import { EventEmitter } from 'events';
import { readdir, readFile, mkdir } from 'fs/promises';
import { join, resolve, dirname } from 'path';
import { existsSync } from 'fs';
import { fileURLToPath } from 'url';
import fetch from 'node-fetch';
import { exec } from 'child_process';
import { promisify } from 'util';
import readline from 'readline';

const execAsync = promisify(exec);

const __filename = fileURLToPath(import.meta.url);
const __dirname = dirname(__filename);

/**
 * Plugin Host - Manages plugin lifecycle and provides plugin API
 */
export class PluginHost extends EventEmitter {
  constructor(options = {}) {
    super();
    this.directoryUrl = options.directoryUrl;
    // Resolve relative to the PluginHost.js file location (src/), then go up one level
    this.pluginsDir = options.pluginsDir ? 
      (options.pluginsDir.startsWith('.') ? resolve(__dirname, '..', options.pluginsDir) : resolve(options.pluginsDir))
      : resolve(__dirname, '../plugins');
    this.autoUpdate = options.autoUpdate ?? true;
    this.updateInterval = options.updateInterval || 300000;
    
    this.plugins = new Map();
    this.pluginRegistry = new Map();
    this.hooks = new Map();
    this._updateTimer = null;
  }

  /**
   * Initialize the plugin host
   */
  async initialize() {
    if (!existsSync(this.pluginsDir)) {
      await mkdir(this.pluginsDir, { recursive: true });
    }

    if (this.autoUpdate && this.directoryUrl) {
      await this.updateRegistry();
      this._updateTimer = setInterval(() => this.updateRegistry(), this.updateInterval);
    }

    this.emit('initialized');
  }

  /**
   * Fetch plugin registry from the directory
   */
  async updateRegistry() {
    try {
      // First fetch the index  to get the list of available plugins
      const indexUrl = `${this.directoryUrl}/index.json`;
      const indexResponse = await fetch(indexUrl);
      
      if (!indexResponse.ok) {
        console.warn('Failed to fetch plugin index:', indexResponse.statusText);
        return;
      }

      const index = await indexResponse.json();
      const pluginIds = index.plugins || [];
      
      console.log(`Found ${pluginIds.length} plugins in directory`);

      // Fetch each plugin definition
      for (const pluginId of pluginIds) {
        const pluginUrl = `${this.directoryUrl}/${pluginId}.json`;
        try {
          const response = await fetch(pluginUrl);
          if (response.ok) {
            const plugin = await response.json();
            this.pluginRegistry.set(plugin.id, plugin);
            console.log(`  ✓ ${plugin.name} v${plugin.version}`);
          }
        } catch (error) {
          console.warn(`  ✗ Could not fetch ${pluginId}:`, error.message);
        }
      }

      this.emit('registry-updated', Array.from(this.pluginRegistry.values()));
    } catch (error) {
      console.error('Error updating plugin registry:', error);
    }
  }

  /**
   * Parse HTML directory listing to find JSON files
   */
  _parseDirectoryListing(html) {
    const files = [];
    const regex = /href="([^"]+\.json)"/g;
    let match;
    while ((match = regex.exec(html)) !== null) {
      files.push(match[1]);
    }
    return files;
  }

  /**
   * Fetch individual plugin definition
   */
  async _fetchPluginDefinition(filename) {
    try {
      const url = `${this.directoryUrl}/${filename}`;
      const response = await fetch(url);
      if (!response.ok) return;

      const definition = await response.json();
      this.pluginRegistry.set(definition.id, definition);
    } catch (error) {
      console.error(`Error fetching plugin definition ${filename}:`, error);
    }
  }

  /**
   * Load all plugins from the plugins directory
   */
  async loadPlugins() {
    try {
      const entries = await readdir(this.pluginsDir, { withFileTypes: true });
      
      for (const entry of entries) {
        if (entry.isDirectory()) {
          await this.loadPlugin(entry.name);
        }
      }
    } catch (error) {
      console.error('Error loading plugins:', error);
    }
  }

  /**
   * Load a specific plugin
   */
  async loadPlugin(pluginName) {
    const pluginPath = join(this.pluginsDir, pluginName);
    const manifestPath = join(pluginPath, 'plugin.json');

    try {
      if (!existsSync(manifestPath)) {
        throw new Error(`Plugin manifest not found: ${manifestPath}`);
      }

      const manifestData = await readFile(manifestPath, 'utf-8');
      const manifest = JSON.parse(manifestData);

      const entryPoint = join(pluginPath, manifest.main || 'index.js');
      if (!existsSync(entryPoint)) {
        throw new Error(`Plugin entry point not found: ${entryPoint}`);
      }

      const pluginModule = await import(`file:///${entryPoint.replace(/\\/g, '/')}`);
      
      const pluginInstance = {
        id: manifest.id,
        name: manifest.name,
        version: manifest.version,
        manifest,
        module: pluginModule,
        context: this._createPluginContext(manifest.id)
      };

      if (typeof pluginModule.activate === 'function') {
        await pluginModule.activate(pluginInstance.context);
      }

      this.plugins.set(manifest.id, pluginInstance);
      this.emit('plugin-loaded', pluginInstance);
      
      console.log(`✓ Loaded plugin: ${manifest.name} v${manifest.version}`);
      return pluginInstance;
    } catch (error) {
      console.error(`Failed to load plugin ${pluginName}:`, error);
      this.emit('plugin-error', { pluginName, error });
      return null;
    }
  }

