// Centralized Application Configuration
// This file consolidates all configuration constants and environment variables
// to eliminate duplication and provide a single source of truth

import { getEnvVar, isProduction, isTest } from '../utils/env';

// Simple console logging for configuration (avoid circular dependency with logger)
const configLog = {
  warn: (message: string) => console.warn(`⚠️ Config: ${message}`),
  error: (message: string) => console.error(`❌ Config: ${message}`),
  info: (message: string) => console.warn(`📋 Config: ${message}`),
};

/**
 * Application Configuration Interface
 */
export interface AppConfig {
  // Application Identity
  name: string;
  version: string;

  // URLs and Endpoints
  baseUrl: string;
  apiUrl: string;

  // Database Configuration
  database: {
    url: string;
    username: string;
    password: string;
    useMock: boolean;
  };

  // Authentication Configuration
  auth: {
    jwtSecret: string;
    jwtExpiresIn: string;
    refreshTokenExpiresIn: string;
    emailVerificationExpiresIn: string;
  };

  // Email Configuration
  email: {
    mailgun: {
      apiKey?: string;
      domain?: string;
      baseUrl: string;
      fromName: string;
      fromEmail?: string;
    };
  };

  // OAuth Configuration
  oauth: {
    google: {
      clientId?: string;
    };
    github: {
      clientId?: string;
    };
  };

  // Feature Flags
  features: {
    enableEmailVerification: boolean;
    enableOAuth: boolean;
    enableAdminInterface: boolean;
    debugMode: boolean;
  };

  // Environment Information
  environment: {
    nodeEnv: string;
    isProduction: boolean;
    isTest: boolean;
    isDevelopment: boolean;
  };
}

/**
 * Default Configuration Values
 */
const DEFAULT_CONFIG: Partial<AppConfig> = {
  name: 'RxMinder',
  version: '1.0.0',
  baseUrl: 'http://localhost:5173',
  apiUrl: 'http://localhost:3000/api',

  database: {
    url: 'http://localhost:5984',
    username: 'admin',
    password: 'password',
    useMock: false,
  },

  auth: {
    jwtSecret: 'your-super-secret-jwt-key-change-in-production',
    jwtExpiresIn: '1h',
    refreshTokenExpiresIn: '7d',
    emailVerificationExpiresIn: '24h',
  },

  email: {
    mailgun: {
      baseUrl: 'https://api.mailgun.net/v3',
      fromName: 'RxMinder',
    },
  },

  features: {
    enableEmailVerification: true,
    enableOAuth: true,
    enableAdminInterface: true,
    debugMode: false,
  },
};

/**
 * Load configuration from environment variables with fallbacks
 */
function loadConfig(): AppConfig {
  const nodeEnv = getEnvVar('NODE_ENV') || 'development';
  const isProd = isProduction();
  const isTestEnv = isTest();
  const isDev = nodeEnv === 'development';

  return {
    // Application Identity
    name:
      getEnvVar('VITE_APP_NAME') ||
      getEnvVar('APP_NAME') ||
      DEFAULT_CONFIG.name!,
    version: getEnvVar('VITE_APP_VERSION') || DEFAULT_CONFIG.version!,

    // URLs and Endpoints
    baseUrl:
      getEnvVar('APP_BASE_URL') ||
      getEnvVar('VITE_BASE_URL') ||
      DEFAULT_CONFIG.baseUrl!,
    apiUrl:
      getEnvVar('API_URL') ||
      getEnvVar('VITE_API_URL') ||
      DEFAULT_CONFIG.apiUrl!,

    // Database Configuration
    database: {
      url:
        getEnvVar('VITE_COUCHDB_URL') ||
        getEnvVar('COUCHDB_URL') ||
        DEFAULT_CONFIG.database!.url,
      username:
        getEnvVar('VITE_COUCHDB_USER') ||
        getEnvVar('COUCHDB_USER') ||
        DEFAULT_CONFIG.database!.username,
      password:
        getEnvVar('VITE_COUCHDB_PASSWORD') ||
        getEnvVar('COUCHDB_PASSWORD') ||
        DEFAULT_CONFIG.database!.password,
      useMock:
        isTestEnv ||
        getEnvVar('USE_MOCK_DB') === 'true' ||
        (!getEnvVar('VITE_COUCHDB_URL') && !getEnvVar('COUCHDB_URL')),
    },

    // Authentication Configuration
    auth: {
      jwtSecret: getEnvVar('JWT_SECRET') || DEFAULT_CONFIG.auth!.jwtSecret,
      jwtExpiresIn:
        getEnvVar('JWT_EXPIRES_IN') || DEFAULT_CONFIG.auth!.jwtExpiresIn,
      refreshTokenExpiresIn:
        getEnvVar('REFRESH_TOKEN_EXPIRES_IN') ||
        DEFAULT_CONFIG.auth!.refreshTokenExpiresIn,
      emailVerificationExpiresIn:
        getEnvVar('EMAIL_VERIFICATION_EXPIRES_IN') ||
        DEFAULT_CONFIG.auth!.emailVerificationExpiresIn,
    },

