// env-loader.js
// This module is responsible for loading environment variables for the PWA

// Store environment variables in a global object
window.ENV_CONFIG = {
  // Default values that will be overridden when config.env.js loads
  PUBLIC_VAPID_KEY: 'your_public_vapid_key_here',
  BACKEND_URL: 'https://your-push-server.example.com'
};

// Function to load environment variables from config.env.js
async function loadEnvVariables() {
  try {
    // Try to fetch the config.env.js file which will be generated at build time or deployment
    const response = await fetch('/config.env.js');
    
    if (!response.ok) {
      console.warn('Could not load config.env.js file. Using default values.');
      return;
    }
    
    const configText = await response.text();
    
    // Extract the configuration object from the JavaScript file
    // The file should be in format: window.ENV_CONFIG = { key: "value" };
    try {
      // Create a safe way to evaluate the config file
      const configScript = document.createElement('script');
      configScript.textContent = configText;
      document.head.appendChild(configScript);
      document.head.removeChild(configScript);
      
      console.log('Environment variables loaded successfully from config.env.js');
      
      // Dispatch an event to notify that environment variables have been loaded
      window.dispatchEvent(new CustomEvent('env-config-loaded', { 
        detail: { config: window.ENV_CONFIG } 
      }));
    } catch (parseError) {
      console.error('Error parsing config.env.js:', parseError);
    }
  } catch (error) {
    console.error('Error loading environment variables:', error);
  }
}

// Export function to initialize environment variables
export async function initEnv() {
  await loadEnvVariables();
  return window.ENV_CONFIG;
}

// Start loading environment variables immediately
initEnv();

// Export access functions for environment variables
export function getEnv(key, defaultValue = '') {
  return window.ENV_CONFIG[key] || defaultValue;
}

// Export a function to wait for environment variables to be loaded
export function waitForEnv() {
  return new Promise((resolve) => {
    // If we already have non-default values, resolve immediately
    if (window.ENV_CONFIG.BACKEND_URL !== 'https://your-push-server.example.com') {
      resolve(window.ENV_CONFIG);
      return;
    }
    
    // Otherwise, wait for the env-config-loaded event
    window.addEventListener('env-config-loaded', (event) => {
      resolve(event.detail.config);
    }, { once: true });
    
    // Set a timeout to resolve with current values if loading takes too long
    setTimeout(() => {
      console.warn('Environment loading timed out, using current values');
      resolve(window.ENV_CONFIG);
    }, 3000);
  });
}

export default {
  initEnv,
  getEnv,
  waitForEnv
};