import { useState, useEffect, useContext, useCallback, useRef } from 'react'
import { useParams, useNavigate } from 'react-router-dom'
import { ArrowLeft, Save, FileText, Image as ImageIcon, Film, Type, Search, Link2, Unlink, Plus, CheckCircle, Clock, X, ExternalLink } from 'lucide-react'
import { AppContext } from '../App'
import { useAuth } from '../contexts/AuthContext'
import { useLanguage } from '../i18n/LanguageContext'
import { api, PLATFORMS } from '../utils/api'
import PlatformIcon from '../components/PlatformIcon'
import StatusBadge from '../components/StatusBadge'
import PortalSelect from '../components/PortalSelect'
import CommentsSection from '../components/CommentsSection'
import ArtefactDetailPanel from '../components/ArtefactDetailPanel'
import { useToast } from '../components/ToastContainer'

const STATUS_OPTS = ['draft', 'in_review', 'approved', 'rejected', 'scheduled', 'published']

// Maps asset type key → composition field name
const PIECE_MAP = { caption: 'caption', body: 'body_copy', design: 'design', video: 'video' }
// Maps asset type key → i18n label key
const LABEL_KEYS = {
  caption: 'postDetail.captionCopy',
  body: 'postDetail.bodyCopy',
  design: 'postDetail.design',
  video: 'postDetail.video',
}
const ASSET_ICONS = { caption: Type, body: FileText, design: ImageIcon, video: Film }
const ASSET_TYPES = ['caption', 'body', 'design', 'video']
// Maps server-generated waiting_on labels → asset type key
const WAITING_TYPE_MAP = { Caption: 'caption', Copy: 'body', Design: 'design', Video: 'video' }

export default function PostDetail() {
  const { id } = useParams()
  const navigate = useNavigate()
  const { brands, getBrandName, teamMembers } = useContext(AppContext)
  const { t, lang } = useLanguage()
  const { user } = useAuth()
  const toast = useToast()

  const [post, setPost] = useState(null)
  const [composition, setComposition] = useState(null)
  const [loading, setLoading] = useState(true)
  const [saving, setSaving] = useState(false)
  const [campaigns, setCampaigns] = useState([])

  // Editable form fields
  const [title, setTitle] = useState('')
  const [status, setStatus] = useState('draft')
  const [brandId, setBrandId] = useState('')
  const [campaignId, setCampaignId] = useState('')
  const [assignedTo, setAssignedTo] = useState('')
  const [platforms, setPlatforms] = useState([])
  const [scheduledDate, setScheduledDate] = useState('')

  // Link pickers / create
  const [creating, setCreating] = useState(false)
  const [activePicker, setActivePicker] = useState(null) // 'caption' | 'body' | 'design' | 'video'
  const [pickerSearch, setPickerSearch] = useState('')
  const [linkCandidates, setLinkCandidates] = useState([])
  const [linking, setLinking] = useState(false)
  const allArtefactsRef = useRef(null)

  // Sub-panels
  const [openArtefact, setOpenArtefact] = useState(null)

  const loadPost = useCallback(async () => {
    try {
      const [p, comp] = await Promise.all([
        api.get(`/posts/${id}`),
        api.get(`/posts/${id}/composition`),
      ])
      setPost(p)
      setComposition(comp)
      setTitle(p.title || '')
      setStatus(p.status || 'draft')
      setBrandId(p.brand_id || p.brandId || '')
      setCampaignId(p.campaign_id || p.campaignId || '')
      setAssignedTo(p.assigned_to || p.assignedTo || '')
      const plats = p.platforms || (p.platform ? [p.platform] : [])
      setPlatforms(Array.isArray(plats) ? plats : [])
      const sd = p.scheduled_date || p.scheduledDate
      setScheduledDate(sd ? new Date(sd).toISOString().slice(0, 10) : '')
    } catch (err) {
      console.error('Failed to load post:', err)
    } finally {
      setLoading(false)
    }
  }, [id])

  useEffect(() => {
    loadPost()
    api.get('/campaigns').then(r => setCampaigns(Array.isArray(r) ? r : [])).catch(() => {})
  }, [loadPost])

