import { useState, useCallback, useMemo, memo } from "react";
import {
  Search,
  Loader2,
  AlertCircle,
  GitBranch,
  RefreshCw,
  X,
  Plus,
  Warehouse,
  UserPlus,
} from "lucide-react";
import TaskFlowView from "./TaskFlowView";
import {
  getTaskTree,
  receiveTask,
  rejectTask,
  transferTask,
} from "../../services/taskApi";
import { useToast } from "../ui/Toast";
import type { ProductScanResponse, TaskResponse } from "../../types/api";
import { getStatusConfig } from "../../constants/task";

// ============================================================
// 通用 Modal 容器
// ============================================================

const Modal = memo(function Modal({
  open,
  onClose,
  title,
  children,
}: {
  open: boolean;
  onClose: () => void;
  title: string;
  children: React.ReactNode;
}) {
  if (!open) return null;

  return (
    <div className="fixed inset-0 z-50 flex items-center justify-center">
      {/* 遮罩 */}
      <div
        className="absolute inset-0 bg-black/40 backdrop-blur-sm"
        onClick={onClose}
      />
      {/* 弹窗 */}
      <div className="relative z-10 mx-4 w-full max-w-md rounded-xl bg-white p-6 shadow-2xl">
        <div className="mb-4 flex items-center justify-between">
          <h3 className="text-base font-bold text-gray-800">{title}</h3>
          <button
            onClick={onClose}
            className="rounded-lg p-1 text-gray-400 hover:bg-gray-100 hover:text-gray-600"
          >
            <X className="h-4 w-4" />
          </button>
        </div>
        {children}
      </div>
    </div>
  );
});

// ============================================================
// 确认接收弹窗
// ============================================================

export const ReceiveConfirmModal = memo(function ReceiveConfirmModal({
  open,
  task,
  submitting,
  onClose,
  onConfirm,
}: {
  open: boolean;
  task: TaskResponse | null;
  submitting: boolean;
  onClose: () => void;
  onConfirm: () => void;
}) {
  if (!task) return null;

  return (
    <Modal open={open} onClose={onClose} title="确认接收任务">
      <div className="mb-6 rounded-lg bg-blue-50 px-3 py-2.5 text-sm text-blue-700">
        <p className="font-medium">{task.task_name}</p>
        <p className="mt-0.5 text-xs text-blue-500">
          当前状态: {getStatusConfig(task.status).label}
          {" → "}
          <span className="font-semibold">进行中 (WIP)</span>
        </p>
      </div>
      <p className="mb-6 text-sm text-gray-500">
        确认接收后，该任务将标记为"进行中"，系统将记录接收时间。
      </p>
      <div className="flex justify-end gap-2">
        <button
          onClick={onClose}
          disabled={submitting}
          className="rounded-lg border border-gray-200 px-4 py-2 text-sm text-gray-600 hover:bg-gray-50 disabled:opacity-50"
        >
          取消
        </button>
        <button
          onClick={onConfirm}
          disabled={submitting}
          className="flex items-center gap-1.5 rounded-lg bg-blue-600 px-4 py-2 text-sm font-medium text-white hover:bg-blue-700 disabled:opacity-50"
        >
          {submitting && <Loader2 className="h-3.5 w-3.5 animate-spin" />}
          确认接收
        </button>
      </div>
    </Modal>
  );
});

// ============================================================
// 品质驳回弹窗
// ============================================================

export const RejectModal = memo(function RejectModal({
  open,
  task,
  submitting,
  onClose,
  onSubmit,
}: {
  open: boolean;
  task: TaskResponse | null;
  submitting: boolean;
  onClose: () => void;
  onSubmit: (reason: string) => void;
}) {
  const [reason, setReason] = useState("");

  if (!task) return null;

  function handleSubmit(e: React.FormEvent) {
    e.preventDefault();
    const trimmed = reason.trim();
    if (!trimmed) return;
    onSubmit(trimmed);
    setReason("");
  }

