/**
 * Peer Directory Plugin
 * 
 * Full implementation of the peer.directory website using the P2NS Plugin SDK.
 * This plugin provides a web interface for browsing and searching P2NS domains.
 * 
 * The plugin serves:
 * - Static files from the www/ directory (HTML, CSS, JS, images)
 * - Dynamic API endpoints for domain listing and search
 */

// Import the P2NS Plugin SDK which provides access to system functionality
const sdk = require('../../includes/plugins/sdk');

/**
 * Categorize and collect all domains from the P2NS system
 * 
 * This function:
 * 1. Fetches all DNS entries from the P2NS network
 * 2. Extracts domain claims (who owns which domains)
 * 3. Includes all plugin domains (domains in plugin-sites/)
 * 4. Categorizes each domain as 'plugin', 'internal', 'local', or 'remote'
 * 5. Retrieves the hash for each domain
 * 6. Returns a structured list of domains with metadata
 * 
 * @returns {Promise<Array>} Array of domain objects with { domain, type, hash, isLocal }
 */
async function categorizeDomains() {
  // Check if DNS service is initialized and ready
  // If not, return empty array to prevent errors
  if (!sdk.utils.isDNSReady()) {
    return [];
  }

  // Fetch all DNS entries from the P2NS network
  // These entries contain domain claims, hashes, and other metadata
  const allEntries = await sdk.dns.getAllEntries();
  
  // If no entries exist yet (system just started), return at least the plugin domains
  // Plugin domains are domains in plugin-sites/ with valid config.json files
  if (!allEntries || allEntries.length === 0) {
    // Get all plugin domains
    const pluginDomains = sdk.plugin.getAllPluginDomains();
    // Get list of internal domains (includes plugins + p2ns.admin)
    const internalDomains = await sdk.utils.getInternalDomains();
    
    // Return them formatted as domain objects
    // Plugin domains get type 'plugin', others get type 'internal'
    return internalDomains.map(domain => {
      const isPlugin = pluginDomains.includes(domain);
      return {
        domain,
        type: isPlugin ? 'plugin' : 'internal',  // Mark as plugin or internal
        hash: 'internal',                         // Internal/plugin domains don't have P2P hashes
        isLocal: true                             // Internal/plugin domains are always local
      };
    });
  }

  // Get the local writer key (this node's identity in the P2P network)
  // This is used to determine if we own a domain (isLocal = true)
  // Use the SDK's localPeerId which returns the persistent hyperswarm public key
  const localWriter = sdk.state.localPeerId;
  
  // Get list of internal domains for comparison
  const internalDomains = await sdk.utils.getInternalDomains();
  
  // Get all domains that have plugins loaded
  // Plugin domains are domains in plugin-sites/ with valid config.json files
  const pluginDomains = sdk.plugin.getAllPluginDomains();
  
  // Convert to Set for faster lookups and ensure we have plugin domains
  const pluginDomainsSet = new Set(pluginDomains);
  if (pluginDomains.length > 0) {
    sdk.log.debug('peer.directory', `Found ${pluginDomains.length} plugin domains: ${pluginDomains.join(', ')}`);
  }
  
  // Step 1: Collect all domain claims from DNS entries
  // DNS entries with keys like "claim:example.tld:claimant-id" indicate ownership
  // We build a map: domain -> Set of claimant IDs
  const domainClaimants = new Map();
  for (const entry of allEntries) {
    // Check if this entry is a domain claim
    if (entry.key.startsWith('claim:')) {
      // Parse the claim key: "claim:domain:claimant"
      const parts = entry.key.split(':');
      if (parts.length === 3) {
        const domain = parts[1];      // The domain being claimed
        const claimant = parts[2];   // The peer ID claiming the domain
        
        // Initialize Set for this domain if it doesn't exist
        if (!domainClaimants.has(domain)) {
          domainClaimants.set(domain, new Set());
        }
        // Add this claimant to the set of claimants for this domain
        domainClaimants.get(domain).add(claimant);
      }
    }
  }

  // Step 2: Build a unique set of all domains
  // Start with all plugin domains and add all claimed domains
  // This ensures all plugin sites are included in the directory
  const domains = new Set();
  
  // Add all plugin domains first (these are guaranteed to be shown)
  for (const pluginDomain of pluginDomains) {
    domains.add(pluginDomain);
  }
  
  // Add all domains from DNS claims
  for (const domain of domainClaimants.keys()) {
    domains.add(domain);
  }

  // Step 3: Build the final domain list with metadata
  const domainList = [];
  for (const domain of domains) {
    // Check if this domain has a plugin (is in plugin-sites/)
    // Use Set for faster lookup - plugin domains should always be detected
    const isPlugin = pluginDomainsSet.has(domain);
    