  const loadComposition = useCallback(async () => {
    try {
      setComposition(await api.get(`/posts/${id}/composition`))
    } catch (err) {
      console.error('Failed to load composition:', err)
    }
  }, [id])

  const handleSave = async () => {
    setSaving(true)
    try {
      await api.patch(`/posts/${id}`, {
        title,
        status,
        brand_id: brandId ? Number(brandId) : null,
        campaign_id: campaignId ? Number(campaignId) : null,
        assigned_to: assignedTo ? Number(assignedTo) : null,
        platforms,
        scheduled_date: scheduledDate || null,
      })
      toast.success(t('posts.updated'))
      // Update local post state — composition is unaffected by metadata changes
      setPost(p => ({ ...p, title, status, brand_id: brandId, campaign_id: campaignId, assigned_to: assignedTo, platforms, scheduled_date: scheduledDate || null }))
    } catch {
      toast.error(t('common.saveFailed'))
    } finally {
      setSaving(false)
    }
  }

  const togglePlatform = (key) => {
    setPlatforms(prev => prev.includes(key) ? prev.filter(p => p !== key) : [...prev, key])
  }

  // ─── Link / Unlink / Create ───

  const TYPE_FILTERS = {
    caption: a => a.type === 'copy' && a.copy_type === 'caption',
    body: a => a.type === 'copy' && (a.copy_type === 'body' || !a.copy_type),
    video: a => a.type === 'video',
    design: a => (a.type || 'design') === 'design',
  }

  const openLinkPicker = async (type) => {
    setActivePicker(type)
    setPickerSearch('')
    try {
      if (!allArtefactsRef.current) allArtefactsRef.current = await api.get('/artefacts')
      const all = Array.isArray(allArtefactsRef.current) ? allArtefactsRef.current : []
      setLinkCandidates(all.filter(a => {
        const linkedTo = a.post_id || a.postId
        return TYPE_FILTERS[type](a) && (!linkedTo || String(linkedTo) !== String(id))
      }))
    } catch {
      setLinkCandidates([])
      toast.error(t('common.error'))
    }
  }

  const handleLink = async (itemId) => {
    setLinking(true)
    try {
      await api.patch(`/artefacts/${itemId}`, { post_id: Number(id) })
      allArtefactsRef.current = null
      toast.success(t('posts.updated'))
      setActivePicker(null)
      loadComposition()
    } catch {
      toast.error(t('common.saveFailed'))
    } finally {
      setLinking(false)
    }
  }

  const handleUnlink = async (type) => {
    const piece = composition?.[PIECE_MAP[type]]
    if (!piece) return
    try {
      await api.patch(`/artefacts/${piece.id}`, { post_id: null })
      allArtefactsRef.current = null
      toast.success(t('posts.updated'))
      loadComposition()
    } catch {
      toast.error(t('common.saveFailed'))
    }
  }

  const handleOpenPiece = async (type) => {
    const piece = composition?.[PIECE_MAP[type]]
    if (!piece) return
    try {
      const full = await api.get(`/artefacts/${piece.id}`)
      setOpenArtefact(full)
    } catch { toast.error(t('common.saveFailed')) }
  }

  const handleCreate = async (type) => {
    if (creating) return
    setCreating(true)
    try {
      const created = await api.post('/artefacts', {
        title: title.trim() ? `${t(LABEL_KEYS[type])} — ${title.trim()}` : t(LABEL_KEYS[type]),
        type: type === 'caption' || type === 'body' ? 'copy' : type,
        copy_type: type === 'caption' ? 'caption' : type === 'body' ? 'body' : undefined,
        post_id: Number(id),
      })
      allArtefactsRef.current = null
      setOpenArtefact(created)
      loadComposition()
    } catch {
      toast.error(t('common.saveFailed'))
    } finally {
      setCreating(false)
    }
  }

