import * as plugins from '../../plugins.js';
import type {
  IRouteConfig,
  IRouteMatch,
  IRouteAction,
  TPortRange
} from './models/route-types.js';
import type {
  ISmartProxyOptions,
  IRoutedSmartProxyOptions
} from './models/interfaces.js';
import {
  isRoutedOptions,
  isLegacyOptions
} from './models/interfaces.js';

/**
 * Result of route matching
 */
export interface IRouteMatchResult {
  route: IRouteConfig;
  // Additional match parameters (path, query, etc.)
  params?: Record<string, string>;
}

/**
 * The RouteManager handles all routing decisions based on connections and attributes
 */
export class RouteManager extends plugins.EventEmitter {
  private routes: IRouteConfig[] = [];
  private portMap: Map<number, IRouteConfig[]> = new Map();
  private options: IRoutedSmartProxyOptions;
  
  constructor(options: ISmartProxyOptions) {
    super();
    
    // We no longer support legacy options, always use provided options
    this.options = options;
    
    // Initialize routes from either source
    this.updateRoutes(this.options.routes);
  }
  
  /**
   * Update routes with new configuration
   */
  public updateRoutes(routes: IRouteConfig[] = []): void {
    // Sort routes by priority (higher first)
    this.routes = [...(routes || [])].sort((a, b) => {
      const priorityA = a.priority ?? 0;
      const priorityB = b.priority ?? 0;
      return priorityB - priorityA;
    });
    
    // Rebuild port mapping for fast lookups
    this.rebuildPortMap();
  }
  
  /**
   * Rebuild the port mapping for fast lookups
   */
  private rebuildPortMap(): void {
    this.portMap.clear();
    
    for (const route of this.routes) {
      const ports = this.expandPortRange(route.match.ports);
      
      for (const port of ports) {
        if (!this.portMap.has(port)) {
          this.portMap.set(port, []);
        }
        this.portMap.get(port)!.push(route);
      }
    }
  }
  
  /**
   * Expand a port range specification into an array of individual ports
   */
  private expandPortRange(portRange: TPortRange): number[] {
    if (typeof portRange === 'number') {
      return [portRange];
    }
    
    if (Array.isArray(portRange)) {
      // Handle array of port objects or numbers
      return portRange.flatMap(item => {
        if (typeof item === 'number') {
          return [item];
        } else if (typeof item === 'object' && 'from' in item && 'to' in item) {
          // Handle port range object
          const ports: number[] = [];
          for (let p = item.from; p <= item.to; p++) {
            ports.push(p);
          }
          return ports;
        }
        return [];
      });
    }
    
    return [];
  }
  
  /**
   * Get all ports that should be listened on
   */
  public getListeningPorts(): number[] {
    return Array.from(this.portMap.keys());
  }
  
  /**
   * Get all routes for a given port
   */
  public getRoutesForPort(port: number): IRouteConfig[] {
    return this.portMap.get(port) || [];
  }
  
  /**
   * Test if a pattern matches a domain using glob matching
   */
  private matchDomain(pattern: string, domain: string): boolean {
    // Convert glob pattern to regex
    const regexPattern = pattern
      .replace(/\./g, '\\.')    // Escape dots
      .replace(/\*/g, '.*');    // Convert * to .*
    
    const regex = new RegExp(`^${regexPattern}$`, 'i');
    return regex.test(domain);
  }
  
  /**
   * Match a domain against all patterns in a route
   */
  private matchRouteDomain(route: IRouteConfig, domain: string): boolean {
    if (!route.match.domains) {
      // If no domains specified, match all domains
      return true;
    }
    
    const patterns = Array.isArray(route.match.domains) 
      ? route.match.domains 
      : [route.match.domains];
    
    return patterns.some(pattern => this.matchDomain(pattern, domain));
  }
  
  /**
   * Check if a client IP is allowed by a route's security settings
   */
  private isClientIpAllowed(route: IRouteConfig, clientIp: string): boolean {
    const security = route.action.security;
    
    if (!security) {
      return true; // No security settings means allowed
    }
    
    // Check blocked IPs first
    if (security.blockedIps && security.blockedIps.length > 0) {
      for (const pattern of security.blockedIps) {
        if (this.matchIpPattern(pattern, clientIp)) {
          return false; // IP is blocked
        }
      }
    }
    
