import { useState, useEffect, useContext } from 'react'
import { Copy, Eye, Lock, Send, Upload, FileText, Trash2, Check, Clock, CheckCircle2, XCircle, FileEdit, Wrench, MessageSquare, Paperclip } from 'lucide-react'
import { api, STATUS_CONFIG, PRIORITY_CONFIG } from '../utils/api'
import TabbedModal from './TabbedModal'
import Modal from './Modal'
import { useToast } from './ToastContainer'
import { AppContext } from '../App'
import { useLanguage } from '../i18n/LanguageContext'

export default function IssueDetailPanel({ issue, onClose, onUpdate, teamMembers, teams = [] }) {
  const { brands } = useContext(AppContext)
  const toast = useToast()
  const { t } = useLanguage()
  const [issueData, setIssueData] = useState(null)
  const [updates, setUpdates] = useState([])
  const [attachments, setAttachments] = useState([])
  const [initialLoading, setInitialLoading] = useState(true)
  const [saving, setSaving] = useState(false)
  const [uploadingFile, setUploadingFile] = useState(false)
  const [activeTab, setActiveTab] = useState('details')

  // Form state
  const [assignedTo, setAssignedTo] = useState('')
  const [teamId, setTeamId] = useState('')
  const [internalNotes, setInternalNotes] = useState('')
  const [resolutionSummary, setResolutionSummary] = useState('')
  const [newUpdate, setNewUpdate] = useState('')
  const [updateIsPublic, setUpdateIsPublic] = useState(false)

  // Modals
  const [showResolveModal, setShowResolveModal] = useState(false)
  const [showDeclineModal, setShowDeclineModal] = useState(false)
  const [confirmDeleteAttId, setConfirmDeleteAttId] = useState(null)

  const issueId = issue?.Id || issue?.id

  useEffect(() => {
    if (issueId) loadIssueDetails()
  }, [issueId])

  const loadIssueDetails = async () => {
    try {
      const data = await api.get(`/issues/${issueId}`)
      setIssueData(data)
      setUpdates(data.updates || [])
      setAttachments(data.attachments || [])
      setAssignedTo(data.assigned_to_id || '')
      setTeamId(data.team_id || '')
      setInternalNotes(data.internal_notes || '')
      setResolutionSummary(data.resolution_summary || '')
    } catch (err) {
      console.error('Failed to load issue:', err)
    } finally {
      setInitialLoading(false)
    }
  }

  const handleUpdateStatus = async (newStatus) => {
    if (saving) return
    try {
      setSaving(true)
      await api.patch(`/issues/${issueId}`, { status: newStatus })
      await onUpdate()
      await loadIssueDetails()
    } catch (err) {
      console.error('Failed to update status:', err)
      toast.error(t('issues.failedToUpdateStatus'))
    } finally {
      setSaving(false)
    }
  }

  const handleResolve = async () => {
    if (saving || !resolutionSummary.trim()) return
    try {
      setSaving(true)
      await api.patch(`/issues/${issueId}`, { status: 'resolved', resolution_summary: resolutionSummary })
      await onUpdate()
      setShowResolveModal(false)
      await loadIssueDetails()
    } catch (err) {
      console.error('Failed to resolve issue:', err)
      toast.error(t('issues.failedToResolve'))
    } finally {
      setSaving(false)
    }
  }

  const handleDecline = async () => {
    if (saving || !resolutionSummary.trim()) return
    try {
      setSaving(true)
      await api.patch(`/issues/${issueId}`, { status: 'declined', resolution_summary: resolutionSummary })
      await onUpdate()
      setShowDeclineModal(false)
      await loadIssueDetails()
    } catch (err) {
      console.error('Failed to decline issue:', err)
      toast.error(t('issues.failedToDecline'))
    } finally {
      setSaving(false)
    }
  }

  const handleAssignmentChange = async (newAssignedTo) => {
    try {
      setAssignedTo(newAssignedTo)
      await api.patch(`/issues/${issueId}`, { assigned_to_id: newAssignedTo || null })
      await onUpdate()
    } catch (err) {
      console.error('Failed to update assignment:', err)
      toast.error(t('issues.failedToUpdateAssignment'))
    }
  }