    // Debug logging for plugin detection issues
    if (!isPlugin && pluginDomains.length > 0) {
      // Log if we have plugin domains but this one isn't detected
      sdk.log.debug('peer.directory', `Domain ${domain} not in plugin list. Available plugins: ${Array.from(pluginDomainsSet).join(', ')}`);
    } else if (isPlugin) {
      sdk.log.debug('peer.directory', `Domain ${domain} correctly detected as plugin`);
    }
    
    // Get the P2P hash for this domain (used for routing/connection)
    // Plugin and internal domains don't have P2P hashes, so use 'internal' or 'none'
    let hash = await sdk.dns.getHashForDomain(domain);
    
    // Determine if this is an internal domain (managed by this P2NS instance)
    // Note: p2ns.admin is always internal but may not have a plugin
    // Also, any domain with hash='internal' (plugin type) should be marked as internal
    let isInternal = internalDomains.includes(domain);
    if (hash === 'internal') {
      // Domain has an internal hash (plugin type), mark it as internal
      isInternal = true;
    }
    
    // If hash is null, set it based on domain type
    if (!hash) {
      hash = (isPlugin || isInternal ? 'internal' : 'none');
    }
    
    // Get all claimants for this domain
    const claimants = domainClaimants.get(domain) || new Set();
    
    // Check if we (the local node) own this domain by checking the resolved claimant
    // The resolved claimant is the one that won the consensus vote, not just any claimant
    let isLocal = false;
    if (localWriter && (isInternal || isPlugin)) {
      // Internal and plugin domains are always local
      isLocal = true;
    } else if (localWriter) {
      // For P2P domains, check if we are the resolved claimant (owner)
      try {
        const consensusState = await sdk.dns.getConsensusState(domain);
        isLocal = consensusState.resolvedClaimant === localWriter;
      } catch (err) {
        // If consensus check fails, fall back to checking if we're in the claimants set
        // This is a fallback for edge cases where consensus state might not be available
        isLocal = claimants.has(localWriter);
        sdk.log.debug('peer.directory', `Consensus check failed for ${domain}, using fallback: ${err.message}`);
      }
    }
    
    // Categorize the domain type:
    // - 'local': Domain we own in the P2P network (includes plugin domains)
    // - 'internal': Internal domain without plugin (e.g., p2ns.admin if no plugin, or domains with hash='internal')
    // - 'remote': Domain owned by other peers
    // Domains with hash='internal' (plugin type) should always be 'internal', not 'local'
    let type;
    if (hash === 'internal') {
      // Domains with internal hash (plugin type) are always 'internal'
      type = 'internal';
    } else if (isPlugin) {
      // Plugin domains are 'local'
      type = 'local';
    } else if (isInternal) {
      // Internal domains are 'internal'
      type = 'internal';
    } else if (isLocal) {
      // Locally owned P2P domains are 'local'
      type = 'local';
    } else {
      type = 'remote';   // Remote domains owned by other peers
    }
    
    // Add this domain to the list with all its metadata
    domainList.push({
      domain,           // Domain name (e.g., 'example.tld')
      type,             // 'plugin', 'internal', 'local', or 'remote'
      hash,             // P2P hash or 'internal' or 'none'
      isLocal: isLocal || isInternal || isPlugin  // True if we own it, it's internal, or it's a plugin
    });
  }

  return domainList;
}

/**
 * Sort domains according to the specified sort option
 * 
 * This function provides multiple sorting strategies:
 * - By type (plugin, internal, local, remote) - default
 * - By domain name (alphabetical, ascending or descending)
 * - By hash (alphabetical, ascending or descending)
 * 
 * When sorting by type, domains are ordered: remote (0) < local (1) < internal (2)
 * Within the same type, domains are sorted alphabetically by name.
 * 
 * @param {Array} domains - Array of domain objects to sort
 * @param {string} sortBy - Sort option: 'type', 'name', 'name-desc', 'hash', 'hash-desc', 'type-desc'
 * @returns {Array} Sorted array of domain objects (mutates original array)
 */
function sortDomains(domains, sortBy = 'type') {
  // Define priority order for domain types (lower number = higher priority)
  // Default order: remote (0) < local (1) < internal (2)
  const typeOrder = { remote: 0, local: 1, internal: 2, plugin: 3 };
  