  /**
   * Create plugin context API
   */
  _createPluginContext(pluginId) {
    return {
      pluginId,
      
      registerHook: (hookName, callback) => {
        if (!this.hooks.has(hookName)) {
          this.hooks.set(hookName, []);
        }
        this.hooks.get(hookName).push({ pluginId, callback });
      },

      unregisterHook: (hookName, callback) => {
        const hooks = this.hooks.get(hookName);
        if (hooks) {
          const index = hooks.findIndex(h => h.pluginId === pluginId && h.callback === callback);
          if (index !== -1) {
            hooks.splice(index, 1);
          }
        }
      },

      runHook: async (hookName, ...args) => {
        return this.runHook(hookName, ...args);
      },

      getConfig: (key) => {
        const plugin = this.plugins.get(pluginId);
        return plugin?.manifest?.config?.[key];
      },

      log: (...args) => {
        console.log(`[${pluginId}]`, ...args);
      },

      on: (event, listener) => {
        this.on(event, listener);
      },

      emit: (event, ...args) => {
        this.emit(event, ...args);
      }
    };
  }

  /**
   * Run all hooks registered for a specific hook name
   */
  async runHook(hookName, ...args) {
    const hooks = this.hooks.get(hookName) || [];
    const results = [];

    for (const { pluginId, callback } of hooks) {
      try {
        const result = await callback(...args);
        results.push({ pluginId, result });
      } catch (error) {
        console.error(`Error running hook ${hookName} in plugin ${pluginId}:`, error);
        results.push({ pluginId, error });
      }
    }

    return results;
  }

  /**
   * Unload a plugin
   */
  async unloadPlugin(pluginId) {
    const plugin = this.plugins.get(pluginId);
    if (!plugin) return false;

    try {
      if (typeof plugin.module.deactivate === 'function') {
        await plugin.module.deactivate(plugin.context);
      }

      // Remove all hooks from this plugin
      for (const [hookName, hooks] of this.hooks.entries()) {
        this.hooks.set(hookName, hooks.filter(h => h.pluginId !== pluginId));
      }

      this.plugins.delete(pluginId);
      this.emit('plugin-unloaded', plugin);
      
      console.log(`✓ Unloaded plugin: ${plugin.name}`);
      return true;
    } catch (error) {
      console.error(`Error unloading plugin ${pluginId}:`, error);
      return false;
    }
  }

  /**
   * Get all loaded plugins
   */
  getLoadedPlugins() {
    return Array.from(this.plugins.values()).map(p => ({
      id: p.id,
      name: p.name,
      version: p.version,
      manifest: p.manifest
    }));
  }

  /**
   * Get plugin registry
   */
  getRegistry() {
    return Array.from(this.pluginRegistry.values());
  }

  /**
   * Install a plugin from its repository
   */
  async installPlugin(pluginId) {
    const pluginDef = this.pluginRegistry.get(pluginId);
    if (!pluginDef) {
      throw new Error(`Plugin ${pluginId} not found in registry`);
    }

    const pluginPath = join(this.pluginsDir, pluginId);
    if (existsSync(pluginPath)) {
      console.log(`⚠ Plugin ${pluginId} already installed`);
      return false;
    }

    console.log(`📥 Installing ${pluginDef.name} v${pluginDef.version}...`);
    
    try {
      await execAsync(`git clone ${pluginDef.repository} "${pluginPath}"`, {
        cwd: this.pluginsDir
      });
      
      console.log(`✅ Installed ${pluginDef.name}`);
      this.emit('plugin-installed', pluginDef);
      return true;
    } catch (error) {
      console.error(`❌ Failed to install ${pluginId}:`, error.message);
      return false;
    }
  }

  /**
   * Interactive plugin installation
   */
  async interactiveInstall() {
    const available = this.getRegistry();
    const loadedIds = new Set(this.getLoadedPlugins().map(p => p.id));
    const installedPluginDirs = existsSync(this.pluginsDir) 
      ? await readdir(this.pluginsDir, { withFileTypes: true }).then(entries => 
          entries.filter(e => e.isDirectory()).map(e => e.name)
        )
      : [];
    const installedIds = new Set(installedPluginDirs);
    
    const installable = available.filter(p => !installedIds.has(p.id));

    if (installable.length === 0) {
      console.log('\n✨ All available plugins are already installed!');
      return;
    }

    console.log('\n📦 Available Plugins to Install:');
    console.log('================================');
    installable.forEach((p, i) => {
      console.log(`${i + 1}. ${p.name} v${p.version} by ${p.author}`);
      console.log(`   ${p.description || 'No description'}`);
    });

    const rl = readline.createInterface({
      input: process.stdin,
      output: process.stdout
    });

    const question = (query) => new Promise(resolve => rl.question(query, resolve));

    console.log('\nEnter plugin numbers to install (comma-separated), or "all" for all plugins:');
    const answer = await question('> ');
    
    rl.close();

    let toInstall = [];
    
    if (answer.toLowerCase().trim() === 'all') {
      toInstall = installable;
    } else {
      const indices = answer.split(',').map(s => parseInt(s.trim()) - 1).filter(i => !isNaN(i));
      toInstall = indices.map(i => installable[i]).filter(Boolean);
    }

    if (toInstall.length === 0) {
      console.log('\n❌ No valid plugins selected');
      return;
    }

    console.log(`\n📥 Installing ${toInstall.length} plugin(s)...`);
    
    for (const plugin of toInstall) {
      await this.installPlugin(plugin.id);
    }

    console.log('\n✅ Installation complete!');
  }

  /**
   * Shutdown the plugin host
   */
  async shutdown() {
    if (this._updateTimer) {
      clearInterval(this._updateTimer);
    }

    for (const pluginId of this.plugins.keys()) {
      await this.unloadPlugin(pluginId);
    }

    this.emit('shutdown');
  }
}