/**
 * Centralized Error Handler Service
 *
 * Provides error classification, user-friendly message translation,
 * and recovery strategy recommendations.
 */

import {
  AppError,
  ErrorCategory,
  ErrorCode,
  ErrorCodes,
  ErrorSeverity,
  FieldError,
  RetryPolicy,
  DefaultRetryPolicies,
} from '@/types/errors';
import { ApiError } from '@/types';

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

// User-friendly messages for error codes
const userMessages: Record<string, string> = {
  // Network
  [ErrorCodes.NETWORK_ERROR]: 'Unable to connect. Please check your internet connection.',
  [ErrorCodes.NETWORK_TIMEOUT]: 'The request timed out. Please try again.',
  [ErrorCodes.NETWORK_OFFLINE]: 'You appear to be offline. Please check your connection.',

  // Authentication
  [ErrorCodes.UNAUTHORIZED]: 'Your session has expired. Please log in again.',
  [ErrorCodes.TOKEN_EXPIRED]: 'Your session has expired. Please log in again.',
  [ErrorCodes.INVALID_CREDENTIALS]: 'Invalid email or password.',
  [ErrorCodes.SESSION_EXPIRED]: 'Your session has expired. Please log in again.',

  // Permission
  [ErrorCodes.FORBIDDEN]: 'You don\'t have permission to perform this action.',
  [ErrorCodes.INSUFFICIENT_PERMISSIONS]: 'You don\'t have sufficient permissions.',

  // Resource
  [ErrorCodes.NOT_FOUND]: 'The requested resource was not found.',
  [ErrorCodes.BENEFICIARY_NOT_FOUND]: 'Beneficiary not found.',
  [ErrorCodes.DEPLOYMENT_NOT_FOUND]: 'Deployment not found.',
  [ErrorCodes.USER_NOT_FOUND]: 'User not found.',

  // Conflict
  [ErrorCodes.CONFLICT]: 'A conflict occurred. Please refresh and try again.',
  [ErrorCodes.DUPLICATE_ENTRY]: 'This entry already exists.',
  [ErrorCodes.VERSION_MISMATCH]: 'Data has changed. Please refresh and try again.',

  // Validation
  [ErrorCodes.VALIDATION_ERROR]: 'Please check your input and try again.',
  [ErrorCodes.INVALID_INPUT]: 'Invalid input. Please check and try again.',
  [ErrorCodes.MISSING_REQUIRED_FIELD]: 'Please fill in all required fields.',
  [ErrorCodes.INVALID_EMAIL]: 'Please enter a valid email address.',
  [ErrorCodes.INVALID_PHONE]: 'Please enter a valid phone number.',
  [ErrorCodes.INVALID_OTP]: 'Invalid verification code. Please try again.',

  // Server
  [ErrorCodes.SERVER_ERROR]: 'Something went wrong on our end. Please try again later.',
  [ErrorCodes.SERVICE_UNAVAILABLE]: 'Service is temporarily unavailable. Please try again later.',
  [ErrorCodes.MAINTENANCE]: 'We\'re currently performing maintenance. Please try again soon.',

  // Rate limiting
  [ErrorCodes.RATE_LIMITED]: 'Too many requests. Please wait a moment and try again.',
  [ErrorCodes.TOO_MANY_REQUESTS]: 'Too many requests. Please wait a moment and try again.',

  // BLE
  [ErrorCodes.BLE_NOT_AVAILABLE]: 'Bluetooth is not available on this device.',
  [ErrorCodes.BLE_NOT_ENABLED]: 'Please enable Bluetooth to continue.',
  [ErrorCodes.BLE_PERMISSION_DENIED]: 'Bluetooth permission is required.',
  [ErrorCodes.BLE_CONNECTION_FAILED]: 'Failed to connect to device. Please try again.',
  [ErrorCodes.BLE_DEVICE_NOT_FOUND]: 'Device not found. Make sure it\'s powered on.',
  [ErrorCodes.BLE_TIMEOUT]: 'Connection timed out. Please try again.',

  // Sensor
  [ErrorCodes.SENSOR_SETUP_FAILED]: 'Sensor setup failed. Please try again.',
  [ErrorCodes.SENSOR_OFFLINE]: 'Sensor is offline. Check the device connection.',
  [ErrorCodes.SENSOR_NOT_RESPONDING]: 'Sensor is not responding. Please try again.',
  [ErrorCodes.SENSOR_WIFI_FAILED]: 'Failed to configure WiFi. Please check credentials.',

  // Subscription
  [ErrorCodes.SUBSCRIPTION_REQUIRED]: 'A subscription is required to access this feature.',
  [ErrorCodes.SUBSCRIPTION_EXPIRED]: 'Your subscription has expired.',
  [ErrorCodes.PAYMENT_FAILED]: 'Payment failed. Please try again or use a different method.',
  [ErrorCodes.PAYMENT_CANCELED]: 'Payment was canceled.',

