// ==========================================
// MEEZAN - ميزان Memory System
// Persistent memory across all conversations
// ==========================================

import * as fs from 'fs';
import * as path from 'path';
import { UserProfile, ConversationHistory, Message, Language } from '../types';

interface Database {
  users: Record<string, UserProfile>;
  conversations: Record<string, ConversationHistory>;
  version: string;
}

export class MemoryManager {
  private dbPath: string;
  private db: Database;

  constructor(dbPath: string = './data/memory.json') {
    this.dbPath = dbPath;
    this.db = this.load();
  }

  private load(): Database {
    const dir = path.dirname(this.dbPath);
    if (!fs.existsSync(dir)) {
      fs.mkdirSync(dir, { recursive: true });
    }

    if (!fs.existsSync(this.dbPath)) {
      const initial: Database = {
        users: {},
        conversations: {},
        version: '1.0.0'
      };
      this.save(initial);
      return initial;
    }

    try {
      const content = fs.readFileSync(this.dbPath, 'utf-8');
      return JSON.parse(content);
    } catch {
      console.error('Memory database corrupted, starting fresh');
      return { users: {}, conversations: {}, version: '1.0.0' };
    }
  }

  private save(data?: Database): void {
    const toSave = data || this.db;
    fs.writeFileSync(this.dbPath, JSON.stringify(toSave, null, 2), 'utf-8');
  }

  // ==========================================
  // User Profile Management
  // ==========================================

  getUser(userId: string): UserProfile | null {
    return this.db.users[userId] || null;
  }

  createUser(userId: string, language: Language = 'ar'): UserProfile {
    const profile: UserProfile = {
      id: userId,
      language,
      city: process.env.DEFAULT_CITY || 'Kuwait City',
      country: process.env.DEFAULT_COUNTRY || 'Kuwait',
      latitude: parseFloat(process.env.DEFAULT_LATITUDE || '29.3759'),
      longitude: parseFloat(process.env.DEFAULT_LONGITUDE || '47.9774'),
      createdAt: new Date().toISOString(),
      updatedAt: new Date().toISOString()
    };
    
    this.db.users[userId] = profile;
    this.save();
    return profile;
  }

  updateUser(userId: string, updates: Partial<UserProfile>): UserProfile {
    const existing = this.getUser(userId) || this.createUser(userId);
    const updated = {
      ...existing,
      ...updates,
      updatedAt: new Date().toISOString()
    };
    this.db.users[userId] = updated;
    this.save();
    return updated;
  }

  getOrCreateUser(userId: string, language?: Language): UserProfile {
    return this.getUser(userId) || this.createUser(userId, language);
  }

  // ==========================================
  // Conversation History
  // ==========================================

  getHistory(userId: string): Message[] {
    const conv = this.db.conversations[userId];
    if (!conv) return [];
    // Return last 20 messages for context window management
    return conv.messages.slice(-20);
  }

  addMessage(userId: string, message: Message): void {
    if (!this.db.conversations[userId]) {
      this.db.conversations[userId] = {
        userId,
        messages: []
      };
    }
    
    this.db.conversations[userId].messages.push(message);
    
    // Keep only last 100 messages per user to prevent DB bloat
    if (this.db.conversations[userId].messages.length > 100) {
      this.db.conversations[userId].messages = 
        this.db.conversations[userId].messages.slice(-100);
    }
    
    this.save();
  }

  clearHistory(userId: string): void {
    if (this.db.conversations[userId]) {
      this.db.conversations[userId].messages = [];
      this.save();
    }
  }

  // ==========================================
  // User Context Helpers
  // ==========================================

  setUserCity(userId: string, city: string, country: string, lat: number, lng: number): void {
    this.updateUser(userId, { city, country, latitude: lat, longitude: lng });
  }

  setUserName(userId: string, name: string): void {
    this.updateUser(userId, { name });
  }

  setUserLanguage(userId: string, language: Language): void {
    this.updateUser(userId, { language });
  }

  setUserMadhab(userId: string, madhab: UserProfile['madhab']): void {
    this.updateUser(userId, { madhab });
  }

  // ==========================================
  // Stats
  // ==========================================

  getTotalUsers(): number {
    return Object.keys(this.db.users).length;
  }

  getTotalMessages(): number {
    return Object.values(this.db.conversations)
      .reduce((sum, conv) => sum + conv.messages.length, 0);
  }
}

export const memory = new MemoryManager(process.env.DB_PATH || './data/memory.json');