'use strict';

const fs = require('fs');
const os = require('os');
const path = require('path');

function parseClientVersion(text) {
  const raw = String(text).match(/^ClientVersion=(\d+)\s*$/m)?.[1] || '';
  if (!raw) return null;
  const version = Number(raw);
  return Number.isInteger(version) && version > 0 && version <= 0xffffffff ? version : null;
}

function parseVersionOverride(value) {
  const raw = String(value ?? '').trim();
  if (!raw) return null;
  if (!/^\d+$/.test(raw)) throw new Error('DOTA_CLIENT_VERSION must contain digits only.');
  const version = Number(raw);
  if (!Number.isInteger(version) || version < 1 || version > 0xffffffff) {
    throw new Error('DOTA_CLIENT_VERSION must be an unsigned 32-bit integer.');
  }
  return version;
}

function defaultSteamInfFiles() {
  const home = os.homedir();
  return [
    process.env.DOTA_STEAM_INF,
    path.join(home, '.local', 'share', 'Steam', 'steamapps', 'common', 'dota 2 beta', 'game', 'dota', 'steam.inf'),
    path.join(home, '.steam', 'steam', 'steamapps', 'common', 'dota 2 beta', 'game', 'dota', 'steam.inf'),
    path.join('/steam', 'steamapps', 'common', 'dota 2 beta', 'game', 'dota', 'steam.inf'),
  ].filter(Boolean);
}

function resolveDotaClientVersion(files = defaultSteamInfFiles()) {
  const override = parseVersionOverride(process.env.DOTA_CLIENT_VERSION);
  if (override) return { version: override, source: 'environment' };

  for (const file of [...new Set(files)]) {
    try {
      const version = parseClientVersion(fs.readFileSync(file, 'utf8'));
      if (version) return { version, source: file };
    } catch (err) {
      if (err.code !== 'ENOENT' && err.code !== 'ENOTDIR') {
        console.warn(`warn: could not read Dota client version ${file}: ${err.message}`);
      }
    }
  }
  return { version: null, source: null };
}

module.exports = {
  parseClientVersion,
  resolveDotaClientVersion,
};