"use client";

import { useEffect, useState } from "react";
import { Task, getTasks, updateTask, createTask } from "@/lib/api";
import TaskModal from "@/components/TaskModal";

const COLUMNS = [
  { key: "draft", label: "Backlog", color: "#737373" },
  { key: "ready", label: "TODO", color: "#3b82f6" },
  { key: "in_progress", label: "In Progress", color: "#f59e0b" },
  { key: "review", label: "Review", color: "#a855f7" },
  { key: "completed", label: "Done", color: "#22c55e" },
];

const PRIORITY_COLORS: Record<string, string> = {
  critical: "#ef4444",
  high: "#f59e0b",
  medium: "#3b82f6",
  low: "#737373",
};

interface Props {
  projectId: string;
}

export default function KanbanBoard({ projectId }: Props) {
  const [tasks, setTasks] = useState<Task[]>([]);
  const [loading, setLoading] = useState(true);
  const [newTaskTitle, setNewTaskTitle] = useState("");
  const [addingTo, setAddingTo] = useState<string | null>(null);
  const [draggedTask, setDraggedTask] = useState<string | null>(null);
  const [activeColumn, setActiveColumn] = useState<string | null>(null);
  const [selectedTask, setSelectedTask] = useState<Task | null>(null);

  const loadTasks = async () => {
    try {
      const data = await getTasks(projectId);
      setTasks(data);
    } finally {
      setLoading(false);
    }
  };

  useEffect(() => {
    loadTasks();
  }, [projectId]);

  const handleDrop = async (status: string) => {
    if (!draggedTask) return;
    const task = tasks.find((t) => t.id === draggedTask);
    if (!task || task.status === status) return;

    setTasks((prev) => prev.map((t) => (t.id === draggedTask ? { ...t, status } : t)));
    setDraggedTask(null);

    try {
      await updateTask(draggedTask, { status });
    } catch {
      loadTasks();
    }
  };

  const handleMoveTask = async (taskId: string, newStatus: string) => {
    setTasks((prev) => prev.map((t) => (t.id === taskId ? { ...t, status: newStatus } : t)));
    try {
      await updateTask(taskId, { status: newStatus });
    } catch {
      loadTasks();
    }
  };

  const handleAddTask = async (status: string) => {
    if (!newTaskTitle.trim()) return;
    try {
      const task = await createTask({
        project_id: projectId,
        title: newTaskTitle.trim(),
        status,
      });
      setTasks((prev) => [...prev, task]);
      setNewTaskTitle("");
      setAddingTo(null);
    } catch (e) {
      console.error(e);
    }
  };

  if (loading) {
    return <div className="flex items-center justify-center h-64 text-[var(--muted)]">Загрузка...</div>;
  }

  // Mobile: column selector + vertical list
  // Desktop: horizontal kanban
  return (
    <div className="h-full flex flex-col">
      {/* Mobile column tabs */}
      <div className="md:hidden flex overflow-x-auto border-b border-[var(--border)] px-2 py-1 gap-1 shrink-0">
        {COLUMNS.map((col) => {
          const count = tasks.filter((t) => t.status === col.key).length;
          return (
            <button
              key={col.key}
              onClick={() => setActiveColumn(col.key)}
              className={`flex items-center gap-1.5 px-3 py-1.5 rounded-full text-xs whitespace-nowrap shrink-0 transition-colors
                ${(activeColumn || "draft") === col.key
                  ? "bg-white/10 text-[var(--fg)]"
                  : "text-[var(--muted)]"
                }`}
            >
              <span className="w-2 h-2 rounded-full" style={{ background: col.color }} />
              {col.label}
              {count > 0 && <span className="text-[var(--muted)]">{count}</span>}
            </button>
          );
        })}
      </div>

      {/* Mobile: single column view */}
      <div className="md:hidden flex-1 overflow-y-auto p-3">
        {(() => {
          const col = COLUMNS.find((c) => c.key === (activeColumn || "draft"))!;
          const colTasks = tasks.filter((t) => t.status === col.key);
          const colIndex = COLUMNS.findIndex((c) => c.key === col.key);
          return (
            <div className="flex flex-col gap-2">
              {colTasks.map((task) => (
                <div
                  key={task.id}
                  className="bg-[var(--card)] border border-[var(--border)] rounded-lg p-3 cursor-pointer
                             hover:border-[var(--accent)] transition-colors"
                  onClick={() => setSelectedTask(task)}
                >
                  <div className="flex items-center gap-1.5 mb-1">
                    <div
                      className="w-2 h-2 rounded-full shrink-0"
                      style={{ background: PRIORITY_COLORS[task.priority] || "#737373" }}
                    />
                    <span className="text-xs text-[var(--muted)]">{task.key}</span>
                  </div>
                  <div className="text-sm ml-3.5">{task.title}</div>
                  {/* Move buttons */}
                  <div className="flex gap-1 mt-2 ml-4">
                    {colIndex > 0 && (
                      <button
                        onClick={(e) => { e.stopPropagation(); handleMoveTask(task.id, COLUMNS[colIndex - 1].key); }}
                        className="text-xs px-2 py-0.5 rounded bg-white/5 text-[var(--muted)]
                                   hover:text-[var(--fg)]"
                      >
                        ← {COLUMNS[colIndex - 1].label}
                      </button>
                    )}
                    {colIndex < COLUMNS.length - 1 && (
                      <button
                        onClick={(e) => { e.stopPropagation(); handleMoveTask(task.id, COLUMNS[colIndex + 1].key); }}
                        className="text-xs px-2 py-0.5 rounded bg-white/5 text-[var(--muted)]
                                   hover:text-[var(--fg)]"
                      >
                        {COLUMNS[colIndex + 1].label} →
                      </button>
                    )}
                  </div>
                </div>
              ))}

