// server/cloudflare-worker/src/index.ts
// D3RO Voice — Global Cloudflare Edge Gateway & Proxy Worker

export interface Env {
  BACKEND_ORIGIN: string
  SERVICE_NAME?: string
}

const CORS_HEADERS: Record<string, string> = {
  'Access-Control-Allow-Origin': '*',
  'Access-Control-Allow-Methods': 'GET, POST, PUT, DELETE, PATCH, OPTIONS',
  'Access-Control-Allow-Headers': 'Content-Type, Authorization, X-Requested-With, Range',
  'Access-Control-Expose-Headers': 'Content-Length, Content-Range, X-D3RO-Status',
  'Access-Control-Max-Age': '86400',
}

export default {
  async fetch(request: Request, env: Env, _ctx: ExecutionContext): Promise<Response> {
    const url = new URL(request.url)

    // 1. Handle CORS Preflight (OPTIONS)
    if (request.method === 'OPTIONS') {
      return new Response(null, {
        status: 204,
        headers: CORS_HEADERS,
      })
    }

    // 2. Edge Health Check Ping (/worker-health)
    if (url.pathname === '/worker-health') {
      return new Response(
        JSON.stringify({
          status: 'Healthy',
          worker: env.SERVICE_NAME ?? 'D3RO Voice Edge Worker',
          backendOrigin: env.BACKEND_ORIGIN,
          timestamp: new Date().toISOString(),
          region: request.cf?.colo ?? 'global',
        }),
        {
          headers: {
            'Content-Type': 'application/json',
            ...CORS_HEADERS,
          },
        }
      )
    }

    // 3. Construct Target Backend URL
    const backendOrigin = (env.BACKEND_ORIGIN || 'https://d3ro.chanpaca.net').replace(/\/$/, '')
    const targetUrl = new URL(`${url.pathname}${url.search}`, backendOrigin)

    // Forward Headers
    const forwardHeaders = new Headers(request.headers)
    forwardHeaders.set('X-Forwarded-Host', url.host)
    forwardHeaders.set('X-Forwarded-Proto', url.protocol.replace(':', ''))
    forwardHeaders.set('X-D3RO-Edge-Proxy', 'Cloudflare-Worker')

    try {
      const response = await fetch(targetUrl.toString(), {
        method: request.method,
        headers: forwardHeaders,
        body: request.method !== 'GET' && request.method !== 'HEAD' ? request.body : undefined,
        redirect: 'follow',
      })

      // Clone response headers and attach CORS
      const newHeaders = new Headers(response.headers)
      for (const [key, value] of Object.entries(CORS_HEADERS)) {
        newHeaders.set(key, value)
      }

      return new Response(response.body, {
        status: response.status,
        statusText: response.statusText,
        headers: newHeaders,
      })
    } catch (err: unknown) {
      const errorMessage = err instanceof Error ? err.message : String(err)
      return new Response(
        JSON.stringify({
          error: 'EdgeGatewayError',
          message: `Unable to connect to origin NAS backend: ${errorMessage}`,
          targetUrl: targetUrl.toString(),
          timestamp: new Date().toISOString(),
        }),
        {
          status: 502,
          headers: {
            'Content-Type': 'application/json',
            ...CORS_HEADERS,
          },
        }
      )
    }
  },
}