  const handleNotesChange = async () => {
    if (saving) return
    try {
      setSaving(true)
      await api.patch(`/issues/${issueId}`, { internal_notes: internalNotes })
    } catch (err) {
      console.error('Failed to save notes:', err)
      toast.error(t('issues.failedToSaveNotes'))
    } finally {
      setSaving(false)
    }
  }

  const handleAddUpdate = async () => {
    if (!newUpdate.trim() || saving) return
    try {
      setSaving(true)
      await api.post(`/issues/${issueId}/updates`, { message: newUpdate, is_public: updateIsPublic })
      setNewUpdate('')
      setUpdateIsPublic(false)
      await loadIssueDetails()
    } catch (err) {
      console.error('Failed to add update:', err)
      toast.error(t('issues.failedToAddUpdate'))
    } finally {
      setSaving(false)
    }
  }

  const handleFileUpload = async (e) => {
    const file = e.target.files?.[0]
    if (!file) return
    try {
      setUploadingFile(true)
      const formData = new FormData()
      formData.append('file', file)
      await api.upload(`/issues/${issueId}/attachments`, formData)
      await loadIssueDetails()
      e.target.value = '' // Reset input
    } catch (err) {
      console.error('Failed to upload file:', err)
      toast.error(t('issues.failedToUploadFile'))
    } finally {
      setUploadingFile(false)
    }
  }

  const handleDeleteAttachment = async (attachmentId) => {
    try {
      await api.delete(`/issue-attachments/${attachmentId}`)
      await loadIssueDetails()
    } catch (err) {
      console.error('Failed to delete attachment:', err)
      toast.error(t('issues.failedToDeleteAttachment'))
    }
  }

  const copyTrackingLink = () => {
    const url = `${window.location.origin}/track/${issueData.tracking_token}`
    navigator.clipboard.writeText(url)
    toast.success(t('issues.trackingLinkCopied'))
  }

  const formatDate = (dateStr) => {
    if (!dateStr) return ''
    const date = new Date(dateStr)
    return date.toLocaleString('en-US', { month: 'short', day: 'numeric', year: 'numeric', hour: '2-digit', minute: '2-digit' })
  }

  const formatFileSize = (bytes) => {
    if (bytes < 1024) return bytes + ' B'
    if (bytes < 1024 * 1024) return (bytes / 1024).toFixed(1) + ' KB'
    return (bytes / (1024 * 1024)).toFixed(1) + ' MB'
  }

  if (initialLoading || !issueData) {
    return (
      <TabbedModal onClose={onClose} size="lg">
        <div className="flex items-center justify-center h-96">
          <div className="animate-spin rounded-full h-12 w-12 border-b-2 border-brand-primary"></div>
        </div>
      </TabbedModal>
    )
  }

  const statusConfig = STATUS_CONFIG[issueData.status] || STATUS_CONFIG.new
  const priorityConfig = PRIORITY_CONFIG[issueData.priority] || PRIORITY_CONFIG.medium

  const tabs = [
    { key: 'details', label: t('issues.details') || 'Details', icon: FileEdit },
    { key: 'actions', label: t('issues.actions') || 'Actions', icon: Wrench },
    { key: 'updates', label: t('issues.updates') || 'Updates', icon: MessageSquare, badge: updates.length },
    { key: 'attachments', label: t('issues.attachments') || 'Attachments', icon: Paperclip, badge: attachments.length },
  ]

