'use client';

import * as React from 'react';
import { useFieldArray, useForm, type UseFormRegisterReturn } from 'react-hook-form';
import { zodResolver } from '@hookform/resolvers/zod';
import { useQuery } from '@tanstack/react-query';
import { Plus, Trash2 } from 'lucide-react';

import { listCustomers } from '@/lib/api/customers';
import { listProducts } from '@/lib/api/products';
import type { SaleInput } from '@/lib/api/sales';
import { saleFormSchema, type SaleFormValues } from '@/lib/validators/sales';
import { formatCurrency, formatDate } from '@/lib/format';
import { CustomerQuickCreateDialog } from '@/components/domain/customer-quick-create-dialog';

import { Badge } from '@/components/ui/badge';
import { Button } from '@/components/ui/button';
import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
import { Combobox } from '@/components/ui/combobox';
import { FormField } from '@/components/ui/form-field';
import { Input } from '@/components/ui/input';
import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from '@/components/ui/select';
import { Textarea } from '@/components/ui/textarea';

function toCents(value: number): number {
  return Math.round(value * 100);
}

function todayIso(): string {
  return new Date().toISOString().slice(0, 10);
}

/** Calcula os vencimentos (30 em 30 dias) só para pré-visualização — o backend recalcula de verdade. */
function previewVencimentosAutomaticos(dataVenda: string, numeroParcelas: number): Date[] {
  const base = dataVenda ? new Date(`${dataVenda}T00:00:00Z`) : new Date();
  return Array.from({ length: numeroParcelas }, (_, i) => {
    const d = new Date(base);
    d.setUTCDate(d.getUTCDate() + 30 * (i + 1));
    return d;
  });
}

export interface VendaFormSubmitHandlers {
  /** Só no modo `create` — salva como orçamento. */
  onSaveDraft?: (input: SaleInput) => void;
  /** No `create`, confirma a venda; no `edit`, salva as alterações (venda continua em orçamento). */
  onConfirmOrSave: (input: SaleInput) => void;
}

interface VendaFormProps extends VendaFormSubmitHandlers {
  mode: 'create' | 'edit';
  defaultValues: SaleFormValues;
  submittingDraft?: boolean;
  submittingConfirmOrSave?: boolean;
  onCancel: () => void;
}

export function VendaForm({
  mode,
  defaultValues,
  submittingDraft,
  submittingConfirmOrSave,
  onSaveDraft,
  onConfirmOrSave,
  onCancel,
}: VendaFormProps) {
  const [quickCreateOpen, setQuickCreateOpen] = React.useState(false);

  const form = useForm<SaleFormValues>({ resolver: zodResolver(saleFormSchema), defaultValues });
  const itensArray = useFieldArray({ control: form.control, name: 'itens' });
  const parcelasArray = useFieldArray({ control: form.control, name: 'parcelasManuais' });

  const customerId = form.watch('customer_id');
  const itens = form.watch('itens');
  const desconto = form.watch('desconto') || 0;
  const dataVenda = form.watch('data_venda');
  const modoParcelas = form.watch('modoParcelas');
  const numeroParcelas = form.watch('numeroParcelas');
  const parcelasManuais = form.watch('parcelasManuais') ?? [];

  const { data: customersData } = useQuery({
    queryKey: ['tenant', 'customers', 'combobox'],
    queryFn: () => listCustomers({ ativo: true, limit: 100 }),
  });
  const { data: productsData } = useQuery({
    queryKey: ['tenant', 'produtos', 'combobox'],
    queryFn: () => listProducts({ ativo: true, limit: 100 }),
  });

  const customerOptions = (customersData?.data ?? []).map((c) => ({
    value: c.id,
    label: c.nome_fantasia || c.razao_social,
  }));
  const productOptions = (productsData?.data ?? []).map((p) => ({
    value: p.id,
    label: p.sku ? `${p.nome} (${p.sku})` : p.nome,
  }));

  const subtotalItens = itens.reduce((acc, item) => acc + item.quantidade * item.valor_unitario, 0);
  const total = Math.max(0, subtotalItens - desconto);
  const descontoExcedeItens = desconto > subtotalItens;

  const somaParcelasManuais = parcelasManuais.reduce((acc, p) => acc + (p.valor || 0), 0);
  const diffParcelas = toCents(total) - toCents(somaParcelasManuais);
  const parcelasBatem = modoParcelas === 'automatico' || diffParcelas === 0;

