import { ServiceImpl } from '@connectrpc/connect'
import { Service } from '../../../proto/bsky_connect.js'
import { FeedType } from '../../../proto/bsky_pb.js'
import { Database } from '../db/index.js'
import { TimeCidKeyset, paginate } from '../db/pagination.js'

export default (db: Database): Partial<ServiceImpl<typeof Service>> => ({
  async getAuthorFeed(req) {
    const { actorDid, limit, cursor, feedType } = req
    const { ref } = db.db.dynamic

    // defaults to posts, reposts, and replies
    let builder = db.db
      .selectFrom('feed_item')
      .innerJoin('post', 'post.uri', 'feed_item.postUri')
      .selectAll('feed_item')
      .where('originatorDid', '=', actorDid)

    if (feedType === FeedType.POSTS_WITH_MEDIA) {
      builder = builder
        // only your own posts
        .where('type', '=', 'post')
        // only posts with media
        .whereExists((qb) =>
          qb
            .selectFrom('post_embed_image')
            .select('post_embed_image.postUri')
            .whereRef('post_embed_image.postUri', '=', 'feed_item.postUri'),
        )
    } else if (feedType === FeedType.POSTS_WITH_VIDEO) {
      builder = builder
        // only your own posts
        .where('type', '=', 'post')
        // only posts with video
        .whereExists((qb) =>
          qb
            .selectFrom('post_embed_video')
            .select('post_embed_video.postUri')
            .whereRef('post_embed_video.postUri', '=', 'feed_item.postUri'),
        )
    } else if (feedType === FeedType.POSTS_NO_REPLIES) {
      builder = builder.where((qb) =>
        qb.where('post.replyParent', 'is', null).orWhere('type', '=', 'repost'),
      )
    } else if (feedType === FeedType.POSTS_AND_AUTHOR_THREADS) {
      builder = builder.where((qb) =>
        qb
          .where('type', '=', 'repost')
          .orWhere('post.replyParent', 'is', null)
          .orWhere('post.replyRoot', 'like', `at://${actorDid}/%`),
      )
    }

    const keyset = new TimeCidKeyset(
      ref('feed_item.sortAt'),
      ref('feed_item.cid'),
    )

    builder = paginate(builder, {
      limit,
      cursor,
      keyset,
    })

    const feedItems = await builder.execute()

    return {
      items: feedItems.map(feedItemFromRow),
      cursor: keyset.packFromResult(feedItems),
    }
  },

  async getTimeline(req) {
    const { actorDid, limit, cursor } = req
    const { ref } = db.db.dynamic

    const keyset = new TimeCidKeyset(
      ref('feed_item.sortAt'),
      ref('feed_item.cid'),
    )

    let followQb = db.db
      .selectFrom('feed_item')
      .innerJoin('follow', 'follow.subjectDid', 'feed_item.originatorDid')
      .where('follow.creator', '=', actorDid)
      .selectAll('feed_item')

    followQb = paginate(followQb, {
      limit,
      cursor,
      keyset,
      tryIndex: true,
    })

    let selfQb = db.db
      .selectFrom('feed_item')
      .where('feed_item.originatorDid', '=', actorDid)
      .selectAll('feed_item')

    selfQb = paginate(selfQb, {
      limit: Math.min(limit, 10),
      cursor,
      keyset,
      tryIndex: true,
    })

    const [followRes, selfRes] = await Promise.all([
      followQb.execute(),
      selfQb.execute(),
    ])

    const feedItems = [...followRes, ...selfRes]
      .sort((a, b) => {
        if (a.sortAt > b.sortAt) return -1
        if (a.sortAt < b.sortAt) return 1
        return a.cid > b.cid ? -1 : 1
      })
      .slice(0, limit)

    return {
      items: feedItems.map(feedItemFromRow),
      cursor: keyset.packFromResult(feedItems),
    }
  },

  async getListFeed(req) {
    const { listUri, cursor, limit } = req
    const { ref } = db.db.dynamic

    let builder = db.db
      .selectFrom('post')
      .selectAll('post')
      .innerJoin('list_item', 'list_item.subjectDid', 'post.creator')
      .where('list_item.listUri', '=', listUri)

    const keyset = new TimeCidKeyset(ref('post.sortAt'), ref('post.cid'))
    builder = paginate(builder, {
      limit,
      cursor,
      keyset,
      tryIndex: true,
    })
    const feedItems = await builder.execute()

    return {
      items: feedItems.map((item) => ({ uri: item.uri, cid: item.cid })),
      cursor: keyset.packFromResult(feedItems),
    }
  },
})

// @NOTE does not support additional fields in the protos specific to author feeds
// and timelines. at the time of writing, hydration/view implementations do not rely on them.
const feedItemFromRow = (row: { postUri: string; uri: string }) => {
  return {
    uri: row.postUri,
    repost: row.uri === row.postUri ? undefined : row.uri,
  }
}