/**
 * 任务流转卡片堆叠视图 — 水平分支 + 卡片层叠布局
 *
 * 将递归任务树按层级拆分为水平分支，每层卡片横向排列，
 * 当前激活（WIP/PENDING）卡片高亮居中，操作按钮集成在卡片底部。
 */
import { memo, useMemo } from "react";
import {
  GitBranch,
  ArrowDown,
  AlertTriangle,
  Clock,
} from "lucide-react";
import type { TaskResponse } from "../../types/api";
import { TASK_STATUS } from "../../types/api";
import { getStatusConfig } from "../../constants/task";
import type { ModalTarget } from "./TaskTreeViewer";

// ---- 耗时计算（复用） ----

function calcDwell(
  receivedAt: string | null,
  completedAt: string | null,
  status: string,
): { text: string; highlight: boolean } | null {
  if (!receivedAt) return null;
  const start = new Date(receivedAt).getTime();
  const end = completedAt ? new Date(completedAt).getTime() : Date.now();
  const diffMs = end - start;
  if (diffMs < 0) return null;

  const totalMin = Math.floor(diffMs / 60000);
  if (totalMin < 1) return { text: "< 1分钟", highlight: status === "WIP" };
  if (totalMin < 60) return { text: `${totalMin}分钟`, highlight: status === "WIP" };

  const hours = Math.floor(totalMin / 60);
  const remainMin = totalMin % 60;
  if (hours < 24) {
    return { text: `${hours}小时${remainMin > 0 ? remainMin + "分钟" : ""}`, highlight: status === "WIP" };
  }

  const days = Math.floor(hours / 24);
  const remainHr = hours % 24;
  return { text: `${days}天${remainHr > 0 ? remainHr + "小时" : ""}`, highlight: status === "WIP" };
}

// ---- 类型 ----

interface LevelGroup {
  depth: number;
  tasks: TaskResponse[];
}

// ---- 将递归树拍平为层级 ----

function flattenLevels(tasks: TaskResponse[], depth: number = 0): LevelGroup[] {
  const result: LevelGroup[] = [];
  if (!tasks || tasks.length === 0) return result;

  // 当前层级
  result.push({ depth, tasks });

  // 递归子层级
  for (const t of tasks) {
    if (t.child_tasks && t.child_tasks.length > 0) {
      const childLevels = flattenLevels(t.child_tasks, depth + 1);
      for (const cl of childLevels) {
        // 合并同深度的层级
        const existing = result.find((r) => r.depth === cl.depth && r !== result[result.indexOf({ depth, tasks })] );
        // 简化：直接 push，在渲染时按 depth 分组
      }
      result.push(...childLevels);
    }
  }

  return result;
}

/** 按 depth 聚合所有层级 */
function groupByDepth(levels: LevelGroup[]): Map<number, TaskResponse[]> {
  const map = new Map<number, TaskResponse[]>();
  for (const lvl of levels) {
    if (!map.has(lvl.depth)) map.set(lvl.depth, []);
    map.get(lvl.depth)!.push(...lvl.tasks);
  }
  return map;
}

// ---- 单张任务卡片 ----

const FlowCard = memo(function FlowCard({
  task,
  isActive,
  onAction,
}: {
  task: TaskResponse;
  isActive: boolean;
  onAction: (target: ModalTarget) => void;
}) {
  const cfg = getStatusConfig(task.status);
  const dwell = calcDwell(task.received_at, task.completed_at, task.status);
  const isCompleted = task.status?.toUpperCase() === TASK_STATUS.COMPLETED;
  const isArchived = task.status?.toUpperCase() === TASK_STATUS.ARCHIVED;

  return (
    <div
      className={`relative shrink-0 w-52 rounded-xl border-2 bg-white p-3.5 shadow-md transition-all ${
        isActive
          ? `border-blue-400 ${cfg.ring} shadow-lg shadow-blue-100 scale-105 z-10`
          : isCompleted || isArchived
            ? "border-gray-150 opacity-70"
            : "border-gray-200 hover:shadow-lg"
      } ${task.is_rework ? "border-l-red-500 border-l-4" : ""}`}
    >
      {/* 返工标记 */}
      {task.is_rework && (
        <div className="absolute -top-2 -left-1 rounded bg-red-600 px-1.5 py-0.5 text-[9px] font-bold text-white animate-pulse">
          <AlertTriangle className="inline h-2.5 w-2.5 mr-0.5" />返工
        </div>
      )}

      {/* 裂变标记 */}
      {task.child_tasks.length > 1 && (
        <div className="absolute -top-2 right-2 rounded bg-purple-100 px-1.5 py-0.5 text-[9px] font-medium text-purple-700">
          <GitBranch className="inline h-2.5 w-2.5 mr-0.5" />
          裂变×{task.child_tasks.length}
        </div>
      )}

      {/* 任务名 */}
      <p className="text-sm font-bold text-gray-800 truncate">{task.task_name}</p>

      {/* 状态 Badge */}
      <div className="mt-1.5 flex items-center gap-1.5 flex-wrap">
        <span className={`inline-flex items-center rounded-full px-2 py-0.5 text-[10px] font-medium ${cfg.bg} ${cfg.text}`}>
          {cfg.label}
        </span>
        {task.assignee_id && (
          <span className="text-[10px] text-gray-400 truncate max-w-[80px]">
            {task.assignee_id}
          </span>
        )}
      </div>