  // Sort by domain name (ascending - A to Z)
  if (sortBy === 'name') {
    return domains.sort((a, b) => a.domain.localeCompare(b.domain, undefined, { sensitivity: 'base' }));
  } 
  // Sort by domain name (descending - Z to A)
  else if (sortBy === 'name-desc') {
    return domains.sort((a, b) => b.domain.localeCompare(a.domain, undefined, { sensitivity: 'base' }));
  } 
  // Sort by hash (ascending - alphabetical)
  else if (sortBy === 'hash') {
    return domains.sort((a, b) => {
      const hashA = (a.hash || 'none').toLowerCase();
      const hashB = (b.hash || 'none').toLowerCase();
      return hashA.localeCompare(hashB, undefined, { sensitivity: 'base' });
    });
  } 
  // Sort by hash (descending - reverse alphabetical)
  else if (sortBy === 'hash-desc') {
    return domains.sort((a, b) => {
      const hashA = (a.hash || 'none').toLowerCase();
      const hashB = (b.hash || 'none').toLowerCase();
      return hashB.localeCompare(hashA, undefined, { sensitivity: 'base' });
    });
  } 
  // Sort by type (descending - remote, local, internal) then alphabetically
  else if (sortBy === 'type-desc') {
    return domains.sort((a, b) => {
      // First compare by type (reverse order)
      const typeDiff = typeOrder[b.type] - typeOrder[a.type];
      if (typeDiff !== 0) return typeDiff;
      // If same type, sort alphabetically by domain name
      return a.domain.localeCompare(b.domain, undefined, { sensitivity: 'base' });
    });
  } 
  // Default: Sort by type (ascending - remote, local, internal) then alphabetically
  else {
    return domains.sort((a, b) => {
      // First compare by type (remote < local < internal)
      const typeDiff = typeOrder[a.type] - typeOrder[b.type];
      if (typeDiff !== 0) return typeDiff;
      // If same type, sort alphabetically by domain name
      return a.domain.localeCompare(b.domain, undefined, { sensitivity: 'base' });
    });
  }
}


/**
 * Plugin Handler
 * 
 * This is the main HTTP request handler for the peer.directory plugin.
 * It processes incoming HTTP requests and routes them to appropriate handlers.
 * 
 * Request Flow:
 * 1. Parse the request URL to extract path and query parameters
 * 2. Check if the path matches any API endpoints we handle
 * 3. If matched, process the request and return a response
 * 4. If not matched, return false to allow static file serving from www/
 * 
 * @param {Object} req - Node.js HTTP request object
 * @param {Object} res - Node.js HTTP response object
 * @returns {Promise<boolean>} 
 *   - true: Request was handled by this plugin
 *   - false: Request should fall back to static file serving
 */
async function handler(req, res) {
  try {
    // Use SDK router to parse the request URL
    // This automatically handles domain prefixes (e.g., '/peer.directory/domains' -> 'domains')
    // Returns: { path: 'domains', query: { page: '1', limit: '10' }, method: 'GET' }
    const { path, query } = sdk.router.parseRequest(req);
    
    // Handle root path (/) - return false to serve index.html from www/ directory
    // The plugin system will automatically serve static files from www/ when handler returns false
    if (path === '' || path === '/') {
      return false;
    }
    
    // Handle the /domains API endpoint
    // This endpoint returns a paginated, sortable list of all P2NS domains
    // Example: GET /domains?page=1&limit=10&sort=type
    if (path === 'domains' || path.startsWith('domains?')) {
      sdk.log.info('peer.directory', 'Serving domains list');
      
      // Check if DNS service is ready before attempting to fetch domains
      // If not ready, return a 503 Service Unavailable response
      if (!sdk.utils.isDNSReady()) {
        sdk.log.error('peer.directory', 'DNS service not initialized');
        // Return empty result set with error status
        return sdk.router.json(res, { domains: [], total: 0, page: 1, limit: 10, totalPages: 0 }, 503);
      }
      
      try {
        // Parse and validate query parameters
        // page: Which page to return (1-indexed, minimum 1)
        const page = Math.max(1, parseInt(query.page) || 1);
        
        // limit: How many domains per page (between 1 and 10, default 10)
        const limit = Math.max(1, Math.min(10, parseInt(query.limit) || 10));
        
        // sort: How to sort the domains (validate against allowed options)
        const validSorts = ['type', 'name', 'name-desc', 'hash', 'hash-desc', 'type-desc'];
        const sortBy = validSorts.includes(query.sort) ? query.sort : 'type';
      
        // Step 1: Fetch and categorize all domains from the P2NS network
        // This gets domains from DNS entries and categorizes them as internal/local/remote
        let domainList = await categorizeDomains();
        
        // Step 2: Apply the requested sorting
        // This mutates domainList in place according to the sortBy parameter
        domainList = sortDomains(domainList, sortBy);
        
