import OpenAI from 'openai';
import { safeSend, broadcastToUser } from './helpers.js';
import { LIGHTNING_BASE, PUBLIC_URL } from './config.js';
import { sessionStore, deviceSessionStore } from './sessionStore.js';
import { rateLimiter } from './rateLimiter.js';
import { initGuestRequestLimiter, consumeGuestRequest } from './guestRequestLimiter.js';
import {
  verifySupabaseToken, getUserSettings, saveUserSettings,
  getUserProfile, setUsername, getSubscriptionInfo,
  getTierConfig, getUsageInfo,
} from './auth.js';
import { streamChat, extractSessionName } from './chatStream.js';
import crypto from 'crypto';

/**
 * Message Structure: Tree-based with versioned tails
 * 
 * Each message has versions, and each version has a complete tail of subsequent messages.
 * Messages only exist within parent tails (no separate flat array).
 * 
 * {
 *   id: "msg-123",
 *   role: "user" | "assistant",
 *   content: string | array,
 *   timestamp: number,
 *   versions: [
 *     {
 *       content: string | array,
 *       tail: [  // Full message objects
 *         { id, role, content, timestamp, versions: [...], currentVersionIdx, ... },
 *         ...
 *       ],
 *       timestamp: number
 *     },
 *     ...
 *   ],
 *   currentVersionIdx: 0,
 *   toolCalls?: [...]
 * }
 */

const activeStreams = new Map();

initGuestRequestLimiter().catch(err => console.error('Failed to initialize guest request limiter:', err));

export async function handleWsMessage(ws, msg, wsClients) {
  const client = wsClients.get(ws); if (!client) return;
  // Require turnstile verification for most message types
  if (!client.verified && msg.type !== 'ping' && msg.type !== 'turnstile:verify') {
    return safeSend(ws, { type: 'error', message: 'turnstile:required' });
  }

  const h = handlers[msg.type];
  if (h) return h(ws, msg, client, wsClients);
  safeSend(ws, { type: 'error', message: `Unknown: ${msg.type}` });
}

function bcast(wsClients, userId, data, excludeWs) {
  broadcastToUser(wsClients, userId, data, excludeWs);
}

const handlers = {
  'ping': (ws) => { safeSend(ws, { type: 'pong' }); },

  'turnstile:verify': async (ws, msg, client) => {
    try {
      const token = msg?.token;
      const secret = process.env.TURNSTILE_SECRET_KEY;
      if (!token || !secret) return safeSend(ws, { type: 'turnstile:error', message: 'Missing token or server not configured' });
      const params = new URLSearchParams(); params.append('secret', secret); params.append('response', token);
      if (client.ip) params.append('remoteip', client.ip);
      const r = await fetch('https://challenges.cloudflare.com/turnstile/v0/siteverify', { method: 'POST', body: params });
      const j = await r.json();
      if (j?.success) { client.verified = true; return safeSend(ws, { type: 'turnstile:ok' }); }
      return safeSend(ws, { type: 'turnstile:error', message: 'Verification failed' });
    } catch (e) { console.error('ws turnstile verify', e); return safeSend(ws, { type: 'turnstile:error', message: 'Server error' }); }
  },

  'auth:login': async (ws, msg, client, wsClients) => {
    const { accessToken, tempId: clientTempId } = msg;
    if (!accessToken) return safeSend(ws, { type: 'auth:error', message: 'Missing token' });
    const user = await verifySupabaseToken(accessToken);
    if (!user) return safeSend(ws, { type: 'auth:error', message: 'Invalid token' });

    client.userId = user.id; client.accessToken = accessToken; client.authenticated = true;
    client.deviceToken = deviceSessionStore.create(user.id, client.ip, client.userAgent);
    sessionStore.markOnline(user.id, ws);

    if (clientTempId) client.tempId = clientTempId;
    const tId = client.tempId;
    await sessionStore.transferTempToUser(tId, user.id, accessToken);

    const [sessions, settings, profile] = await Promise.all([
      sessionStore.loadUserSessions(user.id, accessToken),
      getUserSettings(user.id, accessToken),
      getUserProfile(user.id, accessToken),
    ]);

    safeSend(ws, { type: 'auth:ok', userId: user.id, email: user.email,
      deviceToken: client.deviceToken, sessions: sessions.map(ser), settings, profile });

    bcast(wsClients, user.id, { type: 'auth:newLogin', message: 'New login on your account.',
      ip: client.ip, userAgent: client.userAgent, timestamp: new Date().toISOString() }, ws);
  },