  // General
  [ErrorCodes.UNKNOWN_ERROR]: 'Something went wrong. Please try again.',
  [ErrorCodes.API_ERROR]: 'An error occurred. Please try again.',
  [ErrorCodes.PARSE_ERROR]: 'Failed to process response. Please try again.',
  [ErrorCodes.EXCEPTION]: 'An unexpected error occurred.',
  [ErrorCodes.NOT_AUTHENTICATED]: 'Please log in to continue.',
  [ErrorCodes.NO_BENEFICIARY_SELECTED]: 'Please select a beneficiary.',
  [ErrorCodes.NO_DEPLOYMENT]: 'No deployment configured.',
};

// Action hints for error codes
const actionHints: Record<string, string> = {
  [ErrorCodes.NETWORK_ERROR]: 'Check your Wi-Fi or cellular connection',
  [ErrorCodes.NETWORK_OFFLINE]: 'Connect to the internet to continue',
  [ErrorCodes.UNAUTHORIZED]: 'Tap here to log in again',
  [ErrorCodes.TOKEN_EXPIRED]: 'Tap here to log in again',
  [ErrorCodes.BLE_NOT_ENABLED]: 'Enable Bluetooth in Settings',
  [ErrorCodes.BLE_PERMISSION_DENIED]: 'Grant Bluetooth permission in Settings',
  [ErrorCodes.SUBSCRIPTION_REQUIRED]: 'View subscription options',
  [ErrorCodes.SUBSCRIPTION_EXPIRED]: 'Renew your subscription',
  [ErrorCodes.PAYMENT_FAILED]: 'Try a different payment method',
};

// Classify HTTP status to error category
function classifyHttpStatus(status: number): ErrorCategory {
  if (status === 401) return 'authentication';
  if (status === 403) return 'permission';
  if (status === 404) return 'notFound';
  if (status === 409) return 'conflict';
  if (status === 429) return 'rateLimit';
  if (status === 422 || status === 400) return 'validation';
  if (status >= 500) return 'server';
  if (status >= 400) return 'client';
  return 'unknown';
}

// Classify error code to category
function classifyErrorCode(code: string): ErrorCategory {
  // Check timeout first before network (NETWORK_TIMEOUT should be timeout, not network)
  if (code.includes('TIMEOUT')) return 'timeout';
  if (code.startsWith('NETWORK') || code === 'NETWORK_ERROR') return 'network';
  if (code.includes('AUTH') || code.includes('TOKEN') || code.includes('SESSION') || code === 'UNAUTHORIZED') {
    return 'authentication';
  }
  if (code.includes('PERMISSION') || code === 'FORBIDDEN') return 'permission';
  if (code.includes('NOT_FOUND')) return 'notFound';
  if (code.includes('CONFLICT') || code.includes('DUPLICATE') || code.includes('MISMATCH')) return 'conflict';
  if (code.includes('VALIDATION') || code.includes('INVALID') || code.includes('MISSING')) return 'validation';
  if (code.includes('RATE') || code.includes('TOO_MANY')) return 'rateLimit';
  if (code.includes('SERVER') || code.includes('UNAVAILABLE') || code.includes('MAINTENANCE')) return 'server';
  if (code.startsWith('BLE')) return 'ble';
  if (code.startsWith('SENSOR')) return 'sensor';
  if (code.includes('SUBSCRIPTION') || code.includes('PAYMENT')) return 'subscription';
  return 'unknown';
}

// Determine severity from category and status
function determineSeverity(category: ErrorCategory, status?: number): ErrorSeverity {
  // Critical - app cannot continue
  if (category === 'authentication') return 'error';
  if (status && status >= 500) return 'error';
  if (category === 'server') return 'error';

  // Warning - recoverable
  if (category === 'network' || category === 'timeout') return 'warning';
  if (category === 'rateLimit') return 'warning';

  // Error - operation failed
  if (category === 'validation' || category === 'permission' || category === 'notFound') return 'error';

  // Default to error
  return 'error';
}

// Get user message for error
function getUserMessage(code: string, message?: string): string {
  // Use predefined message if available
  if (userMessages[code]) {
    return userMessages[code];
  }

  // Fall back to provided message or generic
  return message || 'Something went wrong. Please try again.';
}

// Get action hint for error
function getActionHint(code: string): string | undefined {
  return actionHints[code];
}

// Get retry policy for category
function getRetryPolicy(category: ErrorCategory): RetryPolicy {
  return DefaultRetryPolicies[category] || DefaultRetryPolicies.unknown;
}

