import { useDeferredValue, useEffect, useMemo, useRef, useState } from "react";
import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
import { useSearchParams } from "react-router-dom";
import { toast } from "sonner";
import { mapApiErrorMessage } from "../api/errorMessages";
import { isApiError } from "../api/types";
import {
  approveWorkflowTask,
  fetchWorkflowApprovers,
  fetchWorkflowTaskDetail,
  fetchWorkflowTasks,
  rejectWorkflowTask,
  returnWorkflowTask,
  transferWorkflowTask,
  type WorkflowTaskDetail,
  type WorkflowTaskSummary,
} from "../api/workflow";
import { useAuth } from "../auth/AuthContext";
import { hasAnyPermission } from "../auth/permissions";
import { PageHeader } from "../components/common/PageHeader";
import { StatusBadge } from "../components/common/StatusBadge";
import { PageScaffold } from "../components/patterns/PageScaffold";
import { Button } from "../components/ui/button";
import { Input } from "../components/ui/input";
import { Spinner } from "../components/ui/spinner";
import { Tabs, TabsList, TabsTrigger } from "../components/ui/tabs";
import { Textarea } from "../components/ui/textarea";
import { MOBILE_APPROVAL_PERMISSIONS } from "../features/mobile/navigation";
import {
  cacheWorkflowTaskDetail,
  enqueueWorkflowActionDraft,
  getCachedWorkflowTaskDetail,
  listCachedWorkflowTaskDetails,
  listWorkflowActionDrafts,
  removeWorkflowActionDraft,
  resolveWorkflowTaskReferenceSnapshot,
  updateWorkflowActionDraftStatus,
  type WorkflowDraftAction,
  type WorkflowDraftQueueItem,
} from "../mobile/workflowActionQueue";

type MobileAction = "approve" | "reject" | "return" | "transfer";
type MobileTaskTab = "pending" | "completed";
type EntityFilter = "all" | "leave" | "reimbursement" | "purchase_request" | "travel_request";
type ReplayClassification = "failed" | "conflicted";

type VisibleTaskCard = {
  id: string;
  title: string;
  subtitle: string;
  status: string;
  entityType: string | null;
  entityId: string | null;
  reference: string | null;
  applicantName: string | null;
  metric: string | null;
  businessStatus: string | null;
  allowedActions: MobileAction[];
  completedAt: string | null;
  isCached: boolean;
  detail: WorkflowTaskDetail | null;
};

const ENTITY_FILTER_OPTIONS: Array<{ value: EntityFilter; label: string }> = [
  { value: "all", label: "全部" },
  { value: "leave", label: "请假" },
  { value: "reimbursement", label: "报销" },
  { value: "purchase_request", label: "采购" },
  { value: "travel_request", label: "差旅" },
];

function entityLabel(entityType: string | undefined | null) {
  if (entityType === "leave") {
    return "请假";
  }
  if (entityType === "reimbursement") {
    return "报销";
  }
  if (entityType === "purchase_request") {
    return "采购";
  }
  if (entityType === "travel_request") {
    return "差旅";
  }
  return entityType || "未知";
}

function workflowStatusLabel(status: string) {
  if (status === "pending") {
    return "待处理";
  }
  if (status === "completed") {
    return "已处理";
  }
  if (status === "rejected") {
    return "已驳回";
  }
  if (status === "cancelled") {
    return "已取消";
  }
  if (status === "skipped") {
    return "已跳过";
  }
  return status;
}

function businessStatusLabel(status: string | null | undefined) {
  const labels: Record<string, string> = {
    draft: "草稿",
    pending: "待处理",
    reviewing: "审批中",
    submitted: "审批中",
    approved: "已通过",
    rejected: "已驳回",
    returned: "已退回",
    cancelled: "已取消",
    completed: "已完成",
    paid: "已付款",
  };
  return status ? labels[status] ?? status : "-";
}

function isInternalId(value: string | null | undefined) {
  return /^[0-9a-f]{8}-[0-9a-f]{4}-[1-5][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i.test(value ?? "");
}

function publicReference(value: string | null | undefined) {
  if (!value || isInternalId(value)) {
    return null;
  }
  return value;
}

function resolveErrorMessage(error: unknown) {
  if (isApiError(error)) {
    return `${error.code}: ${mapApiErrorMessage(error.code, error.details, error.message)}`;
  }
  if (error instanceof Error) {
    return error.message;
  }
  return "动作执行失败";
}

function isAlreadyProcessedTaskError(error: unknown) {
  return isApiError(error) && error.details?.task === "already_processed";
}

function classifyReplayError(error: unknown): ReplayClassification {
  if (!isApiError(error)) {
    return "failed";
  }

  if (
    (error.status === 409 && error.details?.task === "already_processed") ||
    error.status === 403 ||
    error.status === 404
  ) {
    return "conflicted";
  }

  return "failed";
}

function queueStatusLabel(status: WorkflowDraftQueueItem["status"]) {
  if (status === "queued") {
    return "待同步";
  }
  if (status === "failed") {
    return "同步失败";
  }
  return "存在冲突";
}

function formatDateTime(value: string | null | undefined) {
  if (!value) {
    return "-";
  }

  try {
    return new Date(value).toLocaleString("zh-CN");
  } catch {
    return value;
  }
}

function normalizeSearchValue(value: string | null | undefined) {
  return String(value ?? "").trim().toLowerCase();
}

function isWithinRecentDays(value: string | null | undefined, days: number) {
  if (!value) {
    return false;
  }

  const timestamp = new Date(value).getTime();
  if (Number.isNaN(timestamp)) {
    return false;
  }

  return timestamp >= Date.now() - days * 24 * 60 * 60 * 1000;
}

function matchesEntityFilter(entityType: string | null, filter: EntityFilter) {
  return filter === "all" || entityType === filter;
}

