/**
 * MessageValidator - Validation et sanitisation des messages
 */
export interface ValidationResult {
  isValid: boolean;
  errors: string[];
  sanitizedData?: any;
}

export interface WebSocketMessage {
  flag: string;
  content: any;
  timestamp?: number;
  id?: string;
}

export class MessageValidator {
  private static instance: MessageValidator;
  private maxMessageSize = 50 * 1024 * 1024; // 50MB for large handshake messages
  private maxStringLength = 100000; // Increased for large handshake messages
  private allowedFlags = ['Handshake', 'NewTx', 'Cipher', 'Commit'];

  private constructor() {}

  public static getInstance(): MessageValidator {
    if (!MessageValidator.instance) {
      MessageValidator.instance = new MessageValidator();
    }
    return MessageValidator.instance;
  }

  /**
   * Valide un message WebSocket
   */
  validateWebSocketMessage(data: any): ValidationResult {
    const errors: string[] = [];

    // Vérifier le type de données
    if (typeof data !== 'string') {
      errors.push('Message must be a string');
      return { isValid: false, errors };
    }

    // Vérifier la taille du message
    if (data.length > this.maxMessageSize) {
      errors.push(`Message too large: ${data.length} bytes (max: ${this.maxMessageSize})`);
      return { isValid: false, errors };
    }

    // Parser le JSON
    let parsedMessage: any;
    try {
      parsedMessage = JSON.parse(data);
    } catch (error) {
      errors.push('Invalid JSON format');
      return { isValid: false, errors };
    }

    // Valider la structure du message
    const structureValidation = this.validateMessageStructure(parsedMessage);
    if (!structureValidation.isValid) {
      return structureValidation;
    }

    // Sanitiser le contenu
    const sanitizedContent = this.sanitizeContent(parsedMessage.content);

    return {
      isValid: true,
      errors: [],
      sanitizedData: {
        ...parsedMessage,
        content: sanitizedContent,
        timestamp: Date.now()
      }
    };
  }

  /**
   * Valide la structure d'un message
   */
  private validateMessageStructure(message: any): ValidationResult {
    const errors: string[] = [];

    // Vérifier que c'est un objet
    if (typeof message !== 'object' || message === null) {
      errors.push('Message must be an object');
      return { isValid: false, errors };
    }

    // Vérifier la présence du flag
    if (!message.flag || typeof message.flag !== 'string') {
      errors.push('Message must have a valid flag');
      return { isValid: false, errors };
    }

    // Vérifier que le flag est autorisé
    if (!this.allowedFlags.includes(message.flag)) {
      errors.push(`Invalid flag: ${message.flag}. Allowed: ${this.allowedFlags.join(', ')}`);
      return { isValid: false, errors };
    }

    // Vérifier la présence du contenu
    if (message.content === undefined || message.content === null) {
      errors.push('Message must have content');
      return { isValid: false, errors };
    }

    // Vérifier le type du contenu - peut être un objet ou une string JSON
    if (typeof message.content === 'string') {
      // Parser le contenu JSON si c'est une string
      try {
        message.content = JSON.parse(message.content);
      } catch (error) {
        errors.push('Content must be valid JSON if it is a string');
        return { isValid: false, errors };
      }
    } else if (typeof message.content !== 'object') {
      errors.push('Content must be an object or valid JSON string');
      return { isValid: false, errors };
    }

    return { isValid: true, errors: [] };
  }

  /**
   * Sanitise le contenu d'un message
   */
  private sanitizeContent(content: any): any {
    if (typeof content !== 'object' || content === null) {
      return content;
    }

    const sanitized: any = {};

    for (const [key, value] of Object.entries(content)) {
      // Vérifier la longueur des clés
      if (key.length > this.maxStringLength) {
        continue; // Ignorer les clés trop longues
      }

      // Sanitiser les valeurs
      if (typeof value === 'string') {
        sanitized[key] = this.sanitizeString(value);
      } else if (typeof value === 'object' && value !== null) {
        sanitized[key] = this.sanitizeContent(value);
      } else {
        sanitized[key] = value;
      }
    }

    return sanitized;
  }

  /**
   * Sanitise une chaîne de caractères
   */
  private sanitizeString(str: string): string {
    // Vérifier la longueur
    if (str.length > this.maxStringLength) {
      return str.substring(0, this.maxStringLength) + '...';
    }

    // Supprimer les caractères de contrôle dangereux
    return str.replace(/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]/g, '');
  }

