'use strict';

const { PassThrough } = require('node:stream');
const { NxDebugAdapter } = require('./debugAdapter');

function frameMessage(message) {
  const json = JSON.stringify(message);
  return `Content-Length: ${Buffer.byteLength(json, 'utf8')}\r\n\r\n${json}`;
}

class NxInlineDebugAdapter {
  constructor() {
    this.input = new PassThrough();
    this.output = new PassThrough();
    this.outputBuffer = Buffer.alloc(0);
    this.listeners = new Set();
    this.disposed = false;

    this.onDidSendMessage = (listener, thisArgs, disposables) => {
      const registration = { listener, thisArgs };
      this.listeners.add(registration);
      const disposable = {
        dispose: () => this.listeners.delete(registration),
      };
      if (Array.isArray(disposables)) disposables.push(disposable);
      return disposable;
    };

    this.output.on('data', (chunk) => this.onOutput(chunk));
    this.adapter = new NxDebugAdapter(this.input, this.output);
  }

  handleMessage(message) {
    if (!this.disposed) this.input.write(frameMessage(message));
  }

  onOutput(chunk) {
    this.outputBuffer = Buffer.concat([this.outputBuffer, chunk]);
    while (true) {
      const headerEnd = this.outputBuffer.indexOf('\r\n\r\n');
      if (headerEnd < 0) return;
      const header = this.outputBuffer.subarray(0, headerEnd).toString('ascii');
      const match = /Content-Length:\s*(\d+)/i.exec(header);
      if (!match) throw new Error('missing DAP Content-Length header from NX adapter');
      const contentLength = Number(match[1]);
      const messageEnd = headerEnd + 4 + contentLength;
      if (this.outputBuffer.length < messageEnd) return;

      const payload = this.outputBuffer.subarray(headerEnd + 4, messageEnd).toString('utf8');
      this.outputBuffer = this.outputBuffer.subarray(messageEnd);
      const message = JSON.parse(payload);
      for (const { listener, thisArgs } of [...this.listeners]) {
        listener.call(thisArgs, message);
      }
    }
  }

  dispose() {
    if (this.disposed) return;
    this.disposed = true;
    this.adapter.dispose();
    this.input.end();
    this.output.destroy();
    this.listeners.clear();
  }
}

module.exports = { NxInlineDebugAdapter, frameMessage };