function toVisibleRemoteTask(task: WorkflowTaskSummary): VisibleTaskCard {
  const entityType = task.workflowInstance?.entityType ?? null;
  const summary = task.businessSummary;
  const reference = publicReference(summary?.reference ?? task.workflowInstance?.entityId);
  const metric = summary?.amount ?? summary?.duration ?? null;
  return {
    id: task.id,
    title: summary?.title ?? task.stepName,
    subtitle:
      task.status === "completed"
        ? `业务：${entityLabel(entityType)} · ${reference ?? "未生成业务编号"} · 完成于 ${formatDateTime(task.completedAt)}`
        : `业务：${entityLabel(entityType)} · ${reference ?? "未生成业务编号"}`,
    status: task.status,
    entityType,
    entityId: task.workflowInstance?.entityId ?? null,
    reference,
    applicantName: summary?.applicantName ?? null,
    metric,
    businessStatus: summary?.businessStatus ?? task.workflowInstance?.currentStatus ?? null,
    allowedActions: task.allowedActions,
    completedAt: task.completedAt,
    isCached: false,
    detail: null,
  };
}

function matchesSearch(card: VisibleTaskCard, keyword: string) {
  if (!keyword) {
    return true;
  }

  const searchValue = normalizeSearchValue(keyword);
  const haystack = [
    card.title,
    entityLabel(card.entityType),
    card.id,
    card.entityId,
    card.reference,
    card.applicantName,
    card.metric,
    card.businessStatus,
  ]
    .map((item) => normalizeSearchValue(item))
    .join(" ");

  return haystack.includes(searchValue);
}

export function MobileApprovalsPage() {
  const queryClient = useQueryClient();
  const { me, permissions, accessToken, offlineAccessMode } = useAuth();
  const [searchParams, setSearchParams] = useSearchParams();
  const deepLinkTaskId = searchParams.get("taskId")?.trim() ?? "";

  const [selectedTaskId, setSelectedTaskId] = useState(deepLinkTaskId);
  const [taskTab, setTaskTab] = useState<MobileTaskTab>("pending");
  const [entityFilter, setEntityFilter] = useState<EntityFilter>("all");
  const [searchInput, setSearchInput] = useState("");
  const deferredSearch = useDeferredValue(searchInput);
  const [batchMode, setBatchMode] = useState(false);
  const [selectedBatchTaskIds, setSelectedBatchTaskIds] = useState<string[]>([]);
  const [batchRejectComment, setBatchRejectComment] = useState("");
  const [error, setError] = useState("");
  const [message, setMessage] = useState("");
  const [comment, setComment] = useState("");
  const [transferToApproverId, setTransferToApproverId] = useState("");
  const [transferReason, setTransferReason] = useState("");
  const [offlineDraftSubmitting, setOfflineDraftSubmitting] = useState(false);
  const [isOnline, setIsOnline] = useState(true);
  const autoSyncRequestedRef = useRef(false);
  const detailSectionRef = useRef<HTMLElement | null>(null);

  const ownerEmployeeId = me?.id ?? null;
  const canAccessRemoteApprovals = hasAnyPermission(permissions, [...MOBILE_APPROVAL_PERMISSIONS]);
  const canUseRemote = isOnline && Boolean(accessToken) && canAccessRemoteApprovals;
  const remoteTaskStatus = taskTab === "completed" ? "completed" : "pending";

  useEffect(() => {
    setSelectedTaskId(deepLinkTaskId);
  }, [deepLinkTaskId]);

  useEffect(() => {
    if (taskTab === "completed") {
      setBatchMode(false);
      setSelectedBatchTaskIds([]);
      setBatchRejectComment("");
    }
  }, [taskTab]);

  function updateTaskSelection(taskId: string) {
    setSelectedTaskId(taskId);
    const nextParams = new URLSearchParams(searchParams);
    if (taskId) {
      nextParams.set("taskId", taskId);
    } else {
      nextParams.delete("taskId");
    }
    setSearchParams(nextParams, { replace: true });
  }

  function scrollDetailIntoViewOnMobile() {
    if (typeof window === "undefined" || !window.matchMedia("(max-width: 767px)").matches) {
      return;
    }

    window.requestAnimationFrame(() => {
      detailSectionRef.current?.scrollIntoView({ behavior: "smooth", block: "start" });
    });
  }

  function handleTaskSelection(taskId: string) {
    updateTaskSelection(taskId);
    scrollDetailIntoViewOnMobile();
  }

  async function invalidateWorkflowQueries(taskId: string | null = selectedTaskId) {
    await Promise.all([
      queryClient.invalidateQueries({ queryKey: ["mobile", "workflow", "tasks"] }),
      queryClient.invalidateQueries({ queryKey: ["mobile", "workflow", "task-detail", taskId] }),
      queryClient.invalidateQueries({ queryKey: ["mobile", "workflow", "task-cache", ownerEmployeeId] }),
      queryClient.invalidateQueries({ queryKey: ["mobile", "workflow", "task-cache", ownerEmployeeId, taskId] }),
      queryClient.invalidateQueries({ queryKey: ["mobile", "workflow", "draft-queue", ownerEmployeeId] }),
      queryClient.invalidateQueries({ queryKey: ["mobile", "workflow", "pending-count"] }),
    ]);
  }

  const tasksQuery = useQuery({
    enabled: canUseRemote,
    queryKey: ["mobile", "workflow", "tasks", remoteTaskStatus],
    queryFn: () => fetchWorkflowTasks({ status: remoteTaskStatus, page: 1, pageSize: 100 }),
  });

  const detailQuery = useQuery({
    enabled: Boolean(selectedTaskId) && canUseRemote,
    queryKey: ["mobile", "workflow", "task-detail", selectedTaskId],
    queryFn: () => fetchWorkflowTaskDetail(selectedTaskId),
  });

  const cachedTasksQuery = useQuery({
    enabled: Boolean(ownerEmployeeId),
    queryKey: ["mobile", "workflow", "task-cache", ownerEmployeeId],
    queryFn: () => listCachedWorkflowTaskDetails(ownerEmployeeId),
  });

