/**
 * Standalone test agent — connects to the tunnel server and forwards
 * inbound requests to a local port. Use this to validate Phase 1
 * before the Electron app exists.
 *
 * Usage:
 *   TUNNEL_SERVER=ws://localhost:3002 \
 *   TUNNEL_ID=<uuid> \
 *   TOKEN=<accessToken> \
 *   LOCAL_PORT=11434 \
 *   npm run agent
 */

import 'dotenv/config';
import WebSocket from 'ws';
import http from 'http';

const SERVER     = process.env.TUNNEL_SERVER ?? 'ws://localhost:3002';
const TUNNEL_ID  = process.env.TUNNEL_ID ?? '';
const TOKEN      = process.env.TOKEN ?? '';
const LOCAL_PORT = Number( process.env.LOCAL_PORT ?? 11434 );
const RECONNECT_DELAY_MS = 3_000;

if ( !TUNNEL_ID || !TOKEN )
{
  console.error( 'TUNNEL_ID and TOKEN env vars are required' );
  process.exit( 1 );
}

interface RelayRequest
{
  reqId: string;
  method: string;
  path: string;
  headers: Record<string, string>;
  body: string; // base64
}

interface RelayResponse
{
  reqId: string;
  status: number;
  headers: Record<string, string>;
  body: string; // base64
}

function forward( req: RelayRequest, ws: WebSocket ): void
{
  const bodyBuf = Buffer.from( req.body, 'base64' );

  const options: http.RequestOptions = {
    hostname: 'localhost',
    port: LOCAL_PORT,
    path: req.path,
    method: req.method,
    headers: {
      ...req.headers,
      'content-length': String( bodyBuf.length ),
    },
  };

  const chunks: Buffer[] = [];

  const localReq = http.request( options, ( localRes ) =>
  {
    localRes.on( 'data', chunk => chunks.push( Buffer.from( chunk ) ) );
    localRes.on( 'end', () =>
    {
      const respHeaders: Record<string, string> = {};
      for ( const [ k, v ] of Object.entries( localRes.headers ) )
      {
        if ( typeof v === 'string' ) respHeaders[ k ] = v;
        else if ( Array.isArray( v ) ) respHeaders[ k ] = v.join( ', ' );
      }

      const resp: RelayResponse = {
        reqId: req.reqId,
        status: localRes.statusCode ?? 200,
        headers: respHeaders,
        body: Buffer.concat( chunks ).toString( 'base64' ),
      };
      ws.send( JSON.stringify( resp ) );
    } );
  } );

  localReq.on( 'error', ( err ) =>
  {
    console.error( `[agent] local request failed: ${ err.message }` );
    const errResp: RelayResponse = {
      reqId: req.reqId,
      status: 502,
      headers: { 'content-type': 'application/json' },
      body: Buffer.from( JSON.stringify( { error: 'Local service error', detail: err.message } ) )
            .toString( 'base64' ),
    };
    ws.send( JSON.stringify( errResp ) );
  } );

  if ( bodyBuf.length > 0 ) localReq.write( bodyBuf );
  localReq.end();
}

function connect(): void
{
  const url = `${ SERVER }/api/agent/${ TUNNEL_ID }?token=${ TOKEN }`;
  const ws = new WebSocket( url );

  ws.on( 'open', () =>
    console.log( `[agent] connected → forwarding to localhost:${ LOCAL_PORT }` )
  );

  ws.on( 'message', ( data ) =>
  {
    try
    {
      const req: RelayRequest = JSON.parse( data.toString() );
      console.log( `[agent] → ${ req.method } ${ req.path }` );
      forward( req, ws );
    }
    catch ( err )
    {
      console.error( '[agent] failed to parse message:', err );
    }
  } );

  ws.on( 'close', ( code, reason ) =>
  {
    console.log( `[agent] disconnected (${ code }: ${ reason }). Reconnecting in ${ RECONNECT_DELAY_MS / 1000 }s...` );
    setTimeout( connect, RECONNECT_DELAY_MS );
  } );

  ws.on( 'error', ( err ) => console.error( '[agent] error:', err.message ) );
}

connect();