/**
 * Create AppError from API error
 */
export function createErrorFromApi(apiError: ApiError, context?: Record<string, unknown>): AppError {
  const code = apiError.code || ErrorCodes.API_ERROR;
  const status = apiError.status;
  const category = status ? classifyHttpStatus(status) : classifyErrorCode(code);
  const severity = determineSeverity(category, status);

  return {
    message: apiError.message,
    code,
    severity,
    category,
    status,
    retry: getRetryPolicy(category),
    userMessage: getUserMessage(code, apiError.message),
    actionHint: getActionHint(code),
    context,
    timestamp: new Date(),
    errorId: generateErrorId(),
  };
}

/**
 * Create AppError from JavaScript Error
 */
export function createErrorFromException(
  error: Error,
  code: string = ErrorCodes.EXCEPTION,
  context?: Record<string, unknown>
): AppError {
  const category = classifyErrorCode(code);
  const severity = determineSeverity(category);

  return {
    message: error.message,
    code,
    severity,
    category,
    retry: getRetryPolicy(category),
    userMessage: getUserMessage(code, error.message),
    actionHint: getActionHint(code),
    context,
    timestamp: new Date(),
    errorId: generateErrorId(),
    originalError: error,
  };
}

/**
 * Create AppError from network error
 */
export function createNetworkError(
  message: string = 'Network request failed',
  isTimeout: boolean = false
): AppError {
  const code = isTimeout ? ErrorCodes.NETWORK_TIMEOUT : ErrorCodes.NETWORK_ERROR;
  const category: ErrorCategory = isTimeout ? 'timeout' : 'network';

  return {
    message,
    code,
    severity: 'warning',
    category,
    retry: getRetryPolicy(category),
    userMessage: getUserMessage(code),
    actionHint: getActionHint(code),
    timestamp: new Date(),
    errorId: generateErrorId(),
  };
}

/**
 * Create AppError for validation with field errors
 */
export function createValidationError(
  message: string,
  fieldErrors: FieldError[] = []
): AppError {
  return {
    message,
    code: ErrorCodes.VALIDATION_ERROR,
    severity: 'error',
    category: 'validation',
    retry: { isRetryable: false },
    userMessage: getUserMessage(ErrorCodes.VALIDATION_ERROR, message),
    fieldErrors,
    timestamp: new Date(),
    errorId: generateErrorId(),
  };
}

/**
 * Create AppError from any unknown error
 */
export function createErrorFromUnknown(
  error: unknown,
  defaultCode: string = ErrorCodes.UNKNOWN_ERROR,
  context?: Record<string, unknown>
): AppError {
  // Already an AppError
  if (error && typeof error === 'object' && 'errorId' in error) {
    return error as AppError;
  }

  // JavaScript Error
  if (error instanceof Error) {
    return createErrorFromException(error, defaultCode, context);
  }

  // ApiError-like object
  if (error && typeof error === 'object' && 'message' in error) {
    return createErrorFromApi(error as ApiError, context);
  }

  // String error
  if (typeof error === 'string') {
    return createErrorFromException(new Error(error), defaultCode, context);
  }

  // Unknown
  return {
    message: 'An unknown error occurred',
    code: defaultCode,
    severity: 'error',
    category: 'unknown',
    retry: { isRetryable: false },
    userMessage: getUserMessage(defaultCode),
    timestamp: new Date(),
    errorId: generateErrorId(),
    originalError: error,
    context,
  };
}

/**
 * Create a simple error with predefined code
 */
export function createError(
  code: ErrorCode,
  message?: string,
  context?: Record<string, unknown>
): AppError {
  const category = classifyErrorCode(code);
  const severity = determineSeverity(category);

  return {
    message: message || getUserMessage(code),
    code,
    severity,
    category,
    retry: getRetryPolicy(category),
    userMessage: getUserMessage(code, message),
    actionHint: getActionHint(code),
    context,
    timestamp: new Date(),
    errorId: generateErrorId(),
  };
}

/**
 * Calculate retry delay with optional exponential backoff
 */
export function calculateRetryDelay(policy: RetryPolicy, attempt: number): number {
  if (!policy.retryDelayMs) return 1000;

  if (policy.useExponentialBackoff) {
    // Exponential backoff: delay * 2^attempt with jitter
    const baseDelay = policy.retryDelayMs * Math.pow(2, attempt);
    const jitter = Math.random() * 0.3 * baseDelay; // 0-30% jitter
    return Math.min(baseDelay + jitter, 30000); // Max 30 seconds
  }

  return policy.retryDelayMs;
}

/**
 * Log error for debugging/analytics (placeholder for future integration)
 */
export function logError(error: AppError): void {
  if (__DEV__) {
    console.error(`[${error.severity.toUpperCase()}] ${error.code}:`, error.message, {
      category: error.category,
      errorId: error.errorId,
      context: error.context,
    });
  }

  // TODO: Integrate with error tracking service (e.g., Sentry, Bugsnag)
}

// Export error codes for convenience
export { ErrorCodes };