import { createContext, useContext, useEffect, useMemo, useRef, useState } from 'react';
import { toast, toastAfterReload } from '@/lib/toast';
import AgregarMaterial from './AgregarMaterial';

type Material = {
  id: number;
  nombre: string;
  descripcion: string | null;
  cantidad_disponible: number;
  cantidad_total: number;
  numero_inventario: string | null;
  categoria: { id: number; nombre: string } | null;
};

type CartItem = {
  material_id: number;
  nombre: string;
  cantidad: number;
  cantidad_disponible: number;
  descripcion: string;
};

type CartContextValue = {
  items: CartItem[];
  addItem: (material: { id: number; nombre: string; cantidad_disponible: number }) => void;
  updateCantidad: (material_id: number, n: number) => void;
  updateDescripcion: (material_id: number, texto: string) => void;
  removeItem: (material_id: number) => void;
  has: (material_id: number) => boolean;
};

const CartContext = createContext<CartContextValue | null>(null);

export function useCart() {
  const ctx = useContext(CartContext);
  if (!ctx) throw new Error('useCart debe usarse dentro de CartProvider');
  return ctx;
}

const clamp = (n: number, max: number) => Math.max(1, Math.min(max, n));

export default function CartProvider({ materiales }: { materiales: Material[] }) {
  const [cart, setCart] = useState<Map<number, CartItem>>(new Map());
  const dialogRef = useRef<HTMLDialogElement | null>(null);
  const firstFieldRef = useRef<HTMLInputElement | null>(null);
  const [maestroResponsable, setMaestroResponsable] = useState('');
  const [notas, setNotas] = useState('');
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [ok, setOk] = useState(false);

  const items = useMemo(() => Array.from(cart.values()), [cart]);

  const addItem: CartContextValue['addItem'] = (material) => {
    setCart((prev) => {
      const next = new Map(prev);
      const existing = next.get(material.id);
      if (existing) {
        next.set(material.id, { ...existing, cantidad: clamp(existing.cantidad + 1, material.cantidad_disponible) });
      } else {
        next.set(material.id, {
          material_id: material.id,
          nombre: material.nombre,
          cantidad: 1,
          cantidad_disponible: material.cantidad_disponible,
          descripcion: '',
        });
      }
      return next;
    });
  };

  const updateCantidad: CartContextValue['updateCantidad'] = (material_id, n) => {
    setCart((prev) => {
      const existing = prev.get(material_id);
      if (!existing) return prev;
      const next = new Map(prev);
      next.set(material_id, { ...existing, cantidad: clamp(n, existing.cantidad_disponible) });
      return next;
    });
  };

  const updateDescripcion: CartContextValue['updateDescripcion'] = (material_id, texto) => {
    setCart((prev) => {
      const existing = prev.get(material_id);
      if (!existing) return prev;
      const next = new Map(prev);
      next.set(material_id, { ...existing, descripcion: texto });
      return next;
    });
  };

  const removeItem: CartContextValue['removeItem'] = (material_id) => {
    setCart((prev) => {
      const next = new Map(prev);
      next.delete(material_id);
      return next;
    });
  };

  const has: CartContextValue['has'] = (material_id) => cart.has(material_id);

  const value: CartContextValue = { items, addItem, updateCantidad, updateDescripcion, removeItem, has };

  const titleId = 'checkout-title';

  const openCheckout = () => {
    setError(null);
    setOk(false);
    dialogRef.current?.showModal();
    queueMicrotask(() => firstFieldRef.current?.focus());
  };

  const closeCheckout = () => {
    if (loading) return;
    dialogRef.current?.close();
  };