  'auth:logout': (ws, msg, client) => {
    if (client.deviceToken) deviceSessionStore.revoke(client.deviceToken);
    Object.assign(client, { userId: null, authenticated: false, accessToken: null, deviceToken: null });
    safeSend(ws, { type: 'auth:loggedOut' });
  },

  'auth:guest': (ws, msg, client) => {
    const t = msg.tempId || client.tempId;
    client.tempId = t;
    sessionStore.initTemp(t);
    safeSend(ws, { type: 'auth:guestOk', tempId: t, sessions: sessionStore.getTempSessions(t).map(ser) });
  },

  'sessions:list': (ws, msg, client) => {
    const list = client.userId
      ? sessionStore.getUserSessions(client.userId)
      : sessionStore.getTempSessions(client.tempId);
    list.sort((a, b) => b.created - a.created);
    safeSend(ws, { type: 'sessions:list', sessions: list.map(ser) });
  },

  'sessions:create': async (ws, msg, client) => {
    const s = client.userId
      ? await sessionStore.createUserSession(client.userId, client.accessToken)
      : sessionStore.createTempSession(client.tempId);
    safeSend(ws, { type: 'sessions:created', session: ser(s) });
  },

  'sessions:delete': async (ws, msg, client) => {
    if (client.userId) await sessionStore.deleteUserSession(client.userId, client.accessToken, msg.sessionId);
    else sessionStore.deleteTempSession(client.tempId, msg.sessionId);
    safeSend(ws, { type: 'sessions:deleted', sessionId: msg.sessionId });
  },

  'sessions:deleteAll': async (ws, msg, client) => {
    if (client.userId) await sessionStore.deleteAllUserSessions(client.userId, client.accessToken);
    else sessionStore.deleteTempAll(client.tempId);
    safeSend(ws, { type: 'sessions:deletedAll' });
  },

  'sessions:rename': async (ws, msg, client) => {
    const name = (msg.name || '').trim(); if (!name) return;
    if (client.userId)
      await sessionStore.updateUserSession(client.userId, client.accessToken, msg.sessionId, { name });
    else sessionStore.updateTempSession(client.tempId, msg.sessionId, { name });
    safeSend(ws, { type: 'sessions:renamed', sessionId: msg.sessionId, name });
  },

  'sessions:get': (ws, msg, client) => {
    const s = client.userId
      ? sessionStore.getUserSession(client.userId, msg.sessionId)
      : sessionStore.getTempSession(client.tempId, msg.sessionId);
    if (!s) return safeSend(ws, { type: 'error', message: 'Session not found' });
    safeSend(ws, { type: 'sessions:data', session: ser(s) });
  },

  'sessions:share': async (ws, msg, client) => {
    if (!client.userId) return safeSend(ws, { type: 'error', message: 'Sign in to share' });
    const token = await sessionStore.createShareToken(client.userId, client.accessToken, msg.sessionId);
    if (!token) return safeSend(ws, { type: 'error', message: 'Share failed' });
    safeSend(ws, { type: 'sessions:shareUrl', url: `${PUBLIC_URL}/?share=${token}`, sessionId: msg.sessionId });
  },

  'sessions:import': async (ws, msg, client) => {
    if (!client.userId) return safeSend(ws, { type: 'error', message: 'Sign in to import' });
    const s = await sessionStore.importSharedSession(client.userId, client.accessToken, msg.token);
    if (!s) return safeSend(ws, { type: 'error', message: 'Invalid share link' });
    safeSend(ws, { type: 'sessions:imported', session: ser(s) });
  },

  'chat:send': async (ws, msg, client) => {
    const { sessionId, content, tools } = msg;
    if (!client.userId) {
      const allowed = await consumeGuestRequest(client.ip || 'unknown');
      if (!allowed) return safeSend(ws, { type: 'guest:rateLimit', message: 'Guest request limit exceeded' });
      if (!sessionStore.tempCanSend(client.tempId)) return safeSend(ws, { type: 'chat:limitReached' });
      sessionStore.tempBump(client.tempId);
    }
    const session = client.userId
      ? sessionStore.getUserSession(client.userId, sessionId)
      : sessionStore.getTempSession(client.tempId, sessionId);
    if (!session) return safeSend(ws, { type: 'error', message: 'Session not found' });

    if (activeStreams.has(ws)) activeStreams.get(ws).abort();
    const abort = new AbortController();
    activeStreams.set(ws, abort);
    safeSend(ws, { type: 'chat:start', sessionId });

    let fullText = '';
    const assetsCollected = [], toolCallsCollected = [];

