const { compile } = require('@riotjs/compiler')
const  { Transformer } = require('@parcel/plugin')
const SourceMap = require('@parcel/source-map').default
const { basename } = require('path')

const CONFIG_FILES = ['.riotrc', '.riotrc.js', 'riot.config.js']
const PACKAGE_KEY = 'riot'

/**
 * Generate the hmr code depending on the tag generated by the compiler
 * @param   {string} path - path to the component file
 * @returns {string} the code needed to handle the riot hot reload
 */
function hotReload(path) {
  return `;(() => {
  if (module.hot) {
    const hotReload = require('@riotjs/hot-reload').default
    module.hot.accept()
    if (module.hot.data) {
      const component = require('./${path}').default;
      hotReload(component)
    }
  }
})()`
}

module.exports = new Transformer({
  async loadConfig({config}) {
    const riotConfig = await config.getConfig(
      CONFIG_FILES,
      {
        packageKey: PACKAGE_KEY
      }
    )
    const shouldInvalidateOnStartup = riotConfig &&
      riotConfig?.filePath?.endsWith('.js') ||
      riotConfig?.filePath?.endsWith(CONFIG_FILES[0])

    if (shouldInvalidateOnStartup) {
      config.invalidateOnStartup()
    }

    return riotConfig?.contents ?? {}
  },
  async transform({asset, config, options}) {
    const source = await asset.getCode()
    const sourceMap = new SourceMap(options.projectRoot)

    const {code, map} = compile(source, {
      file: asset.filePath,
      ...config
    })
    
    // the suffix will be added only for the HMR
    const suffix = config?.hot ? hotReload(basename(asset.filePath)) : ''

    asset.type = 'js'
    asset.setCode(`${code}${suffix}`)
    asset.setMap(sourceMap.addVLQMap(map))

    return [asset]
  }
})