  // Cerrar al click en backdrop
  useEffect(() => {
    const dlg = dialogRef.current;
    if (!dlg) return;
    const onClick = (e: MouseEvent) => {
      if (e.target === dlg) closeCheckout();
    };
    dlg.addEventListener('click', onClick);
    return () => dlg.removeEventListener('click', onClick);
  });

  const submit = async (e: React.FormEvent) => {
    e.preventDefault();
    if (loading || items.length === 0) return;
    setLoading(true);
    setError(null);
    try {
      const res = await fetch('/api/solicitudes', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({
          maestro_responsable: maestroResponsable,
          notas: notas || undefined,
          items: items.map((i) => ({
            material_id: i.material_id,
            cantidad: i.cantidad,
            descripcion: i.descripcion || undefined,
          })),
        }),
      });
      const json = await res.json().catch(() => ({}));
      if (!res.ok) {
        throw new Error(json?.error ?? 'No se pudo enviar la solicitud');
      }
      setOk(true);
      toastAfterReload({
        kind: 'success',
        title: 'Solicitud enviada',
        description: `${items.length} material${items.length === 1 ? '' : 'es'} · pendiente de aprobación`,
      });
      setTimeout(() => {
        dialogRef.current?.close();
        setCart(new Map());
        location.reload();
      }, 800);
    } catch (err) {
      const msg = err instanceof Error ? err.message : 'Error inesperado';
      setError(msg);
      toast({ kind: 'error', title: 'No se pudo enviar', description: msg });
    } finally {
      setLoading(false);
    }
  };

  return (
    <CartContext.Provider value={value}>
      <div className="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-3 gap-4">
        {materiales.map((m) => (
          <article key={m.id} className="card flex flex-col gap-3" data-cat={m.categoria?.id ?? 'sin'}>
            <div className="flex items-start justify-between gap-2">
              <h3 className="font-semibold leading-snug">{m.nombre}</h3>
              {m.categoria && (
                <span
                  className="text-xs px-2 py-0.5 rounded-[2px] whitespace-nowrap uppercase tracking-wide"
                  style={{
                    background: 'color-mix(in oklab, var(--color-primary) 25%, white)',
                    color: 'var(--color-ink)',
                    border: '1.5px solid var(--color-primary)',
                  }}
                >
                  {m.categoria.nombre}
                </span>
              )}
            </div>

            {m.descripcion && <p className="text-sm opacity-75 line-clamp-2">{m.descripcion}</p>}

            <dl className="text-xs opacity-70 grid grid-cols-2 gap-1">
              <dt className="opacity-60">Inventario</dt>
              <dd className="text-right font-mono">{m.numero_inventario ?? '—'}</dd>
              <dt className="opacity-60">Disponibles</dt>
              <dd className="text-right" style={{ fontVariantNumeric: 'tabular-nums' }}>
                {m.cantidad_disponible} / {m.cantidad_total}
              </dd>
            </dl>

            <div className="mt-auto">
              <AgregarMaterial material={{ id: m.id, nombre: m.nombre, cantidad_disponible: m.cantidad_disponible }} />
            </div>
          </article>
        ))}
      </div>

      {items.length > 0 && (
        <button
          type="button"
          className="btn btn-primary fixed bottom-24 right-4 md:bottom-6 md:right-6 z-40"
          style={{ boxShadow: 'var(--shadow-hard)' }}
          onClick={openCheckout}
        >
          Ver solicitud ({items.length})
        </button>
      )}

      <dialog
        ref={dialogRef}
        aria-labelledby={titleId}
        className="rounded-lg p-0 bg-white text-[color:var(--color-ink)] border-2 border-[color:var(--color-ink)] shadow-[var(--shadow-hard)] backdrop:bg-black/40 w-[min(92vw,32rem)]"
      >
        <form onSubmit={submit} className="p-5 sm:p-6 flex flex-col gap-4">
          <div className="flex items-start justify-between gap-3">
            <h2 id={titleId} className="text-lg font-semibold">
              Tu solicitud
            </h2>
            <button
              type="button"
              onClick={closeCheckout}
              aria-label="Cerrar"
              className="rounded-lg p-1.5 hover:bg-black/5 transition-colors"
            >
              <svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" aria-hidden="true">
                <path d="M6 18L18 6M6 6l12 12" />
              </svg>
            </button>
          </div>