  return (
    <>
      <TabbedModal
        onClose={onClose}
        size="lg"
        header={
          <>
            <h2 className="text-lg font-bold text-text-primary">{issueData.title}</h2>
            <div className="flex items-center gap-2 flex-wrap mt-2">
              <span className={`text-xs px-2 py-1 rounded-full font-medium flex items-center gap-1.5 ${statusConfig.bg} ${statusConfig.text}`}>
                <span className={`w-1.5 h-1.5 rounded-full ${statusConfig.dot}`}></span>
                {statusConfig.label}
              </span>
              <span className={`text-xs px-2 py-1 rounded-full font-medium ${priorityConfig.bg} ${priorityConfig.text}`}>
                {priorityConfig.label}
              </span>
              <span className="text-xs px-2 py-1 rounded-full bg-surface-tertiary text-text-secondary capitalize">
                {issueData.type}
              </span>
              <span className="text-xs px-2 py-1 rounded-full bg-surface-tertiary text-text-secondary">
                {issueData.category}
              </span>
              {issueData.brand_name && (
                <span className="text-xs px-2 py-1 rounded-full bg-brand-primary/10 text-brand-primary font-medium">
                  {issueData.brand_name}
                </span>
              )}
            </div>
          </>
        }
        tabs={tabs}
        activeTab={activeTab}
        onTabChange={setActiveTab}
        footer={
          <>
            <button
              onClick={copyTrackingLink}
              className="px-4 py-2 bg-brand-primary text-white rounded-lg text-sm font-medium hover:bg-brand-primary-light transition-colors flex items-center gap-2"
            >
              <Copy className="w-4 h-4" />
              {t('issues.publicTrackingLink')}
            </button>
            <button
              onClick={onClose}
              className="px-4 py-2 bg-surface-secondary text-text-primary rounded-lg text-sm font-medium hover:bg-surface-tertiary transition-colors"
            >
              {t('common.close') || 'Close'}
            </button>
          </>
        }
      >
        {/* Details Tab */}
        {activeTab === 'details' && (
          <div className="p-6 space-y-5">
            {/* Submitter Info */}
            <div className="bg-surface-secondary rounded-lg p-4">
              <h3 className="text-sm font-semibold text-text-primary mb-2">{t('issues.submitterInfo')}</h3>
              <div className="space-y-1 text-sm">
                <div><span className="text-text-tertiary">{t('issues.nameLabel')}</span> <span className="text-text-primary font-medium">{issueData.submitter_name}</span></div>
                <div><span className="text-text-tertiary">{t('issues.emailLabel')}</span> <span className="text-text-primary">{issueData.submitter_email}</span></div>
                {issueData.submitter_phone && (
                  <div><span className="text-text-tertiary">{t('issues.phoneLabel')}</span> <span className="text-text-primary">{issueData.submitter_phone}</span></div>
                )}
                <div><span className="text-text-tertiary">{t('issues.submittedLabel')}</span> <span className="text-text-primary">{formatDate(issueData.created_at)}</span></div>
              </div>
            </div>

            {/* Description */}
            <div>
              <h3 className="text-sm font-semibold text-text-primary mb-2">{t('issues.description')}</h3>
              <p className="text-sm text-text-secondary whitespace-pre-wrap">{issueData.description || t('issues.noDescription')}</p>
            </div>

            {/* Assigned To */}
            <div>
              <label className="block text-sm font-semibold text-text-primary mb-2">{t('issues.assignedTo')}</label>
              <select
                value={assignedTo}
                onChange={(e) => handleAssignmentChange(e.target.value)}
                className="w-full px-3 py-2 text-sm border border-border rounded-lg focus:outline-none focus:ring-2 focus:ring-brand-primary/20"
              >
                <option value="">{t('issues.unassigned')}</option>
                {teamMembers.map((member) => (
                  <option key={member.id || member._id} value={member.id || member._id}>
                    {member.name}
                  </option>
                ))}
              </select>
            </div>

            {/* Team */}
            {teams.length > 0 && (
              <div>
                <label className="block text-sm font-semibold text-text-primary mb-2">{t('issues.team')}</label>
                <select
                  value={teamId}
                  onChange={async (e) => {
                    const val = e.target.value || null
                    setTeamId(val || '')
                    try {
                      await api.patch(`/issues/${issueId}`, { team_id: val })
                      await onUpdate()
                      await loadIssueDetails()
                    } catch (err) {
                      console.error('Failed to update team:', err)
                    }
                  }}
                  className="w-full px-3 py-2 text-sm border border-border rounded-lg focus:outline-none focus:ring-2 focus:ring-brand-primary/20"
                >
                  <option value="">{t('issues.allTeams')}</option>
                  {teams.map((team) => (
                    <option key={team.id || team._id} value={team.id || team._id}>{team.name}</option>
                  ))}
                </select>
              </div>
            )}

