import { useEffect, useState } from "react";
import { Link } from "react-router-dom";
import { useQuery } from "@tanstack/react-query";
import {
  fetchEmployeeOrganization,
  type OrganizationDepartmentSection,
  type OrganizationTreeNode,
} from "../api/employees";
import { EmployeeAvatar } from "../components/common/EmployeeAvatar";
import { ListWorkspace, WorkspaceHeader } from "../components/patterns/ListWorkspace";
import { Button } from "../components/ui/button";

function countNodes(nodes: OrganizationTreeNode[]): number {
  return nodes.reduce((total, node) => total + 1 + countNodes(node.children), 0);
}

function countExternalManagers(nodes: OrganizationTreeNode[]): number {
  return nodes.reduce(
    (total, node) => total + (node.externalManager ? 1 : 0) + countExternalManagers(node.children),
    0,
  );
}

function OrganizationNodeCard({ node, depth = 0 }: { node: OrganizationTreeNode; depth?: number }) {
  return (
    <div className="space-y-3">
      <div
        className="finance-list-card"
        style={{ marginLeft: `${Math.min(depth, 4) * 18}px` }}
      >
        <div className="flex flex-col gap-3 md:flex-row md:items-center md:justify-between">
          <div className="flex items-center gap-3">
            <EmployeeAvatar name={node.name} src={node.avatarUrl} size="lg" />
            <div>
              <Link to={`/people/${node.id}`} className="text-base font-semibold text-zinc-900 hover:text-zinc-700">
                {node.name}
              </Link>
              <div className="mt-1 text-sm text-zinc-500">
                {node.employeeNo} · {node.title || "未设置职位"} · {node.department?.name ?? "-"}
              </div>
            </div>
          </div>

          {node.externalManager ? (
            <div className="rounded-xl border border-amber-200 bg-amber-50 px-3 py-2 text-xs text-amber-700">
              跨部门汇报：{node.externalManager.department?.name ?? "未知部门"} · {node.externalManager.name}
            </div>
          ) : null}
        </div>
      </div>

      {node.children.length ? (
        <div className="space-y-3">
          {node.children.map((child) => (
            <OrganizationNodeCard key={child.id} node={child} depth={depth + 1} />
          ))}
        </div>
      ) : null}
    </div>
  );
}

export function OrganizationPage() {
  const organizationQuery = useQuery({
    queryKey: ["employee-organization"],
    queryFn: fetchEmployeeOrganization,
  });
  const [expandedDepartments, setExpandedDepartments] = useState<Record<string, boolean>>({});

  useEffect(() => {
    if (!organizationQuery.data?.items.length) {
      return;
    }

    setExpandedDepartments((current) => {
      const next = { ...current };
      for (const item of organizationQuery.data.items) {
        const key = item.department?.id ?? item.department?.name ?? "unknown";
        if (!(key in next)) {
          next[key] = true;
        }
      }
      return next;
    });
  }, [organizationQuery.data?.items]);

  if (organizationQuery.isLoading) {
    return (
      <ListWorkspace>
        <WorkspaceHeader
          eyebrow="管理"
          title="组织架构"
          subtitle="按部门查看当前 active 员工的汇报关系。"
        />
        <div className="admin-command-panel text-sm text-zinc-500">加载组织架构中...</div>
      </ListWorkspace>
    );
  }

  if (organizationQuery.isError) {
    return (
      <ListWorkspace>
        <WorkspaceHeader
          eyebrow="管理"
          title="组织架构"
          subtitle="按部门查看当前 active 员工的汇报关系。"
        />
        <div className="admin-command-panel text-sm text-red-600">加载组织架构失败</div>
      </ListWorkspace>
    );
  }

  const sections = organizationQuery.data?.items ?? [];
  const totalEmployees = sections.reduce((total, section) => total + countNodes(section.roots), 0);
  const externalManagerCount = sections.reduce((total, section) => total + countExternalManagers(section.roots), 0);
  const expandedCount = sections.filter((section) => {
    const key = section.department?.id ?? section.department?.name ?? "unknown";
    return expandedDepartments[key] ?? true;
  }).length;

  return (
    <ListWorkspace>
      <WorkspaceHeader
        eyebrow="管理"
        title="组织架构"
        subtitle="按部门查看 active 员工的汇报关系，跨部门上级单独标注，便于组织复核。"
        actions={
          <div className="flex gap-2">
            <Button
              type="button"
              variant="secondary"
              onClick={() =>
                setExpandedDepartments(
                  Object.fromEntries(
                    sections.map((item) => [item.department?.id ?? item.department?.name ?? "unknown", true]),
                  ),
                )
              }
            >
              全部展开
            </Button>
            <Button
              type="button"
              variant="secondary"
              onClick={() =>
                setExpandedDepartments(
                  Object.fromEntries(
                    sections.map((item) => [item.department?.id ?? item.department?.name ?? "unknown", false]),
                  ),
                )
              }
            >
              全部折叠
            </Button>
          </div>
        }
      />

      <div className="finance-status-strip" data-testid="organization-summary">
        <div className="finance-metric-card">
          <div className="finance-metric-card__label">部门分组</div>
          <div className="finance-metric-card__value">{sections.length}</div>
        </div>
        <div className="finance-metric-card">
          <div className="finance-metric-card__label">展示员工</div>
          <div className="finance-metric-card__value">{totalEmployees}</div>
        </div>
        <div className="finance-metric-card">
          <div className="finance-metric-card__label">已展开</div>
          <div className="finance-metric-card__value">{expandedCount}</div>
        </div>
        <div className="finance-metric-card">
          <div className="finance-metric-card__label">跨部门汇报</div>
          <div className="finance-metric-card__value">{externalManagerCount}</div>
        </div>
        <div className="finance-metric-card">
          <div className="finance-metric-card__label">视图模式</div>
          <div className="finance-metric-card__value text-base">只读</div>
        </div>
      </div>

      {sections.length ? (
        <div className="space-y-6">
          {sections.map((section: OrganizationDepartmentSection) => {
            const sectionKey = section.department?.id ?? section.department?.name ?? "unknown";
            const expanded = expandedDepartments[sectionKey] ?? true;
            const totalNodes = countNodes(section.roots);

            return (
              <section key={sectionKey} className="admin-command-panel">
                <div className="flex flex-wrap items-center justify-between gap-3">
                  <div>
                    <h2 className="text-base font-semibold text-zinc-900">{section.department?.name ?? "未分配部门"}</h2>
                    <div className="mt-1 text-sm text-zinc-500">{totalNodes} 名员工 · {expanded ? "已展开" : "已折叠"}</div>
                  </div>
                  <Button
                    type="button"
                    variant="secondary"
                    onClick={() =>
                      setExpandedDepartments((current) => ({
                        ...current,
                        [sectionKey]: !expanded,
                      }))
                    }
                  >
                    {expanded ? "折叠" : "展开"}
                  </Button>
                </div>

                {expanded ? (
                  <div className="mt-6 space-y-4">
                    {section.roots.length ? (
                      section.roots.map((root) => <OrganizationNodeCard key={root.id} node={root} />)
                    ) : (
                      <div className="text-sm text-zinc-500">当前部门暂无可展示节点</div>
                    )}
                  </div>
                ) : null}
              </section>
            );
          })}
        </div>
      ) : (
        <div className="admin-command-panel text-sm text-zinc-500">当前没有可展示的 active 员工。</div>
      )}
    </ListWorkspace>
  );
}

export default OrganizationPage;