import { useEffect, useMemo, useState } from 'react';
import { useParams, useNavigate } from 'react-router-dom';
import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
import { useForm } from 'react-hook-form';
import { zodResolver } from '@hookform/resolvers/zod';
import { z } from 'zod';
import { toast } from 'sonner';
import { ChevronRightIcon, PlusIcon, XMarkIcon } from '@heroicons/react/24/outline';
import { api } from '../lib/api';
import type { ApiResponse } from '../lib/api';
import type { PatientRecord, ServiceSection, ServiceItem } from '../types';
import { formatRial } from '../lib/utils';
import SearchableSelect from '../components/ui/SearchableSelect';

const schema = z.object({
  visit_price_rials: z.coerce.number().min(0),
  base_insurance_discount_percent: z.coerce.number().min(0).max(100),
  supplementary_discount_percent: z.coerce.number().min(0).max(100),
  insurance_base_id: z.coerce.number().optional(),
  insurance_supplementary_id: z.coerce.number().optional(),
  payment_method: z.enum(['cash', 'card', 'insurance', 'online', 'pending']),
  notes: z.string().optional(),
});
type FormData = z.infer<typeof schema>;

interface Contract { uuid: string; insurance_id: number; insurance_name: string | null; insurance_kind: string | null; coverage_percent: number; franchise_rials: number; annual_ceiling_rials: number | null }
interface CoverageRow { service_item_uuid: string | null; covered: boolean; coverage_percent: number | null; franchise_rials: number | null; ceiling_rials: number | null }

const PAYMENT_LABELS: Record<string, string> = {
  cash: 'نقدی', card: 'کارت', insurance: 'بیمه', online: 'آنلاین', pending: 'در انتظار',
};

interface Rule { covered: boolean; percent: number; franchise: number; ceiling: number | null }

// (calcFinal قدیمی حذف شد — حالا سهم بیمار خدمات با patientShareOf و قاعده‌ی هر بیمه‌گر محاسبه می‌شود)

// آینه‌ی BillingCalculator سمت سرور: سهم بیمار یک خدمت با پوشش پایه/مکمل.
function patientShareOf(total: number, base: Rule | null, supp: Rule | null): number {
  let baseShare = 0;
  let remaining = total;
  if (base && base.covered) {
    baseShare = Math.round(total * (base.percent / 100));
    if (base.ceiling !== null) baseShare = Math.min(baseShare, base.ceiling);
    remaining = total - baseShare;
  }
  let suppShare = 0;
  if (supp && supp.covered) {
    suppShare = Math.round(remaining * (supp.percent / 100));
    if (supp.ceiling !== null) suppShare = Math.min(suppShare, supp.ceiling);
    remaining = remaining - suppShare;
  }
  const franchise = (base?.franchise ?? 0) + (supp?.franchise ?? 0);
  return Math.min(remaining + franchise, total);
}

const sectionTitle: React.CSSProperties = { fontWeight: 700, fontSize: 13.5, color: 'var(--text-2)', margin: '0 0 12px' };
const fieldLabel: React.CSSProperties = { fontSize: 12.5, fontWeight: 600, marginBottom: 5, display: 'block' };

export default function NewSessionPage() {
  const { recordUuid = '' } = useParams();
  const nav = useNavigate();
  const qc = useQueryClient();

  const [selectedServices, setSelectedServices] = useState<{ uuid: string; name: string; price: number; qty: number; insured: boolean }[]>([]);
  const [sectionUuid, setSectionUuid] = useState('');
  const [itemUuid, setItemUuid] = useState('');
  const [baseId, setBaseId] = useState('');
  const [suppId, setSuppId] = useState('');

  const form = useForm<FormData>({
    resolver: zodResolver(schema),
    defaultValues: { visit_price_rials: 0, base_insurance_discount_percent: 0, supplementary_discount_percent: 0, payment_method: 'cash' },
  });

  const recordQ = useQuery<ApiResponse<PatientRecord>>({
    queryKey: ['patient-detail', recordUuid],
    queryFn: () => api.get(`/api/v1/patient/${recordUuid}`),
    enabled: !!recordUuid,
  });
  const record = (recordQ.data?.data as PatientRecord | undefined) ?? undefined;
  const patientName = record?.user_name || record?.profile?.full_name || '—';