            {/* Brand */}
            <div>
              <label className="block text-sm font-semibold text-text-primary mb-2">{t('issues.brandLabel')}</label>
              <select
                value={issueData.brand_id || ''}
                onChange={async (e) => {
                  const val = e.target.value || null;
                  try {
                    await api.patch(`/issues/${issueId}`, { brand_id: val });
                    loadIssueDetails();
                    onUpdate();
                  } catch {}
                }}
                className="w-full px-3 py-2 text-sm border border-border rounded-lg focus:outline-none focus:ring-2 focus:ring-brand-primary/20"
              >
                <option value="">{t('issues.noBrand')}</option>
                {(brands || []).map((b) => (
                  <option key={b._id || b.Id} value={b._id || b.Id}>{b.name}</option>
                ))}
              </select>
            </div>

            {/* Internal Notes */}
            <div>
              <label className="block text-sm font-semibold text-text-primary mb-2 flex items-center gap-2">
                <Lock className="w-4 h-4" />
                {t('issues.internalNotes')}
              </label>
              <textarea
                value={internalNotes}
                onChange={(e) => setInternalNotes(e.target.value)}
                onBlur={handleNotesChange}
                rows={4}
                placeholder={t('issues.internalNotesPlaceholder')}
                className="w-full px-3 py-2 text-sm border border-border rounded-lg focus:outline-none focus:ring-2 focus:ring-brand-primary/20"
              />
            </div>

            {/* Resolution Summary (if resolved/declined) */}
            {(issueData.status === 'resolved' || issueData.status === 'declined') && issueData.resolution_summary && (
              <div className="bg-emerald-50 border border-emerald-200 rounded-lg p-4">
                <h3 className="text-sm font-semibold text-emerald-900 mb-2 flex items-center gap-2">
                  <CheckCircle2 className="w-4 h-4" />
                  {t('issues.resolutionSummary')}
                </h3>
                <p className="text-sm text-emerald-800 whitespace-pre-wrap">{issueData.resolution_summary}</p>
                {issueData.resolved_at && (
                  <p className="text-xs text-emerald-600 mt-2">{t('issues.resolvedOn')} {formatDate(issueData.resolved_at)}</p>
                )}
              </div>
            )}
          </div>
        )}

        {/* Actions Tab */}
        {activeTab === 'actions' && (
          <div className="p-6 space-y-5">
            {issueData.status !== 'resolved' && issueData.status !== 'declined' ? (
              <div className="space-y-3">
                {issueData.status === 'new' && (
                  <button
                    onClick={() => handleUpdateStatus('acknowledged')}
                    disabled={saving}
                    className="w-full px-4 py-3 bg-blue-600 text-white rounded-lg text-sm font-medium hover:bg-blue-700 disabled:opacity-50 flex items-center justify-center gap-2"
                  >
                    <Check className="w-4 h-4" />
                    {t('issues.acknowledge')}
                  </button>
                )}
                {(issueData.status === 'new' || issueData.status === 'acknowledged') && (
                  <button
                    onClick={() => handleUpdateStatus('in_progress')}
                    disabled={saving}
                    className="w-full px-4 py-3 bg-amber-600 text-white rounded-lg text-sm font-medium hover:bg-amber-700 disabled:opacity-50 flex items-center justify-center gap-2"
                  >
                    <Clock className="w-4 h-4" />
                    {t('issues.startWork')}
                  </button>
                )}
                <button
                  onClick={() => setShowResolveModal(true)}
                  disabled={saving}
                  className="w-full px-4 py-3 bg-emerald-600 text-white rounded-lg text-sm font-medium hover:bg-emerald-700 disabled:opacity-50 flex items-center justify-center gap-2"
                >
                  <CheckCircle2 className="w-4 h-4" />
                  {t('issues.resolve')}
                </button>
                <button
                  onClick={() => setShowDeclineModal(true)}
                  disabled={saving}
                  className="w-full px-4 py-3 bg-gray-600 text-white rounded-lg text-sm font-medium hover:bg-gray-700 disabled:opacity-50 flex items-center justify-center gap-2"
                >
                  <XCircle className="w-4 h-4" />
                  {t('issues.decline')}
                </button>
              </div>
            ) : (
              <div className="text-center py-12">
                <CheckCircle2 className="w-10 h-10 mx-auto mb-3 text-text-tertiary" />
                <p className="text-sm text-text-tertiary">
                  {issueData.status === 'resolved' ? t('issues.issueResolved') || 'This issue has been resolved.' : t('issues.issueDeclined') || 'This issue has been declined.'}
                </p>
              </div>
            )}
          </div>
        )}