  function handleClose() {
    setReason("");
    onClose();
  }

  return (
    <Modal open={open} onClose={handleClose} title="品质驳回">
      <div className="mb-4 rounded-lg bg-red-50 px-3 py-2.5 text-sm text-red-700">
        <p className="font-medium">{task.task_name}</p>
        <p className="mt-0.5 text-xs text-red-500">
          ⚠ 驳回后将自动生成返工任务，分配给上一道工序负责人
        </p>
      </div>
      <form onSubmit={handleSubmit}>
        <label className="mb-1 block text-sm font-medium text-gray-700">
          驳回原因 <span className="text-red-500">*</span>
        </label>
        <textarea
          value={reason}
          onChange={(e) => setReason(e.target.value)}
          placeholder="请详细说明品质驳回的原因（必填）"
          rows={3}
          maxLength={500}
          className="mb-4 w-full resize-none rounded-lg border border-gray-200 px-3 py-2 text-sm focus:border-red-400 focus:outline-none focus:ring-2 focus:ring-red-100"
          autoFocus
        />
        <div className="flex items-center justify-between">
          <span className="text-xs text-gray-400">{reason.length}/500</span>
          <div className="flex gap-2">
            <button
              type="button"
              onClick={handleClose}
              disabled={submitting}
              className="rounded-lg border border-gray-200 px-4 py-2 text-sm text-gray-600 hover:bg-gray-50 disabled:opacity-50"
            >
              取消
            </button>
            <button
              type="submit"
              disabled={submitting || !reason.trim()}
              className="flex items-center gap-1.5 rounded-lg bg-red-600 px-4 py-2 text-sm font-medium text-white hover:bg-red-700 disabled:opacity-50"
            >
              {submitting && <Loader2 className="h-3.5 w-3.5 animate-spin" />}
              确认驳回
            </button>
          </div>
        </div>
      </form>
    </Modal>
  );
});

// ============================================================
// 完工裂变转交弹窗
// ============================================================

export const TransferModal = memo(function TransferModal({
  open,
  task,
  submitting,
  onClose,
  onSubmit,
}: {
  open: boolean;
  task: TaskResponse | null;
  submitting: boolean;
  onClose: () => void;
  onSubmit: (nextTaskName: string, assignees: string[], note: string) => void;
}) {
  const [nextTaskName, setNextTaskName] = useState("");
  const [assigneeInput, setAssigneeInput] = useState("");
  const [assignees, setAssignees] = useState<string[]>([]);
  const [useWarehouse, setUseWarehouse] = useState(false);
  const [note, setNote] = useState("");

  if (!task) return null;

  function handleAddAssignee() {
    const trimmed = assigneeInput.trim();
    if (!trimmed) return;
    if (assignees.includes(trimmed)) {
      setAssigneeInput("");
      return;
    }
    setAssignees((prev) => [...prev, trimmed]);
    setAssigneeInput("");
  }

  function handleRemoveAssignee(id: string) {
    setAssignees((prev) => prev.filter((a) => a !== id));
  }

  function handleAssigneeKeyDown(e: React.KeyboardEvent) {
    if (e.key === "Enter") {
      e.preventDefault();
      handleAddAssignee();
    }
  }

  function handleSubmit(e: React.FormEvent) {
    e.preventDefault();
    const name = nextTaskName.trim();
    if (!name) return;

    const finalAssignees = [...assignees];
    if (useWarehouse) {
      finalAssignees.push("virtual_warehouse");
    }
    if (finalAssignees.length === 0) return;

    onSubmit(name, finalAssignees, note.trim());
    // 重置表单
    setNextTaskName("");
    setAssignees([]);
    setAssigneeInput("");
    setUseWarehouse(false);
    setNote("");
  }

  function handleClose() {
    setNextTaskName("");
    setAssignees([]);
    setAssigneeInput("");
    setUseWarehouse(false);
    setNote("");
    onClose();
  }

  const allAssignees = [
    ...assignees,
    ...(useWarehouse ? ["virtual_warehouse"] : []),
  ];

  return (
    <Modal open={open} onClose={handleClose} title="完工转交 — 裂变到下道工序">
      <div className="mb-4 rounded-lg bg-green-50 px-3 py-2.5 text-sm text-green-700">
        <p className="font-medium">{task.task_name}</p>
        <p className="mt-0.5 text-xs text-green-500">
          完成任务并批量创建下一道工序任务，支持多路裂变分支
        </p>
      </div>

      <form onSubmit={handleSubmit} className="space-y-4">
        {/* 下道工序名称 */}
        <div>
          <label className="mb-1 block text-sm font-medium text-gray-700">
            下一道工序名称 <span className="text-red-500">*</span>
          </label>
          <input
            type="text"
            value={nextTaskName}
            onChange={(e) => setNextTaskName(e.target.value)}
            placeholder="如：组装、质检、包装"
            maxLength={200}
            className="w-full rounded-lg border border-gray-200 px-3 py-2 text-sm focus:border-green-400 focus:outline-none focus:ring-2 focus:ring-green-100"
            autoFocus
          />
        </div>

        {/* 接收人（多选） */}
        <div>
          <label className="mb-1 flex items-center gap-1 text-sm font-medium text-gray-700">
            <UserPlus className="h-3.5 w-3.5" />
            下一道工序接收人 <span className="text-red-500">*</span>
          </label>

