import React, { useState, useEffect, useCallback } from 'react';
import { useAuth } from '../context/AuthContext';
import { useToast, ConfirmModal } from '../components/Toast';
import TaskModal from '../components/TaskModal';
import { apiFetch, safeFileUrl } from '../utils/api';

export default function TasksPage() {
  const { user } = useAuth();
  const toast = useToast();
  const [tasks, setTasks] = useState([]);
  const [totalTasks, setTotalTasks] = useState(0);
  const [totalPages, setTotalPages] = useState(1);
  const [currentPage, setCurrentPage] = useState(1);
  const [selectedTask, setSelectedTask] = useState(null);
  const [loading, setLoading] = useState(true);
  const [filter, setFilter] = useState('all');
  const [searchQuery, setSearchQuery] = useState('');
  const [confirmState, setConfirmState] = useState({ open: false, id: null });

  const fetchTasks = useCallback(async (page = currentPage) => {
    try {
      const statusParam = filter !== 'all' ? `&status=${filter}` : '';
      const res = await apiFetch(`/tasks?page=${page}&limit=20${statusParam}`);
      const data = await res.json();
      setTasks(data.tasks || []);
      setTotalTasks(data.total || 0);
      setTotalPages(data.totalPages || 1);
    } catch (e) {
      console.error('Fehler beim Laden der Aufgaben:', e);
    } finally {
      setLoading(false);
    }
  }, [currentPage, filter]);

  useEffect(() => {
    fetchTasks();
    const interval = setInterval(() => fetchTasks(), 30000);
    return () => clearInterval(interval);
  }, [fetchTasks]);

  const updateStatus = async (taskId, status) => {
    try {
      const res = await apiFetch(`/tasks/${taskId}/status`, {
        method: 'PATCH',
        body: JSON.stringify({ status }),
      });
      if (res.ok) {
        await fetchTasks();
      }
    } catch (e) {
      console.error('Fehler beim Aktualisieren:', e);
    }
  };

  const deleteTask = async (id) => {
    setConfirmState({ open: true, id });
  };

  const confirmDeleteTask = async () => {
    const id = confirmState.id;
    setConfirmState({ open: false, id: null });
    try {
      const res = await apiFetch(`/tasks/${id}`, { method: 'DELETE' });
      if (!res.ok) {
        toast.error('Fehler beim Löschen der Aufgabe.');
        return;
      }
      toast.success('Aufgabe gelöscht.');
      await fetchTasks();
    } catch (e) {
      toast.error('Netzwerkfehler beim Löschen.');
    }
  };

  const filtered = searchQuery.trim()
    ? tasks.filter(t =>
        t.title?.toLowerCase().includes(searchQuery.toLowerCase()) ||
        t.user_name?.toLowerCase().includes(searchQuery.toLowerCase()) ||
        t.template_name?.toLowerCase().includes(searchQuery.toLowerCase())
      )
    : tasks;

  // Reset page when filter changes
  useEffect(() => {
    setCurrentPage(1);
    setLoading(true);
    fetchTasks(1);
  }, [filter]);

  const goToPage = (page) => {
    setCurrentPage(page);
    setLoading(true);
    fetchTasks(page);
  };

  if (loading) {
    return (
      <div className="p-4 md:p-6 space-y-4">
        <div className="flex flex-col sm:flex-row justify-between items-start sm:items-center gap-4 mb-6">
          <div className="static-skeleton h-8 w-32"></div>
          <div className="static-skeleton h-10 w-48 rounded-btn"></div>
        </div>
        <div className="static-skeleton h-40 w-full"></div>
        <div className="static-skeleton h-40 w-full"></div>
      </div>
    );
  }

  return (
    <div className="p-4 md:p-6 h-full flex flex-col min-h-0">
      <div className="flex flex-col sm:flex-row justify-between items-start sm:items-center gap-4 mb-6">
        <h2 className="text-2xl font-bold">Aufgaben</h2>
        <div className="flex flex-wrap items-center gap-2">
          {/* Punkt 7: Suchleiste */}
          <div className="form-control">
            <input
              type="text"
              placeholder="Suche..."
              className="input input-bordered input-sm w-44"
              value={searchQuery}
              onChange={(e) => setSearchQuery(e.target.value)}
            />
          </div>
          <div className="join">
            <button className={`btn join-item btn-sm ${filter === 'all' ? 'btn-active' : ''}`} onClick={() => setFilter('all')}>
              Alle ({totalTasks})
            </button>
            <button className={`btn join-item btn-sm ${filter === 'offen' ? 'btn-active' : ''}`} onClick={() => setFilter('offen')}>
              Offen
            </button>
            <button className={`btn join-item btn-sm ${filter === 'erledigt' ? 'btn-active' : ''}`} onClick={() => setFilter('erledigt')}>
              Erledigt
            </button>
          </div>
        </div>
      </div>

