import { useEffect, useState } from 'react'
import { Link } from 'react-router-dom'
import { api, downloadWithAuth } from '../api'
import ConfirmDialog from '../components/ConfirmDialog'
import { useAuth } from '../context/AuthContext'
import { useI18n } from '../context/I18nContext'
import type { TemplateListItem } from '../types'

export default function TemplatesPage() {
  const { user } = useAuth()
  const { t, formatDate } = useI18n()
  const [templates, setTemplates] = useState<TemplateListItem[]>([])
  const [loading, setLoading] = useState(true)
  const [error, setError] = useState('')
  const [deleteTarget, setDeleteTarget] = useState<TemplateListItem | null>(null)

  const load = async () => {
    try {
      setTemplates(await api.listTemplates())
    } catch (err) {
      setError(err instanceof Error ? err.message : t('errors.loadTemplatesFailed'))
    } finally {
      setLoading(false)
    }
  }

  useEffect(() => {
    load()
  }, [])

  const handleDelete = async () => {
    if (!deleteTarget) return
    try {
      await api.deleteTemplate(deleteTarget.id)
      setTemplates((list) => list.filter((x) => x.id !== deleteTarget.id))
      setDeleteTarget(null)
    } catch (err) {
      alert(err instanceof Error ? err.message : t('errors.deleteFailed'))
    }
  }

  const handleTogglePublic = async (item: TemplateListItem) => {
    try {
      const updated = await api.updateTemplate(item.id, { is_public: !item.is_public })
      setTemplates((list) =>
        list.map((x) =>
          x.id === item.id ? { ...x, is_public: updated.is_public } : x,
        ),
      )
    } catch (err) {
      alert(err instanceof Error ? err.message : t('errors.updateFailed'))
    }
  }

  const handleDownloadSource = async (item: TemplateListItem) => {
    try {
      await downloadWithAuth(api.getTemplateSourceUrl(item.id), item.original_filename)
    } catch (err) {
      alert(err instanceof Error ? err.message : t('errors.downloadFailed'))
    }
  }

  const canManage = (item: TemplateListItem) =>
    item.is_owner || user?.role === 'admin'

  return (
    <div className="container">
      <ConfirmDialog
        open={deleteTarget !== null}
        title={t('templates.deleteTitle')}
        message={
          deleteTarget
            ? t('templates.deleteMessage', {
                name: deleteTarget.name,
                cannotUndo: t('common.cannotUndo'),
              })
            : ''
        }
        confirmLabel={t('common.delete')}
        danger
        onConfirm={() => void handleDelete()}
        onCancel={() => setDeleteTarget(null)}
      />

      <div className="page-header">
        <h1>{t('templates.title')}</h1>
        <Link to="/templates/new" className="btn btn-primary">
          {t('templates.upload')}
        </Link>
      </div>

      {error && <div className="error">{error}</div>}

      {loading ? (
        <p>{t('common.loading')}</p>
      ) : templates.length === 0 ? (
        <div className="card empty-state">
          <p>{t('templates.empty')}</p>
          <Link to="/templates/new" className="btn btn-primary" style={{ marginTop: 16 }}>
            {t('templates.uploadShort')}
          </Link>
        </div>
      ) : (
        <div className="card">
          <table className="table">
            <thead>
              <tr>
                <th>{t('common.name')}</th>
                <th>{t('common.file')}</th>
                <th>{t('common.owner')}</th>
                <th>{t('templates.visibility')}</th>
                <th>{t('templates.variables')}</th>
                <th>{t('common.created')}</th>
                <th>{t('common.actions')}</th>
              </tr>
            </thead>
            <tbody>
              {templates.map((item) => (
                <tr key={item.id}>
                  <td>
                    <strong>{item.name}</strong>
                    {item.description && (
                      <div className="style-hint">{item.description}</div>
                    )}
                  </td>
                  <td>{item.original_filename}</td>
                  <td>{item.owner_username ?? `#${item.owner_id}`}</td>
                  <td>
                    {item.is_public ? (
                      <span className="badge" style={{ background: '#dbeafe', color: '#1d4ed8' }}>
                        {t('visibility.public')}
                      </span>
                    ) : (
                      <span className="badge badge-user">{t('visibility.private')}</span>
                    )}
                  </td>
                  <td>{item.variable_count}</td>
                  <td>{formatDate(item.created_at)}</td>
                  <td style={{ display: 'flex', gap: 8, flexWrap: 'wrap' }}>
                    <Link to={`/templates/${item.id}/fill`} className="btn btn-primary btn-sm">
                      {t('templates.fill')}
                    </Link>
                    <Link to={`/templates/${item.id}`} className="btn btn-secondary btn-sm">
                      {t('common.view')}
                    </Link>
                    <button
                      className="btn btn-secondary btn-sm"
                      onClick={() => handleDownloadSource(item)}
                    >
                      {t('templates.source')}
                    </button>
                    {canManage(item) && (
                      <>
                        <button
                          className="btn btn-secondary btn-sm"
                          onClick={() => handleTogglePublic(item)}
                        >
                          {item.is_public ? t('visibility.makePrivate') : t('visibility.makePublic')}
                        </button>
                        <button
                          className="btn btn-danger btn-sm"
                          onClick={() => setDeleteTarget(item)}
                        >
                          {t('common.delete')}
                        </button>
                      </>
                    )}
                  </td>
                </tr>
              ))}
            </tbody>
          </table>
        </div>
      )}
    </div>
  )
}