          {/* 已添加的接收人标签 */}
          {allAssignees.length > 0 && (
            <div className="mb-2 flex flex-wrap gap-1.5">
              {allAssignees.map((a) => (
                <span
                  key={a}
                  className={`inline-flex items-center gap-1 rounded-full px-2.5 py-1 text-xs font-medium ${
                    a === "virtual_warehouse"
                      ? "bg-purple-100 text-purple-700"
                      : "bg-blue-100 text-blue-700"
                  }`}
                >
                  {a === "virtual_warehouse" ? (
                    <Warehouse className="h-3 w-3" />
                  ) : null}
                  {a === "virtual_warehouse" ? "仓库" : a}
                  {a !== "virtual_warehouse" && (
                    <button
                      type="button"
                      onClick={() => handleRemoveAssignee(a)}
                      className="ml-0.5 rounded-full p-0.5 hover:bg-blue-200"
                    >
                      <X className="h-2.5 w-2.5" />
                    </button>
                  )}
                </span>
              ))}
            </div>
          )}

          {/* 输入 + 添加按钮 */}
          <div className="flex gap-2">
            <input
              type="text"
              value={assigneeInput}
              onChange={(e) => setAssigneeInput(e.target.value)}
              onKeyDown={handleAssigneeKeyDown}
              placeholder="输入接收人 ID，按 Enter 添加"
              maxLength={64}
              className="flex-1 rounded-lg border border-gray-200 px-3 py-2 text-sm focus:border-green-400 focus:outline-none focus:ring-2 focus:ring-green-100"
            />
            <button
              type="button"
              onClick={handleAddAssignee}
              disabled={!assigneeInput.trim()}
              className="flex items-center gap-1 rounded-lg border border-gray-200 px-3 py-2 text-sm text-gray-600 hover:bg-gray-50 disabled:opacity-40"
            >
              <Plus className="h-3.5 w-3.5" />
              添加
            </button>
          </div>
        </div>

        {/* 虚拟入库 */}
        <label className="flex items-center gap-2 cursor-pointer select-none">
          <input
            type="checkbox"
            checked={useWarehouse}
            onChange={(e) => setUseWarehouse(e.target.checked)}
            className="h-4 w-4 rounded border-gray-300 text-purple-600 focus:ring-purple-500"
          />
          <Warehouse className="h-4 w-4 text-purple-500" />
          <span className="text-sm text-gray-700">
            同时入库（产品 current_location → virtual_warehouse）
          </span>
        </label>

        {/* 备注 */}
        <div>
          <label className="mb-1 block text-sm font-medium text-gray-700">
            交接备注 <span className="text-gray-400 font-normal">(可选)</span>
          </label>
          <textarea
            value={note}
            onChange={(e) => setNote(e.target.value)}
            placeholder="转交附言、注意事项等"
            rows={2}
            className="w-full resize-none rounded-lg border border-gray-200 px-3 py-2 text-sm focus:border-green-400 focus:outline-none focus:ring-2 focus:ring-green-100"
          />
        </div>

        {/* 预览 */}
        {allAssignees.length > 0 && nextTaskName.trim() && (
          <div className="rounded-lg bg-gray-50 px-3 py-2.5 text-xs text-gray-500">
            <p className="font-medium text-gray-600">裂变预览：</p>
            <p className="mt-1">
              将创建 <span className="font-semibold text-gray-700">
                {allAssignees.length}
              </span>{" "}
              个「
              <span className="font-semibold text-gray-700">
                {nextTaskName.trim()}
              </span>
              」任务
              {allAssignees.length > 1 && (
                <span className="text-purple-600">
                  {" "}
                  — 触发裂变，父任务为当前任务
                </span>
              )}
            </p>
            <p className="mt-0.5">
              接收人:{" "}
              {allAssignees
                .map((a) => (a === "virtual_warehouse" ? "仓库" : a))
                .join(", ")}
            </p>
          </div>
        )}

        {/* 按钮 */}
        <div className="flex justify-end gap-2 pt-2">
          <button
            type="button"
            onClick={handleClose}
            disabled={submitting}
            className="rounded-lg border border-gray-200 px-4 py-2 text-sm text-gray-600 hover:bg-gray-50 disabled:opacity-50"
          >
            取消
          </button>
          <button
            type="submit"
            disabled={
              submitting ||
              !nextTaskName.trim() ||
              allAssignees.length === 0
            }
            className="flex items-center gap-1.5 rounded-lg bg-green-600 px-4 py-2 text-sm font-medium text-white hover:bg-green-700 disabled:opacity-50"
          >
            {submitting && <Loader2 className="h-3.5 w-3.5 animate-spin" />}
            确认转交
          </button>
        </div>
      </form>
    </Modal>
  );
});