      {/* 停留耗时 */}
      {dwell && (
        <p className={`mt-1 flex items-center gap-1 text-[10px] ${dwell.highlight ? "text-red-500 font-semibold" : "text-orange-500"}`}>
          <Clock className="h-3 w-3" />
          {dwell.highlight ? <span className="animate-pulse">⏳ {dwell.text}</span> : <span>{dwell.text}</span>}
        </p>
      )}

      {/* 驳回原因 */}
      {task.reject_reason && (
        <p className="mt-1 text-[10px] text-red-500 line-clamp-2">{task.reject_reason}</p>
      )}

      {/* 日期 */}
      <p className="mt-1 text-[9px] text-gray-300">
        {task.received_at && `接收: ${new Date(task.received_at).toLocaleDateString("zh-CN")}`}
      </p>

      {/* 操作按钮 — 仅激活态显示 */}
      {isActive && (
        <div className="mt-2 flex gap-1.5 border-t border-gray-100 pt-2">
          {task.status?.toUpperCase() === TASK_STATUS.PENDING && (
            <>
              <button
                onClick={() => onAction({ task, action: "receive" })}
                className="flex-1 rounded border border-blue-200 bg-blue-50 py-1 text-[10px] font-medium text-blue-600 hover:bg-blue-100"
              >
                接收
              </button>
              <button
                onClick={() => onAction({ task, action: "reject" })}
                className="rounded border border-red-200 bg-red-50 px-2 py-1 text-[10px] font-medium text-red-500 hover:bg-red-100"
              >
                驳回
              </button>
              <button
                onClick={() => onAction({ task, action: "transfer" })}
                className="rounded border border-green-200 bg-green-50 px-2 py-1 text-[10px] font-medium text-green-600 hover:bg-green-100"
              >
                转交
              </button>
            </>
          )}
          {task.status?.toUpperCase() === TASK_STATUS.WIP && (
            <>
              <button
                onClick={() => onAction({ task, action: "reject" })}
                className="flex-1 rounded border border-red-200 bg-red-50 py-1 text-[10px] font-medium text-red-500 hover:bg-red-100"
              >
                驳回
              </button>
              <button
                onClick={() => onAction({ task, action: "transfer" })}
                className="flex-1 rounded border border-green-200 bg-green-50 py-1 text-[10px] font-medium text-green-600 hover:bg-green-100"
              >
                转交
              </button>
            </>
          )}
        </div>
      )}
    </div>
  );
});

// ---- 主视图 ----

interface TaskFlowViewProps {
  tasks: TaskResponse[];
  onAction: (target: ModalTarget) => void;
}

export const TaskFlowView = memo(function TaskFlowView({ tasks, onAction }: TaskFlowViewProps) {
  // 按 depth 分组的层级数据
  const depthMap = useMemo(() => {
    if (!tasks || tasks.length === 0) return new Map<number, TaskResponse[]>();
    const flat = flattenLevels(tasks);
    // 按 depth 聚合去重
    const merged = new Map<number, Map<string, TaskResponse>>();
    for (const lvl of flat) {
      if (!merged.has(lvl.depth)) merged.set(lvl.depth, new Map());
      const inner = merged.get(lvl.depth)!;
      for (const t of lvl.tasks) {
        if (!inner.has(t.id)) inner.set(t.id, t);
      }
    }
    const result = new Map<number, TaskResponse[]>();
    for (const [depth, idMap] of merged) {
      result.set(depth, Array.from(idMap.values()));
    }
    return result;
  }, [tasks]);

  const depths = Array.from(depthMap.keys()).sort((a, b) => a - b);

  if (depths.length === 0) return null;

  return (
    <div className="space-y-4">
      {depths.map((depth) => {
        const levelTasks = depthMap.get(depth) || [];
        return (
          <div key={depth}>
            {/* 层级标签 */}
            <div className="mb-2 flex items-center gap-2">
              <span className="text-[10px] font-semibold text-gray-400 uppercase tracking-wider">
                {depth === 0 ? "顶层任务" : `第 ${depth} 层子任务`}
              </span>
              <div className="h-px flex-1 bg-gray-100" />
            </div>

            {/* 卡片横向排列 */}
            <div className="flex gap-3 overflow-x-auto pb-2 pl-2"
                 style={{ scrollSnapType: "x mandatory" }}>
              {levelTasks.map((task) => {
                const isActive =
                  task.status?.toUpperCase() === TASK_STATUS.PENDING ||
                  task.status?.toUpperCase() === TASK_STATUS.WIP;
                return (
                  <div key={task.id} style={{ scrollSnapAlign: "start" }}>
                    <FlowCard
                      task={task}
                      isActive={isActive}
                      onAction={onAction}
                    />
                  </div>
                );
              })}
            </div>

            {/* 层级间连接箭头 */}
            {depth < depths.length - 1 && (
              <div className="flex justify-center py-1">
                <ArrowDown className="h-4 w-4 text-gray-300" />
              </div>
            )}
          </div>
        );
      })}
    </div>
  );
});

export default TaskFlowView;