  const cachedDetailQuery = useQuery({
    enabled: Boolean(selectedTaskId) && Boolean(ownerEmployeeId),
    queryKey: ["mobile", "workflow", "task-cache", ownerEmployeeId, selectedTaskId],
    queryFn: () => getCachedWorkflowTaskDetail(selectedTaskId, ownerEmployeeId),
  });

  const queueQuery = useQuery({
    enabled: Boolean(ownerEmployeeId),
    queryKey: ["mobile", "workflow", "draft-queue", ownerEmployeeId],
    queryFn: () => listWorkflowActionDrafts(ownerEmployeeId),
  });

  useEffect(() => {
    if (!detailQuery.data || !ownerEmployeeId) {
      return;
    }

    void cacheWorkflowTaskDetail(detailQuery.data, ownerEmployeeId).then(async () => {
      await Promise.all([
        queryClient.invalidateQueries({ queryKey: ["mobile", "workflow", "task-cache", ownerEmployeeId] }),
        queryClient.invalidateQueries({
          queryKey: ["mobile", "workflow", "task-cache", ownerEmployeeId, detailQuery.data.task.id],
        }),
      ]);
    });
  }, [detailQuery.data, ownerEmployeeId, queryClient]);

  const baseTaskCards = useMemo<VisibleTaskCard[]>(() => {
    if (canUseRemote) {
      const remoteItems = (tasksQuery.data?.items ?? []).filter((item) =>
        taskTab === "completed" ? isWithinRecentDays(item.completedAt, 30) : true,
      );
      return remoteItems.map(toVisibleRemoteTask);
    }

    if (taskTab === "completed") {
      return [];
    }

    return (cachedTasksQuery.data ?? [])
      .filter((item) => item.detail.task.status === "pending")
      .map((item) => ({
        id: item.detail.task.id,
        title: item.taskSnapshot.stepName ?? item.detail.task.stepName,
        subtitle: `业务：${entityLabel(item.taskSnapshot.entityType ?? item.detail.workflowInstance?.entityType)} · 缓存于 ${formatDateTime(item.savedAt)}`,
        status: item.detail.task.status,
        entityType: item.taskSnapshot.entityType ?? item.detail.workflowInstance?.entityType ?? null,
        entityId: item.taskSnapshot.entityId,
        reference: publicReference(item.taskSnapshot.reference),
        applicantName: null,
        metric: null,
        businessStatus: item.detail.workflowInstance?.currentStatus ?? null,
        allowedActions: item.detail.allowedActions,
        completedAt: item.detail.task.completedAt,
        isCached: true,
        detail: item.detail,
      }));
  }, [cachedTasksQuery.data, canUseRemote, taskTab, tasksQuery.data?.items]);

  const filteredTaskCards = useMemo(
    () =>
      baseTaskCards.filter(
        (card) => matchesEntityFilter(card.entityType, entityFilter) && matchesSearch(card, deferredSearch),
      ),
    [baseTaskCards, deferredSearch, entityFilter],
  );

  const pendingTaskMap = useMemo(
    () => new Map(filteredTaskCards.map((task) => [task.id, task])),
    [filteredTaskCards],
  );

  const selectedCachedTaskDetail = useMemo(
    () => filteredTaskCards.find((task) => task.id === selectedTaskId)?.detail ?? null,
    [filteredTaskCards, selectedTaskId],
  );
  const selectedTaskCard = useMemo(
    () => filteredTaskCards.find((task) => task.id === selectedTaskId) ?? null,
    [filteredTaskCards, selectedTaskId],
  );

  const selectedTask = detailQuery.data ?? cachedDetailQuery.data?.detail ?? selectedCachedTaskDetail;
  const selectedReference = selectedTask ? resolveWorkflowTaskReferenceSnapshot(selectedTask) : null;
  const selectedDisplayReference = selectedTaskCard?.reference ?? publicReference(selectedReference?.reference);
  const selectedTaskAllowsActions = Boolean(taskTab === "pending" && selectedTask?.task.status === "pending");
  const isOfflineUncachedDeepLink = Boolean(selectedTaskId) && !selectedTask && !canUseRemote;

  useEffect(() => {
    const visibleIds = new Set(filteredTaskCards.map((task) => task.id));
    setSelectedBatchTaskIds((current) => current.filter((taskId) => visibleIds.has(taskId)));
  }, [filteredTaskCards]);

  useEffect(() => {
    if (selectedTaskId || !filteredTaskCards.length) {
      return;
    }
    updateTaskSelection(filteredTaskCards[0].id);
  }, [filteredTaskCards, selectedTaskId]);

  const canTransfer = Boolean(
    canUseRemote &&
    selectedTaskAllowsActions &&
    selectedTask?.allowedActions.includes("transfer"),
  );

  const approversQuery = useQuery({
    enabled: Boolean(canTransfer),
    queryKey: ["mobile", "workflow", "approvers"],
    queryFn: () => fetchWorkflowApprovers({ page: 1, pageSize: 100 }),
  });

  async function refreshDraftQueueCache() {
    if (!ownerEmployeeId) {
      return [];
    }
    const drafts = await listWorkflowActionDrafts(ownerEmployeeId);
    queryClient.setQueryData(["mobile", "workflow", "draft-queue", ownerEmployeeId], drafts);
    return drafts;
  }

  const currentQueueItems = queueQuery.data ?? [];
  const retryableQueueItems = useMemo(
    () => currentQueueItems.filter((item) => item.status !== "conflicted"),
    [currentQueueItems],
  );

  async function queueOfflineDraft(action: WorkflowDraftAction) {
    try {
      if (!selectedTaskId) {
        throw new Error("请选择任务");
      }
      if (!selectedTask) {
        throw new Error("当前待办尚未缓存，请联网加载后再操作");
      }
      if (!selectedTask.allowedActions.includes(action)) {
        throw new Error("当前待办不允许该动作");
      }
      if (action === "reject" && !comment.trim()) {
        throw new Error("驳回必须填写意见");
      }

