrls: effectiveRelays,
          since: fetchSince,
          timeoutMs: BACKGROUND_BLOCKLIST_TIMEOUT_MS,
          maxRelays: backgroundRelayLimit,
        }),
        nostrClient.fetchListIncrementally({
          kind: KIND_MUTE_LIST,
          pubkey: normalized,
          dTag: BLOCK_LIST_IDENTIFIER,
          relayUrls: effectiveRelays,
          since: fetchSince,
          timeoutMs: BACKGROUND_BLOCKLIST_TIMEOUT_MS,
          maxRelays: backgroundRelayLimit,
        }),
        nostrClient.fetchListIncrementally({
          kind: 30002,
          pubkey: normalized,
          dTag: BLOCK_LIST_IDENTIFIER,
          relayUrls: effectiveRelays,
          since: fetchSince,
          timeoutMs: BACKGROUND_BLOCKLIST_TIMEOUT_MS,
          maxRelays: backgroundRelayLimit,
        }),
      ]);

      // FAST PATH: Process Standard List immediately
      let standardEvents = [];
      try {
        standardEvents = await standardFetchPromise;
        if (Array.isArray(standardEvents) && standardEvents.length > 0) {
          await applyEvents(standardEvents, { source: "fast-standard" });
          this.loaded = true;
        }
      } catch (standardError) {
        devLogger.warn("[UserBlockList] Standard fetch failed:", standardError);
      }

      // SLOW PATH: Process Legacy Lists (and Standard if it was empty/failed)
      // We do NOT await this for the main return, allowing the UI to unblock immediately
      // if the standard list was found.
      legacyFetchPromise
        .then(async ([backgroundStandardEvents, blockEvents, legacyEvents]) => {
          const combined = [
            ...standardEvents,
            ...backgroundStandardEvents,
            ...blockEvents,
            ...legacyEvents,
          ];

          if (!combined.length) {
            // Only apply empty if we haven't already marked loaded (meaning standard failed or was empty)
            // or if we want to ensure we settle state.
            // If standard was found, we don't need to do anything for empty legacy.
            if (!this.loaded) {
              await applyEvents([], { source: "empty-result" });
            }
          } else {
            // Re-apply merged results to catch any legacy blocks
            await applyEvents(combined, { source: "incremental-merge" });
          }
        })
        .catch((legacyError) => {
          devLogger.warn("[UserBlockList] Legacy fetch failed:", legacyError);
        });


    } catch (error) {
      userLogger.error("[UserBlockList] loadBlocks failed (keeping local state):", error);
      emitStatus({ status: "error", error });
    } finally {
      this.loaded = true;
      emitStatus({ status: "settled" });
    }
  }

  _loadLocal(actorHex) {
    const normalizedActorHex = normalizeHex(actorHex);
    if (!normalizedActorHex) {
      return null;
    }
    const cached = profileCache.getProfileData(normalizedActorHex, "blocks");
    if (Array.isArray(cached)) {
      return { blockedPubkeys: new Set(cached), createdAt: null };
    }
    if (cached && typeof cached === "object") {
      const privateBlocks = new Set(
        Array.isArray(cached.privateBlocks) ? cached.privateBlocks : [],
      );
      const publicMutes = new Set(
        Array.isArray(cached.publicMutes) ? cached.publicMutes : [],
      );
      // Fallback for legacy cache format
      const blockedPubkeys = new Set(
        Array.isArray(cached.blockedPubkeys) ? cached.blockedPubkeys : [],
      );

      return {
        privateBlocks,
        publicMutes,
        blockedPubkeys,
        createdAt: Number.isFinite(cached.createdAt) ? cached.createdAt : null,
      };
    }
    return null;
  }

  _saveLocal(actorHex) {
    const normalizedActorHex = normalizeHex(actorHex);
    if (!normalizedActorHex) {
      return;
    }
    profileCache.setProfileData(normalizedActorHex, "blocks", {
      privateBlocks: Array.from(this._privateBlocks),
      publicMutes: Array.from(this._publicMutes),
      // Keep blockedPubkeys for backward compatibility if needed, or just relying on new keys
      blockedPubkeys: Array.from(this.blockedPubkeys),
      createdAt: this.blockEventCreatedAt,
      version: 2,
    });
  }

  _getSeedState(actorHex) {
    const normalized = normalizeHex(actorHex);
    if (!normalized) {
      return { seeded: false, removals: new Set() };
    }

    if (this.seedStateCache.has(normalized)) {
      return this.seedStateCache.get(normalized);
    }

    const stored =
      profileCache.getProfileData(normalized, "blocks_meta") || {};
    const seeded = !!stored.seeded;
    const removals = new Set(Array.isArray(stored.removals) ? stored.removals : []);

    const state = { seeded, removals };
    this.seedStateCache.set(normalized, state);
    return state;
  }