          {items.length === 0 ? (
            <p className="text-sm opacity-70">Tu solicitud está vacía. Cierra esta ventana y agrega material del catálogo.</p>
          ) : (
            <ul className="flex flex-col gap-3 max-h-64 overflow-y-auto -mx-1 px-1">
              {items.map((item) => (
                <li
                  key={item.material_id}
                  className="flex items-start gap-2 pb-3"
                  style={{ borderBottom: '1.5px solid color-mix(in oklab, var(--color-ink) 15%, transparent)' }}
                >
                  <div className="flex-1 min-w-0">
                    <p className="font-medium text-sm truncate">{item.nombre}</p>
                    <div className="flex items-center gap-2 mt-1.5">
                      <label className="sr-only" htmlFor={`cant-cart-${item.material_id}`}>
                        Cantidad de {item.nombre}
                      </label>
                      <input
                        id={`cant-cart-${item.material_id}`}
                        className="input"
                        type="number"
                        min={1}
                        max={item.cantidad_disponible}
                        value={item.cantidad}
                        inputMode="numeric"
                        onChange={(e) => updateCantidad(item.material_id, Number(e.target.value) || 1)}
                        style={{ width: '4.5rem', minHeight: '36px', paddingBlock: '0.25rem', fontVariantNumeric: 'tabular-nums' }}
                      />
                      <span className="text-xs opacity-60">de {item.cantidad_disponible}</span>
                    </div>
                    <label className="sr-only" htmlFor={`desc-cart-${item.material_id}`}>
                      Nota para {item.nombre}
                    </label>
                    <input
                      id={`desc-cart-${item.material_id}`}
                      className="input mt-2"
                      type="text"
                      maxLength={200}
                      value={item.descripcion}
                      onChange={(e) => updateDescripcion(item.material_id, e.target.value)}
                      placeholder="Nota opcional: color, con webcam…"
                      style={{ minHeight: '36px', paddingBlock: '0.25rem' }}
                    />
                  </div>
                  <button
                    type="button"
                    onClick={() => removeItem(item.material_id)}
                    aria-label={`Quitar ${item.nombre}`}
                    className="rounded-lg p-1.5 hover:bg-black/5 transition-colors shrink-0"
                  >
                    <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" aria-hidden="true">
                      <path d="M6 18L18 6M6 6l12 12" />
                    </svg>
                  </button>
                </li>
              ))}
            </ul>
          )}

          <div>
            <label className="label" htmlFor="maestro-responsable">Maestro responsable</label>
            <input
              ref={firstFieldRef}
              id="maestro-responsable"
              className="input"
              type="text"
              required
              maxLength={200}
              value={maestroResponsable}
              onChange={(e) => setMaestroResponsable(e.target.value)}
            />
          </div>

          <div>
            <label className="label" htmlFor="notas-cart">Motivo del préstamo</label>
            <textarea
              id="notas-cart"
              className="input"
              rows={3}
              maxLength={500}
              value={notas}
              onChange={(e) => setNotas(e.target.value)}
              placeholder="¿Para qué clase o proyecto lo necesitas?"
              style={{ minHeight: '96px' }}
              aria-describedby="notas-cart-hint"
            />
            <p id="notas-cart-hint" className="text-xs opacity-60 mt-1">
              Ejemplo: Clase de Electrónica Analógica · Prof. Gómez · práctica 3. (Opcional)
            </p>
          </div>

          {error && (
            <p role="alert" className="text-sm" style={{ color: 'var(--color-danger-text)' }}>
              {error} · Ajusta la solicitud e intenta de nuevo.
            </p>
          )}
          {ok && (
            <p role="status" className="text-sm" style={{ color: 'var(--color-positive)' }}>
              Solicitud enviada. Actualizando…
            </p>
          )}

          <div className="flex gap-2 justify-end pt-2">
            <button type="button" className="btn btn-ghost" onClick={closeCheckout} disabled={loading}>
              Cancelar
            </button>
            <button type="submit" className="btn btn-primary" disabled={loading || ok || items.length === 0}>
              {loading ? 'Enviando…' : 'Enviar solicitud'}
            </button>
          </div>
        </form>
      </dialog>
    </CartContext.Provider>
  );
}