    // Extract flat history from tree structure
    const rootMessage = session.history?.[0];
    const flatHistory = rootMessage ? extractFlatHistory(rootMessage) : [];

    await streamChat({
      sessionId,
      model: session.model,
      history: flatHistory, 
      userMessage: content, 
      tools: tools || {},
      accessToken: client.accessToken, 
      clientId: msg.clientId, 
      abortSignal: abort.signal,
      onToken(t) { fullText += t; safeSend(ws, { type: 'chat:token', token: t, sessionId }); },
      onToolCall(call) {
        safeSend(ws, { type: 'chat:toolCall', call, sessionId });
        if (call.state === 'resolved' || call.state === 'canceled') toolCallsCollected.push(call);
      },
      onNewAsset(asset) { safeSend(ws, { type: 'chat:asset', asset, sessionId }); assetsCollected.push(asset); },
      async onDone(text, toolCalls, aborted, sessionNameFromTag) {
        activeStreams.delete(ws);
        const finalText = text || fullText;
        
        // Only create user entry if content was actually provided
        const hasContent = content !== undefined && content !== null && content !== '' && 
          !(Array.isArray(content) && content.length === 0);
        const userEntry = hasContent
          ? buildEntry('user', content)
          : null;

        const resolvedMap = new Map(toolCallsCollected.map(c => [c.id, c]));
        const mergedCalls = (toolCalls || []).map(c => {
          const resolved = resolvedMap.get(c.id) || {};
          return { ...c, state: resolved.state || 'resolved', result: resolved.result };
        });
        const asstEntry = buildEntry('assistant', finalText, mergedCalls);

        // Rebuild tree structure with new messages appended
        let newRootMessage = rootMessage ? validateAndRepairTree(JSON.parse(JSON.stringify(rootMessage))) : null;
        
        if (!newRootMessage) {
          // First message in session - must have user entry
          if (!userEntry) return safeSend(ws, { type: 'error', message: 'No content for first message' });
          newRootMessage = userEntry;
          const asstWrap = { ...asstEntry };
          newRootMessage.versions[0].tail = [asstWrap];
        } else {
          // Append to current tail
          const currentVerIdx = newRootMessage.currentVersionIdx ?? 0;
          let currentTail = newRootMessage.versions[currentVerIdx].tail || [];
          currentTail = JSON.parse(JSON.stringify(currentTail));
          if (userEntry) {
            currentTail.push(userEntry);
          }
          currentTail.push(asstEntry);
          newRootMessage.versions[currentVerIdx].tail = currentTail;
        }

        const newHistory = [newRootMessage];

        let newName = session.name;
        if (sessionNameFromTag) {
          newName = sessionNameFromTag;
        } else if (!session.history?.length || session.name === 'New Chat') {
          newName = session.name;
        }

        if (client.userId)
          await sessionStore.updateUserSession(client.userId, client.accessToken, sessionId, { history: newHistory, name: newName });
        else sessionStore.updateTempSession(client.tempId, sessionId, { history: newHistory, name: newName });
        
        safeSend(ws, { type: aborted ? 'chat:aborted' : 'chat:done', sessionId, name: newName, history: extractFlatHistory(newRootMessage) });
      },
      onError(err) { 
        activeStreams.delete(ws);
        console.error('streamChat error:', err);
        safeSend(ws, { type: 'chat:error', error: String(err), sessionId }); 
      },
    });
  },

  'chat:stop': (ws) => { if (activeStreams.has(ws)) { activeStreams.get(ws).abort(); activeStreams.delete(ws); } },

  'chat:editMessage': async (ws, msg, client) => {
    const { sessionId, messageIndex, newContent } = msg;
    const session = client.userId
      ? sessionStore.getUserSession(client.userId, sessionId)
      : sessionStore.getTempSession(client.tempId, sessionId);
    if (!session) return safeSend(ws, { type: 'error', message: 'Session not found' });
    
    const rootMessage = session.history?.[0];
    if (!rootMessage) return safeSend(ws, { type: 'error', message: 'No history' });
    
    const flatHistory = extractFlatHistory(rootMessage);
    const targetMsg = flatHistory[messageIndex];
    if (!targetMsg) {
      console.error(`chat:editMessage: Message at index ${messageIndex} not found. History length: ${flatHistory.length}`);
      return safeSend(ws, { type: 'error', message: 'Message not found' });
    }
    console.log(`chat:editMessage: Editing message ${targetMsg.id} at index ${messageIndex}`);
    