        {/* Updates Tab */}
        {activeTab === 'updates' && (
          <div className="p-6 space-y-5">
            {/* Add Update */}
            <div className="bg-surface-secondary rounded-lg p-3">
              <textarea
                value={newUpdate}
                onChange={(e) => setNewUpdate(e.target.value)}
                placeholder={t('issues.addUpdatePlaceholder')}
                rows={3}
                className="w-full px-3 py-2 text-sm border border-border rounded-lg focus:outline-none focus:ring-2 focus:ring-brand-primary/20 mb-2"
              />
              <div className="flex items-center justify-between">
                <label className="flex items-center gap-2 text-sm text-text-secondary cursor-pointer">
                  <input
                    type="checkbox"
                    checked={updateIsPublic}
                    onChange={(e) => setUpdateIsPublic(e.target.checked)}
                    className="rounded"
                  />
                  <Eye className="w-4 h-4" />
                  {t('issues.makePublic')}
                </label>
                <button
                  onClick={handleAddUpdate}
                  disabled={!newUpdate.trim() || saving}
                  className="px-4 py-2 bg-brand-primary text-white rounded-lg text-sm font-medium hover:bg-brand-primary-light disabled:opacity-50 transition-colors flex items-center gap-2"
                >
                  <Send className="w-4 h-4" />
                  {t('issues.addUpdate')}
                </button>
              </div>
            </div>

            {/* Updates List */}
            <div className="space-y-3">
              {updates.map((update) => (
                <div
                  key={update.Id || update.id}
                  className={`p-3 rounded-lg border ${update.is_public ? 'bg-brand-primary/5 border-brand-primary/20' : 'bg-surface-secondary border-border'}`}
                >
                  <div className="flex items-start justify-between gap-2 mb-2">
                    <div className="flex items-center gap-2">
                      <span className="text-sm font-medium text-text-primary">{update.author_name}</span>
                      <span className={`text-xs px-2 py-0.5 rounded-full ${update.author_type === 'staff' ? 'bg-purple-100 text-purple-700' : 'bg-surface-tertiary text-text-secondary'}`}>
                        {update.author_type}
                      </span>
                      {update.is_public ? (
                        <Eye className="w-3.5 h-3.5 text-blue-600" title="Public" />
                      ) : (
                        <Lock className="w-3.5 h-3.5 text-text-secondary" title="Internal only" />
                      )}
                    </div>
                    <span className="text-xs text-text-tertiary">{formatDate(update.created_at)}</span>
                  </div>
                  <p className="text-sm text-text-secondary whitespace-pre-wrap">{update.message}</p>
                </div>
              ))}
              {updates.length === 0 && (
                <p className="text-sm text-text-tertiary text-center py-6">{t('issues.noUpdates')}</p>
              )}
            </div>
          </div>
        )}

        {/* Attachments Tab */}
        {activeTab === 'attachments' && (
          <div className="p-6 space-y-5">
            {/* Upload */}
            <label className="block">
              <input type="file" onChange={handleFileUpload} disabled={uploadingFile} className="hidden" />
              <div className="border-2 border-dashed border-border rounded-lg p-4 text-center cursor-pointer hover:bg-surface-secondary transition-colors">
                <Upload className="w-6 h-6 mx-auto mb-2 text-text-tertiary" />
                <p className="text-sm text-text-secondary">
                  {uploadingFile ? t('issues.uploading') : t('issues.clickToUpload')}
                </p>
              </div>
            </label>