    // If there are allowed IPs, check them
    if (security.allowedIps && security.allowedIps.length > 0) {
      for (const pattern of security.allowedIps) {
        if (this.matchIpPattern(pattern, clientIp)) {
          return true; // IP is allowed
        }
      }
      return false; // IP not in allowed list
    }
    
    // No allowed IPs specified, so IP is allowed
    return true;
  }
  
  /**
   * Match an IP against a pattern
   */
  private matchIpPattern(pattern: string, ip: string): boolean {
    // Handle exact match
    if (pattern === ip) {
      return true;
    }
    
    // Handle CIDR notation (e.g., 192.168.1.0/24)
    if (pattern.includes('/')) {
      return this.matchIpCidr(pattern, ip);
    }
    
    // Handle glob pattern (e.g., 192.168.1.*)
    if (pattern.includes('*')) {
      const regexPattern = pattern.replace(/\./g, '\\.').replace(/\*/g, '.*');
      const regex = new RegExp(`^${regexPattern}$`);
      return regex.test(ip);
    }
    
    return false;
  }
  
  /**
   * Match an IP against a CIDR pattern
   */
  private matchIpCidr(cidr: string, ip: string): boolean {
    try {
      // In a real implementation, you'd use a proper IP library
      // This is a simplified implementation
      const [subnet, bits] = cidr.split('/');
      const mask = parseInt(bits, 10);
      
      // Convert IP addresses to numeric values
      const ipNum = this.ipToNumber(ip);
      const subnetNum = this.ipToNumber(subnet);
      
      // Calculate subnet mask
      const maskNum = ~(2 ** (32 - mask) - 1);
      
      // Check if IP is in subnet
      return (ipNum & maskNum) === (subnetNum & maskNum);
    } catch (e) {
      console.error(`Error matching IP ${ip} against CIDR ${cidr}:`, e);
      return false;
    }
  }
  
  /**
   * Convert an IP address to a numeric value
   */
  private ipToNumber(ip: string): number {
    const parts = ip.split('.').map(part => parseInt(part, 10));
    return (parts[0] << 24) | (parts[1] << 16) | (parts[2] << 8) | parts[3];
  }
  
  /**
   * Find the matching route for a connection
   */
  public findMatchingRoute(options: {
    port: number;
    domain?: string;
    clientIp: string;
    path?: string;
    tlsVersion?: string;
  }): IRouteMatchResult | null {
    const { port, domain, clientIp, path, tlsVersion } = options;
    
    // Get all routes for this port
    const routesForPort = this.getRoutesForPort(port);
    
    // Find the first matching route based on priority order
    for (const route of routesForPort) {
      // Check domain match if specified
      if (domain && !this.matchRouteDomain(route, domain)) {
        continue;
      }
      
      // Check path match if specified in both route and request
      if (path && route.match.path) {
        if (!this.matchPath(route.match.path, path)) {
          continue;
        }
      }
      
      // Check client IP match
      if (route.match.clientIp && !route.match.clientIp.some(pattern => 
        this.matchIpPattern(pattern, clientIp))) {
        continue;
      }
      
      // Check TLS version match
      if (tlsVersion && route.match.tlsVersion && 
          !route.match.tlsVersion.includes(tlsVersion)) {
        continue;
      }
      
      // Check security settings
      if (!this.isClientIpAllowed(route, clientIp)) {
        continue;
      }
      
      // All checks passed, this route matches
      return { route };
    }
    
    return null;
  }
  
  /**
   * Match a path against a pattern
   */
  private matchPath(pattern: string, path: string): boolean {
    // Convert the glob pattern to a regex
    const regexPattern = pattern
      .replace(/\./g, '\\.')    // Escape dots
      .replace(/\*/g, '.*')     // Convert * to .*
      .replace(/\//g, '\\/');   // Escape slashes
    
    const regex = new RegExp(`^${regexPattern}$`);
    return regex.test(path);
  }
  
  /**
   * Convert a domain config to routes
   * (For backward compatibility with code that still uses domainConfigs)
   */
  public domainConfigToRoutes(domainConfig: IDomainConfig): IRouteConfig[] {
    const routes: IRouteConfig[] = [];
    const { domains, forwarding } = domainConfig;
    