    // Find the target message in the tree and add new version
    const newRoot = validateAndRepairTree(JSON.parse(JSON.stringify(rootMessage)));
    const found = findAndUpdateMessage(newRoot, targetMsg.id, (msgInTree) => {
      // Add new version with EMPTY tail (no responses yet for this edited version)
      msgInTree.versions.push({
        content: newContent,
        tail: [],  // New version starts fresh, no tail
        timestamp: Date.now()
      });
      msgInTree.currentVersionIdx = msgInTree.versions.length - 1;
      msgInTree.content = newContent;
    });
    
    if (!found) return;
    
    const newHistory = [newRoot];
    if (client.userId) {
      await sessionStore.updateUserSession(client.userId, client.accessToken, sessionId, { history: newHistory });
    } else {
      sessionStore.updateTempSession(client.tempId, sessionId, { history: newHistory });
    }
    
    // Send back the updated message with its ID and the full flat history
    const updatedFlatHistory = extractFlatHistory(newRoot);
    const updatedTargetMsg = updatedFlatHistory[messageIndex];
    
    if (!updatedTargetMsg) {
      console.error(`chat:editMessage: Updated message not found at index ${messageIndex}. Updated history length: ${updatedFlatHistory.length}`);
      return safeSend(ws, { type: 'error', message: 'Failed to apply edit - message lost' });
    }
    
    console.log(`chat:editMessage: Edit complete. Message ${updatedTargetMsg.id} now has ${updatedTargetMsg.versions?.length ?? 0} versions`);
    safeSend(ws, { type: 'chat:messageEdited', sessionId, messageId: targetMsg.id, messageIndex, message: updatedTargetMsg, history: updatedFlatHistory });
  },

  'chat:selectVersion': async (ws, msg, client) => {
    const { sessionId, messageIndex, versionIdx } = msg;
    const session = client.userId
      ? sessionStore.getUserSession(client.userId, sessionId)
      : sessionStore.getTempSession(client.tempId, sessionId);
    if (!session) return;
    
    const rootMessage = session.history?.[0];
    if (!rootMessage) return;
    
    const flatHistory = extractFlatHistory(rootMessage);
    const targetMsg = flatHistory[messageIndex];
    if (!targetMsg || !targetMsg.versions || versionIdx >= targetMsg.versions.length) return;
    
    // Find and update the message in tree, switching to specified version
    const newRoot = validateAndRepairTree(JSON.parse(JSON.stringify(rootMessage)));
    const found = findAndUpdateMessage(newRoot, targetMsg.id, (msgInTree) => {
      msgInTree.currentVersionIdx = versionIdx;
      msgInTree.content = msgInTree.versions[versionIdx].content;
      // Tail is automatically correct since each version has its own tail
    });
    
    if (!found) return;
    
    const newHistory = [newRoot];
    if (client.userId) {
      await sessionStore.updateUserSession(client.userId, client.accessToken, sessionId, { history: newHistory });
    } else {
      sessionStore.updateTempSession(client.tempId, sessionId, { history: newHistory });
    }
    
    // Send back with messageId for clarity
    safeSend(ws, { type: 'chat:versionSelected', sessionId, messageId: targetMsg.id, messageIndex, history: extractFlatHistory(newRoot) });
  },

  'settings:get': async (ws, msg, client) => {
    const s = client.userId
      ? await getUserSettings(client.userId, client.accessToken)
      : { theme: 'dark', webSearch: true, imageGen: true, videoGen: true, audioGen: true };
    safeSend(ws, { type: 'settings:data', settings: s });
  },
  'settings:save': async (ws, msg, client, wsClients) => {
    if (!client.userId) return;
    await saveUserSettings(client.userId, client.accessToken, msg.settings);
    safeSend(ws, { type: 'settings:saved' });
    bcast(wsClients, client.userId, { type: 'settings:updated', settings: msg.settings }, ws);
  },

  'account:getProfile':      async (ws, msg, c) => { if (!c.userId) return; safeSend(ws, { type: 'account:profile', profile: await getUserProfile(c.userId, c.accessToken) }); },
  'account:setUsername':     async (ws, msg, c) => { if (!c.userId) return; safeSend(ws, { type: 'account:usernameResult', ...await setUsername(c.userId, c.accessToken, msg.username) }); },
  'account:getSubscription': async (ws, msg, c) => { if (!c.userId) return; safeSend(ws, { type: 'account:subscription', info: await getSubscriptionInfo(c.accessToken) }); },
  'account:getUsage':        async (ws, msg, c) => { safeSend(ws, { type: 'account:usage', usage: await getUsageInfo(c.accessToken) }); },
  'account:getTierConfig':   async (ws)          => { safeSend(ws, { type: 'account:tierConfig', config: await getTierConfig() }); },
  'account:getSessions':     (ws, msg, c)         => { if (!c.userId) return; safeSend(ws, { type: 'account:deviceSessions', sessions: deviceSessionStore.getForUser(c.userId), currentToken: c.deviceToken }); },
  'account:revokeSession':   (ws, msg, c)         => { if (!c.userId) return; deviceSessionStore.revoke(msg.token); safeSend(ws, { type: 'account:sessionRevoked', token: msg.token }); },
  'account:revokeAllOthers': (ws, msg, c, wsClients) => {
    if (!c.userId) return;
    deviceSessionStore.revokeAllExcept(c.userId, c.deviceToken);
    for (const [ows, oc] of wsClients)
      if (oc.userId === c.userId && ows !== ws) safeSend(ows, { type: 'auth:forcedLogout', reason: 'Session revoked by another device' });
    safeSend(ws, { type: 'account:allOthersRevoked' });
  },
};

