import { createEffect, createMemo, createSignal, For, onMount, Show } from 'solid-js'
import type { Topic } from '../../graphql/types.gen'

import { setTopicsSort, useTopicsStore } from '../../stores/zine/topics'
import { useRouter } from '../../stores/router'
import { TopicCard } from '../Topic/Card'
import { clsx } from 'clsx'
import { useSession } from '../../context/session'
import { translit } from '../../utils/ru2en'
import styles from '../../styles/AllTopics.module.scss'
import { SearchField } from '../_shared/SearchField'
import { scrollHandler } from '../../utils/scroll'
import { StatMetrics } from '../_shared/StatMetrics'
import { useLocalize } from '../../context/localize'

type AllTopicsPageSearchParams = {
  by: 'shouts' | 'authors' | 'title' | ''
}

type AllTopicsViewProps = {
  topics: Topic[]
}

const PAGE_SIZE = 20
const ALPHABET = [...'АБВГДЕЁЖЗИЙКЛМНОПРСТУФХЦЧШЩЪЫЬЭЮЯ#']

export const AllTopicsView = (props: AllTopicsViewProps) => {
  const { t, lang } = useLocalize()
  const { searchParams, changeSearchParam } = useRouter<AllTopicsPageSearchParams>()
  const [limit, setLimit] = createSignal(PAGE_SIZE)

  const { sortedTopics } = useTopicsStore({
    topics: props.topics,
    sortBy: searchParams().by || 'shouts'
  })

  const { session } = useSession()

  onMount(() => {
    if (!searchParams().by) {
      changeSearchParam('by', 'shouts')
    }
  })

  createEffect(() => {
    setTopicsSort(searchParams().by || 'shouts')
  })

  const byLetter = createMemo<{ [letter: string]: Topic[] }>(() => {
    return sortedTopics().reduce((acc, topic) => {
      let letter = topic.title[0].toUpperCase()
      if (/[^ËА-яё]/.test(letter) && lang() === 'ru') letter = '#'
      if (!acc[letter]) acc[letter] = []
      acc[letter].push(topic)
      return acc
    }, {} as { [letter: string]: Topic[] })
  })

  const sortedKeys = createMemo<string[]>(() => {
    const keys = Object.keys(byLetter())
    keys.sort()
    keys.push(keys.shift())
    return keys
  })

  const subscribed = (s) => Boolean(session()?.news?.topics && session()?.news?.topics?.includes(s || ''))

  const showMore = () => setLimit((oldLimit) => oldLimit + PAGE_SIZE)

  const [searchQuery, setSearchQuery] = createSignal('')

  const filteredResults = createMemo(() => {
    /* very stupid filter by string algorithm with no deps */
    let q = searchQuery().toLowerCase()
    if (q.length === 0) {
      return sortedTopics()
    }

    if (lang() === 'ru') {
      q = translit(q)
    }

    return sortedTopics().filter((topic) => {
      if (topic.slug.split('-').some((w) => w.startsWith(q))) {
        return true
      }

      let title = topic.title.toLowerCase()
      if (lang() === 'ru') {
        title = translit(title)
      }

      return title.split(' ').some((word) => word.startsWith(q))
    })
  })

  const AllTopicsHead = () => (
    <div class="row">
      <div class="col-lg-20 col-xl-18">
        <h1>{t('Topics')}</h1>
        <p>{t('Subscribe what you like to tune your personal feed')}</p>

        <ul class={clsx(styles.viewSwitcher, 'view-switcher')}>
          <li classList={{ selected: searchParams().by === 'shouts' }}>
            <a href="/topics?by=shouts">{t('By shouts')}</a>
          </li>
          <li classList={{ selected: searchParams().by === 'authors' }}>
            <a href="/topics?by=authors">{t('By authors')}</a>
          </li>
          <li classList={{ selected: searchParams().by === 'title' }}>
            <a href="/topics?by=title">{t('By title')}</a>
          </li>
          <Show when={searchParams().by !== 'title'}>
            <li class="view-switcher__search">
              <SearchField onChange={(value) => setSearchQuery(value)} />
            </li>
          </Show>
        </ul>
      </div>
    </div>
  )

  return (
    <div class={clsx(styles.allTopicsPage, 'wide-container')}>
      <div class="row">
        <div class="col-md-19 offset-md-5">
          <AllTopicsHead />

          <Show when={filteredResults().length > 0}>
            <Show when={searchParams().by === 'title'}>
              <div class="col-lg-20 col-xl-18">
                <ul class={clsx('nodash', styles.alphabet)}>
                  <For each={ALPHABET}>
                    {(letter, index) => (
                      <li>
                        <Show when={letter in byLetter()} fallback={letter}>
                          <a
                            href={`/topics?by=title#letter-${index()}`}
                            onClick={(event) => {
                              event.preventDefault()
                              scrollHandler(`letter-${index()}`)
                            }}
                          >
                            {letter}
                          </a>
                        </Show>
                      </li>
                    )}
                  </For>
                </ul>
              </div>

              <For each={sortedKeys()}>
                {(letter) => (
                  <div class={clsx(styles.group, 'group')}>
                    <h2 id={`letter-${ALPHABET.indexOf(letter)}`}>{letter}</h2>
                    <div class="container">
                      <div class="row">
                        <div class="col-lg-20">
                          <div class="row">
                            <For each={byLetter()[letter]}>
                              {(topic) => (
                                <div class={clsx(styles.topic, 'topic col-sm-12 col-md-8')}>
                                  <a href={`/topic/${topic.slug}`}>{topic.title}</a>
                                  <span class={styles.articlesCounter}>{topic.stat.shouts}</span>
                                </div>
                              )}
                            </For>
                          </div>
                        </div>
                      </div>
                    </div>
                  </div>
                )}
              </For>
            </Show>

            <Show when={searchParams().by && searchParams().by !== 'title'}>
              <For each={filteredResults().slice(0, limit())}>
                {(topic) => (
                  <>
                    <TopicCard
                      topic={topic}
                      compact={false}
                      subscribed={subscribed(topic.slug)}
                      showPublications={true}
                    />
                    <StatMetrics fields={['shouts', 'authors', 'followers']} stat={topic.stat} />
                  </>
                )}
              </For>
            </Show>

            <Show when={filteredResults().length > limit() && searchParams().by !== 'title'}>
              <div class={clsx(styles.loadMoreContainer, 'col-24 col-md-20 col-lg-14 offset-md-2')}>
                <button class={clsx('button', styles.loadMoreButton)} onClick={showMore}>
                  {t('Load more')}
                </button>
              </div>
            </Show>
          </Show>
        </div>
      </div>
    </div>
  )
}