  // ─── Rendering ───

  if (loading) {
    return (
      <div className="space-y-6 animate-pulse">
        <div className="flex items-start gap-4">
          <div className="w-8 h-8 bg-surface-tertiary rounded-lg"></div>
          <div className="flex-1">
            <div className="h-6 bg-surface-tertiary rounded w-64 mb-2"></div>
            <div className="h-4 bg-surface-tertiary rounded w-96"></div>
          </div>
        </div>
        <div className="grid grid-cols-1 md:grid-cols-2 gap-4">
          {[1,2,3,4].map(i => <div key={i} className="h-40 bg-surface-tertiary rounded-xl"></div>)}
        </div>
      </div>
    )
  }

  if (!post) {
    return (
      <div className="text-center py-12 text-text-tertiary">
        {t('common.noResults')}{' '}
        <button onClick={() => navigate('/posts')} className="text-brand-primary underline">{t('common.goBack')}</button>
      </div>
    )
  }

  const filteredCandidates = linkCandidates.filter(c => {
    if (!pickerSearch) return true
    return (c.title || '').toLowerCase().includes(pickerSearch.toLowerCase())
  })

  const isDirty = Boolean(post) && (
    title !== (post.title || '') ||
    status !== (post.status || 'draft') ||
    String(brandId) !== String(post.brand_id || post.brandId || '') ||
    String(campaignId) !== String(post.campaign_id || post.campaignId || '') ||
    String(assignedTo) !== String(post.assigned_to || post.assignedTo || '') ||
    JSON.stringify(platforms) !== JSON.stringify(Array.isArray(post.platforms) ? post.platforms : (post.platform ? [post.platform] : [])) ||
    scheduledDate !== ((post.scheduled_date || post.scheduledDate) ? new Date(post.scheduled_date || post.scheduledDate).toISOString().slice(0, 10) : '')
  )

  const waitingOn = composition?.waiting_on || []
  const piecesReady = composition?.pieces_ready || false
  const hasPieces = composition?.caption || composition?.body_copy || composition?.design || composition?.video

  return (
    <div className="space-y-6 animate-fade-in">
      {/* ─── HEADER ─── */}
      <div className="space-y-3">
        <div className="flex items-center gap-3">
          <button onClick={() => navigate('/posts')} className="p-1.5 hover:bg-surface-tertiary rounded-lg">
            <ArrowLeft className="w-5 h-5 text-text-secondary" />
          </button>
          <input
            type="text"
            value={title}
            onChange={e => setTitle(e.target.value)}
            className="flex-1 text-xl font-bold text-text-primary bg-transparent border-none outline-none focus:ring-0 placeholder:text-text-tertiary"
            placeholder={t('posts.postTitlePlaceholder')}
          />
        </div>

        <div className="flex items-center gap-2 flex-wrap">
          <PortalSelect
            value={status}
            onChange={val => setStatus(val)}
            options={STATUS_OPTS.map(s => ({ value: s, label: t(`posts.status.${s}`) }))}
            className="text-xs"
          />

          <PortalSelect
            value={brandId}
            onChange={val => setBrandId(val)}
            options={[
              { value: '', label: t('posts.selectBrand') },
              ...brands.map(b => ({ value: String(b._id), label: lang === 'ar' && b.name_ar ? b.name_ar : b.name }))
            ]}
            placeholder={t('posts.selectBrand')}
            className="text-xs"
          />

          <PortalSelect
            value={campaignId}
            onChange={val => setCampaignId(val)}
            options={[
              { value: '', label: t('posts.noCampaign') },
              ...campaigns.map(c => ({ value: String(c._id || c.id), label: c.name }))
            ]}
            placeholder={t('posts.noCampaign')}
            className="text-xs"
          />

          <PortalSelect
            value={assignedTo}
            onChange={val => setAssignedTo(val)}
            options={[
              { value: '', label: t('common.unassigned') },
              ...teamMembers.map(m => ({ value: String(m._id), label: m.name }))
            ]}
            placeholder={t('common.unassigned')}
            className="text-xs"
          />
        </div>

        {/* Platforms */}
        <div className="flex items-center gap-1.5 flex-wrap">
          {Object.entries(PLATFORMS).map(([key, p]) => (
            <button
              key={key}
              onClick={() => togglePlatform(key)}
              className={`flex items-center gap-1 px-2 py-1 rounded-lg text-xs font-medium border transition-colors ${
                platforms.includes(key)
                  ? 'border-brand-primary bg-brand-primary/10 text-brand-primary'
                  : 'border-border text-text-tertiary hover:border-brand-primary/40'
              }`}
            >
              <PlatformIcon platform={key} size={14} />
              {p.label}
            </button>
          ))}
        </div>