  const { data: sectionsData } = useQuery<ApiResponse<ServiceSection[]>>({
    queryKey: ['service-sections'], queryFn: () => api.get('/api/v1/service-sections'),
  });
  const { data: itemsData } = useQuery<ApiResponse<ServiceItem[]>>({
    queryKey: ['service-items-for-session', sectionUuid],
    queryFn: () => api.get(`/api/v1/service-items/${sectionUuid}`),
    enabled: !!sectionUuid,
  });
  const { data: contractsData } = useQuery<{ data: { data: Contract[] } }>({
    queryKey: ['tenant-insurances'], queryFn: () => api.get('/api/v1/billing/tenant-insurances'),
  });
  const { data: pricingData } = useQuery<{ data: { free_visit_price_rials: number } }>({
    queryKey: ['insurance-pricing'], queryFn: () => api.get('/api/v1/insurance-pricing'),
  });
  const freeVisit = (pricingData as any)?.data?.free_visit_price_rials ?? 0;

  useEffect(() => {
    if (freeVisit > 0 && !form.getValues('visit_price_rials')) {
      form.setValue('visit_price_rials', freeVisit);
    }
  }, [freeVisit]);

  const contracts = (contractsData as any)?.data?.data as Contract[] | undefined ?? [];
  const baseOpts = contracts.filter(c => c.insurance_kind === 'basic').map(c => ({ value: String(c.insurance_id), label: c.insurance_name ?? `#${c.insurance_id}` }));
  const suppOpts = contracts.filter(c => c.insurance_kind === 'supplementary').map(c => ({ value: String(c.insurance_id), label: c.insurance_name ?? `#${c.insurance_id}` }));

  const sectionOptions = (sectionsData?.data ?? []).map(s => ({ value: s.uuid, label: s.name }));
  const itemOptions = (itemsData?.data ?? []).filter(i => i.active).map(i => ({ value: i.uuid, label: `${i.name} — ${formatRial(i.price_rials)}` }));

  const baseContract = contracts.find(c => String(c.insurance_id) === baseId) ?? null;
  const suppContract = contracts.find(c => String(c.insurance_id) === suppId) ?? null;

  const baseCoverageQ = useQuery<{ data: { data: CoverageRow[] } }>({
    queryKey: ['service-coverage', baseContract?.uuid],
    queryFn: () => api.get(`/api/v1/billing/tenant-insurances/${baseContract!.uuid}/service-coverage`),
    enabled: !!baseContract,
  });
  const suppCoverageQ = useQuery<{ data: { data: CoverageRow[] } }>({
    queryKey: ['service-coverage', suppContract?.uuid],
    queryFn: () => api.get(`/api/v1/billing/tenant-insurances/${suppContract!.uuid}/service-coverage`),
    enabled: !!suppContract,
  });
  const baseCoverage = (baseCoverageQ.data as any)?.data?.data as CoverageRow[] | undefined ?? [];
  const suppCoverage = (suppCoverageQ.data as any)?.data?.data as CoverageRow[] | undefined ?? [];

  // قاعده‌ی پوشش یک خدمت تحت یک قرارداد: override خدمت اگر باشد، وگرنه پیش‌فرض قرارداد.
  const ruleFor = (contract: Contract | null, coverage: CoverageRow[], serviceUuid: string): Rule | null => {
    if (!contract) return null;
    const ov = coverage.find(r => r.service_item_uuid === serviceUuid);
    if (ov && !ov.covered) return { covered: false, percent: 0, franchise: 0, ceiling: null };
    return {
      covered: true,
      percent:   ov?.coverage_percent ?? contract.coverage_percent,
      franchise: ov?.franchise_rials  ?? contract.franchise_rials,
      ceiling:   ov?.ceiling_rials     ?? contract.annual_ceiling_rials,
    };
  };

  const coverageOf = (id: string): number => contracts.find(c => String(c.insurance_id) === id)?.coverage_percent ?? 0;
  const applyBase = (id: string) => {
    setBaseId(id);
    form.setValue('insurance_base_id', id ? Number(id) : undefined);
    form.setValue('base_insurance_discount_percent', id ? coverageOf(id) : 0);
  };
  const applySupp = (id: string) => {
    setSuppId(id);
    form.setValue('insurance_supplementary_id', id ? Number(id) : undefined);
    form.setValue('supplementary_discount_percent', id ? coverageOf(id) : 0);
  };

  const addService = () => {
    if (!itemUuid) return;
    const found = itemsData?.data?.find(i => i.uuid === itemUuid);
    if (!found || selectedServices.some(s => s.uuid === found.uuid)) return;
    setSelectedServices(p => [...p, { uuid: found.uuid, name: found.name, price: found.price_rials, qty: 1, insured: !!found.insurance_covered }]);
    setItemUuid('');
  };

  const setQty = (uuid: string, qty: number) =>
    setSelectedServices(p => p.map(s => s.uuid === uuid ? { ...s, qty: Math.max(1, qty) } : s));