      setOfflineDraftSubmitting(true);
      await enqueueWorkflowActionDraft({
        taskId: selectedTaskId,
        action,
        comment: action === "reject" ? comment.trim() : null,
        ownerEmployeeId,
        detail: selectedTask,
      });
      await refreshDraftQueueCache();
      await queryClient.invalidateQueries({ queryKey: ["mobile", "workflow", "task-cache", ownerEmployeeId] });
      setComment("");
      setError("");
      setMessage(action === "approve" ? "当前离线，通过草稿已加入待同步队列。" : "当前离线，驳回草稿已加入待同步队列。");
      toast.success(action === "approve" ? "已加入通过草稿队列" : "已加入驳回草稿队列");
    } catch (actionError) {
      const nextError = resolveErrorMessage(actionError);
      setError(nextError);
      setMessage("");
      toast.error(nextError);
    } finally {
      setOfflineDraftSubmitting(false);
    }
  }

  const actionMutation = useMutation({
    mutationFn: async (action: MobileAction) => {
      if (!canUseRemote) {
        throw new Error("当前离线，请使用离线草稿动作");
      }
      if (!selectedTaskId) {
        throw new Error("请选择任务");
      }
      if (!selectedTask) {
        throw new Error("当前待办尚未缓存，请联网加载后再操作");
      }
      if (!selectedTask.allowedActions.includes(action)) {
        throw new Error("当前待办不允许该动作");
      }

      if (action === "approve") {
        await approveWorkflowTask(selectedTaskId);
        return { action };
      }

      if (action === "reject") {
        if (!comment.trim()) {
          throw new Error("驳回必须填写意见");
        }
        await rejectWorkflowTask(selectedTaskId, comment.trim());
        return { action };
      }

      if (action === "return") {
        if (!comment.trim()) {
          throw new Error("退回必须填写意见");
        }
        await returnWorkflowTask(selectedTaskId, comment.trim());
        return { action };
      }

      if (!transferToApproverId) {
        throw new Error("请选择转审目标审批人");
      }
      if (transferReason.trim().length < 10) {
        throw new Error("转审理由至少 10 个字");
      }

      await transferWorkflowTask(selectedTaskId, transferToApproverId, transferReason.trim());
      return { action };
    },
    onSuccess: async () => {
      await invalidateWorkflowQueries(selectedTaskId);
      setComment("");
      setTransferReason("");
      setTransferToApproverId("");
      setError("");
      setMessage("");
      updateTaskSelection("");
      toast.success("操作成功");
    },
    onError: (actionError) => {
      if (isAlreadyProcessedTaskError(actionError)) {
        void invalidateWorkflowQueries(selectedTaskId);
      }
      const nextError = resolveErrorMessage(actionError);
      setError(nextError);
      setMessage("");
      toast.error(nextError);
    },
  });

  const batchActionMutation = useMutation({
    mutationFn: async (input: { action: WorkflowDraftAction; taskIds: string[]; comment?: string }) => {
      if (!input.taskIds.length) {
        throw new Error("请先选择至少一条待办");
      }
      if (input.action === "reject" && !input.comment?.trim()) {
        throw new Error("批量驳回必须填写共享意见");
      }

      let succeeded = 0;
      let failed = 0;
      let skipped = 0;
      const failures: string[] = [];

      for (const taskId of input.taskIds) {
        const taskCard = pendingTaskMap.get(taskId);
        if (!taskCard) {
          skipped += 1;
          failures.push(`${taskId}: 当前筛选结果中找不到该待办`);
          continue;
        }

        if (!taskCard.allowedActions.includes(input.action)) {
          skipped += 1;
          failures.push(`${taskId}: 当前待办不允许${input.action === "approve" ? "通过" : "驳回"}`);
          continue;
        }

        try {
          if (canUseRemote) {
            if (input.action === "approve") {
              await approveWorkflowTask(taskId);
            } else {
              await rejectWorkflowTask(taskId, input.comment!.trim());
            }
          } else {
            if (!taskCard.detail) {
              throw new Error("当前待办尚未缓存，请联网后重试");
            }
            await enqueueWorkflowActionDraft({
              taskId,
              action: input.action,
              comment: input.action === "reject" ? input.comment?.trim() ?? null : null,
              ownerEmployeeId,
              detail: taskCard.detail,
            });
          }
          succeeded += 1;
        } catch (batchError) {
          failed += 1;
          failures.push(`${taskId}: ${resolveErrorMessage(batchError)}`);
        }
      }

      return { ...input, succeeded, failed, skipped, failures };
    },
    onSuccess: async (result) => {
      if (canUseRemote) {
        await invalidateWorkflowQueries(selectedTaskId);
      } else {
        await refreshDraftQueueCache();
        await queryClient.invalidateQueries({ queryKey: ["mobile", "workflow", "task-cache", ownerEmployeeId] });
      }

      const actionLabel = result.action === "approve" ? "通过" : "驳回";
      const summary = canUseRemote
        ? `批量${actionLabel}完成：成功 ${result.succeeded}，失败 ${result.failed}，跳过 ${result.skipped}`
        : `离线批量${actionLabel}已入队：成功 ${result.succeeded}，失败 ${result.failed}，跳过 ${result.skipped}`;

      setBatchMode(false);
      setSelectedBatchTaskIds([]);
      setBatchRejectComment("");
      setComment("");
      setError(result.failures.length ? result.failures.slice(0, 3).join("；") : "");
      setMessage(summary);
      if (canUseRemote && result.taskIds.includes(selectedTaskId)) {
        updateTaskSelection("");
      }

      if (result.failed > 0) {
        toast.error(summary);
        return;
      }

      toast.success(summary);
    },
    onError: (batchError) => {
      const nextError = resolveErrorMessage(batchError);
      setError(nextError);
      setMessage("");
      toast.error(nextError);
    },
  });

