/**
 * ============================================================
 * identity-resolver.js — Resolución de Miembros en 5 Capas
 * ============================================================
 * 1. Discord ID (snowflake) — confianza 1.0
 * 2. Mención Discord (<@ID>) — confianza 1.0
 * 3. Username exacto en DB — confianza 0.95
 * 4. Coincidencia exacta en Discord — confianza 0.9
 * 5. Fuzzy matching (Levenshtein) — confianza variable
 */

import * as db from './db.js';

// ── Levenshtein distance ──────────────────────────────────────────────────────
function levenshtein(a, b) {
  const dp = Array.from({length: a.length+1}, (_,i) =>
    Array.from({length: b.length+1}, (_,j) => i===0?j:j===0?i:0));
  for (let i=1;i<=a.length;i++)
    for (let j=1;j<=b.length;j++)
      dp[i][j] = a[i-1]===b[j-1] ? dp[i-1][j-1] : 1+Math.min(dp[i-1][j],dp[i][j-1],dp[i-1][j-1]);
  return dp[a.length][b.length];
}

function similarityScore(a, b) {
  if (!a||!b) return 0;
  const dist = levenshtein(a.toLowerCase(), b.toLowerCase());
  return 1 - dist / Math.max(a.length, b.length);
}

// ── Identity Cache ────────────────────────────────────────────────────────────
export const identityCache = new Map(); // discordId → fullProfile
let _guild = null;

export async function buildIdentityCache(guild) {
  if (!guild) return;
  _guild = guild;
  try {
    const members = await guild.members.fetch();
    for (const [id, member] of members) {
      const dbRecord = await db.getUserWithRoles(id).catch(() => null);
      identityCache.set(id, {
        discordId        : id,
        discordUsername  : member.user.username,
        displayName      : member.displayName,
        roles            : member.roles.cache.map(r => r.name).filter(n => n !== '@everyone'),
        minecraftUsername: dbRecord?.minecraft_username || null,
        dbRecord         : dbRecord || null,
        cachedAt         : Date.now(),
      });
    }
    console.log('[IDENTITY] Cache construido: ' + identityCache.size + ' miembros');
  } catch (e) {
    console.error('[IDENTITY] Error construyendo cache:', e.message);
  }
}

export function invalidateIdentityCache(userId) {
  identityCache.delete(userId);
  console.log('[IDENTITY] Cache invalidado para ' + userId);
}

// ── Resolver principal ────────────────────────────────────────────────────────
export async function resolvePlayer(identifier, guildMembers, dbRef = null) {
  const dbInst = dbRef ?? db;
  if (!identifier) return { member: null, dbRecord: null, confidence: 0, method: 'empty' };

  // CAPA 1: Discord snowflake ID
  if (/^\d{17,19}$/.test(identifier)) {
    const member = guildMembers?.get?.(identifier) ?? _guild?.members.cache.get(identifier);
    if (member) {
      const dbRecord = await dbInst.getUserWithRoles(identifier).catch(() => null);
      return { member, dbRecord, confidence: 1.0, method: 'discord_id' };
    }
  }

  // CAPA 2: Mención <@ID> o <@!ID>
  const mentionMatch = identifier.match(/^<@!?(\d{17,19})>$/);
  if (mentionMatch) return resolvePlayer(mentionMatch[1], guildMembers, dbRef);

  const q = identifier.toLowerCase();

  // CAPA 3: Username exacto en DB
  try {
    const rows = await dbInst.db.execute({
      sql : 'SELECT * FROM users WHERE LOWER(username)=? OR LOWER(nickname)=? LIMIT 1',
      args: [q, q],
    });
    if (rows.rows.length > 0) {
      const rec    = rows.rows[0];
      const member = guildMembers?.find?.(m => m.id === rec.user_id) || _guild?.members.cache.get(rec.user_id);
      return { member: member || null, dbRecord: rec, confidence: 0.95, method: 'exact_db' };
    }
  } catch {}

  // CAPA 4: Coincidencia exacta en Discord
  const members = guildMembers ?? _guild?.members.cache;
  if (members) {
    const exactMember = members.find?.(m =>
      m.user.username.toLowerCase() === q ||
      (m.nickname ?? '').toLowerCase() === q ||
      m.displayName.toLowerCase() === q
    );
    if (exactMember) {
      const dbRecord = await dbInst.getUserWithRoles(exactMember.id).catch(() => null);
      return { member: exactMember, dbRecord, confidence: 0.9, method: 'exact_discord' };
    }
  }

  // CAPA 5: Fuzzy matching
  const candidates = [];
  if (members) {
    for (const [, m] of (members.entries?.() ?? [])) {
      const s = Math.max(
        similarityScore(identifier, m.user.username),
        similarityScore(identifier, m.displayName),
        m.nickname ? similarityScore(identifier, m.nickname) : 0
      );
      if (s > 0.6) candidates.push({ member: m, dbRecord: null, score: s, method: 'fuzzy_discord' });
    }
  }

  // Fuzzy en DB
  try {
    const all = await dbInst.db.execute({
      sql : 'SELECT * FROM users WHERE is_active=1 AND bot=0 LIMIT 200',
      args: [],
    });
    for (const rec of all.rows) {
      const s = Math.max(
        rec.username ? similarityScore(identifier, rec.username) : 0,
        rec.nickname ? similarityScore(identifier, rec.nickname) : 0
      );
      if (s > 0.6) {
        const member = _guild?.members.cache.get(rec.user_id) || null;
        candidates.push({ member, dbRecord: rec, score: s, method: 'fuzzy_db' });
      }
    }
  } catch {}

  if (!candidates.length) return { member: null, dbRecord: null, confidence: 0, method: 'not_found' };

  candidates.sort((a, b) => b.score - a.score);
  const best = candidates[0];

  if (best.member && !best.dbRecord) {
    best.dbRecord = await dbInst.getUserWithRoles(best.member.id).catch(() => null);
  }

  const ambiguous = candidates.filter(c => c.score > best.score - 0.1);
  if (ambiguous.length > 1 && best.score < 0.9) {
    return {
      member      : best.member,
      dbRecord    : best.dbRecord,
      confidence  : best.score,
      method      : 'ambiguous',
      alternatives: ambiguous.slice(1, 4),
    };
  }

  return { member: best.member, dbRecord: best.dbRecord, confidence: best.score, method: best.method };
}

// ── Ambiguity handler para Discord ────────────────────────────────────────────
export async function resolveOrAskDiscord(identifier, guildMembers, replyFn) {
  const resolved = await resolvePlayer(identifier, guildMembers);

  if (resolved.confidence >= 0.9) return resolved;

  if (resolved.confidence >= 0.7) {
    await replyFn('⚠️ Asumiendo que te refieres a **' + (resolved.member?.displayName ?? '?') + '** (' + (resolved.confidence*100).toFixed(0) + '% seguro). Si no, usa @mención directa.');
    return resolved;
  }

  if (resolved.method === 'ambiguous' || resolved.confidence < 0.7) {
    const opts = [resolved, ...(resolved.alternatives ?? [])].slice(0, 3)
      .map((c, i) => (i+1) + '. **' + (c.member?.displayName ?? '?') + '** — ' + (c.score*100).toFixed(0) + '% similitud');
    await replyFn('❓ No estoy segura a quién te refieres con "' + identifier + '".\n' + opts.join('\n') + '\n\n_Usa @usuario para evitar confusiones._');
    return null;
  }

  await replyFn('❌ No encontré a nadie que coincida con "' + identifier + '".');
  return null;
}