/**
 * Cloudflare Worker: Dynamic Edge JSON Minifier & Cache Gateway
 */
export default {
  async fetch(request: Request, env: any, ctx: ExecutionContext): Promise<Response> {
    // 1. Fetch response from Origin API server
    const response = await fetch(request);

    // Only process successful HTTP 200 responses returning JSON content
    const contentType = response.headers.get('content-type') || '';
    if (response.status !== 200 || !contentType.includes('application/json')) {
      return response;
    }

    // 2. Clone response headers and adjust metadata
    const newHeaders = new Headers(response.headers);
    newHeaders.set('X-Edge-Minified', 'true');

    // Read origin JSON text
    const rawJsonText = await response.text();

    try {
      // 3. Perform high-speed state-machine minification at the Edge
      const minifiedJson = minifyJsonEdge(rawJsonText);
      newHeaders.set('Content-Length', String(new Blob([minifiedJson]).size));

      return new Response(minifiedJson, {
        status: response.status,
        statusText: response.statusText,
        headers: newHeaders,
      });
    } catch (e) {
      // If minification fails due to malformed origin JSON, fallback gracefully
      return new Response(rawJsonText, {
        status: response.status,
        headers: response.headers,
      });
    }
  },
};

/**
 * Lightweight, zero-allocation state-machine JSON minifier for Edge Isolates
 */
function minifyJsonEdge(input: string): string {
  let out = '';
  let inString = false;
  let isEscaped = false;

  for (let i = 0; i < input.length; i++) {
    const char = input[i];

    if (inString) {
      out += char;
      if (isEscaped) {
        isEscaped = false;
      } else if (char === '\\') {
        isEscaped = true;
      } else if (char === '"') {
        inString = false;
      }
    } else {
      if (char === '"') {
        inString = true;
        out += char;
      } else if (char !== ' ' && char !== '\n' && char !== '\r' && char !== '\t') {
        out += char;
      }
    }
  }

  return out;
}