  function addItem(productId: string) {
    const produto = productsData?.data.find((p) => p.id === productId);
    if (!produto) return;
    if (itensArray.fields.some((f) => f.product_service_id === productId)) return;
    itensArray.append({
      product_service_id: produto.id,
      nome: produto.nome,
      quantidade: 1,
      valor_unitario: Number(produto.valor_venda),
      valor_catalogo: Number(produto.valor_venda),
    });
  }

  function buildInput(values: SaleFormValues): SaleInput | null {
    if (values.modoParcelas === 'manual') {
      if (!values.parcelasManuais || values.parcelasManuais.length === 0) {
        form.setError('parcelasManuais', { message: 'Adicione pelo menos uma parcela' });
        return null;
      }
      if (!parcelasBatem) {
        form.setError('parcelasManuais', {
          message: `A soma das parcelas não bate com o total da venda (diferença de ${formatCurrency(Math.abs(diffParcelas) / 100)})`,
        });
        return null;
      }
    } else if (!values.numeroParcelas || values.numeroParcelas < 1) {
      form.setError('numeroParcelas', { message: 'Informe o número de parcelas' });
      return null;
    }

    return {
      customer_id: values.customer_id,
      data_venda: values.data_venda,
      desconto: values.desconto || undefined,
      observacoes: values.observacoes || undefined,
      itens: values.itens.map((item) => ({
        product_service_id: item.product_service_id,
        quantidade: item.quantidade,
        valor_unitario: item.valor_unitario,
      })),
      ...(values.modoParcelas === 'manual'
        ? { parcelas: values.parcelasManuais!.map((p) => ({ valor: p.valor, vencimento: p.vencimento })) }
        : { numero_parcelas: values.numeroParcelas }),
    };
  }

  const vencimentosPreview =
    modoParcelas === 'automatico' && numeroParcelas
      ? previewVencimentosAutomaticos(dataVenda, numeroParcelas)
      : [];

  return (
    <div className="flex flex-col gap-6 pb-24 lg:pb-0">
      <div className="grid grid-cols-1 gap-6 lg:grid-cols-[1fr_380px]">
        <div className="flex flex-col gap-6">
          <Card>
            <CardHeader>
              <CardTitle>Cliente e data</CardTitle>
            </CardHeader>
            <CardContent className="flex flex-col gap-4">
              <div className="flex items-end gap-2">
                <FormField
                  label="Cliente"
                  id="customer_id"
                  className="flex-1"
                  error={form.formState.errors.customer_id?.message}
                  required
                >
                  <Combobox
                    id="customer_id"
                    options={customerOptions}
                    value={customerId}
                    onChange={(value) => form.setValue('customer_id', value, { shouldValidate: true })}
                    placeholder="Selecionar cliente..."
                    searchPlaceholder="Buscar cliente..."
                  />
                </FormField>
                <Button type="button" variant="outline" onClick={() => setQuickCreateOpen(true)}>
                  <Plus /> Novo
                </Button>
              </div>
              <FormField label="Data da venda" error={form.formState.errors.data_venda?.message} required>
                <Input type="date" {...form.register('data_venda')} />
              </FormField>
              <FormField label="Observações" error={form.formState.errors.observacoes?.message}>
                <Textarea rows={2} {...form.register('observacoes')} />
              </FormField>
            </CardContent>
          </Card>

          <Card>
            <CardHeader className="flex flex-row items-center justify-between gap-2 space-y-0">
              <CardTitle>Itens da venda</CardTitle>
              <div className="w-64">
                <Combobox
                  options={productOptions}
                  value=""
                  onChange={addItem}
                  placeholder="Adicionar item..."
                  searchPlaceholder="Buscar produto/serviço..."
                />
              </div>
            </CardHeader>
            <CardContent className="flex flex-col gap-3">
              {form.formState.errors.itens?.message && (
                <p className="text-sm text-destructive">{form.formState.errors.itens.message}</p>
              )}
              {itensArray.fields.length === 0 ? (
                <p className="py-6 text-center text-sm text-muted-foreground">
                  Nenhum item adicionado ainda — busque um produto ou serviço acima.
                </p>
              ) : (
                <div className="flex flex-col divide-y divide-border">
                  {itensArray.fields.map((field, index) => {
                    const item = itens[index];
                    const alterado = item && item.valor_unitario !== item.valor_catalogo;
                    return (
                      <div key={field.id} className="flex flex-wrap items-end gap-3 py-3">
                        <div className="min-w-40 flex-1">
                          <p className="text-sm font-medium text-foreground">{field.nome}</p>
                          {alterado && (
                            <Badge variant="outline" className="mt-1">
                              Valor alterado do catálogo ({formatCurrency(field.valor_catalogo)})
                            </Badge>
                          )}
                        </div>
                        <FormField label="Qtd." className="w-24">
                          <Input
                            type="number"
                            step="0.01"
                            min="0.01"
                            {...form.register(`itens.${index}.quantidade`, { valueAsNumber: true })}
                          />
                        </FormField>
                        <FormField label="Valor unit. (R$)" className="w-32">
                          <Input
                            type="number"
                            step="0.01"
                            min="0"
                            {...form.register(`itens.${index}.valor_unitario`, { valueAsNumber: true })}
                          />
                        </FormField>
                        <div className="w-28 text-right">
                          <p className="text-xs text-muted-foreground">Subtotal</p>
                          <p className="font-medium tabular-nums text-foreground">
                            {formatCurrency((item?.quantidade || 0) * (item?.valor_unitario || 0))}
                          </p>
                        </div>
                        <Button
                          type="button"
                          variant="ghost"
                          size="icon-sm"
                          aria-label="Remover item"
                          onClick={() => itensArray.remove(index)}
                        >
                          <Trash2 className="size-4" />
                        </Button>
                      </div>
                    );
                  })}
                </div>
              )}
            </CardContent>
          </Card>

