import { useEffect } from 'react';
import { Alert, Button, Descriptions, Form, Input, Space, Tag, Typography, message } from 'antd';
import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query';
import { Link, useLocation, useNavigate, useParams, useSearchParams } from 'react-router-dom';
import { api } from '../api/client';
import { FormDrawer } from './FormDrawer';
import { CostObjectFields } from './CostObjectFields';
import { FileAttachments } from './FileAttachments';
import { belongLabel, CostTargetLink } from './FinanceCells';
import { COST_TYPE_LABEL, LOAN_STATUS_META, money } from './financeStatus';

type Loan = {
  id: string;
  loanNo: string;
  costType: string;
  amount: string | number;
  remaining?: number;
  purpose: string;
  status: string;
  remark?: string | null;
  createdAt?: string;
  bidCase?: { id: string; bidNo: string; name?: string; externalNo?: string } | null;
  project?: { id?: string; projectNo: string; name?: string } | null;
  applicant?: { displayName: string; employee?: { department?: { name?: string } } };
  myActions?: { canEdit: boolean; canSubmit: boolean; canDelete?: boolean; canReview: boolean; canOffset: boolean };
};

export default function LoanDetailPage() {
  const { id } = useParams();
  const [params] = useSearchParams();
  const location = useLocation();
  const onDesk = location.pathname.startsWith('/finance');
  const listPath = onDesk ? '/finance/loans' : '/office/expenses';
  const selfPath = onDesk ? '/finance/loans' : '/office/loans';
  const isNew = id === 'new' || !id;
  const navigate = useNavigate();
  const qc = useQueryClient();
  const [form] = Form.useForm();
  const q = useQuery({
    queryKey: ['loan', id],
    enabled: !isNew && Boolean(id),
    queryFn: () => api.get(`/loans/${id}`),
  });
  const row = q.data?.data as Loan | undefined;

  useEffect(() => {
    if (isNew) {
      form.setFieldsValue({
        costType: params.get('costType') || 'BID',
        bidCaseId: params.get('bidCaseId') || undefined,
        projectId: params.get('projectId') || undefined,
        purpose: params.get('purpose') || undefined,
      });
      return;
    }
    if (!row) return;
    form.setFieldsValue({
      costType: row.costType,
      bidCaseId: row.bidCase?.id,
      projectId: row.project ? (row as Loan & { project?: { id?: string } }).project?.id : undefined,
      amount: Number(row.amount),
      purpose: row.purpose,
      remark: row.remark || undefined,
    });
  }, [isNew, row, form, params]);

  const saveMut = useMutation({
    mutationFn: (body: Record<string, unknown>) => (isNew ? api.post('/loans', body) : api.patch(`/loans/${id}`, body)),
    onSuccess: async (res: { data?: { id?: string } }) => {
      message.success('已保存');
      await qc.invalidateQueries();
      if (isNew && res.data?.id) navigate(`${selfPath}/${res.data.id}`, { replace: true });
    },
    onError: (e: Error) => message.error(e.message),
  });
  const submitMut = useMutation({
    mutationFn: async (savedId?: string) => {
      const target = savedId || id;
      if (!target || target === 'new') throw new Error('请先保存');
      return api.post(`/loans/${target}/submit`);
    },
    onSuccess: async () => {
      message.success('已提交财务确认');
      await qc.invalidateQueries();
    },
    onError: (e: Error) => message.error(e.message),
  });
  const reviewMut = useMutation({
    mutationFn: (body: { result: 'APPROVED' | 'REJECTED'; comment?: string }) => api.post(`/loans/${id}/reviews`, body),
    onSuccess: async () => {
      message.success('已办理');
      await qc.invalidateQueries();
    },
    onError: (e: Error) => message.error(e.message),
  });
  const delMut = useMutation({
    mutationFn: () => api.delete(`/loans/${id}`),
    onSuccess: () => {
      message.success('已删除');
      navigate(listPath);
    },
    onError: (e: Error) => message.error(e.message),
  });

  const meta = LOAN_STATUS_META[row?.status || 'DRAFT'] || LOAN_STATUS_META.DRAFT;
  const editable = isNew || row?.myActions?.canEdit;