    // Determine the action based on forwarding type
    let action: IRouteAction = {
      type: 'forward',
      target: {
        host: forwarding.target.host,
        port: forwarding.target.port
      }
    };
    
    // Set TLS mode based on forwarding type
    switch (forwarding.type) {
      case 'http-only':
        // No TLS settings needed
        break;
      case 'https-passthrough':
        action.tls = { mode: 'passthrough' };
        break;
      case 'https-terminate-to-http':
        action.tls = { 
          mode: 'terminate',
          certificate: forwarding.https?.customCert ? {
            key: forwarding.https.customCert.key,
            cert: forwarding.https.customCert.cert
          } : 'auto'
        };
        break;
      case 'https-terminate-to-https':
        action.tls = { 
          mode: 'terminate-and-reencrypt',
          certificate: forwarding.https?.customCert ? {
            key: forwarding.https.customCert.key,
            cert: forwarding.https.customCert.cert
          } : 'auto'
        };
        break;
    }
    
    // Add security settings if present
    if (forwarding.security) {
      action.security = {
        allowedIps: forwarding.security.allowedIps,
        blockedIps: forwarding.security.blockedIps,
        maxConnections: forwarding.security.maxConnections
      };
    }
    
    // Add advanced settings if present
    if (forwarding.advanced) {
      action.advanced = {
        timeout: forwarding.advanced.timeout,
        headers: forwarding.advanced.headers,
        keepAlive: forwarding.advanced.keepAlive
      };
    }
    
    // Determine which port to use based on forwarding type
    const defaultPort = forwarding.type.startsWith('https') ? 443 : 80;
    
    // Add the main route
    routes.push({
      match: {
        ports: defaultPort,
        domains
      },
      action,
      name: `Route for ${domains.join(', ')}`
    });
    
    // Add HTTP redirect if needed
    if (forwarding.http?.redirectToHttps) {
      routes.push({
        match: {
          ports: 80,
          domains
        },
        action: {
          type: 'redirect',
          redirect: {
            to: 'https://{domain}{path}',
            status: 301
          }
        },
        name: `HTTP Redirect for ${domains.join(', ')}`,
        priority: 100 // Higher priority for redirects
      });
    }
    
    // Add port ranges if specified
    if (forwarding.advanced?.portRanges) {
      for (const range of forwarding.advanced.portRanges) {
        routes.push({
          match: {
            ports: [{ from: range.from, to: range.to }],
            domains
          },
          action,
          name: `Port Range ${range.from}-${range.to} for ${domains.join(', ')}`
        });
      }
    }
    
    return routes;
  }
  
  /**
   * Update routes based on domain configs
   * (For backward compatibility with code that still uses domainConfigs)
   */
  public updateFromDomainConfigs(domainConfigs: IDomainConfig[]): void {
    const routes: IRouteConfig[] = [];
    
    // Convert each domain config to routes
    for (const config of domainConfigs) {
      routes.push(...this.domainConfigToRoutes(config));
    }
    
    // Merge with existing routes that aren't derived from domain configs
    const nonDomainRoutes = this.routes.filter(r => 
      !r.name || !r.name.includes('for '));
    
    this.updateRoutes([...nonDomainRoutes, ...routes]);
  }
  
  /**
   * Validate the route configuration and return any warnings
   */
  public validateConfiguration(): string[] {
    const warnings: string[] = [];
    const duplicatePorts = new Map<number, number>();
    
    // Check for routes with the same exact match criteria
    for (let i = 0; i < this.routes.length; i++) {
      for (let j = i + 1; j < this.routes.length; j++) {
        const route1 = this.routes[i];
        const route2 = this.routes[j];
        