  _persistSeedState(actorHex) {
    const normalized = normalizeHex(actorHex);
    if (!normalized) return;
    const state = this.seedStateCache.get(normalized);
    if (!state) return;

    profileCache.setProfileData(normalized, "blocks_meta", {
      seeded: state.seeded,
      removals: Array.from(state.removals),
    });
  }

  _setSeeded(actorHex, seeded) {
    const normalized = normalizeHex(actorHex);
    if (!normalized) return;

    const state = this._getSeedState(normalized);
    state.seeded = Boolean(seeded);
    this._persistSeedState(normalized);
  }

  _addSeedRemoval(actorHex, targetHex) {
    const normalizedActor = normalizeHex(actorHex);
    const normalizedTarget = normalizeHex(targetHex);
    if (!normalizedActor || !normalizedTarget) return;

    const state = this._getSeedState(normalizedActor);
    if (!state.removals.has(normalizedTarget)) {
      state.removals.add(normalizedTarget);
      this._persistSeedState(normalizedActor);
    }
  }

  _clearSeedRemoval(actorHex, targetHex) {
    const normalizedActor = normalizeHex(actorHex);
    const normalizedTarget = normalizeHex(targetHex);
    if (!normalizedActor || !normalizedTarget) return;

    const state = this._getSeedState(normalizedActor);
    if (state.removals.delete(normalizedTarget)) {
      this._persistSeedState(normalizedActor);
    }
  }

  async seedWithNpubs(userPubkey, candidateNpubs = []) {
    const actorHex = normalizeHex(userPubkey);
    if (!actorHex) {
      return { ok: false, seeded: false, reason: "invalid-user" };
    }

    await this.ensureLoaded(actorHex);

    const state = this._getSeedState(actorHex);
    if (state.seeded) {
      return { ok: true, seeded: false, reason: "already-seeded" };
    }

    const removals = state.removals;
    const additions = new Set();
    let invalidCount = 0;

    const candidates = Array.isArray(candidateNpubs) ? candidateNpubs : [];
    for (const candidate of candidates) {
      const candidateHex = normalizeHex(candidate);
      if (!candidateHex) {
        invalidCount += 1;
        continue;
      }
      if (candidateHex === actorHex) {
        continue;
      }
      if (this.blockedPubkeys.has(candidateHex)) {
        continue;
      }
      if (removals.has(candidateHex)) {
        continue;
      }
      additions.add(candidateHex);
    }

    if (!additions.size) {
      if (candidates.length) {
        devLogger.info(
          "[UserBlockList] Seed candidates resolved to zero additions.",
          {
            actorPubkey: actorHex,
            candidateCount: candidates.length,
            invalidCount,
            blockedCount: this.blockedPubkeys.size,
            removalCount: removals.size,
          },
        );
      }
      return { ok: true, seeded: false, reason: "no-candidates" };
    }

    const snapshotPrivate = new Set(this._privateBlocks);
    const snapshotPublic = new Set(this._publicMutes);
    const snapshotUnion = new Set(this.blockedPubkeys);

    additions.forEach((hex) => {
      this._privateBlocks.add(hex);
      this.blockedPubkeys.add(hex);
    });

    try {
      await this.publishBlockList(actorHex);
    } catch (error) {
      this._privateBlocks = snapshotPrivate;
      this._publicMutes = snapshotPublic;
      this.blockedPubkeys = snapshotUnion;
      throw error;
    }

    this._setSeeded(actorHex, true);
    additions.forEach((hex) => this._clearSeedRemoval(actorHex, hex));
    this._saveLocal(actorHex);

    try {
      this.emitter.emit(USER_BLOCK_EVENTS.CHANGE, {
        action: "seed",
        actorPubkey: actorHex,
        blockedPubkeys: Array.from(this.blockedPubkeys),
        addedPubkeys: Array.from(additions),
      });
    } catch (error) {
      userLogger.warn("[UserBlockList] Failed to emit seed change event:", error);
    }

    return { ok: true, seeded: true, addedPubkeys: Array.from(additions) };
  }

  async seedLocalBaseline(userPubkey, candidateNpubs = []) {
    const actorHex = normalizeHex(userPubkey);
    if (!actorHex) {
      return { ok: false, seeded: false, reason: "invalid-user" };
    }

    await this.ensureLoaded(actorHex);