      {filtered.length === 0 ? (
        <div className="hero min-h-[40vh] bg-base-200 rounded-lg">
          <div className="hero-content text-center">
            <div>
              <p className="text-lg opacity-70">
                {filter === 'all' ? 'Noch keine Aufgaben vorhanden.' : `Keine ${filter === 'offen' ? 'offenen' : 'erledigten'} Aufgaben.`}
              </p>
            </div>
          </div>
        </div>
      ) : (
        <>
          {/* Scrollbare Table-Liste — füllt die restliche Seitenhöhe */}
          <div className="card bg-base-200 shadow-sm rounded-xl overflow-hidden flex-1 min-h-0 flex flex-col">
            <div className="divide-y divide-base-300 flex-1 min-h-0 overflow-y-auto">
              {filtered.map((task) => (
              <div
                key={task.id}
                className="p-4 sm:p-5 hover:bg-base-300/40 transition-colors cursor-pointer"
                onClick={() => setSelectedTask(task)}
              >
                <div className="flex flex-col sm:flex-row sm:items-center justify-between gap-3">
                  <div className="flex-1 min-w-0">
                    <div className="flex items-center gap-3">
                      <h4 className="font-bold text-base truncate">{task.title}</h4>
                      <span className="text-sm opacity-50 whitespace-nowrap">
                        {new Date(task.created_at).toLocaleDateString('de-DE')}
                      </span>
                    </div>
                    <div className="flex flex-wrap items-center gap-x-3 gap-y-1 mt-1">
                      {task.user_name && <span className="text-sm opacity-70">{task.user_name}</span>}
                      {task.template_name && task.title !== task.template_name && (
                        <span className="text-sm opacity-70">{task.template_name}</span>
                      )}
                    </div>
                    {/* File attachments in row — H1: nur validierte Upload-Pfade als Link */}
                    {safeFileUrl(task.file_path) && (
                      <div className="mt-2">
                        <a
                          href={safeFileUrl(task.file_path)}
                          target="_blank"
                          rel="noopener noreferrer"
                          className="inline-flex items-center gap-1 text-sm text-primary hover:underline"
                          onClick={(e) => e.stopPropagation()}
                        >
                          <svg xmlns="http://www.w3.org/2000/svg" className="h-4 w-4" fill="none" viewBox="0 0 24 24" stroke="currentColor"><path strokeLinecap="round" strokeLinejoin="round" strokeWidth="2" d="M15.172 7l-6.586 6.586a2 2 0 102.828 2.828l6.414-6.586a4 4 0 00-5.656-5.656l-6.415 6.585a6 6 0 108.486 8.486L20.5 13" /></svg>
                          Dateianhang
                        </a>
                      </div>
                    )}
                    {/* File attachments from task values — H1: nur validierte Upload-Pfade als Link */}
                    {task.values?.filter(v => v.step_type === 'file_upload' && safeFileUrl(v.value)).length > 0 && (
                      <div className="mt-2 flex flex-wrap gap-2">
                        {task.values.filter(v => v.step_type === 'file_upload' && safeFileUrl(v.value)).map(v => (
                          <a
                            key={v.id}
                            href={safeFileUrl(v.value)}
                            target="_blank"
                            rel="noopener noreferrer"
                            className="inline-flex items-center gap-1 text-sm text-primary hover:underline"
                            onClick={(e) => e.stopPropagation()}
                          >
                            <svg xmlns="http://www.w3.org/2000/svg" className="h-4 w-4" fill="none" viewBox="0 0 24 24" stroke="currentColor"><path strokeLinecap="round" strokeLinejoin="round" strokeWidth="2" d="M15.172 7l-6.586 6.586a2 2 0 102.828 2.828l6.414-6.586a4 4 0 00-5.656-5.656l-6.415 6.585a6 6 0 108.486 8.486L20.5 13" /></svg>
                            {v.step_label}
                          </a>
                        ))}
                      </div>
                    )}
                  </div>
                  <div className="flex items-center gap-2 flex-shrink-0">
                    <button
                      className={`btn btn-sm ${task.status === 'offen' ? 'btn-outline' : 'btn-success'}`}
                      onClick={(e) => {
                        e.stopPropagation();
                        updateStatus(task.id, task.status === 'offen' ? 'erledigt' : 'offen');
                      }}
                    >
                      {task.status === 'offen' ? 'Offen' : 'Erledigt'}
                    </button>
                    <button
                      className="btn btn-ghost btn-sm text-error"
                      onClick={(e) => { e.stopPropagation(); deleteTask(task.id); }}
                      title="Aufgabe löschen"
                    >
                      <svg xmlns="http://www.w3.org/2000/svg" className="h-4 w-4" fill="none" viewBox="0 0 24 24" stroke="currentColor"><path strokeLinecap="round" strokeLinejoin="round" strokeWidth="2" d="M19 7l-.867 12.142A2 2 0 0116.138 21H7.862a2 2 0 01-1.995-1.858L5 7m5 4v6m4-6v6m1-10V4a1 1 0 00-1-1h-4a1 1 0 00-1 1v3M4 7h16" /></svg>
                    </button>
                  </div>
                </div>
              </div>
            ))}
            </div>
          </div>
        </>
      )}

      {selectedTask && (
        <TaskModal task={selectedTask} currentUserRole={user?.role} onClose={() => setSelectedTask(null)} onTaskUpdated={() => fetchTasks()} />
      )}

      {/* Confirm Delete Modal */}
      <ConfirmModal
        open={confirmState.open}
        title="Aufgabe löschen"
        message="Möchtest du diese Aufgabe wirklich löschen?"
        confirmLabel="Löschen"
        onConfirm={confirmDeleteTask}
        onCancel={() => setConfirmState({ open: false, id: null })}
      />

      {/* Pagination */}
      {totalPages > 1 && (
        <div className="flex justify-center items-center gap-2 mt-6">
          <button
            className="btn btn-sm btn-outline"
            disabled={currentPage <= 1}
            onClick={() => goToPage(currentPage - 1)}
          >
            « Zurück
          </button>
          <span className="text-sm opacity-70">
            Seite {currentPage} von {totalPages}
          </span>
          <button
            className="btn btn-sm btn-outline"
            disabled={currentPage >= totalPages}
            onClick={() => goToPage(currentPage + 1)}
          >
            Weiter »
          </button>
        </div>
      )}
    </div>
  );
}