  const isActionSubmitting = actionMutation.isPending || offlineDraftSubmitting;

  const syncMutation = useMutation({
    mutationFn: async (items: WorkflowDraftQueueItem[]) => {
      let succeeded = 0;
      let failed = 0;
      let conflicted = 0;

      for (const item of items.sort((a, b) => a.updatedAt.localeCompare(b.updatedAt))) {
        try {
          if (item.action === "approve") {
            await approveWorkflowTask(item.taskId);
          } else {
            await rejectWorkflowTask(item.taskId, item.comment ?? "");
          }
          await removeWorkflowActionDraft(item.taskId, ownerEmployeeId);
          succeeded += 1;
        } catch (syncError) {
          const classification = classifyReplayError(syncError);
          const lastError = resolveErrorMessage(syncError);
          await updateWorkflowActionDraftStatus({
            taskId: item.taskId,
            ownerEmployeeId,
            status: classification,
            lastError,
          });

          if (classification === "conflicted") {
            conflicted += 1;
          } else {
            failed += 1;
          }
        }
      }

      return { succeeded, failed, conflicted };
    },
    onSuccess: async (result) => {
      await invalidateWorkflowQueries(selectedTaskId);
      setError("");
      setMessage(`草稿同步完成：成功 ${result.succeeded}，失败 ${result.failed}，冲突 ${result.conflicted}`);
      if (result.succeeded || result.failed || result.conflicted) {
        toast.success(`草稿同步完成：成功 ${result.succeeded}，失败 ${result.failed}，冲突 ${result.conflicted}`);
      }
    },
    onError: (syncError) => {
      const nextError = resolveErrorMessage(syncError);
      setError(nextError);
      setMessage("");
      toast.error(nextError);
    },
  });

  useEffect(() => {
    const onOnline = () => {
      setIsOnline(true);
      autoSyncRequestedRef.current = true;
    };
    const onOffline = () => {
      setIsOnline(false);
    };

    window.addEventListener("online", onOnline);
    window.addEventListener("offline", onOffline);

    return () => {
      window.removeEventListener("online", onOnline);
      window.removeEventListener("offline", onOffline);
    };
  }, []);

  useEffect(() => {
    if (accessToken) {
      setIsOnline(true);
    }
  }, [accessToken]);

  useEffect(() => {
    if (!autoSyncRequestedRef.current || !canUseRemote || syncMutation.isPending) {
      return;
    }

    autoSyncRequestedRef.current = false;
    if (retryableQueueItems.length) {
      syncMutation.mutate(retryableQueueItems);
    }
  }, [canUseRemote, retryableQueueItems, syncMutation]);

  function toggleBatchTask(taskId: string) {
    setSelectedBatchTaskIds((current) =>
      current.includes(taskId) ? current.filter((id) => id !== taskId) : [...current, taskId],
    );
  }

  function toggleSelectAllVisibleTasks() {
    const visibleIds = filteredTaskCards.map((task) => task.id);
    const allSelected = visibleIds.length > 0 && visibleIds.every((taskId) => selectedBatchTaskIds.includes(taskId));
    if (allSelected) {
      setSelectedBatchTaskIds([]);
      return;
    }
    setSelectedBatchTaskIds(visibleIds);
  }

  function handleBatchAction(action: WorkflowDraftAction) {
    batchActionMutation.mutate({
      action,
      taskIds: selectedBatchTaskIds,
      comment: action === "reject" ? batchRejectComment : undefined,
    });
  }

  const listTitle = taskTab === "pending" ? "待办任务" : "已处理任务";
  const allVisibleSelected =
    filteredTaskCards.length > 0 && filteredTaskCards.every((task) => selectedBatchTaskIds.includes(task.id));

  return (
    <PageScaffold className="space-y-4">
      <PageHeader
        title="移动审批"
        subtitle={deepLinkTaskId ? "已定位指定待办。" : "处理待办。"}
      />

      {!isOnline ? (
        <p className="rounded-lg border border-orange-200 bg-orange-50 px-3 py-2 text-sm text-orange-700">
          当前离线{offlineAccessMode ? "，已使用本地会话快照进入移动审批壳。" : "。"}仅支持查看已缓存待办，并保存通过 / 驳回草稿；联网同步成功后才会正式提交。
        </p>
      ) : null}

      {error ? (
        <p className="rounded-lg border border-red-200 bg-red-50 px-3 py-2 text-sm text-red-600">{error}</p>
      ) : null}

      {message ? (
        <p className="rounded-lg border border-emerald-200 bg-emerald-50 px-3 py-2 text-sm text-emerald-700">{message}</p>
      ) : null}

      <section className="mobile-card space-y-4" data-testid="mobile-approvals-list">
        <div className="flex flex-wrap items-center justify-between gap-3">
          <div>
            <h3 className="text-base font-semibold text-zinc-900">{listTitle}</h3>
            <p className="mt-1 text-sm text-zinc-500">{filteredTaskCards.length} 条</p>
          </div>
          <span className={`text-sm ${isOnline ? "text-emerald-600" : "text-orange-600"}`}>{isOnline ? "在线" : "离线"}</span>
        </div>

        <Tabs value={taskTab} onValueChange={(value) => setTaskTab(value as MobileTaskTab)}>
          <TabsList className="flex w-full justify-start gap-1">
            <TabsTrigger value="pending">待处理</TabsTrigger>
            <TabsTrigger value="completed" disabled={!canUseRemote}>已处理</TabsTrigger>
          </TabsList>
        </Tabs>

        <div className="space-y-3">
          <Input
            data-testid="mobile-approvals-search"
            value={searchInput}
            onChange={(event) => setSearchInput(event.target.value)}
            placeholder="搜索待办"
          />