// ============================================================
// 操作弹窗目标类型
// ============================================================

export interface ModalTarget {
  task: TaskResponse;
  action: "receive" | "reject" | "transfer";
}

// ============================================================
// 主容器组件
// ============================================================

export default function TaskTreeViewer() {
  const { toast } = useToast();

  // 搜索状态
  const [serial, setSerial] = useState("");
  const [product, setProduct] = useState<ProductScanResponse | null>(null);
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);

  // 弹窗状态
  const [modalTarget, setModalTarget] = useState<ModalTarget | null>(null);
  const [submitting, setSubmitting] = useState(false);

  // ---- 数据刷新 ----
  const refresh = useCallback(async () => {
    const trimmed = serial.trim();
    if (trimmed.length !== 16) return;
    try {
      const result = await getTaskTree(trimmed);
      setProduct(result);
    } catch {
      // 静默失败 — 不影响当前展示
    }
  }, [serial]);

  async function handleSearch(e?: React.FormEvent) {
    e?.preventDefault();
    const trimmed = serial.trim();
    if (trimmed.length !== 16) {
      setError("请输入 16 位产品身份证");
      return;
    }

    setLoading(true);
    setError(null);
    setProduct(null);

    try {
      const result = await getTaskTree(trimmed);
      setProduct(result);
    } catch (err: any) {
      const msg =
        err?.response?.status === 404
          ? `未找到产品身份证 ${trimmed} 对应的产品`
          : err?.response?.data?.detail ??
            err?.message ??
            "查询失败，请检查后端服务";
      setError(msg);
    } finally {
      setLoading(false);
    }
  }

  // ---- 操作处理 ----

  async function handleReceive() {
    if (!modalTarget) return;
    setSubmitting(true);
    try {
      await receiveTask(modalTarget.task.id);
      toast("任务已接收 (PENDING → WIP)", "success");
      setModalTarget(null);
      await refresh();
    } catch (err: any) {
      toast(
        err?.response?.data?.detail ?? err?.message ?? "接收失败",
        "error"
      );
    } finally {
      setSubmitting(false);
    }
  }

  async function handleReject(reason: string) {
    if (!modalTarget) return;
    setSubmitting(true);
    try {
      await rejectTask(modalTarget.task.id, reason);
      toast("任务已驳回，已自动创建返工任务", "success");
      setModalTarget(null);
      await refresh();
    } catch (err: any) {
      toast(
        err?.response?.data?.detail ?? err?.message ?? "驳回失败",
        "error"
      );
    } finally {
      setSubmitting(false);
    }
  }

  async function handleTransfer(
    nextTaskName: string,
    assignees: string[],
    note: string
  ) {
    if (!modalTarget) return;
    setSubmitting(true);
    try {
      const result = await transferTask(
        modalTarget.task.id,
        assignees,
        nextTaskName,
        note || undefined
      );
      toast(result.message, "success");
      setModalTarget(null);
      await refresh();
    } catch (err: any) {
      toast(
        err?.response?.data?.detail ?? err?.message ?? "转交失败",
        "error"
      );
    } finally {
      setSubmitting(false);
    }
  }

  // ---- 渲染 ----

  // 🚀 缓存递归计算 — 仅在 task_tree 变化时重新计算
  const totalTaskCount = useMemo(
    () => (product?.task_tree ? countAllTasks(product.task_tree) : 0),
    [product?.task_tree],
  );

  const modalTask = modalTarget?.task ?? null;

  return (
    <div>
      {/* ---- 搜索栏 ---- */}
      <div className="mb-6">
        <h2 className="text-xl font-bold text-gray-800">任务全景树</h2>
        <p className="mt-1 text-sm text-gray-500">
          输入 16 位产品身份证，查看完整任务流转十字矩阵树状图
        </p>