              {addingTo === col.key ? (
                <input
                  autoFocus
                  className="w-full bg-[var(--card)] border border-[var(--border)] rounded-lg px-3 py-2
                             text-sm outline-none focus:border-[var(--accent)]"
                  placeholder="Название задачи..."
                  value={newTaskTitle}
                  onChange={(e) => setNewTaskTitle(e.target.value)}
                  onKeyDown={(e) => {
                    if (e.key === "Enter") handleAddTask(col.key);
                    if (e.key === "Escape") setAddingTo(null);
                  }}
                  onBlur={() => !newTaskTitle.trim() && setAddingTo(null)}
                />
              ) : (
                <button
                  className="text-sm text-[var(--muted)] hover:text-[var(--fg)] py-2"
                  onClick={() => setAddingTo(col.key)}
                >
                  + Добавить задачу
                </button>
              )}
            </div>
          );
        })()}
      </div>

      {/* Desktop: horizontal kanban */}
      <div className="hidden md:flex gap-4 overflow-x-auto p-4 flex-1">
        {COLUMNS.map((col) => {
          const colTasks = tasks.filter((t) => t.status === col.key);
          return (
            <div
              key={col.key}
              className="flex flex-col min-w-[280px] w-[280px] shrink-0"
              onDragOver={(e) => e.preventDefault()}
              onDrop={() => handleDrop(col.key)}
            >
              <div className="flex items-center gap-2 mb-3 px-1">
                <div className="w-3 h-3 rounded-full" style={{ background: col.color }} />
                <span className="font-semibold text-sm">{col.label}</span>
                <span className="text-xs text-[var(--muted)] ml-auto">{colTasks.length}</span>
              </div>

              <div className="flex flex-col gap-2 flex-1 min-h-[100px] rounded-lg bg-[var(--bg)] p-2">
                {colTasks.map((task) => (
                  <div
                    key={task.id}
                    draggable
                    onDragStart={() => setDraggedTask(task.id)}
                    onClick={() => setSelectedTask(task)}
                    className="bg-[var(--card)] border border-[var(--border)] rounded-lg p-3 cursor-grab
                               hover:border-[var(--accent)] transition-colors active:cursor-grabbing"
                  >
                    <div className="flex items-center gap-1.5 mb-1">
                      <div
                        className="w-2 h-2 rounded-full shrink-0"
                        style={{ background: PRIORITY_COLORS[task.priority] || "#737373" }}
                        title={task.priority}
                      />
                      <span className="text-xs text-[var(--muted)]">{task.key}</span>
                    </div>
                    <div className="text-sm ml-3.5">{task.title}</div>
                  </div>
                ))}

                {addingTo === col.key ? (
                  <input
                    autoFocus
                    className="w-full bg-[var(--card)] border border-[var(--border)] rounded px-2 py-1.5
                               text-sm outline-none focus:border-[var(--accent)]"
                    placeholder="Название задачи..."
                    value={newTaskTitle}
                    onChange={(e) => setNewTaskTitle(e.target.value)}
                    onKeyDown={(e) => {
                      if (e.key === "Enter") handleAddTask(col.key);
                      if (e.key === "Escape") setAddingTo(null);
                    }}
                    onBlur={() => !newTaskTitle.trim() && setAddingTo(null)}
                  />
                ) : (
                  <button
                    className="text-xs text-[var(--muted)] hover:text-[var(--fg)] mt-1 text-left px-2 py-1"
                    onClick={() => setAddingTo(col.key)}
                  >
                    + Добавить
                  </button>
                )}
              </div>
            </div>
          );
        })}
      </div>
      {/* Task modal */}
      {selectedTask && (
        <TaskModal
          task={selectedTask}
          projectId={projectId}
          onClose={() => setSelectedTask(null)}
          onUpdated={(updated) => {
            setTasks((prev) => prev.map((t) => (t.id === updated.id ? updated : t)));
            setSelectedTask(updated);
          }}
          onDeleted={(id) => {
            setTasks((prev) => prev.filter((t) => t.id !== id));
            setSelectedTask(null);
          }}
        />
      )}
    </div>
  );
}