        {/* Date + Save */}
        <div className="flex items-center gap-3">
          <input
            type="date"
            value={scheduledDate}
            onChange={e => setScheduledDate(e.target.value)}
            className="text-xs border border-border rounded-lg px-2.5 py-1.5 bg-surface text-text-secondary focus:outline-none focus:ring-2 focus:ring-brand-primary/20"
          />
          <button
            onClick={handleSave}
            disabled={saving}
            className={`flex items-center gap-1.5 px-4 py-1.5 rounded-lg text-sm font-medium shadow-sm disabled:opacity-50 transition-colors ${
              isDirty ? 'bg-amber-500 hover:bg-amber-600 text-white' : 'bg-brand-primary hover:bg-brand-primary-light text-white'
            }`}
          >
            <Save className="w-4 h-4" />
            {saving ? t('common.loading') : t('common.save')}
            {isDirty && !saving && <span className="w-1.5 h-1.5 rounded-full bg-white/70 ms-0.5" />}
          </button>
        </div>
      </div>

      {/* ─── ASSET CARDS ─── */}
      <div className="grid grid-cols-1 md:grid-cols-2 gap-4">
        {ASSET_TYPES.map(type => (
          <AssetCard
            key={type}
            id={`asset-${type}`}
            type={type}
            label={t(LABEL_KEYS[type])}
            icon={ASSET_ICONS[type]}
            piece={composition?.[PIECE_MAP[type]]}
            onCreate={() => handleCreate(type)}
            creating={creating}
            onOpen={() => handleOpenPiece(type)}
            onUnlink={() => handleUnlink(type)}
            onOpenPicker={() => openLinkPicker(type)}
            activePicker={activePicker}
            pickerSearch={pickerSearch}
            filteredCandidates={filteredCandidates}
            linking={linking}
            onLink={handleLink}
            onPickerSearchChange={setPickerSearch}
            onClosePicker={() => setActivePicker(null)}
            t={t}
          />
        ))}
      </div>

      {/* ─── READINESS ─── */}
      <div className="bg-surface rounded-xl border border-border p-5">
        <h3 className="text-xs uppercase tracking-wider text-text-tertiary font-medium mb-3">{t('postDetail.readiness')}</h3>
        {!hasPieces ? (
          <p className="text-sm text-text-tertiary">{t('postDetail.noAssets')}</p>
        ) : piecesReady ? (
          <div className="flex items-center gap-2 text-emerald-600">
            <CheckCircle className="w-5 h-5" />
            <span className="text-sm font-medium">{t('postDetail.allPiecesApproved')}</span>
          </div>
        ) : (
          <div className="flex items-start gap-2 text-amber-600">
            <Clock className="w-5 h-5 shrink-0 mt-0.5" />
            <div className="flex flex-wrap gap-1.5 items-center">
              <span className="text-sm font-medium">{t('postDetail.waitingOn')}:</span>
              {waitingOn.map(label => {
                const type = WAITING_TYPE_MAP[label]
                return type ? (
                  <button
                    key={label}
                    onClick={() => document.getElementById(`asset-${type}`)?.scrollIntoView({ behavior: 'smooth', block: 'center' })}
                    className="text-xs px-2 py-0.5 rounded-full bg-amber-100 text-amber-700 hover:bg-amber-200 transition-colors font-medium"
                  >
                    {label}
                  </button>
                ) : <span key={label} className="text-sm">{label}</span>
              })}
            </div>
          </div>
        )}
      </div>

      {/* ─── COMMENTS ─── */}
      <div className="bg-surface rounded-xl border border-border p-5">
        <h3 className="text-xs uppercase tracking-wider text-text-tertiary font-medium mb-3">{t('posts.discussion')}</h3>
        <CommentsSection entityType="post" entityId={Number(id)} />
      </div>