          <Card>
            <CardHeader>
              <CardTitle>Parcelas</CardTitle>
            </CardHeader>
            <CardContent className="flex flex-col gap-4">
              <Select
                value={modoParcelas}
                onValueChange={(value) => form.setValue('modoParcelas', value as 'automatico' | 'manual')}
              >
                <SelectTrigger className="w-full sm:w-64" aria-label="Modo de parcelamento">
                  <SelectValue />
                </SelectTrigger>
                <SelectContent>
                  <SelectItem value="automatico">Gerar parcelas automaticamente</SelectItem>
                  <SelectItem value="manual">Definir parcelas manualmente</SelectItem>
                </SelectContent>
              </Select>

              {modoParcelas === 'automatico' ? (
                <div className="flex flex-col gap-3">
                  <FormField
                    label="Número de parcelas"
                    helpText="Vencimentos calculados de 30 em 30 dias a partir da data da venda"
                    error={form.formState.errors.numeroParcelas?.message}
                    className="w-40"
                  >
                    <Input
                      type="number"
                      min="1"
                      {...form.register('numeroParcelas', {
                        setValueAs: (v) => (v === '' ? undefined : Number(v)),
                      })}
                    />
                  </FormField>
                  {vencimentosPreview.length > 0 && (
                    <ul className="flex flex-col gap-1 text-sm text-muted-foreground">
                      {vencimentosPreview.map((date, i) => (
                        <li key={i} className="flex justify-between tabular-nums">
                          <span>Parcela {i + 1}</span>
                          <span>{formatDate(date)}</span>
                        </li>
                      ))}
                    </ul>
                  )}
                </div>
              ) : (
                <div className="flex flex-col gap-3">
                  {form.formState.errors.parcelasManuais?.message && (
                    <p className="text-sm text-destructive">{form.formState.errors.parcelasManuais.message}</p>
                  )}
                  {parcelasArray.fields.map((field, index) => (
                    <div key={field.id} className="flex items-end gap-2">
                      <FormField label={`Parcela ${index + 1} — valor`} className="flex-1">
                        <Input
                          type="number"
                          step="0.01"
                          min="0"
                          {...form.register(`parcelasManuais.${index}.valor`, { valueAsNumber: true })}
                        />
                      </FormField>
                      <FormField label="Vencimento" className="flex-1">
                        <Input type="date" {...form.register(`parcelasManuais.${index}.vencimento`)} />
                      </FormField>
                      <Button
                        type="button"
                        variant="ghost"
                        size="icon-sm"
                        aria-label="Remover parcela"
                        onClick={() => parcelasArray.remove(index)}
                      >
                        <Trash2 className="size-4" />
                      </Button>
                    </div>
                  ))}
                  <Button
                    type="button"
                    variant="outline"
                    size="sm"
                    className="self-start"
                    onClick={() => parcelasArray.append({ valor: 0, vencimento: dataVenda || todayIso() })}
                  >
                    <Plus /> Adicionar parcela
                  </Button>
                  <div
                    className={`rounded-lg p-3 text-sm ${
                      parcelasBatem ? 'bg-success/10 text-success' : 'bg-danger/10 text-danger'
                    }`}
                  >
                    Soma das parcelas: {formatCurrency(somaParcelasManuais)} —{' '}
                    {parcelasBatem ? 'bate com o total' : `diferença de ${formatCurrency(Math.abs(diffParcelas) / 100)}`}
                  </div>
                </div>
              )}
            </CardContent>
          </Card>
        </div>

