"use client";

import { useState } from "react";
import { useRouter } from "next/navigation";
import type { CustomerDetail, CustomerInput, Currency } from "@/lib/types";
import { createCustomer, updateCustomer } from "@/lib/api";

/** ISO date (yyyy-mm-dd) for a date input, from an API date string. */
function toDateInput(v: string | null | undefined): string {
  if (!v) return "";
  const d = new Date(v);
  return isNaN(d.getTime()) ? "" : d.toISOString().slice(0, 10);
}

function numOrUndef(v: string | number | null | undefined): number | undefined {
  if (v === null || v === undefined || v === "") return undefined;
  const n = Number(v);
  return isNaN(n) ? undefined : n;
}

type Values = {
  name: string;
  addressLine1: string;
  addressLine2: string;
  city: string;
  state: string;
  zipCode: string;
  country: string;
  phone: string;
  mobile: string;
  fax: string;
  email: string;
  identificationType: string;
  identificationNumber: string;
  identificationExpiration: string;
  customerSince: string;
  preferredCurrency: Currency;
  minimumBalance: string;
  feeAmount: string;
  status: boolean;
  notes: string;
};

function initial(c?: CustomerDetail): Values {
  return {
    name: c?.name ?? "",
    addressLine1: c?.addressLine1 ?? "",
    addressLine2: c?.addressLine2 ?? "",
    city: c?.city ?? "",
    state: c?.state ?? "",
    zipCode: c?.zipCode ?? "",
    country: c?.country ?? "",
    phone: c?.phone ?? "",
    mobile: c?.mobile ?? "",
    fax: c?.fax ?? "",
    email: c?.email ?? "",
    identificationType: c?.identificationType ?? "",
    identificationNumber: c?.identificationNumber ?? "",
    identificationExpiration: toDateInput(c?.identificationExpiration),
    customerSince: toDateInput(c?.customerSince),
    preferredCurrency: (c?.preferredCurrency as Currency) ?? "USD",
    minimumBalance: c?.minimumBalance != null ? String(c.minimumBalance) : "",
    feeAmount: c?.feeAmount != null ? String(c.feeAmount) : "",
    status: c?.status ?? true,
    notes: c?.notes ?? "",
  };
}

/** Empty string -> undefined so we don't send blanks as real values. */
function s(v: string): string | undefined {
  const t = v.trim();
  return t === "" ? undefined : t;
}

/**
 * Shared create/edit form. When `customer` is given it edits (PATCH), otherwise
 * it creates (POST). Redirects to the customer's detail page on success.
 */
export function CustomerForm({ customer }: { customer?: CustomerDetail }) {
  const router = useRouter();
  const editing = !!customer;
  const [v, setV] = useState<Values>(() => initial(customer));
  const [saving, setSaving] = useState(false);
  const [error, setError] = useState<string | null>(null);

  function set<K extends keyof Values>(key: K, val: Values[K]) {
    setV((prev) => ({ ...prev, [key]: val }));
  }

  async function submit(e: React.FormEvent) {
    e.preventDefault();
    setSaving(true);
    setError(null);
    const payload: CustomerInput = {
      name: v.name.trim(),
      addressLine1: s(v.addressLine1),
      addressLine2: s(v.addressLine2),
      city: s(v.city),
      state: s(v.state),
      zipCode: s(v.zipCode),
      country: s(v.country),
      phone: s(v.phone),
      mobile: s(v.mobile),
      fax: s(v.fax),
      email: s(v.email),
      identificationType: s(v.identificationType),
      identificationNumber: s(v.identificationNumber),
      identificationExpiration: s(v.identificationExpiration),
      customerSince: s(v.customerSince),
      preferredCurrency: v.preferredCurrency,
      minimumBalance: numOrUndef(v.minimumBalance),
      feeAmount: numOrUndef(v.feeAmount),
      status: v.status,
      notes: s(v.notes),
    };
    try {
      const saved = editing
        ? await updateCustomer(customer!.id, payload)
        : await createCustomer(payload);
      router.push(`/clientes/${saved.id}`);
    } catch (e2) {
      setError((e2 as Error)?.message ?? "No se pudo guardar el cliente.");
      setSaving(false);
    }
  }

  return (
    <form onSubmit={submit}>
      {error && <div className="state-box state-error">{error}</div>}