      {/* ─── SUB-PANELS (they render their own SlidePanel internally) ─── */}
      {openArtefact && (
        <ArtefactDetailPanel
          key={openArtefact._id}
          artefact={openArtefact}
          onClose={() => { setOpenArtefact(null); loadComposition() }}
          onUpdate={loadComposition}
          onDelete={() => { setOpenArtefact(null); loadComposition() }}
          assignableUsers={teamMembers}
        />
      )}
    </div>
  )
}

// ─── Asset Card Component ───

function AssetCard({
  id, type, label, icon: Icon, piece,
  onCreate, creating, onOpen, onUnlink,
  onOpenPicker, activePicker, pickerSearch, filteredCandidates, linking,
  onLink, onPickerSearchChange, onClosePicker, t,
}) {
  const isPickerOpen = activePicker === type
  const isCopy = type === 'caption' || type === 'body'

  const isPending = piece?.status === 'pending_review'
  const isApproved = piece?.status === 'approved'

  return (
    <div id={id} className="bg-surface rounded-xl border border-border p-4 flex flex-col">
      {/* Header */}
      <div className="flex items-center gap-2 mb-3">
        <Icon className="w-4 h-4 text-text-tertiary" />
        <h4 className="text-xs uppercase tracking-wider text-text-tertiary font-medium flex-1">{label}</h4>
      </div>

      {/* ─── State 2: Linked ─── */}
      {piece && (
        <>
          <div className="flex-1">
            {/* Thumbnail for design/video */}
            {!isCopy && piece.thumbnail_url && (
              <div className="mb-3 rounded-lg overflow-hidden border border-border-light bg-surface-secondary">
                <img src={piece.thumbnail_url} alt={piece.title} className="w-full h-32 object-cover" loading="lazy" />
              </div>
            )}
            {!isCopy && !piece.thumbnail_url && (
              <div className="mb-3 rounded-lg border border-border-light bg-surface-secondary flex items-center justify-center h-24">
                <Icon className="w-8 h-8 text-text-tertiary/30" />
              </div>
            )}

            <div className="flex items-center gap-2 mb-1">
              <span className="text-sm font-medium text-text-primary truncate">{piece.title}</span>
              <StatusBadge status={piece.status} size="xs" />
            </div>

            {/* Copy: content preview + languages */}
            {isCopy && piece.content_preview && (
              <p className="text-xs text-text-secondary mt-1 line-clamp-2">{piece.content_preview}</p>
            )}
            {isCopy && piece.languages && piece.languages.length > 0 && (
              <div className="flex flex-wrap gap-1 mt-2">
                {piece.languages.map((l, i) => (
                  <span key={i} className={`text-[10px] px-1.5 py-0.5 rounded-full font-medium ${
                    l.status === 'approved' ? 'bg-emerald-100 text-emerald-700' :
                    l.status === 'in_review' ? 'bg-amber-100 text-amber-700' :
                    'bg-surface-tertiary text-text-tertiary'
                  }`}>
                    {l.language}
                  </span>
                ))}
              </div>
            )}
            {isCopy && (!piece.languages || piece.languages.length === 0) && piece.language && (
              <p className="text-xs text-text-tertiary mt-1">{piece.language}</p>
            )}

            {/* Design/Video: version info */}
            {!isCopy && piece.current_version && (
              <p className="text-xs text-text-tertiary mt-1">v{piece.current_version}</p>
            )}

            {/* Approval info */}
            <div className="mt-3 space-y-2">
              {isPending && piece.approver_name && (
                <p className="text-xs text-amber-600 flex items-center gap-1.5">
                  <Clock className="w-3.5 h-3.5" />
                  {t('postDetail.pendingReviewBy')} {piece.approver_name}
                </p>
              )}
              {isApproved && (
                <p className="text-xs text-emerald-600 flex items-center gap-1.5">
                  <CheckCircle className="w-3.5 h-3.5" />
                  {t('postDetail.approved')}{piece.approver_name ? ` — ${piece.approver_name}` : ''}
                </p>
              )}
            </div>
          </div>