          <details className="mobile-subcard bg-zinc-50/70 text-sm">
            <summary className="cursor-pointer select-none font-medium text-zinc-700">
              筛选与批量
            </summary>
            <div className="mt-3 space-y-3">
              <Tabs value={entityFilter} onValueChange={(value) => setEntityFilter(value as EntityFilter)}>
                <TabsList className="flex w-full flex-wrap justify-start gap-1">
                  {ENTITY_FILTER_OPTIONS.map((option) => (
                    <TabsTrigger key={option.value} value={option.value}>
                      {option.label}
                    </TabsTrigger>
                  ))}
                </TabsList>
              </Tabs>

              {taskTab === "pending" ? (
                <div className="grid gap-2 sm:flex sm:flex-wrap sm:items-center">
                  <Button
                    type="button"
                    size="sm"
                    variant={batchMode ? "default" : "secondary"}
                    className="min-h-11 w-full sm:w-auto"
                    disabled={!filteredTaskCards.length}
                    onClick={() => {
                      setBatchMode((current) => !current);
                      setSelectedBatchTaskIds([]);
                      setBatchRejectComment("");
                    }}
                  >
                    {batchMode ? "退出批量" : "批量"}
                  </Button>
                  {batchMode ? (
                    <Button
                      type="button"
                      size="sm"
                      variant="secondary"
                      className="min-h-11 w-full sm:w-auto"
                      disabled={!filteredTaskCards.length}
                      onClick={toggleSelectAllVisibleTasks}
                    >
                      {allVisibleSelected ? "清空选择" : "全选当前"}
                    </Button>
                  ) : null}
                  <span className="text-sm text-zinc-500 sm:ml-1">
                    当前 {filteredTaskCards.length} 条
                    {batchMode ? `，已选 ${selectedBatchTaskIds.length}` : ""}
                  </span>
                </div>
              ) : (
                <p className="text-sm text-zinc-500">仅显示最近 30 天。</p>
              )}
            </div>
          </details>
        </div>

        {batchMode ? (
          <div className="mobile-subcard bg-zinc-50 text-sm">
            <div className="flex flex-wrap items-center justify-between gap-3">
              <div className="text-zinc-700">已选 {selectedBatchTaskIds.length} 条</div>
              <div className="grid w-full gap-2 sm:flex sm:w-auto sm:flex-wrap">
                <Button
                  type="button"
                  size="sm"
                  className="min-h-11 w-full sm:w-auto"
                  disabled={!selectedBatchTaskIds.length || batchActionMutation.isPending}
                  onClick={() => handleBatchAction("approve")}
                >
                  {canUseRemote ? "批量通过" : "保存通过草稿"}
                </Button>
                <Button
                  type="button"
                  size="sm"
                  variant="secondary"
                  className="min-h-11 w-full sm:w-auto"
                  disabled={!selectedBatchTaskIds.length || batchActionMutation.isPending || !batchRejectComment.trim()}
                  onClick={() => handleBatchAction("reject")}
                >
                  {canUseRemote ? "批量驳回" : "保存驳回草稿"}
                </Button>
              </div>
            </div>
            <Textarea
              className="mt-3"
              rows={3}
              value={batchRejectComment}
              onChange={(event) => setBatchRejectComment(event.target.value)}
              placeholder="驳回意见。"
            />
          </div>
        ) : null}

        {canUseRemote && tasksQuery.isLoading ? (
          <div className="flex items-center gap-2 text-sm text-zinc-500">
            <Spinner size="sm" />
            加载中...
          </div>
        ) : null}

        {canUseRemote && tasksQuery.isError ? (
          <p className="rounded-lg border border-red-200 bg-red-50 px-3 py-2 text-sm text-red-600">
            {resolveErrorMessage(tasksQuery.error)}
          </p>
        ) : null}

        {!canUseRemote && taskTab === "completed" ? (
          <p className="text-sm text-zinc-500">离线模式仅缓存待处理任务详情；已处理历史需联网查看。</p>
        ) : null}

        {!filteredTaskCards.length && !(canUseRemote && tasksQuery.isLoading) ? (
          <p className="text-sm text-zinc-500">
            {taskTab === "completed"
              ? "最近 30 天暂无符合筛选条件的已处理任务。"
              : !canAccessRemoteApprovals && isOnline
                ? "暂无审批待办；收到企业微信审批消息后可从这里查看。"
                : canUseRemote
                  ? "暂无符合筛选条件的待办任务。"
                  : "暂无符合筛选条件的已缓存待办。"}
          </p>
        ) : null}

        <div className="space-y-2">
          {filteredTaskCards.map((task) => {
            const isSelected = selectedTaskId === task.id;
            const isBatchSelected = selectedBatchTaskIds.includes(task.id);

            if (batchMode && taskTab === "pending") {
              return (
                <div
                  key={task.id}
                  className={`mobile-list-card flex gap-3 ${
                    isBatchSelected ? "border-primary bg-primary-50" : "border-zinc-200 bg-white"
                  }`}
                >
                  <input
                    type="checkbox"
                    className="mt-1 h-4 w-4 rounded border-zinc-300"
                    checked={isBatchSelected}
                    onChange={() => toggleBatchTask(task.id)}
                    aria-label={`选择${entityLabel(task.entityType)}待办`}
                  />
                  <button
                    type="button"
                    className="min-h-16 min-w-0 flex-1 text-left"
                    data-testid={`mobile-approvals-task-${task.id}`}
                    onClick={() => toggleBatchTask(task.id)}
                  >
                    <div className="flex items-center justify-between gap-3">
                      <div className="font-medium text-zinc-900">{task.title}</div>
                      <StatusBadge status={task.status} label={workflowStatusLabel(task.status)} />
                    </div>
                    <div className="mt-1 text-xs text-zinc-500">{task.subtitle}</div>
                    {task.reference ? <div className="mt-1 text-xs text-zinc-500">业务单号：{task.reference}</div> : null}
                    <div className="mt-1 text-xs text-zinc-500">
                      申请人：{task.applicantName ?? "-"} · 金额/天数：{task.metric ?? "-"} · 业务状态：{businessStatusLabel(task.businessStatus)}
                    </div>
                    {task.isCached ? <div className="mt-1 text-xs text-zinc-500">来源：离线缓存</div> : null}
                  </button>
                </div>
              );
            }

