const fs = require('fs');
const path = require('path');
const YAML = require('yaml');

const configPath = path.join(__dirname, 'app.yaml');

function toInt(value, fallback) {
  const parsed = Number.parseInt(value, 10);
  return Number.isFinite(parsed) ? parsed : fallback;
}

function loadYamlConfig(filePath) {
  if (!fs.existsSync(filePath)) {
    throw new Error(`config file not found: ${filePath}`);
  }

  const raw = fs.readFileSync(filePath, 'utf8');
  return YAML.parse(raw) || {};
}

function buildConfig() {
  const parsed = loadYamlConfig(configPath);
  const host = parsed.host || {};
  const instrumentEntities = Object.entries(parsed)
    .filter(([key, value]) => key !== 'host' && key !== 'instruments' && value && typeof value === 'object')
    .map(([instrumentId, value]) => ({ instrument_id: instrumentId, ...value }));

  return {
    env: host.env || 'development',
    db: {
      path: host.db?.path || 'middleware/data/workstation.sqlite',
      busyTimeout: toInt(host.db?.busyTimeout, 5000)
    },
    connectors: {
      httpJsonPort: toInt(host.connectors?.httpJsonPort, 3001),
      hl7TcpPort: toInt(host.connectors?.hl7TcpPort, 3002),
      astmSerialPath: host.connectors?.astmSerialPath || 'COM1',
      astmSerialBaudRate: toInt(host.connectors?.astmSerialBaudRate, 9600),
      astmSerialDataBits: toInt(host.connectors?.astmSerialDataBits, 8),
      astmSerialStopBits: toInt(host.connectors?.astmSerialStopBits, 1),
      astmSerialParity: host.connectors?.astmSerialParity || 'none'
    },
    clqms: {
      url: host.url || host.clqms?.url || '',
      token: host.apikey || host.clqms?.token || '',
      timeout: toInt(host.clqms?.timeout, 8000)
    },
    healthPort: toInt(host.port || host.healthPort, 4001),
    worker: {
      pollInterval: toInt(host.worker?.pollInterval, 5000),
      batchSize: toInt(host.worker?.batchSize, 5),
      lockTTLSeconds: toInt(host.worker?.lockTTLSeconds, 60),
      workerId: host.worker?.workerId || 'worker-default'
    },
    retries: {
      schedule: host.retries?.schedule || [30, 120, 600, 1800, 7200, 21600],
      maxAttempts: toInt(host.retries?.maxAttempts, 10)
    },
    instruments: Array.isArray(parsed.instruments) ? parsed.instruments : [],
    instrumentEntities,
    configPath
  };
}

module.exports = buildConfig();