    const state = this._getSeedState(actorHex);
    if (state.seeded) {
      return { ok: true, seeded: false, reason: "already-seeded" };
    }

    if (this.blockedPubkeys.size > 0) {
      return { ok: true, seeded: false, reason: "non-empty" };
    }

    const removals = state.removals;
    const additions = new Set();
    let invalidCount = 0;

    const candidates = Array.isArray(candidateNpubs) ? candidateNpubs : [];
    for (const candidate of candidates) {
      const candidateHex = normalizeHex(candidate);
      if (!candidateHex) {
        invalidCount += 1;
        continue;
      }
      if (candidateHex === actorHex) {
        continue;
      }
      if (removals.has(candidateHex)) {
        continue;
      }
      additions.add(candidateHex);
    }

    if (!additions.size) {
      if (candidates.length) {
        devLogger.info(
          "[UserBlockList] Local seed candidates resolved to zero additions.",
          {
            actorPubkey: actorHex,
            candidateCount: candidates.length,
            invalidCount,
            removalCount: removals.size,
          },
        );
      }
      this._setSeeded(actorHex, true);
      return { ok: true, seeded: true, addedPubkeys: [] };
    }

    additions.forEach((hex) => {
      this._privateBlocks.add(hex);
      this.blockedPubkeys.add(hex);
    });

    this._setSeeded(actorHex, true);
    additions.forEach((hex) => this._clearSeedRemoval(actorHex, hex));

    try {
      this.emitter.emit(USER_BLOCK_EVENTS.CHANGE, {
        action: "seed",
        actorPubkey: actorHex,
        blockedPubkeys: Array.from(this.blockedPubkeys),
        addedPubkeys: Array.from(additions),
        localOnly: true,
      });
    } catch (error) {
      userLogger.warn("[UserBlockList] Failed to emit local seed change event:", error);
    }

    return { ok: true, seeded: true, addedPubkeys: Array.from(additions) };
  }

  async seedBaselineDelta(userPubkey, candidateNpubs = []) {
    const actorHex = normalizeHex(userPubkey);
    if (!actorHex) {
      return { ok: false, seeded: false, reason: "invalid-user" };
    }

    await this.ensureLoaded(actorHex);

    const state = this._getSeedState(actorHex);
    const removals = state.removals;
    const additions = new Set();
    let invalidCount = 0;

    const candidates = Array.isArray(candidateNpubs) ? candidateNpubs : [];
    for (const candidate of candidates) {
      const candidateHex = normalizeHex(candidate);
      if (!candidateHex) {
        invalidCount += 1;
        continue;
      }
      if (candidateHex === actorHex) {
        continue;
      }
      if (this.blockedPubkeys.has(candidateHex)) {
        continue;
      }
      if (removals.has(candidateHex)) {
        continue;
      }
      additions.add(candidateHex);
    }

    if (!additions.size) {
      if (candidates.length) {
        devLogger.info(
          "[UserBlockList] Baseline delta candidates resolved to zero additions.",
          {
            actorPubkey: actorHex,
            candidateCount: candidates.length,
            invalidCount,
            blockedCount: this.blockedPubkeys.size,
            removalCount: removals.size,
          },
        );
      }
      if (!state.seeded) {
        this._setSeeded(actorHex, true);
      }
      return { ok: true, seeded: state.seeded, reason: "no-candidates" };
    }

    additions.forEach((hex) => {
      this._privateBlocks.add(hex);
      this.blockedPubkeys.add(hex);
    });

    this._setSeeded(actorHex, true);
    this._saveLocal(actorHex);

    try {
      this.emitter.emit(USER_BLOCK_EVENTS.CHANGE, {
        action: "seed-delta",
        actorPubkey: actorHex,
        blockedPubkeys: Array.from(this.blockedPubkeys),
        addedPubkeys: Array.from(additions),
        localOnly: true,
      });
    } catch (error) {
      userLogger.warn("[UserBlockList] Failed to emit delta seed change event:", error);
    }

    return { ok: true, seeded: true, addedPubkeys: Array.from(additions) };
  }

  async addBlock(targetPubkey, userPubkey) {
    return this.modifyList("block", targetPubkey, userPubkey);
  }

  async removeBlock(targetPubkey, userPubkey) {
    return this.modifyList("unblock", targetPubkey, userPubkey);
  }

  async addMute(targetPubkey, userPubkey) {
    return this.modifyList("mute", targetPubkey, userPubkey);
  }

  async removeMute(targetPubkey, userPubkey) {
    return this.modifyList("unmute", targetPubkey, userPubkey);
  }

