import { useState } from 'react';
import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
import { CheckIcon, XMarkIcon, PaperAirplaneIcon, BanknotesIcon } from '@heroicons/react/24/outline';
import { toast } from 'sonner';
import { api } from '../lib/api';
import { formatRial, formatNumber } from '../lib/utils';
import PageHeader from '../components/ui/PageHeader';
import Modal from '../components/ui/Modal';

interface ClaimItem {
  invoice_item_id: number;
  claimed_rials: number;
  approved_rials: number | null;
}

interface Claim {
  uuid: string;
  insurance_id: number;
  insurance_kind: string;
  total_claimed_rials: number;
  total_approved_rials: number | null;
  total_paid_rials: number | null;
  status: string;
  reject_reason: string | null;
  items: ClaimItem[];
}

interface DebtRow {
  insurance_id: number;
  claimed: number;
  approved: number;
  paid: number;
  debt: number;
}

const STATUS_META: Record<string, { label: string; cls: string }> = {
  pending: { label: 'در انتظار', cls: 'gray' },
  submitted: { label: 'ارسال‌شده', cls: 'blue' },
  approved: { label: 'تأییدشده', cls: 'amber' },
  rejected: { label: 'ردشده', cls: 'red' },
  paid: { label: 'پرداخت‌شده', cls: 'green' },
};

const KIND_LABEL: Record<string, string> = { base: 'پایه', supplementary: 'تکمیلی' };
const STATUS_FILTERS = ['', 'pending', 'submitted', 'approved', 'rejected', 'paid'];

export default function ClaimsPage() {
  const qc = useQueryClient();
  const [statusFilter, setStatusFilter] = useState('');
  const [rejectTarget, setRejectTarget] = useState<Claim | null>(null);
  const [rejectReason, setRejectReason] = useState('');

  const claimsQuery = useQuery<{ data: { data: Claim[] } }>({
    queryKey: ['claims', statusFilter],
    queryFn: () => api.get(`/api/v1/billing/claims${statusFilter ? `?status=${statusFilter}` : ''}`),
  });

  const debtQuery = useQuery<{ data: { data: DebtRow[] } }>({
    queryKey: ['insurance-debt'],
    queryFn: () => api.get('/api/v1/billing/reports/insurance-debt'),
  });

  const claims = (claimsQuery.data as any)?.data?.data ?? [];
  const debt = (debtQuery.data as any)?.data?.data ?? [];

  const transitionMut = useMutation({
    mutationFn: ({ uuid, action, body }: { uuid: string; action: string; body?: object }) =>
      api.post(`/api/v1/billing/claims/${uuid}/${action}`, body ?? {}),
    onSuccess: () => {
      toast.success('وضعیت مطالبه به‌روزرسانی شد');
      setRejectTarget(null);
      setRejectReason('');
      qc.invalidateQueries({ queryKey: ['claims'] });
      qc.invalidateQueries({ queryKey: ['insurance-debt'] });
    },
    onError: (e: Error) => toast.error(e.message),
  });

  return (
    <div className="fade-in">
      <PageHeader title="مطالبات بیمه" description="پیگیری مطالبات و بدهی بیمه‌ها" />

      <div className="card" style={{ padding: 18, marginBottom: 16 }}>
        <div style={{ display: 'flex', alignItems: 'center', gap: 8, marginBottom: 12 }}>
          <BanknotesIcon style={{ width: 18, color: 'var(--text-3)' }} />
          <h2 style={{ fontSize: 14, fontWeight: 700, margin: 0 }}>بدهی بیمه‌ها</h2>
        </div>
        {debtQuery.isLoading ? (
          <div className="muted" style={{ fontSize: 13 }}>در حال بارگذاری...</div>
        ) : debt.length === 0 ? (
          <div style={{ fontSize: 12.5, color: 'var(--text-3)' }}>بدهی‌ای ثبت نشده است.</div>
        ) : (
          <div style={{ display: 'flex', flexDirection: 'column', gap: 6 }}>
            {debt.map((d: DebtRow) => (
              <div key={d.insurance_id} style={{ display: 'flex', justifyContent: 'space-between', alignItems: 'center', padding: '8px 12px', borderRadius: 8, border: '1px solid var(--border)', fontSize: 13 }}>
                <span style={{ fontWeight: 600 }}>بیمه #{formatNumber(d.insurance_id)}</span>
                <span style={{ color: 'var(--text-3)' }}>ادعا {formatRial(d.claimed)} · پرداخت {formatRial(d.paid)}</span>
                <span style={{ fontWeight: 700, color: d.debt > 0 ? 'var(--danger)' : 'var(--success, #16a34a)' }}>بدهی {formatRial(d.debt)}</span>
              </div>
            ))}
          </div>
        )}
      </div>

