<?php
// Define a constant to indicate index.php is included, not accessed directly
define('FILE_IS_INCLUDED', true);

// Include the index.php file, which contains shared configuration and logic
include('index.php');

// Only allow this script to run from the command line interface
if (php_sapi_name() !== 'cli') {
  error_deny();  // Deny access if run from a browser or non-CLI environment
}

/**
 * Main logic handler
 */
main();

/**
 * Main routine that processes domain updates based on `meta.json`.
 *
 * - Loads domain configuration data.
 * - Applies updates for domains where `"changed": 1`.
 * - Resets the change flag after successful update.
 * - Reloads NGINX only if at least one domain was updated.
 * - Saves the updated metadata back to disk.
 *
 * Exits with error code 1 on failure to save updated data.
 */
function main(): void {
  // Load content of meta.json
  $domains = loadJson(METAFILE);

  // Ensure meta is valid and contains domain entries
  if (isEmpty($domains)) {
    echo "No valid domains in meta.json\n";
    exit(1);
  }

  // Loop through all domains and apply updates if 'changed' flag is set
  $changed = false;
  foreach ($domains as $name => $meta) {
    if (!isset($meta['changed']) || !$meta['changed']) {
      continue;
    }

    // Process and detect if actual change occurred
    $changed |= processDomain($name, $meta);

    // Reset 'changed' flag after processing
    $domains[$name]['changed'] = 0;
  }

  // Restart nginx if any updates were made and save new state
  if ($changed) {
    shell_exec("sudo nginx -t && sudo systemctl reload nginx");
    echo "Reloaded nginx configuration.\n";

    // Save updated meta.json back to file
    if (!saveJson(METAFILE, $domains)) {
      exit(1);
    }
  }

  echo "All applicable domains processed.\n";
}

/**
 * Modify the proxy_pass value inside a specific location block
 */
function updateProxyPassInLocation(string $nginxConf, string $locationPath, string $newProxyPass): string {
  $lines          = explode("\n", $nginxConf); // Split config into lines
  $inBlock        = false;                     // Flag: inside target location block
  $locationStart  = false;
  $braceLevel     = 0;                         // Tracks nested braces

  foreach ($lines as $i => $line) {
    $escapedLocation = preg_quote($locationPath, '/');  // Escape location for regex
    if (preg_match("/^\s*location\s+$escapedLocation\s*\{\s*$/", $line)) {
      $inBlock        = true;
      $locationStart  = true;
      $braceLevel     = 1;
      continue;
    }

    if ($inBlock) {
      if (strpos($line, '{') !== false) $braceLevel++;
      if (strpos($line, '}') !== false) $braceLevel--;

      // Replace existing proxy_pass directive
      if (preg_match("/proxy_pass\\s+.+;/", $line)) {
         $lines[$i] = preg_replace("/proxy_pass\\s+.+;/", "proxy_pass $newProxyPass;", $line);
      }

      // Exit block if all braces are closed
      if ($braceLevel === 0) {
        $inBlock = false;
      }
    }
  }

  return implode("\n", $lines);  // Return modified config
}

/**
 * Processes a single domain configuration from meta.json.
 *
 * - Verifies all required fields are present and non-empty.
 * - Constructs the expected proxy_pass value from protocol, domain, and port.
 * - Replaces only the proxy_pass directive within the specified location block.
 * - If the config changes, it is saved and NGINX will be marked for reload.
 * - Even if no actual config differences are found, a restart can still be triggered
 *   by manually setting `"changed": 1` in meta.json.
 *
 * @param string $name The key in meta.json (usually target vhost name)
 * @param array  $meta The domain's metadata including IP, protocol, port, location, etc.
 * @return bool        True if a reload should be performed, false otherwise
 */
function processDomain(string $name, array $meta): bool {
  $requiredFields = ['domain', 'ip', 'protocol', 'port', 'location'];  // Required keys
  $missing        = [];
  $result         = false;

  // Collect any missing or empty required fields
  foreach ($requiredFields as $field) {
    if (isEmpty($meta[$field])) {
      $missing[] = $field;
    }
  }

  // Skip this domain if required fields are missing
  if (!isEmpty($missing)) {
    echo "Skipping '$name': missing or empty field(s): " . implode(', ', $missing) . "\n";
    return false;
  }

  // Allow forced reloads even without content change by setting "changed": 1 in meta.json
  $result = boolval($meta['changed'] ?? 1);
  if (!$result) {
    echo "No changes for $name\n";
    return false;
  }

  // Full path to nginx config file for this domain
  $systemConfPath = VHOST_BASE . '/' . $name . '/conf/' . NGINX_CONF_NAME;

  // Check file existence and permissions
  if (!file_exists($systemConfPath)) {
    echo "System config not found for $name\n";
    return false;
  }
  if (!is_readable($systemConfPath) || !is_writable($systemConfPath)) {
    echo "Permission denied for $systemConfPath\n";
    return false;
  }

  // Read current nginx config
  $original = file_get_contents($systemConfPath);

  // Build new proxy_pass target
  $proxyTarget = $meta['protocol'] . '://' . $meta['domain'] . ':' . $meta['port'];

  // Apply transformation inside matching location block
  $modified = updateProxyPassInLocation($original, $meta['location'], $proxyTarget);

  // Write only if content changed
  if ($original !== $modified) {
    $result = (file_put_contents($systemConfPath, $modified) !== false);
    echo "Updated proxy_pass for $name\n";
  } else {
    echo "No changes for $name\n";
  }

  return $result;
}