  /**
   * Valide un message de pairing
   */
  validatePairingMessage(message: any): ValidationResult {
    const errors: string[] = [];

    if (!message.type) {
      errors.push('Pairing message must have a type');
      return { isValid: false, errors };
    }

    const allowedTypes = [
      'PAIRING_4WORDS_CREATE',
      'PAIRING_4WORDS_JOIN',
      'PAIRING_4WORDS_WORDS_GENERATED',
      'PAIRING_4WORDS_STATUS_UPDATE',
      'PAIRING_4WORDS_SUCCESS',
      'PAIRING_4WORDS_ERROR'
    ];

    if (!allowedTypes.includes(message.type)) {
      errors.push(`Invalid pairing message type: ${message.type}`);
      return { isValid: false, errors };
    }

    // Validation spécifique selon le type
    switch (message.type) {
      case 'PAIRING_4WORDS_JOIN':
        if (!message.words || typeof message.words !== 'string') {
          errors.push('PAIRING_4WORDS_JOIN requires words');
        }
        if (message.words && message.words.length > 100) {
          errors.push('Words too long');
        }
        break;
    }

    return { isValid: errors.length === 0, errors };
  }

  /**
   * Valide un message de processus
   */
  validateProcessMessage(message: any): ValidationResult {
    const errors: string[] = [];

    if (!message.type) {
      errors.push('Process message must have a type');
      return { isValid: false, errors };
    }

    const allowedTypes = [
      'CREATE_PROCESS',
      'UPDATE_PROCESS',
      'GET_PROCESSES',
      'GET_MY_PROCESSES'
    ];

    if (!allowedTypes.includes(message.type)) {
      errors.push(`Invalid process message type: ${message.type}`);
      return { isValid: false, errors };
    }

    return { isValid: errors.length === 0, errors };
  }

  /**
   * Valide un message de données
   */
  validateDataMessage(message: any): ValidationResult {
    const errors: string[] = [];

    if (!message.type) {
      errors.push('Data message must have a type');
      return { isValid: false, errors };
    }

    const allowedTypes = [
      'RETRIEVE_DATA',
      'STORE_DATA',
      'DELETE_DATA'
    ];

    if (!allowedTypes.includes(message.type)) {
      errors.push(`Invalid data message type: ${message.type}`);
      return { isValid: false, errors };
    }

    // Vérifier la présence des données requises
    if (message.type === 'STORE_DATA' && !message.data) {
      errors.push('STORE_DATA requires data');
    }

    if (message.type === 'RETRIEVE_DATA' && !message.key) {
      errors.push('RETRIEVE_DATA requires key');
    }

    return { isValid: errors.length === 0, errors };
  }

  /**
   * Valide un message de token
   */
  validateTokenMessage(message: any): ValidationResult {
    const errors: string[] = [];

    if (!message.type) {
      errors.push('Token message must have a type');
      return { isValid: false, errors };
    }

    const allowedTypes = [
      'VALIDATE_TOKEN',
      'RENEW_TOKEN',
      'REVOKE_TOKEN'
    ];

    if (!allowedTypes.includes(message.type)) {
      errors.push(`Invalid token message type: ${message.type}`);
      return { isValid: false, errors };
    }

    // Vérifier la présence du token
    if (!message.token) {
      errors.push('Token message requires token');
      return { isValid: false, errors };
    }

    // Valider le format du token
    if (typeof message.token !== 'string' || message.token.length < 10) {
      errors.push('Invalid token format');
      return { isValid: false, errors };
    }

    return { isValid: errors.length === 0, errors };
  }

  /**
   * Valide un message générique
   */
  validateGenericMessage(message: any): ValidationResult {
    const errors: string[] = [];

    if (!message.type) {
      errors.push('Message must have a type');
      return { isValid: false, errors };
    }

    // Vérifier la longueur du type
    if (typeof message.type !== 'string' || message.type.length > 100) {
      errors.push('Invalid message type');
      return { isValid: false, errors };
    }

    // Vérifier la présence de données si nécessaire
    if (message.data && typeof message.data !== 'object') {
      errors.push('Message data must be an object');
      return { isValid: false, errors };
    }

    return { isValid: errors.length === 0, errors };
  }

  /**
   * Valide un message en fonction de son type
   */
  validateMessage(message: any): ValidationResult {
    if (!message.type) {
      return { isValid: false, errors: ['Message must have a type'] };
    }

    // Validation spécifique selon le type
    if (message.type.startsWith('PAIRING_')) {
      return this.validatePairingMessage(message);
    } else if (message.type.includes('PROCESS')) {
      return this.validateProcessMessage(message);
    } else if (message.type.includes('DATA')) {
      return this.validateDataMessage(message);
    } else if (message.type.includes('TOKEN')) {
      return this.validateTokenMessage(message);
    } else {
      return this.validateGenericMessage(message);
    }
  }
}

// Instance singleton pour l'application
export const messageValidator = MessageValidator.getInstance();