    // Email Configuration
    email: {
      mailgun: {
        apiKey:
          getEnvVar('VITE_MAILGUN_API_KEY') || getEnvVar('MAILGUN_API_KEY'),
        domain: getEnvVar('VITE_MAILGUN_DOMAIN') || getEnvVar('MAILGUN_DOMAIN'),
        baseUrl:
          getEnvVar('VITE_MAILGUN_BASE_URL') ||
          getEnvVar('MAILGUN_BASE_URL') ||
          DEFAULT_CONFIG.email!.mailgun!.baseUrl,
        fromName:
          getEnvVar('VITE_MAILGUN_FROM_NAME') ||
          getEnvVar('MAILGUN_FROM_NAME') ||
          DEFAULT_CONFIG.email!.mailgun!.fromName,
        fromEmail:
          getEnvVar('VITE_MAILGUN_FROM_EMAIL') ||
          getEnvVar('MAILGUN_FROM_EMAIL'),
      },
    },

    // OAuth Configuration
    oauth: {
      google: {
        clientId:
          getEnvVar('VITE_GOOGLE_CLIENT_ID') || getEnvVar('GOOGLE_CLIENT_ID'),
      },
      github: {
        clientId:
          getEnvVar('VITE_GITHUB_CLIENT_ID') || getEnvVar('GITHUB_CLIENT_ID'),
      },
    },

    // Feature Flags
    features: {
      enableEmailVerification:
        getEnvVar('ENABLE_EMAIL_VERIFICATION') !== 'false',
      enableOAuth: getEnvVar('ENABLE_OAUTH') !== 'false',
      enableAdminInterface: getEnvVar('ENABLE_ADMIN_INTERFACE') !== 'false',
      debugMode: isDev || getEnvVar('DEBUG_MODE') === 'true',
    },

    // Environment Information
    environment: {
      nodeEnv,
      isProduction: isProd,
      isTest: isTestEnv,
      isDevelopment: isDev,
    },
  };
}

/**
 * Validate configuration and warn about missing values
 */
function validateConfig(config: AppConfig): void {
  const warnings: string[] = [];
  const errors: string[] = [];

  // Check critical configuration
  if (config.environment.isProduction) {
    if (config.auth.jwtSecret === DEFAULT_CONFIG.auth!.jwtSecret) {
      errors.push('JWT_SECRET must be changed in production');
    }

    if (config.database.password === DEFAULT_CONFIG.database!.password) {
      warnings.push(
        'Consider changing default database password in production'
      );
    }
  }

  // Check email configuration if email verification is enabled
  if (config.features.enableEmailVerification) {
    if (!config.email.mailgun.apiKey) {
      warnings.push(
        'MAILGUN_API_KEY not configured - email features will use console logging'
      );
    }

    if (!config.email.mailgun.domain) {
      warnings.push(
        'MAILGUN_DOMAIN not configured - email features may not work properly'
      );
    }
  }

  // Check OAuth configuration if OAuth is enabled
  if (config.features.enableOAuth) {
    if (!config.oauth.google.clientId && !config.oauth.github.clientId) {
      warnings.push(
        'No OAuth client IDs configured - OAuth features will be disabled'
      );
    }
  }

  // Log warnings and errors
  if (warnings.length > 0) {
    configLog.warn('Configuration warnings:');
    warnings.forEach(warning => configLog.warn(`   - ${warning}`));
  }

  if (errors.length > 0) {
    configLog.error('Configuration errors:');
    errors.forEach(error => configLog.error(`   - ${error}`));
    throw new Error('Critical configuration errors detected');
  }
}

/**
 * Load and validate application configuration
 */
export function createAppConfig(): AppConfig {
  const config = loadConfig();

  // Only validate in non-test environments to avoid test noise
  if (!config.environment.isTest) {
    validateConfig(config);
  }

  return config;
}

/**
 * Singleton application configuration instance
 */
export const appConfig = createAppConfig();

/**
 * Utility functions for common configuration access patterns
 */
export const CONFIG = {
  // Application
  APP_NAME: appConfig.name,
  APP_VERSION: appConfig.version,
  BASE_URL: appConfig.baseUrl,

  // Database
  DATABASE_URL: appConfig.database.url,
  USE_MOCK_DB: appConfig.database.useMock,

  // Environment
  IS_PRODUCTION: appConfig.environment.isProduction,
  IS_DEVELOPMENT: appConfig.environment.isDevelopment,
  IS_TEST: appConfig.environment.isTest,
  DEBUG_MODE: appConfig.features.debugMode,

  // Features
  FEATURES: appConfig.features,
} as const;

/**
 * Get configuration for specific modules
 */
export const getAuthConfig = () => appConfig.auth;
export const getDatabaseConfig = () => appConfig.database;
export const getEmailConfig = () => appConfig.email;
export const getOAuthConfig = () => appConfig.oauth;

/**
 * Development helper to log current configuration
 */
export function logConfig(): void {
  if (appConfig.features.debugMode) {
    configLog.info('Application Configuration');
    configLog.info(`Environment: ${appConfig.environment.nodeEnv}`);
    configLog.info(`App Name: ${appConfig.name}`);
    configLog.info(`Base URL: ${appConfig.baseUrl}`);
    configLog.info(
      `Database Strategy: ${appConfig.database.useMock ? 'Mock' : 'Production'}`
    );
    configLog.info(`Features: ${JSON.stringify(appConfig.features)}`);
  }
}

// Auto-log configuration in development
if (appConfig.features.debugMode && typeof window !== 'undefined') {
  logConfig();
}