        // Step 3: Calculate pagination metadata
        const total = domainList.length;                    // Total number of domains
        const totalPages = Math.ceil(total / limit);         // Total number of pages
        const startIndex = (page - 1) * limit;              // Starting index for this page
        
        // Step 4: Extract the domains for the requested page
        // slice(startIndex, startIndex + limit) gets the domains for this page
        const paginatedDomains = domainList.slice(startIndex, startIndex + limit);
        
        // Step 5: Return the paginated response as JSON
        // The response includes:
        // - domains: Array of domain objects for this page
        // - total: Total number of domains (for pagination UI)
        // - page: Current page number
        // - limit: Domains per page
        // - totalPages: Total number of pages (for pagination UI)
        return sdk.router.json(res, {
          domains: paginatedDomains,
          total,
          page,
          limit,
          totalPages
        });
      } catch (err) {
        // If anything goes wrong while processing, log the error and return empty result
        sdk.log.error('peer.directory', `Failed to fetch domains: ${err.message}`);
        return sdk.router.json(res, { domains: [], total: 0, page: 1, limit: 10, totalPages: 0 }, 500);
      }
    }
    
    // Handle favicon requests - browsers automatically request /favicon.ico
    // We don't have a favicon, so return 404
    if (path === 'favicon.ico') {
      sdk.log.debug('peer.directory', 'Favicon requested, returning 404');
      return sdk.router.notFound(res, 'Favicon Not Found');
    }
    
    // For all other paths, return false to allow static file serving
    // This means requests for CSS, JS, images, etc. will be served from www/ directory
    return false;
  } catch (err) {
    // Catch any unexpected errors in the handler
    // Log the error and return a 500 Internal Server Error response
    sdk.log.error('peer.directory', `Error handling request: ${err.message}`);
    return sdk.router.error(res, 'Internal Server Error', 500);
  }
}

/**
 * Plugin Initialization Hook
 * 
 * Called automatically when the plugin is loaded by the P2NS system.
 * This is the place to:
 * - Initialize resources
 * - Set up timers or intervals
 * - Pre-load data
 * - Check system state
 * 
 * This function is called once when the plugin is first loaded.
 */
async function onInit() {
  sdk.log.info('peer.directory', 'Plugin initialized');
  
  // Check if DNS service is ready
  // DNS service may not be ready immediately on startup, so we check and log the status
  if (sdk.utils.isDNSReady()) {
    sdk.log.info('peer.directory', 'DNS service is ready');
  } else {
    // This is not necessarily an error - DNS service may still be initializing
    sdk.log.warn('peer.directory', 'DNS service is not ready yet');
  }
  
  // Register admin panel actions
  sdk.admin.registerAction('refreshDomains', async () => {
    // Force refresh by invalidating any caches
    // The plugin itself doesn't cache, but this action can be useful
    return {
      success: true,
      message: 'Domain list will be refreshed on next request',
      timestamp: Date.now()
    };
  }, {
    label: 'Refresh Domains',
    description: 'Trigger a refresh of the domain list',
    icon: '🔄'
  });
  
  // Register admin panel settings
  sdk.admin.registerSetting('defaultSort', {
    type: 'select',
    label: 'Default Sort Order',
    description: 'Default sorting method for domain list',
    default: 'type',
    options: [
      { value: 'type', label: 'By Type' },
      { value: 'name', label: 'By Name (A-Z)' },
      { value: 'name-desc', label: 'By Name (Z-A)' },
      { value: 'hash', label: 'By Hash' }
    ]
  });
  
  sdk.admin.registerSetting('itemsPerPage', {
    type: 'number',
    label: 'Items Per Page',
    description: 'Number of domains to show per page',
    default: 10
  });
}

/**
 * Plugin Shutdown Hook
 * 
 * Called automatically when the plugin is unloaded by the P2NS system.
 * This is the place to:
 * - Clean up resources
 * - Close connections
 * - Stop timers or intervals
 * - Save state if needed
 * 
 * This function is called when:
 * - The plugin is being reloaded
 * - The P2NS system is shutting down
 * - The plugin is being disabled
 */
async function onShutdown() {
  sdk.log.info('peer.directory', 'Plugin shutting down');
  // Currently no cleanup needed, but this is where you would:
  // - Clear any caches
  // - Close database connections
  // - Stop background tasks
}

// Export the plugin interface
// The plugin system expects an object with these three optional functions:
// - handler: Main HTTP request handler (required if you want dynamic routes)
// - onInit: Initialization hook (optional)
// - onShutdown: Cleanup hook (optional)
module.exports = {
  handler,      // HTTP request handler - processes all incoming requests
  onInit,      // Called when plugin loads
  onShutdown   // Called when plugin unloads
};