        // Check if route match criteria are the same
        if (this.areMatchesSimilar(route1.match, route2.match)) {
          warnings.push(
            `Routes "${route1.name || i}" and "${route2.name || j}" have similar match criteria. ` +
            `The route with higher priority (${Math.max(route1.priority || 0, route2.priority || 0)}) will be used.`
          );
        }
      }
    }
    
    // Check for routes that may never be matched due to priority
    for (let i = 0; i < this.routes.length; i++) {
      const route = this.routes[i];
      const higherPriorityRoutes = this.routes.filter(r => 
        (r.priority || 0) > (route.priority || 0));
      
      for (const higherRoute of higherPriorityRoutes) {
        if (this.isRouteShadowed(route, higherRoute)) {
          warnings.push(
            `Route "${route.name || i}" may never be matched because it is shadowed by ` +
            `higher priority route "${higherRoute.name || 'unnamed'}"`
          );
          break;
        }
      }
    }
    
    return warnings;
  }
  
  /**
   * Check if two route matches are similar (potential conflict)
   */
  private areMatchesSimilar(match1: IRouteMatch, match2: IRouteMatch): boolean {
    // Check port overlap
    const ports1 = new Set(this.expandPortRange(match1.ports));
    const ports2 = new Set(this.expandPortRange(match2.ports));
    
    let havePortOverlap = false;
    for (const port of ports1) {
      if (ports2.has(port)) {
        havePortOverlap = true;
        break;
      }
    }
    
    if (!havePortOverlap) {
      return false;
    }
    
    // Check domain overlap
    if (match1.domains && match2.domains) {
      const domains1 = Array.isArray(match1.domains) ? match1.domains : [match1.domains];
      const domains2 = Array.isArray(match2.domains) ? match2.domains : [match2.domains];
      
      // Check if any domain pattern from match1 could match any from match2
      let haveDomainOverlap = false;
      for (const domain1 of domains1) {
        for (const domain2 of domains2) {
          if (domain1 === domain2 || 
              (domain1.includes('*') || domain2.includes('*'))) {
            haveDomainOverlap = true;
            break;
          }
        }
        if (haveDomainOverlap) break;
      }
      
      if (!haveDomainOverlap) {
        return false;
      }
    } else if (match1.domains || match2.domains) {
      // One has domains, the other doesn't - they could overlap
      // The one with domains is more specific, so it's not exactly a conflict
      return false;
    }
    
    // Check path overlap
    if (match1.path && match2.path) {
      // This is a simplified check - in a real implementation,
      // you'd need to check if the path patterns could match the same paths
      return match1.path === match2.path || 
             match1.path.includes('*') || 
             match2.path.includes('*');
    } else if (match1.path || match2.path) {
      // One has a path, the other doesn't
      return false;
    }
    
    // If we get here, the matches have significant overlap
    return true;
  }
  
  /**
   * Check if a route is completely shadowed by a higher priority route
   */
  private isRouteShadowed(route: IRouteConfig, higherPriorityRoute: IRouteConfig): boolean {
    // If they don't have similar match criteria, no shadowing occurs
    if (!this.areMatchesSimilar(route.match, higherPriorityRoute.match)) {
      return false;
    }
    
    // If higher priority route has more specific criteria, no shadowing
    if (this.isRouteMoreSpecific(higherPriorityRoute.match, route.match)) {
      return false;
    }
    
    // If higher priority route is equally or less specific but has higher priority,
    // it shadows the lower priority route
    return true;
  }
  
  /**
   * Check if route1 is more specific than route2
   */
  private isRouteMoreSpecific(match1: IRouteMatch, match2: IRouteMatch): boolean {
    // Check if match1 has more specific criteria
    let match1Points = 0;
    let match2Points = 0;
    
    // Path is the most specific
    if (match1.path) match1Points += 3;
    if (match2.path) match2Points += 3;
    
    // Domain is next most specific
    if (match1.domains) match1Points += 2;
    if (match2.domains) match2Points += 2;
    
    // Client IP and TLS version are least specific
    if (match1.clientIp) match1Points += 1;
    if (match2.clientIp) match2Points += 1;
    
    if (match1.tlsVersion) match1Points += 1;
    if (match2.tlsVersion) match2Points += 1;
    
    return match1Points > match2Points;
  }
}