/**
 * Error Handling Utilities
 * Provides consistent error handling, logging, and user-friendly messaging across the application
 */

import { ApiError } from '@/lib/http-client';

// Error severity levels
export enum ErrorSeverity {
  LOW = 'low',       // User can retry, minor inconvenience
  MEDIUM = 'medium', // User experience impacted but recoverable
  HIGH = 'high',     // Critical functionality broken
  CRITICAL = 'critical' // Application unusable
}

// Error categories for better handling
export enum ErrorCategory {
  NETWORK = 'network',
  AUTHENTICATION = 'authentication',
  AUTHORIZATION = 'authorization',
  VALIDATION = 'validation',
  SERVER = 'server',
  CLIENT = 'client',
  TIMEOUT = 'timeout',
  RATE_LIMIT = 'rate_limit',
  UNKNOWN = 'unknown',
}

// Enhanced error interface
export interface AppError {
  id: string;
  message: string;
  userMessage: string;
  technicalMessage?: string;
  category: ErrorCategory;
  severity: ErrorSeverity;
  statusCode?: number;
  timestamp: Date;
  context?: Record<string, unknown>;
  retryable: boolean;
  originalError?: Error;
}

// Error handler configuration
interface ErrorHandlerConfig {
  enableLogging: boolean;
  enableSentry?: boolean;
  enableAnalytics?: boolean;
  userMessageOverrides?: Record<string, string>;
}

/**
 * Error Handler Class
 */
export class ErrorHandler {
  private config: Required<Omit<ErrorHandlerConfig, 'enableSentry' | 'enableAnalytics'>> & Pick<ErrorHandlerConfig, 'enableSentry' | 'enableAnalytics'>;

  constructor(config: ErrorHandlerConfig = {}) {
    this.config = {
      enableLogging: import.meta.env.DEV,
      enableSentry: false,
      enableAnalytics: false,
      userMessageOverrides: {},
      ...config,
    };
  }

  /**
   * Handle any error and convert to AppError
   */
  handle(error: unknown, context?: Record<string, unknown>): AppError {
    const appError = this.normalizeError(error, context);

    // Log error
    if (this.config.enableLogging) {
      this.logError(appError);
    }

    // Send to error tracking services
    if (this.config.enableSentry) {
      this.sendToSentry(appError);
    }

    if (this.config.enableAnalytics) {
      this.sendToAnalytics(appError);
    }

    return appError;
  }

  /**
   * Convert various error types to AppError
   */
  private normalizeError(error: unknown, context?: Record<string, unknown>): AppError {
    const timestamp = new Date();
    const id = this.generateErrorId();

    // Handle ApiError
    if (error instanceof ApiError) {
      return {
        id,
        message: error.message,
        userMessage: this.getUserMessage(error),
        technicalMessage: import.meta.env.DEV ? error.data?.error : undefined,
        category: this.categorizeApiError(error),
        severity: this.getSeverity(error),
        statusCode: error.status,
        timestamp,
        context,
        retryable: error.retryable,
        originalError: error,
      };
    }

    // Handle ZodError
    if (error && typeof error === 'object' && 'name' in error && error.name === 'ZodError') {
      const zodError = error as { message: string; issues?: unknown[] };
      return {
        id,
        message: 'Validation failed',
        userMessage: 'Please check your input and try again.',
        technicalMessage: import.meta.env.DEV ? zodError.message : undefined,
        category: ErrorCategory.VALIDATION,
        severity: ErrorSeverity.MEDIUM,
        timestamp,
        context,
        retryable: false,
        originalError: new Error(zodError.message),
      };
    }

    // Handle standard Error
    if (error instanceof Error) {
      return {
        id,
        message: error.message,
        userMessage: this.getGenericUserMessage(error),
        technicalMessage: import.meta.env.DEV ? error.stack : undefined,
        category: this.categorizeGenericError(error),
        severity: ErrorSeverity.MEDIUM,
        timestamp,
        context,
        retryable: this.isRetryableError(error),
        originalError: error,
      };
    }

    // Handle string error
    if (typeof error === 'string') {
      return {
        id,
        message: error,
        userMessage: error,
        category: ErrorCategory.UNKNOWN,
        severity: ErrorSeverity.MEDIUM,
        timestamp,
        context,
        retryable: false,
      };
    }

    // Handle unknown error
    return {
      id,
      message: 'An unknown error occurred',
      userMessage: 'Something went wrong. Please try again.',
      category: ErrorCategory.UNKNOWN,
      severity: ErrorSeverity.MEDIUM,
      timestamp,
      context,
      retryable: true,
    };
  }

  /**
   * Categorize API errors
   */
  private categorizeApiError(error: ApiError): ErrorCategory {
    switch (error.status) {
      case 0:
        return ErrorCategory.NETWORK;
      case 401:
        return ErrorCategory.AUTHENTICATION;
      case 403:
        return ErrorCategory.AUTHORIZATION;
      case 408:
      case 504:
        return ErrorCategory.TIMEOUT;
      case 429:
        return ErrorCategory.RATE_LIMIT;
      case 422:
        return ErrorCategory.VALIDATION;
      case 400:
      case 404:
        return ErrorCategory.CLIENT;
      default:
        return error.status >= 500 ? ErrorCategory.SERVER : ErrorCategory.CLIENT;
    }
  }