          {/* Open + Unlink */}
          <div className="flex items-center justify-between mt-3 pt-3 border-t border-border-light">
            <button
              onClick={onOpen}
              className="flex items-center gap-1.5 px-2.5 py-1 text-xs font-medium text-brand-primary hover:bg-brand-primary/10 rounded-lg transition-colors"
            >
              <ExternalLink className="w-3.5 h-3.5" />
              {t('postDetail.viewDetails')}
            </button>
            <button
              onClick={onUnlink}
              className="flex items-center gap-1 px-2.5 py-1 text-xs font-medium text-red-500 hover:bg-red-50 rounded-lg transition-colors"
            >
              <Unlink className="w-3.5 h-3.5" />
              {t('postDetail.unlink')}
            </button>
          </div>
        </>
      )}

      {/* ─── State 1: Empty (no asset) ─── */}
      {!piece && (
        <>
          <div className="flex-1 flex items-center justify-center py-4">
            <p className="text-sm text-text-tertiary">{t('postDetail.notLinked')}</p>
          </div>
          {!isPickerOpen && (
            <div className="flex items-center gap-2 mt-3 pt-3 border-t border-border-light">
              <button
                onClick={onOpenPicker}
                className="flex items-center gap-1 px-2.5 py-1 text-xs font-medium text-brand-primary hover:bg-brand-primary/10 rounded-lg transition-colors"
              >
                <Link2 className="w-3.5 h-3.5" />
                {t('postDetail.linkExisting')}
              </button>
              <button
                onClick={onCreate}
                disabled={creating}
                className="flex items-center gap-1 px-2.5 py-1 text-xs font-medium text-brand-primary hover:bg-brand-primary/10 rounded-lg transition-colors disabled:opacity-50 disabled:cursor-not-allowed"
              >
                <Plus className="w-3.5 h-3.5" />
                {creating ? t('common.loading') : t('postDetail.createNew')}
              </button>
            </div>
          )}
        </>
      )}

      {/* Inline link picker */}
      {isPickerOpen && (
        <div className="mt-3 pt-3 border-t border-border-light animate-fade-in">
          <div className="flex items-center gap-2 mb-2">
            <div className="relative flex-1">
              <Search className="absolute start-2 top-1/2 -translate-y-1/2 w-3.5 h-3.5 text-text-tertiary" />
              <input
                type="text"
                value={pickerSearch}
                onChange={e => onPickerSearchChange(e.target.value)}
                placeholder={t('common.search')}
                className="w-full ps-7 pe-2 py-1.5 text-xs border border-border rounded-lg bg-surface focus:outline-none focus:ring-2 focus:ring-brand-primary/20"
                autoFocus
              />
            </div>
            <button onClick={onClosePicker} className="p-1 hover:bg-surface-tertiary rounded">
              <X className="w-3.5 h-3.5 text-text-tertiary" />
            </button>
          </div>
          <div className="max-h-32 overflow-y-auto space-y-1">
            {filteredCandidates.length === 0 ? (
              <p className="text-xs text-text-tertiary text-center py-2">{t('common.noResults')}</p>
            ) : (
              filteredCandidates.slice(0, 10).map(c => (
                <button
                  key={c._id || c.id}
                  onClick={() => onLink(c._id || c.id)}
                  disabled={linking}
                  className="w-full text-start px-2 py-2 text-xs rounded-lg hover:bg-surface-secondary transition-colors flex items-start gap-2 disabled:opacity-50"
                >
                  {!isCopy && (c.thumbnail_url || c.file_url) && (
                    <img src={c.thumbnail_url || c.file_url} alt="" className="w-10 h-10 rounded object-cover shrink-0" loading="lazy" />
                  )}
                  <div className="flex-1 min-w-0">
                    <div className="flex items-center gap-1.5">
                      <span className="truncate text-text-primary font-medium">{c.title || t('common.untitled')}</span>
                      <StatusBadge status={c.status} size="xs" />
                    </div>
                    {isCopy && (
                      <p className="text-text-tertiary mt-0.5 truncate">
                        {c.source_language && <span className="uppercase">{c.source_language} · </span>}
                        {(c.source_content || '').slice(0, 60)}
                      </p>
                    )}
                    {!isCopy && c.type && (
                      <p className="text-text-tertiary mt-0.5 capitalize">{c.type}</p>
                    )}
                  </div>
                </button>
              ))
            )}
          </div>
        </div>
      )}
    </div>
  )
}