import { useEffect, useState } from 'react'
import { Link, useParams, useNavigate } from 'react-router-dom'
import { SearchableSelect } from '../components/SearchableSelect'
import { ImageCropper } from '../components/ImageCropper'
import { TagInput } from '../components/TagInput'
import { RichTextEditor } from '../components/RichTextEditor'
import { Breadcrumbs } from '../components/Breadcrumbs'
import { useToast } from '../context/ToastContext'
import { useT } from '../i18n/useT'
import { ApiError } from '../lib/api'
import {
  listInstructionCategories,
  mapInstructionCategoryToUi,
} from '../services/instructionCategoryService'
import {
  resolveDataUrlToMediaId,
  resolveHtmlEmbeddedDataUrls,
} from '../services/mediaService'
import {
  createInstruction,
  getInstruction,
  mapInstructionApiToFormState,
  updateInstruction,
} from '../services/instructionService'
import type { Category } from '../types/category'
import type { VideoProvider } from '../types/instruction'
import { VIDEO_PROVIDER_OPTIONS } from '../types/instruction'
import { flattenCategories } from '../utils/categories'
import pageStyles from '../components/PageContent.module.css'
import styles from './AddNewProductPage.module.css'

export function AddNewInstructionPage() {
  const { id } = useParams()
  const navigate = useNavigate()
  const { showToast } = useToast()
  const t = useT()
  const isEdit = Boolean(id)

  const [categories, setCategories] = useState<Category[]>([])
  const [categoryId, setCategoryId] = useState('')
  const [titleFa, setTitleFa] = useState('')
  const [titleEn, setTitleEn] = useState('')
  const [abstract, setAbstract] = useState('')
  const [descriptionHtml, setDescriptionHtml] = useState('')
  const [videoProvider, setInstructionProvider] = useState<VideoProvider>('youtube')
  const [embedCode, setEmbedCode] = useState('')
  const [coverImage, setCoverImage] = useState<string | null>(null)
  const [tags, setTags] = useState<string[]>([])
  const [featuredMediaId, setFeaturedMediaId] = useState<string | null>(null)
  const [loaded, setLoaded] = useState(!isEdit)
  const [isSubmitting, setIsSubmitting] = useState(false)
  const [error, setError] = useState('')

  const categoryOptions = flattenCategories(categories)

  useEffect(() => {
    const controller = new AbortController()

    async function loadCategories() {
      try {
        const items = await listInstructionCategories(controller.signal)
        setCategories(items.map(mapInstructionCategoryToUi))
      } catch (err) {
        if (err instanceof DOMException && err.name === 'AbortError') return
        if (err instanceof ApiError) {
          setError(err.message)
        } else {
          setError(t('instruction.categories.errorLoad'))
        }
      }
    }

    void loadCategories()
    return () => controller.abort()
  }, [])

  useEffect(() => {
    if (!isEdit || !id) return

    const controller = new AbortController()

    async function loadVideo() {
      setError('')
      try {
        const video = await getInstruction(id!, controller.signal)
        const form = mapInstructionApiToFormState(video)
        setCategoryId(form.categoryId)
        setTitleFa(form.titleFa)
        setTitleEn(form.titleEn)
        setAbstract(form.abstract)
        setDescriptionHtml(form.descriptionHtml)
        setInstructionProvider(form.videoProvider)
        setEmbedCode(form.embedCode)
        setCoverImage(form.coverImage)
        setTags(form.tags)
        setFeaturedMediaId(form.featuredMediaId)
        setLoaded(true)
      } catch (err) {
        if (err instanceof DOMException && err.name === 'AbortError') return
        navigate('/instructions/list', { replace: true })
      }
    }

    void loadVideo()
    return () => controller.abort()
  }, [isEdit, id, navigate])

  if (!loaded) return null

  async function handleSubmit(e: React.FormEvent<HTMLFormElement>) {
    e.preventDefault()
    setIsSubmitting(true)
    setError('')

    try {
      const nextFeaturedMediaId = await resolveDataUrlToMediaId(
        coverImage,
        'instruction-cover-image.jpg',
        featuredMediaId,
      )
      const resolvedDescriptionHtml = await resolveHtmlEmbeddedDataUrls(descriptionHtml)

      const trimmedEmbed = embedCode.trim()
      const payload = {
        titleFa: titleFa.trim(),
        titleEn: titleEn.trim() || undefined,
        abstract: abstract.trim(),
        descriptionHtml: resolvedDescriptionHtml,
        videoProvider: trimmedEmbed ? videoProvider : undefined,
        embedCode: trimmedEmbed || undefined,
        categoryId: categoryId || undefined,
        featuredMediaId: nextFeaturedMediaId ?? undefined,
        tags,
        status: 'published' as const,
      }

      if (isEdit && id) {
        await updateInstruction(id, {
          ...payload,
          categoryId: categoryId || null,
          featuredMediaId: nextFeaturedMediaId,
        })
        showToast(t('instruction.form.toast.updated'), 'success')
      } else {
        await createInstruction(payload)
        showToast(t('instruction.form.toast.created'), 'success')
      }

      navigate('/instructions/list')
    } catch (err) {
      if (err instanceof ApiError) {
        setError(err.message)
      } else if (err instanceof Error) {
        setError(err.message)
      } else {
        setError(t('instruction.form.errorSave'))
      }
    } finally {
      setIsSubmitting(false)
    }
  }