  const visit = Number(form.watch('visit_price_rials')) || 0;
  const base = Number(form.watch('base_insurance_discount_percent')) || 0;
  const supp = Number(form.watch('supplementary_discount_percent')) || 0;
  const servicesTotal = useMemo(() => selectedServices.reduce((s, x) => s + x.price * x.qty, 0), [selectedServices]);
  const servicesPatient = useMemo(
    () => selectedServices.reduce((sum, x) => {
      const total = x.price * x.qty;
      // پرچم سرویس gate نهایی: اگر «شامل بیمه» نباشد، کامل سهم بیمار است.
      if (!x.insured) return sum + total;
      return sum + patientShareOf(
        total,
        ruleFor(baseContract, baseCoverage, x.uuid),
        ruleFor(suppContract, suppCoverage, x.uuid),
      );
    }, 0),
    [selectedServices, baseContract, suppContract, baseCoverage, suppCoverage],
  );
  const servicesInsured = servicesTotal - servicesPatient;
  const afterBase = Math.round(visit * (1 - base / 100));
  const afterSupp = Math.round(afterBase * (1 - supp / 100));
  const finalPrice = Math.round(afterSupp) + servicesPatient;

  const createMut = useMutation({
    mutationFn: (body: object) => api.post(`/api/v1/patient/${recordUuid}/session`, body),
    onSuccess: () => {
      qc.invalidateQueries({ queryKey: ['patient-sessions', recordUuid] });
      toast.success('مراجعه ثبت شد');
      nav(-1);
    },
    onError: (e: Error) => toast.error(e.message),
  });

  const submit = form.handleSubmit((d) => {
    createMut.mutate({ ...d, services: selectedServices.map(s => ({ service_item_uuid: s.uuid, quantity: s.qty })) });
  });

  const summaryRow = (label: string, val: number, strong = false) => (
    <div style={{ display: 'flex', justifyContent: 'space-between', fontSize: strong ? 15 : 13, fontWeight: strong ? 700 : 400, color: strong ? 'var(--text)' : 'var(--text-3)' }}>
      <span>{label}</span>
      <span style={strong ? { color: 'var(--primary)' } : undefined}>{formatRial(val)}</span>
    </div>
  );

  return (
    <div className="fade-in" style={{ maxWidth: 1100, margin: '0 auto' }}>
      <div style={{ display: 'flex', alignItems: 'center', gap: 10, marginBottom: 16 }}>
        <button className="btn ghost sm" onClick={() => nav(-1)}>
          <ChevronRightIcon style={{ width: 15 }} /> بازگشت
        </button>
        <div>
          <h1 className="section-title" style={{ margin: 0 }}>ثبت مراجعه جدید</h1>
          <div className="muted" style={{ fontSize: 13, marginTop: 2 }}>بیمار: {patientName}</div>
        </div>
      </div>

      <form onSubmit={submit} style={{ display: 'grid', gridTemplateColumns: 'minmax(0,1fr) 320px', gap: 16, alignItems: 'start' }}>
        <div style={{ display: 'flex', flexDirection: 'column', gap: 16 }}>
          <div className="card" style={{ padding: 20 }}>
            <h3 style={sectionTitle}>بیمه و مبلغ ویزیت</h3>
            <div style={{ display: 'grid', gridTemplateColumns: '1fr 1fr', gap: 12, marginBottom: 12 }}>
              <div>
                <label style={fieldLabel}>بیمه پایه</label>
                <SearchableSelect options={baseOpts} value={baseId} onChange={v => applyBase(v ? String(v) : '')} placeholder="بدون بیمه پایه" isClearable />
              </div>
              <div>
                <label style={fieldLabel}>بیمه تکمیلی</label>
                <SearchableSelect options={suppOpts} value={suppId} onChange={v => applySupp(v ? String(v) : '')} placeholder="بدون بیمه تکمیلی" isClearable />
              </div>
            </div>
            <div style={{ display: 'grid', gridTemplateColumns: '1fr 1fr 1fr', gap: 12 }}>
              <div>
                <label style={fieldLabel}>قیمت ویزیت (تومان)</label>
                <input className="input" type="number" min={0} dir="ltr" {...form.register('visit_price_rials')} />
              </div>
              <div>
                <label style={fieldLabel}>تخفیف بیمه پایه (%)</label>
                <input className="input" type="number" min={0} max={100} dir="ltr" {...form.register('base_insurance_discount_percent')} />
              </div>
              <div>
                <label style={fieldLabel}>تخفیف تکمیلی (%)</label>
                <input className="input" type="number" min={0} max={100} dir="ltr" {...form.register('supplementary_discount_percent')} />
              </div>
            </div>
          </div>