            return (
              <button
                key={task.id}
                className={`mobile-list-card min-h-20 w-full text-left transition-colors ${
                  isSelected ? "border-primary bg-primary-50" : "border-zinc-200 bg-white"
                }`}
                data-testid={`mobile-approvals-task-${task.id}`}
                onClick={() => handleTaskSelection(task.id)}
                type="button"
              >
                <div className="flex items-center justify-between gap-3">
                  <div className="font-medium text-zinc-900">{task.title}</div>
                  <StatusBadge status={task.status} label={workflowStatusLabel(task.status)} />
                </div>
                <div className="mt-1 text-xs text-zinc-500">{task.subtitle}</div>
                {task.reference ? <div className="mt-1 text-xs text-zinc-500">业务单号：{task.reference}</div> : null}
                <div className="mt-1 text-xs text-zinc-500">
                  申请人：{task.applicantName ?? "-"} · 金额/天数：{task.metric ?? "-"} · 业务状态：{businessStatusLabel(task.businessStatus)}
                </div>
                {task.isCached ? <div className="mt-1 text-xs text-zinc-500">来源：离线缓存</div> : null}
              </button>
            );
          })}
        </div>
      </section>

      <section ref={detailSectionRef} className="mobile-card scroll-mt-4 space-y-3" data-testid="mobile-approvals-detail">
        <h3 className="text-base font-semibold text-zinc-900">处理</h3>

        {!selectedTaskId ? <p className="text-sm text-zinc-500">请先选择任务。</p> : null}

        {selectedTaskId && canUseRemote && detailQuery.isLoading ? (
          <p className="text-sm text-zinc-500">加载任务详情中...</p>
        ) : null}

        {selectedTaskId && canUseRemote && detailQuery.isError ? (
          <p className="rounded-lg border border-red-200 bg-red-50 px-3 py-2 text-sm text-red-600">
            {resolveErrorMessage(detailQuery.error)}
          </p>
        ) : null}

        {isOfflineUncachedDeepLink ? (
          <p className="rounded-lg border border-orange-200 bg-orange-50 px-3 py-2 text-sm text-orange-700">
            离线未缓存该待办，请联网后重试。
          </p>
        ) : null}

        {selectedTask ? (
          <>
            <div className="mobile-list-card text-sm">
              <div>任务状态：{workflowStatusLabel(selectedTask.task.status)}</div>
              <div>步骤：{selectedTask.task.stepName}</div>
              <div>对象类型：{entityLabel(selectedTask.workflowInstance?.entityType)}</div>
              <div>业务单号：{selectedDisplayReference ?? "-"}</div>
              <div>业务状态：{businessStatusLabel(selectedTaskCard?.businessStatus ?? selectedTask.workflowInstance?.currentStatus)}</div>
              <div>申请人：{selectedTaskCard?.applicantName ?? "-"}</div>
              <div>金额/天数：{selectedTaskCard?.metric ?? "-"}</div>
              <div>创建时间：{formatDateTime(selectedTask.task.createdAt)}</div>
              <div>完成时间：{formatDateTime(selectedTask.task.completedAt)}</div>
              {selectedTask.reimbursement ? (
                <>
                  <div>报销单号：{selectedTask.reimbursement.formNumber ?? "-"}</div>
                  <div>金额：{selectedTask.reimbursement.totalAmount ?? "-"}</div>
                  <div>提交人：{selectedTask.reimbursement.submitter?.name ?? "-"}</div>
                </>
              ) : null}
              {selectedTask.leaveRequest ? (
                <>
                  <div>假期类型：{selectedTask.leaveRequest.leaveType?.name ?? "-"}</div>
                  <div>申请人：{selectedTask.leaveRequest.owner?.name ?? "-"}</div>
                  <div>请假天数：{selectedTask.leaveRequest.requestedDays}</div>
                </>
              ) : null}
              {selectedTask.purchaseRequest ? (
                <>
                  <div>采购单号：{selectedTask.purchaseRequest.requestNo ?? "-"}</div>
                  <div>申请人：{selectedTask.purchaseRequest.applicant?.name ?? "-"}</div>
                  <div>供应商：{selectedTask.purchaseRequest.supplier?.name ?? "-"}</div>
                  <div>金额：{selectedTask.purchaseRequest.totalAmount ?? "-"}</div>
                </>
              ) : null}
              {selectedTask.travelRequest ? (
                <>
                  <div>差旅单号：{selectedTask.travelRequest.requestNo ?? "-"}</div>
                  <div>申请人：{selectedTask.travelRequest.applicant?.name ?? "-"}</div>
                  <div>出差类型：{selectedTask.travelRequest.tripType === "international" ? "国际" : "国内"}</div>
                  <div>预估金额：{selectedTask.travelRequest.estimatedAmount ?? "-"}</div>
                </>
              ) : null}
            </div>

            {!selectedTaskAllowsActions ? (
              <p className="rounded-lg border border-zinc-200 bg-zinc-50 px-3 py-2 text-sm text-zinc-600">
                当前任务已处理，仅供查看，不支持再次审批。
              </p>
            ) : (
              <>
                <Textarea
                  data-testid="mobile-approvals-comment"
                  onChange={(event) => setComment(event.target.value)}
                  placeholder="意见（驳回/退回必填）"
                  rows={3}
                  value={comment}
                />

                {!canUseRemote ? (
                  <p className="text-xs text-zinc-500">离线仅保存通过 / 驳回草稿，联网同步成功后才会正式提交。</p>
                ) : null}