  return (
    <main className={pageStyles.content}>
      <Breadcrumbs
        items={
          isEdit
            ? [
                { label: 'Dashboard', href: '/' },
                { label: 'Instructions', href: '/instructions' },
                { label: 'My Instructions', href: '/instructions/list' },
                { label: 'Edit Instruction' },
              ]
            : [
                { label: 'Dashboard', href: '/' },
                { label: 'Instructions', href: '/instructions' },
                { label: 'Add New Instruction' },
              ]
        }
      />
      <div className={pageStyles.pageHeader}>
        <div>
          <h2 className={pageStyles.pageTitle}>
            {isEdit ? t('title.editInstruction') : t('title.addInstruction')}
          </h2>
          <p className={pageStyles.pageSubtitle}>
            {isEdit ? t('instruction.form.edit.subtitle') : t('instruction.form.add.subtitle')}
          </p>
        </div>
      </div>

      {error && (
        <div className={styles.error} role="alert">
          {error}
        </div>
      )}

      <form className={styles.form} onSubmit={handleSubmit}>
        <div className={styles.formGrid}>
          <div className={`${styles.field} ${styles.col3} ${styles.rowSpan4}`}>
            <label>{t('instruction.form.coverImage')}</label>
            <ImageCropper
              value={coverImage}
              onChange={setCoverImage}
              aspect={3 / 2}
              uploadLabel={t('instruction.form.uploadCoverImage')}
              hint={t('instruction.form.cropHint')}
              changeLabel={t('instruction.form.changeCoverImage')}
            />
          </div>

          <div className={styles.formColumn}>
            <div className={styles.field}>
              <label>{t('instruction.form.category')}</label>
              <SearchableSelect
                options={categoryOptions}
                value={categoryId}
                onChange={setCategoryId}
                placeholder={t('instruction.form.categoryPlaceholder')}
              />
            </div>

            <div className={styles.titleRow}>
              <div className={styles.field}>
                <label htmlFor="instruction-title-fa">{t('instruction.form.titleFa')}</label>
                <input
                  id="instruction-title-fa"
                  name="titleFa"
                  type="text"
                  dir="rtl"
                  lang="fa"
                  className="faText"
                  placeholder={t('instruction.form.titleFaPlaceholder')}
                  value={titleFa}
                  onChange={(e) => setTitleFa(e.target.value)}
                  required
                  disabled={isSubmitting}
                />
              </div>

              <div className={styles.field}>
                <label htmlFor="instruction-title-en">{t('instruction.form.titleEn')}</label>
                <input
                  id="instruction-title-en"
                  name="titleEn"
                  type="text"
                  dir="ltr"
                  placeholder={t('instruction.form.titleEnPlaceholder')}
                  value={titleEn}
                  onChange={(e) => setTitleEn(e.target.value)}
                  disabled={isSubmitting}
                />
              </div>
            </div>

            <div className={styles.field}>
              <label htmlFor="instruction-abstract">{t('instruction.form.abstract')}</label>
              <textarea
                id="instruction-abstract"
                name="abstract"
                rows={4}
                placeholder={t('instruction.form.abstractPlaceholder')}
                value={abstract}
                onChange={(e) => setAbstract(e.target.value)}
                required
                disabled={isSubmitting}
              />
            </div>
          </div>

          <div className={styles.videoEmbedRow}>
            <div className={styles.providerPanel}>
              <span className={styles.providerLabel}>{t('instruction.form.provider')}</span>
              <div
                className={styles.providerRadioGroup}
                role="radiogroup"
                aria-label={t('instruction.form.provider')}
              >
                {VIDEO_PROVIDER_OPTIONS.map((option) => (
                  <label key={option.value} className={styles.providerRadioOption}>
                    <input
                      type="radio"
                      name="videoProvider"
                      value={option.value}
                      checked={videoProvider === option.value}
                      onChange={() => setInstructionProvider(option.value)}
                      disabled={isSubmitting}
                    />
                    <span>{option.label}</span>
                  </label>
                ))}
              </div>
            </div>

            <div className={styles.embedPanel}>
              <label htmlFor="instruction-embed">{t('instruction.form.embedCode')}</label>
              <textarea
                id="instruction-embed"
                name="embedCode"
                rows={5}
                dir="ltr"
                placeholder={t('instruction.form.embedCodePlaceholder')}
                value={embedCode}
                onChange={(e) => setEmbedCode(e.target.value)}
                disabled={isSubmitting}
              />
            </div>
          </div>

          <div className={`${styles.field} ${styles.col12}`}>
            <label>{t('instruction.form.description')}</label>
            <RichTextEditor
              value={descriptionHtml}
              onChange={setDescriptionHtml}
              placeholder={t('instruction.form.descriptionPlaceholder')}
              allowImages
              editorMinHeight={320}
            />
          </div>

          <div className={`${styles.field} ${styles.col12}`}>
            <label>{t('instruction.form.tags')}</label>
            <TagInput tags={tags} onChange={setTags} />
          </div>
        </div>

        <div className={styles.actions}>
          <Link to="/instructions/list" className={styles.cancelBtn}>
            {t('instruction.form.cancel')}
          </Link>
          <button type="submit" className={styles.submitBtn} disabled={isSubmitting}>
            {isSubmitting
              ? t('instruction.form.saving')
              : isEdit
                ? t('instruction.form.update')
                : t('instruction.form.save')}
          </button>
        </div>
      </form>
    </main>
  )
}