'use strict';
const fs = require('fs');
const path = require('path');

const MAX_LOG_LINES = 500;
const LOG_FILE = path.join(__dirname, 'runtime.log');

class Logger {
  constructor() {
    this._logs = [];
    this._listeners = new Set();
    this._origLog = console.log;
    this._origError = console.error;
    this._origWarn = console.warn;
    this._capturing = false;
  }

  start() {
    if (this._capturing) return;
    this._capturing = true;

    const self = this;
    console.log = function() {
      const msg = Array.from(arguments).map(a => typeof a === 'object' ? JSON.stringify(a) : String(a)).join(' ');
      self._append('log', msg);
      self._origLog.apply(console, arguments);
    };
    console.error = function() {
      const msg = Array.from(arguments).map(a => typeof a === 'object' ? JSON.stringify(a) : String(a)).join(' ');
      self._append('error', msg);
      self._origError.apply(console, arguments);
    };
    console.warn = function() {
      const msg = Array.from(arguments).map(a => typeof a === 'object' ? JSON.stringify(a) : String(a)).join(' ');
      self._append('warn', msg);
      self._origWarn.apply(console, arguments);
    };
  }

  _append(level, message) {
    const entry = {
      time: new Date().toISOString(),
      level,
      message: message.slice(0, 2000),
    };
    this._logs.push(entry);
    if (this._logs.length > MAX_LOG_LINES) this._logs.shift();

    // Write to file
    try {
      const line = `[${entry.time}] [${level.toUpperCase()}] ${entry.message}\n`;
      fs.appendFileSync(LOG_FILE, line);
    } catch (_) {}

    // Notify SSE listeners
    for (const cb of this._listeners) {
      try { cb(entry); } catch (_) {}
    }
  }

  getLogs(count = 100) {
    return this._logs.slice(-count);
  }

  onLog(cb) {
    this._listeners.add(cb);
    return () => this._listeners.delete(cb);
  }

  stop() {
    console.log = this._origLog;
    console.error = this._origError;
    console.warn = this._origWarn;
    this._capturing = false;
    this._listeners.clear();
  }
}

module.exports = { Logger };