            {/* Attachments List */}
            <div className="space-y-2">
              {attachments.map((att) => (
                <div key={att.Id || att.id} className="flex items-center justify-between p-3 bg-surface-secondary rounded-lg">
                  <div className="flex items-center gap-3 flex-1 min-w-0">
                    <FileText className="w-5 h-5 text-text-tertiary shrink-0" />
                    <div className="flex-1 min-w-0">
                      <p className="text-sm font-medium text-text-primary truncate">{att.original_name}</p>
                      <p className="text-xs text-text-tertiary">
                        {formatFileSize(att.size)} &bull; {att.uploaded_by}
                      </p>
                    </div>
                  </div>
                  <div className="flex items-center gap-2">
                    <a
                      href={`/api/uploads/${att.filename}`}
                      target="_blank"
                      rel="noopener noreferrer"
                      className="text-xs text-brand-primary hover:underline"
                    >
                      {t('issues.download')}
                    </a>
                    <button onClick={() => setConfirmDeleteAttId(att.Id || att.id)} className="p-1 hover:bg-surface-tertiary rounded">
                      <Trash2 className="w-4 h-4 text-red-600" />
                    </button>
                  </div>
                </div>
              ))}
              {attachments.length === 0 && (
                <p className="text-sm text-text-tertiary text-center py-4">{t('issues.noAttachments')}</p>
              )}
            </div>
          </div>
        )}
      </TabbedModal>

      {/* Resolve Modal */}
      {showResolveModal && (
        <Modal isOpen title={t('issues.resolveIssue')} onClose={() => setShowResolveModal(false)}>
          <div className="space-y-4">
            <p className="text-sm text-text-secondary">{t('issues.resolveSummaryHint')}</p>
            <textarea
              value={resolutionSummary}
              onChange={(e) => setResolutionSummary(e.target.value)}
              placeholder={t('issues.resolutionPlaceholder')}
              rows={5}
              className="w-full px-3 py-2 text-sm border border-border rounded-lg focus:outline-none focus:ring-2 focus:ring-brand-primary/20"
            />
            <div className="flex gap-2 justify-end">
              <button
                onClick={() => setShowResolveModal(false)}
                className="px-4 py-2 bg-surface-secondary text-text-primary rounded-lg text-sm font-medium hover:bg-surface-tertiary"
              >
                {t('common.cancel')}
              </button>
              <button
                onClick={handleResolve}
                disabled={!resolutionSummary.trim() || saving}
                className="px-4 py-2 bg-emerald-600 text-white rounded-lg text-sm font-medium hover:bg-emerald-700 disabled:opacity-50"
              >
                {saving ? t('issues.resolving') : t('issues.markAsResolved')}
              </button>
            </div>
          </div>
        </Modal>
      )}

      {/* Decline Modal */}
      {showDeclineModal && (
        <Modal isOpen title={t('issues.declineIssue')} onClose={() => setShowDeclineModal(false)}>
          <div className="space-y-4">
            <p className="text-sm text-text-secondary">{t('issues.declineReasonHint')}</p>
            <textarea
              value={resolutionSummary}
              onChange={(e) => setResolutionSummary(e.target.value)}
              placeholder={t('issues.declinePlaceholder')}
              rows={5}
              className="w-full px-3 py-2 text-sm border border-border rounded-lg focus:outline-none focus:ring-2 focus:ring-brand-primary/20"
            />
            <div className="flex gap-2 justify-end">
              <button
                onClick={() => setShowDeclineModal(false)}
                className="px-4 py-2 bg-surface-secondary text-text-primary rounded-lg text-sm font-medium hover:bg-surface-tertiary"
              >
                {t('common.cancel')}
              </button>
              <button
                onClick={handleDecline}
                disabled={!resolutionSummary.trim() || saving}
                className="px-4 py-2 bg-gray-600 text-white rounded-lg text-sm font-medium hover:bg-gray-700 disabled:opacity-50"
              >
                {saving ? t('issues.declining') : t('issues.declineIssue')}
              </button>
            </div>
          </div>
        </Modal>
      )}

      {/* Delete Attachment Confirmation */}
      <Modal
        isOpen={!!confirmDeleteAttId}
        onClose={() => setConfirmDeleteAttId(null)}
        title={t('issues.deleteAttachment')}
        isConfirm
        danger
        onConfirm={() => handleDeleteAttachment(confirmDeleteAttId)}
        confirmText={t('common.delete')}
      >
        {t('issues.deleteAttachmentDesc')}
      </Modal>
    </>
  )
}