  async modifyList(action, targetPubkey, userPubkey) {
    const actorHex = normalizeHex(userPubkey);
    if (!actorHex) {
      throw new Error("Invalid user pubkey.");
    }

    const targetHex = normalizeHex(targetPubkey);
    if (!targetHex) {
      const err = new Error("Invalid target pubkey.");
      err.code = "invalid";
      throw err;
    }

    if (actorHex === targetHex) {
      const err = new Error("Cannot block/mute yourself.");
      err.code = "self";
      throw err;
    }

    await this.ensureLoaded(actorHex);

    const snapshotPrivate = new Set(this._privateBlocks);
    const snapshotPublic = new Set(this._publicMutes);
    const snapshotUnion = new Set(this.blockedPubkeys);

    let changed = false;

    if (action === "block") {
      if (this._privateBlocks.has(targetHex)) {
        return { ok: true, already: true };
      }
      this._privateBlocks.add(targetHex);
      changed = true;
    } else if (action === "unblock") {
      const inPrivate = this._privateBlocks.delete(targetHex);
      const inPublic = this._publicMutes.delete(targetHex);
      changed = inPrivate || inPublic;
    } else if (action === "mute") {
      if (this._publicMutes.has(targetHex)) {
        return { ok: true, already: true };
      }
      this._publicMutes.add(targetHex);
      changed = true;
    } else if (action === "unmute") {
      const inPublic = this._publicMutes.delete(targetHex);
      changed = inPublic;
    }

    if (!changed) {
      return { ok: true, already: true };
    }

    this.blockedPubkeys = new Set([...this._privateBlocks, ...this._publicMutes]);

    const loggedInPubkey = normalizeHex(nostrClient?.pubkey);
    const sessionPubkey = normalizeHex(nostrClient?.sessionActor?.pubkey);
    const isSessionActor =
      !!actorHex && !loggedInPubkey && actorHex === sessionPubkey;

    if (isSessionActor) {
      this._saveLocal(actorHex);
      this.emitter.emit(USER_BLOCK_EVENTS.CHANGE, {
        action,
        targetPubkey: targetHex,
        actorPubkey: actorHex,
      });
      if (action === "block" || action === "mute") {
        this._clearSeedRemoval(actorHex, targetHex);
      } else {
        this._addSeedRemoval(actorHex, targetHex);
      }
      return { ok: true };
    }

    try {
      await this.publishBlockList(actorHex);
      this.emitter.emit(USER_BLOCK_EVENTS.CHANGE, {
        action,
        targetPubkey: targetHex,
        actorPubkey: actorHex,
      });
      if (action === "block" || action === "mute") {
        this._clearSeedRemoval(actorHex, targetHex);
      } else {
        this._addSeedRemoval(actorHex, targetHex);
      }
      return { ok: true };
    } catch (err) {
      this._privateBlocks = snapshotPrivate;
      this._publicMutes = snapshotPublic;
      this.blockedPubkeys = snapshotUnion;
      throw err;
    }
  }

  async publishBlockList(userPubkey, options = {}) {
    if (isSessionActor(nostrClient)) {
      const error = new Error(
        "Publishing block lists is not allowed for session actors."
      );
      error.code = "session-actor-publish-blocked";
      throw error;
    }

    const onStatus =
      options && typeof options.onStatus === "function" ? options.onStatus : null;

    onStatus?.({ status: "publishing" });

    let signer = getActiveSigner();
    if (!signer) {
      signer = await nostrClient.ensureActiveSignerForPubkey(userPubkey);
    }

    if (!signer) {
      const err = new Error(
        "An active signer is required to update the block list."
      );
      err.code = "signer-missing";
      throw err;
    }

    if (signer.type === "extension" || signer.type === "nip07") {
      const permissionResult = await requestDefaultExtensionPermissions(
        DEFAULT_NIP07_ENCRYPTION_METHODS,
      );
      if (!permissionResult.ok) {
        userLogger.warn(
          "[UserBlockList] Signer permissions denied while updating the block list.",
          permissionResult.error,
        );
        const err = new Error(
          "The active signer must allow encryption before updating the block list.",
        );
        err.code = "extension-encryption-permission-denied";
        err.cause = permissionResult.error;
        throw err;
      }
    }

    if (typeof signer.signEvent !== "function") {
      const err = new Error("Active signer missing signEvent support.");
      err.code = "sign-event-missing";
      throw err;
    }

    const normalized = normalizeHex(userPubkey);
    if (!normalized) {
      throw new Error("Invalid user pubkey.");
    }