      <div className="card" style={{ padding: 18 }}>
        <div style={{ display: 'flex', justifyContent: 'space-between', alignItems: 'center', marginBottom: 12 }}>
          <h2 style={{ fontSize: 14, fontWeight: 700, margin: 0 }}>مطالبات</h2>
          <select className="input" style={{ maxWidth: 160 }} value={statusFilter} onChange={(e) => setStatusFilter(e.target.value)}>
            {STATUS_FILTERS.map((s) => (
              <option key={s} value={s}>{s === '' ? 'همه وضعیت‌ها' : STATUS_META[s]?.label}</option>
            ))}
          </select>
        </div>

        {claimsQuery.isLoading ? (
          <div className="muted" style={{ fontSize: 13 }}>در حال بارگذاری...</div>
        ) : claims.length === 0 ? (
          <div style={{ fontSize: 12.5, color: 'var(--text-3)', padding: '12px 0' }}>مطالبه‌ای یافت نشد.</div>
        ) : (
          <div style={{ display: 'flex', flexDirection: 'column', gap: 8 }}>
            {claims.map((c: Claim) => {
              const meta = STATUS_META[c.status] ?? { label: c.status, cls: 'gray' };
              return (
                <div key={c.uuid} style={{ padding: '12px 14px', borderRadius: 10, border: '1px solid var(--border)' }}>
                  <div style={{ display: 'flex', justifyContent: 'space-between', alignItems: 'flex-start', gap: 10 }}>
                    <div>
                      <div style={{ fontWeight: 600, fontSize: 13.5 }}>
                        بیمه #{formatNumber(c.insurance_id)}
                        <span className="badge gray" style={{ fontSize: 10, marginInlineStart: 6 }}>{KIND_LABEL[c.insurance_kind] ?? c.insurance_kind}</span>
                        <span className={`badge ${meta.cls}`} style={{ fontSize: 10, marginInlineStart: 4 }}><span className="bdot" />{meta.label}</span>
                      </div>
                      <div style={{ fontSize: 11.5, color: 'var(--text-3)', marginTop: 3 }}>
                        ادعا {formatRial(c.total_claimed_rials)}
                        {c.total_approved_rials != null && ` · تأیید ${formatRial(c.total_approved_rials)}`}
                        {c.total_paid_rials != null && ` · پرداخت ${formatRial(c.total_paid_rials)}`}
                        {c.reject_reason && ` · دلیل رد: ${c.reject_reason}`}
                      </div>
                    </div>
                    <div style={{ display: 'flex', gap: 6, flexShrink: 0 }}>
                      {c.status === 'pending' && (
                        <button className="btn primary sm" disabled={transitionMut.isPending} onClick={() => transitionMut.mutate({ uuid: c.uuid, action: 'submit' })}>
                          <PaperAirplaneIcon style={{ width: 13 }} /> ارسال
                        </button>
                      )}
                      {c.status === 'submitted' && (
                        <>
                          <button className="btn primary sm" disabled={transitionMut.isPending} onClick={() => transitionMut.mutate({ uuid: c.uuid, action: 'approve' })}>
                            <CheckIcon style={{ width: 13 }} /> تأیید
                          </button>
                          <button className="btn danger sm" onClick={() => { setRejectTarget(c); setRejectReason(''); }}>
                            <XMarkIcon style={{ width: 13 }} /> رد
                          </button>
                        </>
                      )}
                      {c.status === 'approved' && (
                        <button className="btn primary sm" disabled={transitionMut.isPending} onClick={() => transitionMut.mutate({ uuid: c.uuid, action: 'pay' })}>
                          <BanknotesIcon style={{ width: 13 }} /> پرداخت
                        </button>
                      )}
                    </div>
                  </div>
                </div>
              );
            })}
          </div>
        )}
      </div>

      <Modal open={!!rejectTarget} onClose={() => setRejectTarget(null)} title="رد مطالبه"
        footer={
          <>
            <button className="btn ghost sm" onClick={() => setRejectTarget(null)}>انصراف</button>
            <button className="btn danger sm" disabled={!rejectReason || transitionMut.isPending}
              onClick={() => rejectTarget && transitionMut.mutate({ uuid: rejectTarget.uuid, action: 'reject', body: { reason: rejectReason } })}>
              رد کردن
            </button>
          </>
        }
      >
        <div className="field">
          <label>دلیل رد</label>
          <textarea className="input" rows={3} dir="rtl" value={rejectReason} onChange={(e) => setRejectReason(e.target.value)} placeholder="دلیل رد را بنویسید..." />
        </div>
      </Modal>
    </div>
  );
}