  return (
    <FormDrawer
      title={isNew ? '申请借款' : row?.loanNo || '借款单'}
      extra="取标差旅等先借款。报销时必须冲这笔借款，不能再领一笔。"
      open
      onClose={() => navigate(listPath)}
      hideOk
      createdAt={isNew ? undefined : row?.createdAt}
    >
      {row ? (
        <Space style={{ marginBottom: 16 }} wrap>
          <Tag color={meta.color}>{meta.text}</Tag>
          <Tag>{COST_TYPE_LABEL[row.costType] || row.costType}</Tag>
          <span>未还 {money(row.remaining ?? row.amount)}</span>
        </Space>
      ) : null}
      {row?.myActions?.canReview ? (
        <Alert
          type="info"
          showIcon
          style={{ marginBottom: 16 }}
          message="请确认借款。通过后申请人待办会出现「报销冲账」。"
          action={
            <Space>
              <Button type="primary" onClick={() => reviewMut.mutate({ result: 'APPROVED' })}>
                通过
              </Button>
              <Button
                danger
                onClick={() => {
                  const comment = window.prompt('打回意见');
                  if (comment) reviewMut.mutate({ result: 'REJECTED', comment });
                }}
              >
                打回
              </Button>
            </Space>
          }
        />
      ) : null}
      {row?.myActions?.canOffset ? (
        <Alert
          type="warning"
          showIcon
          style={{ marginBottom: 16 }}
          message="借款未还，请报销冲账，不要另报一笔。"
          action={
            <Button type="primary">
              <Link to={`/office/expenses/new?loanId=${row.id}&costType=${row.costType}&bidCaseId=${row.bidCase?.id || ''}`} style={{ color: 'inherit' }}>
                去冲账
              </Link>
            </Button>
          }
        />
      ) : null}

      {!editable && row ? (
        <Descriptions bordered size="small" column={2}>
          <Descriptions.Item label="金额">{money(row.amount)}</Descriptions.Item>
          <Descriptions.Item label="未还">{money(row.remaining)}</Descriptions.Item>
          <Descriptions.Item label="用途" span={2}>
            {row.purpose}
          </Descriptions.Item>
          <Descriptions.Item label="申请人">{row.applicant?.displayName || '—'}</Descriptions.Item>
          <Descriptions.Item label="归属">{belongLabel(row)}</Descriptions.Item>
          <Descriptions.Item label="对象">
            <CostTargetLink costType={row.costType} bid={row.bidCase} project={row.project} />
          </Descriptions.Item>
          <Descriptions.Item label="备注" span={2}>
            {row.remark || '—'}
          </Descriptions.Item>
        </Descriptions>
      ) : (
        <Form form={form} layout="vertical" style={{ maxWidth: 640 }} onFinish={(v) => saveMut.mutate(v)}>
          <CostObjectFields />
          <Form.Item name="purpose" label="用途" rules={[{ required: true, message: '请填写用途' }]}>
            <Input placeholder="如：取标差旅、预办证照" />
          </Form.Item>
          <FileAttachments bizType="LOAN" bizId={isNew ? undefined : id} disabled={!editable} label="借据 / 凭证" />
          <Space>
            <Button type="primary" htmlType="submit" loading={saveMut.isPending}>
              保存草稿
            </Button>
            <Button
              loading={submitMut.isPending}
              onClick={async () => {
                const v = await form.validateFields();
                if (isNew) {
                  const res = await saveMut.mutateAsync(v);
                  const newId = (res as { data?: { id?: string } }).data?.id;
                  if (newId) await submitMut.mutateAsync(newId);
                } else {
                  await saveMut.mutateAsync(v);
                  await submitMut.mutateAsync(id);
                }
              }}
            >
              保存并提交
            </Button>
            {row?.myActions?.canDelete ? (
              <Button danger onClick={() => delMut.mutate()}>
                删除
              </Button>
            ) : null}
          </Space>
        </Form>
      )}
      {!editable && row ? <FileAttachments bizType="LOAN" bizId={id} disabled label="借据 / 凭证" /> : null}
      {!editable && row?.myActions?.canSubmit ? (
        <Button type="primary" style={{ marginTop: 16 }} onClick={() => submitMut.mutate()}>
          提交确认
        </Button>
      ) : null}
      <Typography.Paragraph type="secondary" style={{ marginTop: 24 }}>
        财务确认借款后才会放款记账；报销通过才冲减未还金额。
      </Typography.Paragraph>
    </FormDrawer>
  );
}