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

let dienstenCache = null

function getDienstenDir() {
  if (!process.env.DIENSTEN_DIR) {
    throw new Error('DIENSTEN_DIR is required; configure the canonical Whatsapp_Dienst/diensten directory')
  }
  return path.resolve(process.env.DIENSTEN_DIR)
}

function loadDiensten() {
  if (dienstenCache) return dienstenCache

  const dienstenDir = getDienstenDir()
  const jsonPath = path.join(dienstenDir, 'dienst-tijden.json')
  let raw
  try {
    raw = fs.readFileSync(jsonPath, 'utf-8')
  } catch (err) {
    throw new Error(`Failed to read canonical diensten JSON at ${jsonPath}: ${err.message}`)
  }

  try {
    dienstenCache = JSON.parse(raw)
  } catch (err) {
    throw new Error(`Failed to parse canonical diensten JSON at ${jsonPath}: ${err.message}`)
  }

  return dienstenCache
}

function findDienst(dienstnummer) {
  const diensten = loadDiensten()
  return diensten.find(d => String(d.dienstnummer) === dienstnummer) || null
}

function getPngFilePaths(dienst) {
  const pngDir = path.join(getDienstenDir(), 'png')
  return dienst.paginas.map(p => path.join(pngDir, p.bestandsnaam))
}

module.exports = { loadDiensten, findDienst, getPngFilePaths }