    // Encrypt private blocks
    const privateBlockArray = Array.from(this._privateBlocks);
    const sanitizedPrivateTags = sanitizeMuteTags(privateBlockArray, normalized);
    const plaintext = serializeBlockListTagMatrix(sanitizedPrivateTags, normalized, {
      logDiscarded: false,
    });

    const encryptors = [];
    const registerEncryptor = (scheme, handler) => {
      if (!scheme || typeof handler !== "function") {
        return;
      }
      encryptors.push({ scheme, handler });
    };

    if (typeof signer.nip44Encrypt === "function") {
      registerEncryptor("nip44_v2", (value) => signer.nip44Encrypt(normalized, value));
      registerEncryptor("nip44", (value) => signer.nip44Encrypt(normalized, value));
    }

    if (typeof signer.nip04Encrypt === "function") {
      registerEncryptor("nip04", (value) => signer.nip04Encrypt(normalized, value));
    }

    let cipherText = "";
    let encryptionScheme = "";
    const seenSchemes = new Set();
    const encryptionErrors = [];

    // Only attempt encryption if we have private blocks
    if (privateBlockArray.length > 0) {
      if (!encryptors.length) {
        const err = new Error(
          "An encryption-capable signer is required to update private blocks."
        );
        err.code = "block-list-missing-encryptor";
        throw err;
      }

      for (const candidate of encryptors) {
        if (seenSchemes.has(candidate.scheme)) {
          continue;
        }
        seenSchemes.add(candidate.scheme);
        try {
          const encrypted = await candidate.handler(plaintext);
          if (typeof encrypted === "string" && encrypted) {
            cipherText = encrypted;
            encryptionScheme = candidate.scheme;
            break;
          }
        } catch (error) {
          encryptionErrors.push({ scheme: candidate.scheme, error });
        }
      }

      if (!cipherText) {
        const err = new Error("Failed to encrypt block list.");
        err.code = "block-list-encrypt-failed";
        err.cause = encryptionErrors;
        throw err;
      }
    }

    const encryptionTagValue =
      encryptionScheme === "nip44_v2"
        ? "nip44_v2"
        : encryptionScheme === "nip44"
          ? "nip44"
          : encryptionScheme === "nip04"
            ? "nip04"
            : undefined;

    // Build event with both public mutes (p tags) and private blocks (encrypted content)
    const publicMuteArray = Array.from(this._publicMutes);
    const sanitizedPublicTags = sanitizeMuteTags(publicMuteArray, normalized);
    const pTags = sanitizedPublicTags.map((tag) => tag[1]);

    const event = buildMuteListEvent({
      pubkey: normalized,
      created_at: Math.floor(Date.now() / 1000),
      content: cipherText,
      pTags,
      encrypted: !!encryptionTagValue,
      encryptionTag: encryptionTagValue,
    });

    const signedEvent = await signer.signEvent(event);

    const publishResults = await publishEventToRelays(
      nostrClient.pool,
      nostrClient.relays,
      signedEvent
    );

    let publishSummary;
    try {
      publishSummary = assertAnyRelayAccepted(publishResults, {
        context: "mute list",
      });
    } catch (publishError) {
      if (publishError?.relayFailures?.length) {
        publishError.relayFailures.forEach(
          ({ url, error: relayError, reason }) => {
            userLogger.error(
              `[UserBlockList] Mute list rejected by ${url}: ${reason}`,
              relayError || reason
            );
          }
        );
      }
      throw publishError;
    }

    if (publishSummary.failed.length) {
      publishSummary.failed.forEach(({ url, error: relayError }) => {
        const reason =
          relayError instanceof Error
            ? relayError.message
            : relayError
            ? String(relayError)
            : "publish failed";
        userLogger.warn(
          `[UserBlockList] Mute list not accepted by ${url}: ${reason}`,
          relayError
        );
      });
    }

    this.blockEventId = signedEvent.id;
    this.blockEventCreatedAt = Number.isFinite(signedEvent?.created_at)
      ? signedEvent.created_at
      : event.created_at;
    this.lastPublishedCreatedAt = this.blockEventCreatedAt;
    onStatus?.({ status: "published", event: signedEvent });

    try {
      await this.loadBlocks(normalized, {
        since: this.lastPublishedCreatedAt ?? undefined,
        statusCallback: (detail) => {
          if (!onStatus) {
            return;
          }
          onStatus({ status: "relay", detail });
        },
      });
    } catch (refreshError) {
      onStatus?.({ status: "relay-error", error: refreshError });
    }

    return signedEvent;
  }
}

export const userBlocks = new UserBlockListManager();

if (typeof window !== "undefined") {
  window.userBlocks = userBlocks;
}