import { useCallback, useState } from 'react'
import { Post, PostComment, PostMedia, PostReaction } from './posts.ts'
import { Temporal } from '@js-temporal/polyfill'
import { produce } from 'immer'

export interface PostInfo {
  postId: string
  authorName: string
  content: string
  createdAt: Temporal.Instant
  media: PostMedia[]
  possibleReactions: string[]
  comments: PostComment[]
}

type ReactionMap = Record<string, PostReaction[]>

export function usePostViewModel() {
  const [posts, _setPosts] = useState<PostInfo[]>([])
  const [reactions, setReactions] = useState<ReactionMap>({})

  const setPosts = useCallback((posts: Post[]) => {
    _setPosts([...posts])

    setReactions(
      posts.reduce((acc, post) => {
        acc[post.postId] = [...post.reactions]
        return acc
      }, {} as ReactionMap),
    )
  }, [])

  const addPosts = useCallback((posts: Post[]) => {
    _setPosts((current) => {
      return [...current, ...posts]
    })

    setReactions((current) =>
      produce(current, (draft) => {
        for (const post of posts) {
          draft[post.postId] = [...post.reactions]
        }
      }),
    )
  }, [])

  function addReaction(
    postId: string,
    emoji: string,
    authorName: string,
    reactedOn: Temporal.Instant,
  ) {
    setReactions((current) =>
      produce(current, (draft) => {
        if (draft[postId]?.some((r) => r.emoji === emoji && r.authorName == authorName)) {
          return
        }

        const reaction: PostReaction = { emoji, authorName, reactedOn }

        if (!draft[postId]) {
          draft[postId] = [{ ...reaction }]
        } else {
          draft[postId].push({ ...reaction })
        }
      }),
    )
  }

  function removeReaction(postId: string, emoji: string, authorName: string) {
    setReactions((current) =>
      produce(current, (draft) => {
        if (!draft[postId]) return

        draft[postId] = draft[postId].filter(
          (r) => r.emoji !== emoji || r.authorName !== authorName,
        )
      }),
    )
  }

  return { posts, reactions, addPosts, setPosts, addReaction, removeReaction }
}