import { resolveLookup } from '../../resolvers'

const SIZES = new Map([
  [null, null],
  [250, 250],
  [500, 500],
  ['FULL', null],
  ['SMALL', 250],
  ['LARGE', 500]
])

function resolveImage(coverArt, args, { loaders }, info) {
  // Since migrating the schema to an extension, we lost custom enum values
  // for the time being. Translate any incoming `size` arg to the old enum
  // values.
  const size = SIZES.get(args.size)
  // Field should be `front` or `back`.
  const field = info.fieldName
  if (coverArt.images) {
    const matches = coverArt.images.filter(image => image[field])
    if (!matches.length) {
      return null
    } else if (matches.length === 1) {
      const match = matches[0]
      if (size === 250) {
        return match.thumbnails.small
      } else if (size === 500) {
        return match.thumbnails.large
      } else {
        return match.image
      }
    }
  }
  const entityType = coverArt._entityType
  const id = coverArt._id
  const releaseID = coverArt._releaseID
  if (entityType === 'release-group' && field === 'front') {
    // Release groups only have an endpoint to retrieve the front image.
    // If someone requests the back of a release group, return the back of the
    // release that the release group's cover art response points to.
    return loaders.coverArtArchiveURL.load(['release-group', id, field, size])
  } else {
    return loaders.coverArtArchiveURL.load(['release', releaseID, field, size])
  }
}

export default {
  CoverArtArchiveImage: {
    fileID: image => image.id
  },
  CoverArtArchiveRelease: {
    front: resolveImage,
    back: resolveImage,
    images: coverArt => coverArt.images,
    artwork: coverArt => coverArt.images.length > 0,
    count: coverArt => coverArt.images.length,
    release: (coverArt, args, context, info) => {
      const mbid = coverArt._releaseID
      if (mbid) {
        return resolveLookup(coverArt, { mbid }, context, info)
      }
      return null
    }
  },
  Release: {
    coverArtArchive: (release, args, { loaders }) => {
      return loaders.coverArtArchive.load(['release', release.id])
    }
  },
  ReleaseGroup: {
    coverArtArchive: (releaseGroup, args, { loaders }) => {
      return loaders.coverArtArchive.load(['release-group', releaseGroup.id])
    }
  }
}