                <div className="grid gap-2 min-[390px]:grid-cols-3">
                  <Button
                    className="min-h-12 w-full"
                    data-testid="mobile-approvals-approve"
                    disabled={isActionSubmitting || !selectedTask.allowedActions.includes("approve")}
                    onClick={() => {
                      if (canUseRemote) {
                        actionMutation.mutate("approve");
                        return;
                      }
                      void queueOfflineDraft("approve");
                    }}
                    type="button"
                  >
                    {canUseRemote ? "通过" : "保存通过草稿"}
                  </Button>
                  <Button
                    className="min-h-12 w-full"
                    data-testid="mobile-approvals-reject"
                    disabled={isActionSubmitting || !selectedTask.allowedActions.includes("reject")}
                    onClick={() => {
                      if (canUseRemote) {
                        actionMutation.mutate("reject");
                        return;
                      }
                      void queueOfflineDraft("reject");
                    }}
                    type="button"
                    variant="secondary"
                  >
                    {canUseRemote ? "驳回" : "保存驳回草稿"}
                  </Button>
                  <Button
                    className="min-h-12 w-full"
                    data-testid="mobile-approvals-return"
                    disabled={isActionSubmitting || !canUseRemote || !selectedTask.allowedActions.includes("return")}
                    onClick={() => actionMutation.mutate("return")}
                    type="button"
                    variant="secondary"
                  >
                    退回
                  </Button>
                </div>

                {canTransfer ? (
                  <div className="mobile-list-card space-y-3 text-sm">
                    <p className="font-medium text-zinc-800">转审</p>
                    <select
                      className="h-10 w-full rounded-lg border border-zinc-300 bg-white px-3 py-2 text-sm"
                      data-testid="mobile-approvals-transfer-to"
                      onChange={(event) => setTransferToApproverId(event.target.value)}
                      value={transferToApproverId}
                    >
                      <option value="">请选择目标审批人</option>
                      {(approversQuery.data?.items ?? []).map((approver) => (
                        <option key={approver.id} value={approver.id}>
                          {approver.name} ({approver.employeeNo})
                        </option>
                      ))}
                    </select>

                    <Textarea
                      data-testid="mobile-approvals-transfer-reason"
                      onChange={(event) => setTransferReason(event.target.value)}
                      placeholder="转审理由（至少10字）"
                      rows={2}
                      value={transferReason}
                    />

                    <Button
                      className="min-h-12 w-full"
                      data-testid="mobile-approvals-transfer"
                      disabled={isActionSubmitting || !selectedTask.allowedActions.includes("transfer")}
                      onClick={() => actionMutation.mutate("transfer")}
                      type="button"
                      variant="secondary"
                    >
                      提交转审
                    </Button>
                  </div>
                ) : null}
              </>
            )}
          </>
        ) : null}
      </section>

      <section className="mobile-card space-y-3" data-testid="mobile-approvals-queue">
        <div className="flex items-center justify-between gap-3">
          <h3 className="text-base font-semibold text-zinc-900">离线草稿</h3>
          <span className="text-sm text-zinc-500">{currentQueueItems.length ? `待同步 ${currentQueueItems.length}` : "无草稿"}</span>
        </div>

        {currentQueueItems.length ? (
          <div className="grid gap-2 sm:flex sm:flex-wrap">
            <Button
              className="min-h-11 w-full sm:w-auto"
              data-testid="mobile-approvals-sync-queue"
              disabled={!canUseRemote || syncMutation.isPending || !retryableQueueItems.length}
              onClick={() => syncMutation.mutate(retryableQueueItems)}
              type="button"
              variant="secondary"
            >
              {syncMutation.isPending ? "同步中..." : `同步草稿 (${retryableQueueItems.length})`}
            </Button>
          </div>
        ) : null}

        {!currentQueueItems.length ? <p className="text-sm text-zinc-500">暂无待同步草稿。</p> : null}

        {currentQueueItems.map((item) => (
          <div key={item.id} className="mobile-list-card text-sm">
            <div className="font-medium text-zinc-900">
              {publicReference(item.taskSnapshot.reference) ?? entityLabel(item.taskSnapshot.entityType)} · {item.action === "approve" ? "通过" : "驳回"}
            </div>
            <div className="text-zinc-500">业务：{entityLabel(item.taskSnapshot.entityType)} · 步骤：{item.taskSnapshot.stepName ?? "-"}</div>
            <div className="text-zinc-500">状态：{queueStatusLabel(item.status)} · 更新时间：{formatDateTime(item.updatedAt)}</div>
            <div className="text-zinc-500">意见：{item.comment ?? "-"}</div>
            <div className="text-zinc-500">最近错误：{item.lastError ?? "-"}</div>
            <div className="mt-2 grid gap-2 sm:flex sm:flex-wrap">
              <Button
                type="button"
                size="sm"
                variant="secondary"
                className="min-h-11 w-full sm:w-auto"
                onClick={() => handleTaskSelection(item.taskId)}
              >
                查看任务
              </Button>
              {item.status === "failed" ? (
                <Button
                  type="button"
                  size="sm"
                  variant="secondary"
                  className="min-h-11 w-full sm:w-auto"
                  disabled={syncMutation.isPending}
                  onClick={async () => {
                    await updateWorkflowActionDraftStatus({
                      taskId: item.taskId,
                      ownerEmployeeId,
                      status: "queued",
                      lastError: null,
                    });
                    await refreshDraftQueueCache();
                    if (canUseRemote) {
                      syncMutation.mutate([{ ...item, status: "queued", lastError: null }]);
                    }
                  }}
                >
                  重试
                </Button>
              ) : null}
              <Button
                type="button"
                size="sm"
                variant="secondary"
                className="min-h-11 w-full sm:w-auto"
                onClick={async () => {
                  await removeWorkflowActionDraft(item.taskId, ownerEmployeeId);
                  await refreshDraftQueueCache();
                }}
              >
                丢弃草稿
              </Button>
            </div>
          </div>
        ))}
      </section>
    </PageScaffold>
  );
}