import { z } from 'zod';

/**
 * Environment variable schema.
 */
const envSchema = z.object({
  NODE_ENV: z.enum(['development', 'production', 'test']).default('development'),
  NEXT_PUBLIC_BASE_URL: z.string().url().default('http://localhost:3000'),
  
  // Analytics
  NEXT_PUBLIC_UMAMI_WEBSITE_ID: z.string().optional(),
  NEXT_PUBLIC_UMAMI_SCRIPT_URL: z.string().url().default('https://analytics.infra.mintel.me/script.js'),
  
  // Error Tracking
  SENTRY_DSN: z.string().optional(),
  
  // Cache
  REDIS_URL: z.string().optional(),
  REDIS_KEY_PREFIX: z.string().default('klz:'),
  
  // Logging
  LOG_LEVEL: z.enum(['debug', 'info', 'warn', 'error']).default('info'),
  
  // Mail
  MAIL_HOST: z.string().optional(),
  MAIL_PORT: z.coerce.number().default(587),
  MAIL_USERNAME: z.string().optional(),
  MAIL_PASSWORD: z.string().optional(),
  MAIL_FROM: z.string().optional(),
  MAIL_RECIPIENTS: z.string().optional().transform(val => val?.split(',').filter(Boolean) || []),
});

/**
 * Helper to get environment variables.
 */
function getRawEnv() {
  const isServer = typeof window === 'undefined';

  if (!isServer) {
    // Client-side: only return NEXT_PUBLIC_ variables
    return {
      NEXT_PUBLIC_BASE_URL: process.env.NEXT_PUBLIC_BASE_URL,
      NEXT_PUBLIC_UMAMI_WEBSITE_ID: process.env.NEXT_PUBLIC_UMAMI_WEBSITE_ID,
      NEXT_PUBLIC_UMAMI_SCRIPT_URL: process.env.NEXT_PUBLIC_UMAMI_SCRIPT_URL,
    };
  }

  // Server-side: return all variables
  return {
    NODE_ENV: process.env.NODE_ENV,
    NEXT_PUBLIC_BASE_URL: process.env.NEXT_PUBLIC_BASE_URL,
    NEXT_PUBLIC_UMAMI_WEBSITE_ID: process.env.NEXT_PUBLIC_UMAMI_WEBSITE_ID,
    NEXT_PUBLIC_UMAMI_SCRIPT_URL: process.env.NEXT_PUBLIC_UMAMI_SCRIPT_URL,
    SENTRY_DSN: process.env.SENTRY_DSN,
    REDIS_URL: process.env.REDIS_URL,
    REDIS_KEY_PREFIX: process.env.REDIS_KEY_PREFIX,
    LOG_LEVEL: process.env.LOG_LEVEL,
    MAIL_HOST: process.env.MAIL_HOST,
    MAIL_PORT: process.env.MAIL_PORT,
    MAIL_USERNAME: process.env.MAIL_USERNAME,
    MAIL_PASSWORD: process.env.MAIL_PASSWORD,
    MAIL_FROM: process.env.MAIL_FROM,
    MAIL_RECIPIENTS: process.env.MAIL_RECIPIENTS,
  };
}

/**
 * Validated environment variables.
 * We use safeParse during build to avoid crashing the build process.
 */
const isBuildTime = process.env.NEXT_PHASE === 'phase-production-build';
const parsed = isBuildTime 
  ? envSchema.safeParse(getRawEnv())
  : { success: true, data: envSchema.parse(getRawEnv()) };

export const env = parsed.success ? parsed.data : envSchema.parse({});