function ser(s) { return { id: s.id, name: s.name, created: s.created, history: s.history || [], model: s.model }; }

function generateMessageId() {
  return `msg-${Date.now()}-${Math.random().toString(36).substr(2, 9)}`;
}

function buildEntry(role, content, toolCalls = []) {
  const normalizedCalls = toolCalls.map(c => ({
    id:     c.id,
    name:   c.name || c.function?.name,
    args:   c.args ?? (c.function?.arguments ? (() => { try { return JSON.parse(c.function.arguments); } catch { return c.function.arguments; } })() : {}),
    state:  c.state || 'resolved',
    result: c.result,
  }));
  const validContent = (content === undefined || content === null) ? '' : content;
  return { 
    id: generateMessageId(),
    role, 
    content: validContent, 
    timestamp: Date.now(),
    versions: [{ content: validContent, tail: [], timestamp: Date.now() }], 
    currentVersionIdx: 0,
    ...(normalizedCalls.length ? { toolCalls: normalizedCalls } : {}) 
  };
}

/**
 * Validate and repair tree structure after cloning/modification
 * Ensures all messages and versions have valid content property
 */
function validateAndRepairTree(rootMessage) {
  const repair = (msg) => {
    if (!msg) return;
    // Ensure message has content
    if (msg.content === undefined || msg.content === null) {
      msg.content = '';
    }
    // Ensure versions array and each version's content
    if (msg.versions && Array.isArray(msg.versions)) {
      for (const version of msg.versions) {
        if (version.content === undefined || version.content === null) {
          version.content = '';
        }
        // Recursively repair tail messages
        if (version.tail && Array.isArray(version.tail)) {
          for (const tailMsg of version.tail) {
            repair(tailMsg);
          }
        }
      }
    }
  };
  repair(rootMessage);
  return rootMessage;
}

function extractFlatHistory(rootMessage) {
  if (!rootMessage) return [];
  
  // Helper to ensure message has valid content
  const ensureValidContent = (msg) => {
    if (msg.content === undefined || msg.content === null) {
      msg.content = '';
    }
    return msg;
  };
  
  const history = [ensureValidContent(rootMessage)];
  const currentVerIdx = rootMessage.currentVersionIdx ?? 0;
  
  if (!Array.isArray(rootMessage.versions)) {
    console.warn(`extractFlatHistory: Root message ${rootMessage.id} missing versions array`);
    return history;
  }
  
  if (currentVerIdx >= rootMessage.versions.length) {
    console.warn(`extractFlatHistory: Root message currentVersionIdx ${currentVerIdx} out of bounds (${rootMessage.versions.length} versions)`);
    return history;
  }
  
  const currentTail = rootMessage.versions[currentVerIdx]?.tail;
  
  if (currentTail && Array.isArray(currentTail)) {
    const walkTail = (tail) => {
      for (const msg of tail) {
        history.push(ensureValidContent(msg));
        const ver = msg.versions?.[msg.currentVersionIdx ?? 0];
        if (ver?.tail && Array.isArray(ver.tail)) {
          walkTail(ver.tail);
        }
      }
    };
    walkTail(currentTail);
  }
  return history;
}

function findAndUpdateMessage(rootMessage, targetId, updateFn) {
  if (rootMessage.id === targetId) {
    updateFn(rootMessage);
    return true;
  }
  
  const search = (msg) => {
    const verIdx = msg.currentVersionIdx ?? 0;
    const tail = msg.versions?.[verIdx]?.tail;
    if (!tail || !Array.isArray(tail)) return false;
    
    for (const child of tail) {
      if (child.id === targetId) {
        updateFn(child);
        return true;
      }
      if (search(child)) return true;
    }
    return false;
  };
  
  return search(rootMessage);
}