'use client'

import React, { useEffect, useState, useCallback, use } from 'react'
import { SeverityBadge } from '../../_components/SeverityBadge'

interface BacklogItem {
  rank: number
  req_id: string
  title: string
  category: string
  severity: string
  annex_anchor: string
  description: string
  effort_days: number
  mapped_measure_names: { id: string; name: string }[]
  status: string
  priority_score: number
}

interface BacklogResponse {
  project_id: string
  classification: string | null
  days_to_ce_deadline: number
  deadlines: { date: string; label: string }[]
  total: number
  items: BacklogItem[]
}

export default function BacklogPage({
  params,
}: {
  params: Promise<{ projectId: string }>
}) {
  const { projectId } = use(params)
  const [data, setData] = useState<BacklogResponse | null>(null)
  const [loading, setLoading] = useState(true)
  const [error, setError] = useState('')

  const load = useCallback(async () => {
    try {
      const res = await fetch(`/api/sdk/v1/cra/projects/${projectId}/backlog`, {
        headers: { 'X-Tenant-ID': '00000000-0000-0000-0000-000000000001' },
      })
      if (!res.ok) throw new Error(await res.text())
      setData(await res.json())
    } catch (e) {
      setError(e instanceof Error ? e.message : 'Fehler beim Laden')
    } finally {
      setLoading(false)
    }
  }, [projectId])

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

  if (loading) return <div className="min-h-screen bg-gray-50 p-8"><p className="text-gray-500">Laedt...</p></div>
  if (error) return <div className="min-h-screen bg-gray-50 p-8"><p className="text-red-600">{error}</p></div>
  if (!data) return null

  return (
    <div className="min-h-screen bg-gray-50 py-8">
      <div className="max-w-6xl mx-auto px-4">
        <div className="mb-6">
          <a href={`/sdk/cra/${projectId}`} className="text-sm text-blue-600 hover:underline">
            &larr; Zurueck zum Projekt
          </a>
          <h1 className="text-2xl font-bold text-gray-900 mt-2">Prioritaeten-Backlog</h1>
          <p className="text-sm text-gray-600 mt-1">
            Sortiert nach Severity × Deadline-Druck × Effort. Was du heute tust, was naechsten Sprint, was vor 11.12.2027.
          </p>
        </div>

        {/* Deadline-Banner */}
        <div className="grid grid-cols-1 md:grid-cols-3 gap-3 mb-6">
          {data.deadlines.map(d => {
            const days = Math.max(0, Math.round((new Date(d.date).getTime() - Date.now()) / 86400000))
            const isPast = new Date(d.date).getTime() < Date.now()
            return (
              <div
                key={d.date}
                className={`rounded-xl border p-4 ${
                  isPast ? 'bg-gray-100 border-gray-200' :
                  days < 90 ? 'bg-red-50 border-red-200' :
                  days < 365 ? 'bg-orange-50 border-orange-200' :
                  'bg-blue-50 border-blue-200'
                }`}
              >
                <div className="text-xs text-gray-500">{d.date}</div>
                <div className="font-semibold text-gray-900 text-sm mt-0.5">{d.label}</div>
                <div className={`text-xs mt-1 ${isPast ? 'text-gray-500' : 'text-gray-700'}`}>
                  {isPast ? 'bereits abgelaufen' : `noch ${days} Tage`}
                </div>
              </div>
            )
          })}
        </div>

        {/* Backlog */}
        <div className="bg-white rounded-xl shadow-sm border border-gray-200 overflow-hidden">
          <table className="w-full">
            <thead className="bg-gray-50 border-b border-gray-200">
              <tr>
                <th className="px-3 py-2 text-left text-xs font-medium text-gray-500 uppercase">Rang</th>
                <th className="px-3 py-2 text-left text-xs font-medium text-gray-500 uppercase">Anforderung</th>
                <th className="px-3 py-2 text-left text-xs font-medium text-gray-500 uppercase">Severity</th>
                <th className="px-3 py-2 text-left text-xs font-medium text-gray-500 uppercase">Score</th>
                <th className="px-3 py-2 text-left text-xs font-medium text-gray-500 uppercase">Aufwand</th>
                <th className="px-3 py-2 text-left text-xs font-medium text-gray-500 uppercase">Massnahme</th>
                <th className="px-3 py-2 text-left text-xs font-medium text-gray-500 uppercase">Aktion</th>
              </tr>
            </thead>
            <tbody className="divide-y divide-gray-100">
              {data.items.map(item => (
                <tr key={item.req_id} className="hover:bg-gray-50">
                  <td className="px-3 py-3 text-sm font-bold text-gray-700">{item.rank}</td>
                  <td className="px-3 py-3">
                    <div className="text-sm font-medium text-gray-900">{item.title}</div>
                    <div className="text-xs text-gray-500">{item.category} · {item.annex_anchor}</div>
                  </td>
                  <td className="px-3 py-3"><SeverityBadge value={item.severity} /></td>
                  <td className="px-3 py-3 text-sm font-mono text-gray-700">{item.priority_score}</td>
                  <td className="px-3 py-3 text-sm text-gray-600">{item.effort_days} PT</td>
                  <td className="px-3 py-3 text-xs text-gray-600">
                    {item.mapped_measure_names.length > 0 ? (
                      <div className="space-y-0.5">
                        {item.mapped_measure_names.map(m => (
                          <div key={m.id} title={m.name}>
                            <span className="font-mono text-gray-400">{m.id}:</span> {m.name.length > 50 ? m.name.slice(0, 50) + '...' : m.name}
                          </div>
                        ))}
                      </div>
                    ) : (
                      <span className="text-gray-400">—</span>
                    )}
                  </td>
                  <td className="px-3 py-3">
                    <button
                      className="px-2 py-1 text-xs bg-purple-100 text-purple-800 rounded hover:bg-purple-200"
                      onClick={() => alert(`Jira-Export fuer ${item.req_id} — Phase-4-Feature`)}
                    >
                      → Jira
                    </button>
                  </td>
                </tr>
              ))}
            </tbody>
          </table>
        </div>

        <p className="text-xs text-gray-500 mt-4 text-center">
          Tage bis CE-Marking-Pflicht (11.12.2027): <span className="font-semibold">{data.days_to_ce_deadline}</span>
        </p>
      </div>
    </div>
  )
}