          <div className="card" style={{ padding: 20 }}>
            <h3 style={sectionTitle}>خدمات</h3>
            <div style={{ display: 'flex', gap: 8, marginBottom: selectedServices.length ? 12 : 0 }}>
              <div style={{ flex: 1 }}>
                <SearchableSelect options={sectionOptions} value={sectionUuid} onChange={v => { setSectionUuid(v ? String(v) : ''); setItemUuid(''); }} placeholder="انتخاب بخش..." />
              </div>
              <div style={{ flex: 1 }}>
                <SearchableSelect options={itemOptions} value={itemUuid} onChange={v => setItemUuid(v ? String(v) : '')} placeholder="انتخاب سرویس..." isDisabled={!sectionUuid} />
              </div>
              <button type="button" className="btn primary sm" onClick={addService} disabled={!itemUuid}>
                <PlusIcon style={{ width: 14 }} />
              </button>
            </div>
            {selectedServices.length > 0 && (
              <div style={{ display: 'flex', flexDirection: 'column', gap: 8 }}>
                {selectedServices.map(svc => (
                  <div key={svc.uuid} style={{ display: 'flex', alignItems: 'center', gap: 12, padding: '8px 12px', borderRadius: 10, border: '1px solid var(--border)' }}>
                    <span style={{ flex: 1, fontWeight: 500, fontSize: 13 }}>{svc.name}</span>
                    <div style={{ display: 'flex', alignItems: 'center', gap: 4 }}>
                      <button type="button" className="mini-btn" onClick={() => setQty(svc.uuid, svc.qty - 1)} disabled={svc.qty <= 1}>−</button>
                      <span style={{ minWidth: 26, textAlign: 'center', fontWeight: 600, fontSize: 13 }}>{svc.qty}</span>
                      <button type="button" className="mini-btn" onClick={() => setQty(svc.uuid, svc.qty + 1)}>+</button>
                    </div>
                    <span style={{ color: 'var(--primary)', fontWeight: 600, fontSize: 13, minWidth: 90, textAlign: 'left' }} dir="ltr">{formatRial(svc.price * svc.qty)}</span>
                    <button type="button" style={{ background: 'none', border: 'none', cursor: 'pointer', color: 'var(--danger)', padding: 0, display: 'flex' }}
                      onClick={() => setSelectedServices(p => p.filter(s => s.uuid !== svc.uuid))}>
                      <XMarkIcon style={{ width: 15 }} />
                    </button>
                  </div>
                ))}
              </div>
            )}
          </div>

          <div className="card" style={{ padding: 20 }}>
            <h3 style={sectionTitle}>پرداخت و یادداشت</h3>
            <div style={{ marginBottom: 12 }}>
              <label style={fieldLabel}>روش پرداخت</label>
              <SearchableSelect
                options={Object.entries(PAYMENT_LABELS).map(([v, l]) => ({ value: v, label: l }))}
                value={form.watch('payment_method')}
                onChange={v => form.setValue('payment_method', (v as FormData['payment_method']) || 'cash')}
                placeholder="روش پرداخت"
              />
            </div>
            <div>
              <label style={fieldLabel}>یادداشت</label>
              <textarea className="input" rows={3} dir="rtl" placeholder="یادداشت پزشک..." {...form.register('notes')} />
            </div>
          </div>
        </div>

        <div className="card" style={{ padding: 20, position: 'sticky', top: 16, display: 'flex', flexDirection: 'column', gap: 8 }}>
          <h3 style={sectionTitle}>خلاصه</h3>
          {summaryRow('ویزیت آزاد', visit)}
          {base > 0 && summaryRow('پس از بیمه پایه', afterBase)}
          {supp > 0 && summaryRow('پس از بیمه تکمیلی', afterSupp)}
          {servicesTotal > 0 && summaryRow('جمع خدمات', servicesTotal)}
          {servicesInsured > 0 && summaryRow('سهم بیمه از خدمات', servicesInsured)}
          {servicesInsured > 0 && summaryRow('سهم بیمار از خدمات', servicesTotal - servicesInsured)}
          <div style={{ borderTop: '1px solid var(--border)', paddingTop: 8, marginTop: 2 }}>
            {summaryRow('مبلغ نهایی (سهم بیمار)', finalPrice, true)}
          </div>
          <button type="submit" className="btn primary block" style={{ marginTop: 8 }} disabled={createMut.isPending}>
            {createMut.isPending ? 'در حال ذخیره...' : 'ثبت مراجعه'}
          </button>
          <button type="button" className="btn ghost block" onClick={() => nav(-1)}>انصراف</button>
        </div>
      </form>
    </div>
  );
}