      <div className="card" style={{ padding: 20, marginBottom: 16 }}>
        <h2 className="section-title" style={{ marginBottom: 14 }}>Identidad</h2>
        <div className="form-grid">
          <Field label="Nombre" required>
            <input className="input" required value={v.name}
              onChange={(e) => set("name", e.target.value)} />
          </Field>
          <Field label="Correo">
            <input className="input" type="email" value={v.email}
              onChange={(e) => set("email", e.target.value)} />
          </Field>
          <Field label="Teléfono">
            <input className="input" value={v.phone}
              onChange={(e) => set("phone", e.target.value)} />
          </Field>
          <Field label="Celular">
            <input className="input" value={v.mobile}
              onChange={(e) => set("mobile", e.target.value)} />
          </Field>
          <Field label="Fax">
            <input className="input" value={v.fax}
              onChange={(e) => set("fax", e.target.value)} />
          </Field>
          <Field label="Cliente desde">
            <input className="input" type="date" value={v.customerSince}
              onChange={(e) => set("customerSince", e.target.value)} />
          </Field>
        </div>
      </div>

      <div className="card" style={{ padding: 20, marginBottom: 16 }}>
        <h2 className="section-title" style={{ marginBottom: 14 }}>Domicilio</h2>
        <div className="form-grid">
          <Field label="Dirección 1">
            <input className="input" value={v.addressLine1}
              onChange={(e) => set("addressLine1", e.target.value)} />
          </Field>
          <Field label="Dirección 2">
            <input className="input" value={v.addressLine2}
              onChange={(e) => set("addressLine2", e.target.value)} />
          </Field>
          <Field label="Ciudad">
            <input className="input" value={v.city}
              onChange={(e) => set("city", e.target.value)} />
          </Field>
          <Field label="Estado">
            <input className="input" value={v.state}
              onChange={(e) => set("state", e.target.value)} />
          </Field>
          <Field label="Código postal">
            <input className="input" value={v.zipCode}
              onChange={(e) => set("zipCode", e.target.value)} />
          </Field>
          <Field label="País">
            <input className="input" value={v.country}
              onChange={(e) => set("country", e.target.value)} />
          </Field>
        </div>
      </div>

      <div className="card" style={{ padding: 20, marginBottom: 16 }}>
        <h2 className="section-title" style={{ marginBottom: 14 }}>
          Identificación y cuenta
        </h2>
        <div className="form-grid">
          <Field label="Tipo de identificación">
            <input className="input" value={v.identificationType}
              onChange={(e) => set("identificationType", e.target.value)} />
          </Field>
          <Field label="Número de identificación">
            <input className="input" value={v.identificationNumber}
              onChange={(e) => set("identificationNumber", e.target.value)} />
          </Field>
          <Field label="Vence identificación">
            <input className="input" type="date" value={v.identificationExpiration}
              onChange={(e) => set("identificationExpiration", e.target.value)} />
          </Field>
          <Field label="Moneda preferida">
            <select className="select" value={v.preferredCurrency}
              onChange={(e) => set("preferredCurrency", e.target.value as Currency)}>
              <option value="USD">USD</option>
              <option value="MXN">MXN</option>
            </select>
          </Field>
          <Field label="Saldo mínimo">
            <input className="input" type="number" step="0.01" value={v.minimumBalance}
              onChange={(e) => set("minimumBalance", e.target.value)} />
          </Field>
          <Field label="Cuota">
            <input className="input" type="number" step="0.01" value={v.feeAmount}
              onChange={(e) => set("feeAmount", e.target.value)} />
          </Field>
          <Field label="Activo">
            <input type="checkbox" checked={v.status}
              onChange={(e) => set("status", e.target.checked)} />
          </Field>
        </div>
        <label className="field" style={{ marginTop: 16 }}>
          <span className="field-label">Notas</span>
          <textarea className="input" rows={3} value={v.notes}
            onChange={(e) => set("notes", e.target.value)} />
        </label>
      </div>

      <div className="form-actions">
        <button type="submit" className="btn btn-primary" disabled={saving}>
          {saving ? "Guardando…" : editing ? "Guardar cambios" : "Crear cliente"}
        </button>
        <button type="button" className="btn btn-outline" onClick={() => router.back()}>
          Cancelar
        </button>
      </div>
    </form>
  );
}

function Field({
  label,
  required,
  children,
}: {
  label: string;
  required?: boolean;
  children: React.ReactNode;
}) {
  return (
    <label className="field">
      <span className="field-label">
        {label}
        {required && <span aria-hidden> *</span>}
      </span>
      {children}
    </label>
  );
}