        <div className="hidden flex-col gap-4 lg:flex">
          <ResumoCard
            subtotalItens={subtotalItens}
            desconto={desconto}
            total={total}
            descontoExcedeItens={descontoExcedeItens}
            formErrorDesconto={form.formState.errors.desconto?.message}
            registerDesconto={form.register('desconto', { valueAsNumber: true })}
            mode={mode}
            submittingDraft={submittingDraft}
            submittingConfirmOrSave={submittingConfirmOrSave}
            onSaveDraft={onSaveDraft ? () => { const input = buildInput(form.getValues()); if (input) onSaveDraft(input); } : undefined}
            onConfirmOrSave={() => { const input = buildInput(form.getValues()); if (input) onConfirmOrSave(input); }}
            onCancel={onCancel}
          />
        </div>
      </div>

      {/* Mobile: resumo + ações fixos no rodapé, sempre visíveis */}
      <div className="fixed inset-x-0 bottom-16 z-10 border-t border-border bg-surface p-4 shadow-lg lg:hidden">
        <div className="mb-3 flex items-center justify-between">
          <span className="text-sm text-muted-foreground">Total da venda</span>
          <span className="text-lg font-semibold tabular-nums text-foreground">{formatCurrency(total)}</span>
        </div>
        <div className="flex gap-2">
          {onSaveDraft && (
            <Button
              type="button"
              variant="outline"
              className="flex-1"
              loading={submittingDraft}
              onClick={() => {
                const input = buildInput(form.getValues());
                if (input) onSaveDraft(input);
              }}
            >
              Orçamento
            </Button>
          )}
          <Button
            type="button"
            className="flex-1"
            loading={submittingConfirmOrSave}
            onClick={() => {
              const input = buildInput(form.getValues());
              if (input) onConfirmOrSave(input);
            }}
          >
            {mode === 'create' ? 'Confirmar venda' : 'Salvar alterações'}
          </Button>
        </div>
      </div>

      <CustomerQuickCreateDialog
        open={quickCreateOpen}
        onOpenChange={setQuickCreateOpen}
        onCreated={(customer) => form.setValue('customer_id', customer.id, { shouldValidate: true })}
      />
    </div>
  );
}

function ResumoCard({
  subtotalItens,
  desconto,
  total,
  descontoExcedeItens,
  formErrorDesconto,
  registerDesconto,
  mode,
  submittingDraft,
  submittingConfirmOrSave,
  onSaveDraft,
  onConfirmOrSave,
  onCancel,
}: {
  subtotalItens: number;
  desconto: number;
  total: number;
  descontoExcedeItens: boolean;
  formErrorDesconto?: string;
  registerDesconto: UseFormRegisterReturn<'desconto'>;
  mode: 'create' | 'edit';
  submittingDraft?: boolean;
  submittingConfirmOrSave?: boolean;
  onSaveDraft?: () => void;
  onConfirmOrSave: () => void;
  onCancel: () => void;
}) {
  return (
    <Card className="sticky top-4">
      <CardHeader>
        <CardTitle>Resumo</CardTitle>
      </CardHeader>
      <CardContent className="flex flex-col gap-4">
        <FormField label="Desconto geral (R$)" error={formErrorDesconto || (descontoExcedeItens ? 'Desconto maior que a soma dos itens' : undefined)}>
          <Input type="number" step="0.01" min="0" {...registerDesconto} />
        </FormField>
        <div className="flex flex-col gap-1.5 border-t border-border pt-3 text-sm">
          <div className="flex justify-between text-muted-foreground">
            <span>Subtotal itens</span>
            <span className="tabular-nums">{formatCurrency(subtotalItens)}</span>
          </div>
          <div className="flex justify-between text-muted-foreground">
            <span>Desconto</span>
            <span className="tabular-nums">-{formatCurrency(desconto)}</span>
          </div>
          <div className="flex justify-between text-base font-semibold text-foreground">
            <span>Total</span>
            <span className="tabular-nums">{formatCurrency(total)}</span>
          </div>
        </div>
        <div className="flex flex-col gap-2">
          {onSaveDraft && (
            <Button type="button" variant="outline" loading={submittingDraft} onClick={onSaveDraft}>
              Salvar como orçamento
            </Button>
          )}
          <Button type="button" loading={submittingConfirmOrSave} onClick={onConfirmOrSave}>
            {mode === 'create' ? 'Confirmar venda' : 'Salvar alterações'}
          </Button>
          <Button type="button" variant="ghost" onClick={onCancel}>
            Cancelar
          </Button>
        </div>
      </CardContent>
    </Card>
  );
}