/**
 * Rate limiting utility to prevent abuse
 */

class RateLimiter {
  constructor() {
    // Map of peer ID to request timestamps
    this.requests = new Map();
    
    // Configuration — sized for interactive UI (auto-refresh, dashboard,
    // multi-tab inspect) without tripping under normal operator use.
    this.config = {
      maxRequests: 3000,       // Max non-stream RPCs per window (~50/s avg)
      windowMs: 60000,         // 1 minute window
      commandLimits: {
        deployContainer: { max: 30, windowMs: 60000 },   // deploys per minute
        dockerCommand: { max: 200, windowMs: 10000 },    // host docker CLI / 10s
        startContainer: { max: 120, windowMs: 60000 },  // starts per minute
        stopContainer: { max: 120, windowMs: 60000 },   // stops per minute
      },
    };

    /**
     * High-frequency stream methods (keystrokes, resizes, chunks).
     * Exempt from the general cap; optional soft ceiling.
     */
    this.streamMethods = new Set([
      'terminalInput',
      'terminalResize',
      'execInput',
      'attachInput',
      'loadImageChunk',
      'binaryStreamChunk',
      'dockerTerminalResize',
    ]);
    this.streamLimit = { max: 18000, windowMs: 60000 }; // ~300/s sustained
  }

  /**
   * Get peer identifier
   * @param {Object} peer - Peer object
   * @returns {string} - Peer identifier
   */
  getPeerId(peer) {
    if (peer?.id && typeof peer.id === 'string') return peer.id
    if (peer?.remotePublicKey) {
      return typeof peer.remotePublicKey === 'string'
        ? peer.remotePublicKey
        : Buffer.from(peer.remotePublicKey).toString('hex')
    }
    return 'unknown'
  }

  /**
   * Check if request is within rate limit
   * @param {Object} peer - Peer object
   * @param {string} command - Command name
   * @returns {boolean} - True if allowed
   */
  isAllowed(peer, command) {
    const peerId = this.getPeerId(peer);
    const now = Date.now();
    
    // Clean up old entries
    this.cleanup(now);
    
    // Initialize peer entry if needed
    if (!this.requests.has(peerId)) {
      this.requests.set(peerId, {
        general: [],
        stream: [],
        commands: {}
      });
    }
    
    const peerData = this.requests.get(peerId);
    if (!peerData.stream) peerData.stream = [];

    // Stream methods: separate high ceiling, never consume general budget
    if (this.streamMethods.has(command)) {
      const streamWindow = now - this.streamLimit.windowMs;
      peerData.stream = peerData.stream.filter((t) => t > streamWindow);
      if (peerData.stream.length >= this.streamLimit.max) {
        return false;
      }
      peerData.stream.push(now);
      return true;
    }
    
    // Check general rate limit
    const generalWindow = now - this.config.windowMs;
    peerData.general = peerData.general.filter(timestamp => timestamp > generalWindow);
    
    if (peerData.general.length >= this.config.maxRequests) {
      return false;
    }
    
    // Check command-specific rate limit
    if (this.config.commandLimits[command]) {
      const limit = this.config.commandLimits[command];
      const commandWindow = now - limit.windowMs;
      
      if (!peerData.commands[command]) {
        peerData.commands[command] = [];
      }
      
      peerData.commands[command] = peerData.commands[command].filter(
        timestamp => timestamp > commandWindow
      );
      
      if (peerData.commands[command].length >= limit.max) {
        return false;
      }
      
      // Record command request
      peerData.commands[command].push(now);
    }
    
    // Record general request
    peerData.general.push(now);
    
    return true;
  }

  /** @param {string} method */
  isStreamMethod(method) {
    return this.streamMethods.has(method);
  }

  /**
   * Clean up old entries
   * @param {number} now - Current timestamp
   */
  cleanup(now) {
    const maxAge = Math.max(
      this.config.windowMs,
      ...Object.values(this.config.commandLimits).map(l => l.windowMs)
    );
    
    for (const [peerId, peerData] of this.requests.entries()) {
      // Clean general requests
      peerData.general = peerData.general.filter(timestamp => timestamp > now - maxAge);
      
      // Clean command requests
      for (const [command, timestamps] of Object.entries(peerData.commands)) {
        const limit = this.config.commandLimits[command];
        if (limit) {
          peerData.commands[command] = timestamps.filter(
            timestamp => timestamp > now - limit.windowMs
          );
        }
      }
      
      // Remove peer if no active requests
      if (peerData.general.length === 0 && 
          Object.values(peerData.commands).every(arr => arr.length === 0)) {
        this.requests.delete(peerId);
      }
    }
  }

  /**
   * Reset rate limit for a peer (useful for testing or manual override)
   * @param {Object} peer - Peer object
   */
  reset(peer) {
    const peerId = this.getPeerId(peer);
    this.requests.delete(peerId);
  }
}

// Singleton instance
const rateLimiter = new RateLimiter();

export default rateLimiter;