        <form onSubmit={handleSearch} className="mt-4 flex items-center gap-2">
          <div className="relative flex-1 max-w-md">
            <Search className="absolute left-3 top-1/2 h-4 w-4 -translate-y-1/2 text-gray-400" />
            <input
              type="text"
              value={serial}
              onChange={(e) => setSerial(e.target.value)}
              placeholder="输入 16 位产品身份证，如 X20260801000001"
              maxLength={16}
              className="w-full rounded-lg border border-gray-200 py-2.5 pl-9 pr-3 font-mono text-sm tracking-widest placeholder:tracking-normal placeholder:font-sans focus:border-blue-400 focus:outline-none focus:ring-2 focus:ring-blue-100"
            />
          </div>
          <button
            type="submit"
            disabled={loading}
            className="flex items-center gap-1.5 rounded-lg bg-blue-600 px-5 py-2.5 text-sm font-medium text-white transition-colors hover:bg-blue-700 disabled:opacity-50"
          >
            {loading ? (
              <Loader2 className="h-4 w-4 animate-spin" />
            ) : (
              <Search className="h-4 w-4" />
            )}
            查询
          </button>
          {product && (
            <button
              type="button"
              onClick={() => handleSearch()}
              className="flex items-center gap-1.5 rounded-lg border border-gray-200 bg-white px-3 py-2.5 text-sm text-gray-500 transition-colors hover:bg-gray-50"
              title="刷新"
            >
              <RefreshCw
                className={`h-4 w-4 ${loading ? "animate-spin" : ""}`}
              />
            </button>
          )}
        </form>
      </div>

      {/* ---- 错误 ---- */}
      {error && (
        <div className="mb-4 flex items-center gap-2 rounded-lg border border-red-200 bg-red-50 px-4 py-3 text-sm text-red-700">
          <AlertCircle className="h-4 w-4 shrink-0" />
          {error}
        </div>
      )}

      {/* ---- 加载中 ---- */}
      {loading && (
        <div className="flex items-center justify-center py-20">
          <Loader2 className="h-8 w-8 animate-spin text-blue-500" />
        </div>
      )}

      {/* ---- 产品信息摘要 ---- */}
      {product && !loading && (
        <div className="mb-6">
          <div className="flex flex-wrap items-center gap-3 rounded-xl bg-white p-4 shadow-sm">
            <div>
              <span className="text-xs text-gray-400">产品身份证</span>
              <p className="font-mono text-base font-bold tracking-widest text-gray-800">
                {product.serial_number}
              </p>
            </div>
            <div className="hidden h-8 w-px bg-gray-200 sm:block" />
            <div>
              <span className="text-xs text-gray-400">订单编号</span>
              <p className="text-sm font-medium text-gray-600">
                {product.order_no || "—"}
              </p>
            </div>
            <div className="hidden h-8 w-px bg-gray-200 sm:block" />
            <div>
              <span className="text-xs text-gray-400">当前位置</span>
              <p className="text-sm font-medium text-gray-600">
                {product.current_location_id === "virtual_warehouse" ? (
                  <span className="inline-flex items-center gap-1 rounded bg-purple-50 px-1.5 py-0.5 text-xs font-medium text-purple-600">
                    🏭 仓库
                  </span>
                ) : (
                  product.current_location_id ?? "—"
                )}
              </p>
            </div>
            <div className="hidden h-8 w-px bg-gray-200 sm:block" />
            <div>
              <span className="text-xs text-gray-400">任务总数</span>
              <p className="text-sm font-semibold text-gray-800">
                {product.top_level_tasks?.length ?? 0} 顶层
                {product.task_tree?.length
                  ? ` · ${totalTaskCount} 总计`
                  : ""}
              </p>
            </div>
          </div>
        </div>
      )}

      {/* ---- 任务流转分支/卡片视图 ---- */}
      {product && !loading && (
        <>
          {product.task_tree && product.task_tree.length > 0 ? (
            <div className="rounded-xl bg-white p-6 shadow-sm overflow-hidden">
              <TaskFlowView
                tasks={product.task_tree}
                onAction={setModalTarget}
              />
            </div>
          ) : (
            <div className="flex flex-col items-center justify-center rounded-xl bg-white py-16 text-gray-400 shadow-sm">
              <GitBranch className="mb-3 h-10 w-10" />
              <p className="text-sm">该产品暂无关联任务</p>
            </div>
          )}
        </>
      )}

      {/* ---- 弹窗 ---- */}
      <ReceiveConfirmModal
        open={modalTarget?.action === "receive"}
        task={modalTask}
        submitting={submitting}
        onClose={() => setModalTarget(null)}
        onConfirm={handleReceive}
      />
      <RejectModal
        open={modalTarget?.action === "reject"}
        task={modalTask}
        submitting={submitting}
        onClose={() => setModalTarget(null)}
        onSubmit={handleReject}
      />
      <TransferModal
        open={modalTarget?.action === "transfer"}
        task={modalTask}
        submitting={submitting}
        onClose={() => setModalTarget(null)}
        onSubmit={handleTransfer}
      />
    </div>
  );
}

// ============================================================
// 工具函数：递归统计任务总数
// ============================================================

function countAllTasks(tasks: TaskResponse[]): number {
  return tasks.reduce((sum, t) => sum + 1 + countAllTasks(t.child_tasks), 0);
}