  /**
   * Categorize generic errors
   */
  private categorizeGenericError(error: Error): ErrorCategory {
    const message = error.message.toLowerCase();

    if (message.includes('network') || message.includes('fetch')) {
      return ErrorCategory.NETWORK;
    }
    if (message.includes('timeout')) {
      return ErrorCategory.TIMEOUT;
    }
    if (message.includes('validation') || message.includes('invalid')) {
      return ErrorCategory.VALIDATION;
    }

    return ErrorCategory.UNKNOWN;
  }

  /**
   * Get severity level for API errors
   */
  private getSeverity(error: ApiError): ErrorSeverity {
    if (error.status >= 500) return ErrorSeverity.HIGH;
    if (error.status === 429) return ErrorSeverity.MEDIUM;
    if (error.status === 401 || error.status === 403) return ErrorSeverity.HIGH;
    if (error.status === 0) return ErrorSeverity.CRITICAL; // Network completely down
    return ErrorSeverity.LOW;
  }

  /**
   * Check if generic error is retryable
   */
  private isRetryableError(error: Error): boolean {
    const message = error.message.toLowerCase();
    return message.includes('network') || message.includes('timeout') || message.includes('temporary');
  }

  /**
   * Get user-friendly message for API errors
   */
  private getUserMessage(error: ApiError): string {
    // Check for custom overrides
    if (this.config.userMessageOverrides[error.status]) {
      return this.config.userMessageOverrides[error.status];
    }

    // Use the ApiError's user-friendly message if available
    if (error.message && !error.message.includes('HTTP')) {
      return error.message;
    }

    // Default messages based on status
    switch (error.status) {
      case 0:
        return 'Unable to connect. Please check your internet connection.';
      case 401:
        return 'Please log in to continue.';
      case 403:
        return 'You don\'t have permission to perform this action.';
      case 404:
        return 'The requested item was not found.';
      case 408:
      case 504:
        return 'The request timed out. Please try again.';
      case 429:
        return 'Too many requests. Please wait a moment before trying again.';
      case 422:
        return 'Please check your input and try again.';
      case 500:
        return 'A server error occurred. Please try again later.';
      case 502:
      case 503:
        return 'Service temporarily unavailable. Please try again later.';
      default:
        return 'Something went wrong. Please try again.';
    }
  }

  /**
   * Get user-friendly message for generic errors
   */
  private getGenericUserMessage(error: Error): string {
    const message = error.message.toLowerCase();

    if (message.includes('network') || message.includes('fetch')) {
      return 'Network connection failed. Please check your internet connection.';
    }
    if (message.includes('timeout')) {
      return 'The request timed out. Please try again.';
    }
    if (message.includes('validation')) {
      return 'Please check your input and try again.';
    }

    return 'An unexpected error occurred. Please try again.';
  }

  /**
   * Log error with appropriate level
   */
  private logError(error: AppError): void {
    const logData = {
      id: error.id,
      message: error.message,
      category: error.category,
      severity: error.severity,
      statusCode: error.statusCode,
      retryable: error.retryable,
      context: error.context,
      timestamp: error.timestamp.toISOString(),
    };

    switch (error.severity) {
      case ErrorSeverity.CRITICAL:
        console.error('🚨 CRITICAL ERROR:', logData);
        break;
      case ErrorSeverity.HIGH:
        console.error('❌ HIGH PRIORITY ERROR:', logData);
        break;
      case ErrorSeverity.MEDIUM:
        console.warn('⚠️ MEDIUM PRIORITY ERROR:', logData);
        break;
      default:
        console.info('ℹ️ LOW PRIORITY ERROR:', logData);
    }

    // Log technical details in development
    if (import.meta.env.DEV && error.technicalMessage) {
      console.debug('Technical details:', error.technicalMessage);
    }
  }

  /**
   * Send error to Sentry (placeholder)
   */
  private sendToSentry(error: AppError): void {
    // Placeholder for Sentry integration
    if (typeof window !== 'undefined' && (window as any).Sentry) {
      (window as any).Sentry.captureException(error.originalError || new Error(error.message), {
        tags: {
          category: error.category,
          severity: error.severity,
        },
        extra: {
          errorId: error.id,
          context: error.context,
        },
      });
    }
  }

  /**
   * Send error to analytics (placeholder)
   */
  private sendToAnalytics(error: AppError): void {
    // Placeholder for analytics integration
    if (typeof window !== 'undefined' && (window as any).gtag) {
      (window as any).gtag('event', 'exception', {
        description: error.message,
        fatal: error.severity === ErrorSeverity.CRITICAL,
      });
    }
  }

  /**
   * Generate unique error ID
   */
  private generateErrorId(): string {
    return `error_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`;
  }
}

// Global error handler instance
export const errorHandler = new ErrorHandler({
  enableLogging: import.meta.env.DEV,
});

/**
 * Hook for handling errors in React components
 */
export function useErrorHandler() {
  return {
    handleError: (error: unknown, context?: Record<string, unknown>) =>
      errorHandler.handle(error, context),
  };
}

/**
 * Utility function for consistent error handling in async operations
 */
export async function withErrorHandling<T>(
  operation: () => Promise<T>,
  context?: Record<string, unknown>
): Promise<T> {
  try {
    return await operation();
  } catch (error) {
    const appError = errorHandler.handle(error, context);
    throw appError;
  }
}

/**
 * Error boundary helper for consistent error reporting
 */
export function reportError(error: unknown, context?: Record<string, unknown>): AppError {
  return errorHandler.handle(error, context);
}