'use client'

import { useMemo, useState } from 'react'
import type { GiftCategory, GiftItem } from '@/lib/gift'
import { CharacterSelect, type CharOption } from '@/components/CharacterSelect'

// Tope de cantidad en la interfaz. El servidor lo revalida en priceCart (fuente de verdad).
const MAX_QTY = 100

interface CartEntry {
  item: GiftItem
  qty: number
}

/** Campo con ojo para mostrar/ocultar el token de seguridad. */
function SecretInput({
  value,
  onChange,
  placeholder,
}: {
  value: string
  onChange: (v: string) => void
  placeholder: string
}) {
  const [show, setShow] = useState(false)
  return (
    <>
      <input
        type={show ? 'text' : 'password'}
        id="security-token"
        maxLength={6}
        value={value}
        onChange={(e) => onChange(e.target.value)}
        placeholder={placeholder}
        required
      />{' '}
      <span
        className={`far ${show ? 'fa-eye-slash' : 'fa-eye'} toggle-token`}
        role="button"
        tabIndex={0}
        onClick={() => setShow((s) => !s)}
      />
    </>
  )
}

export function SendGiftForm({
  characters,
  catalog,
  currency = '€',
}: {
  characters: CharOption[]
  catalog: GiftCategory[]
  currency?: string
}) {
  const [source, setSource] = useState('')
  const [destination, setDestination] = useState('')
  const [token, setToken] = useState('')
  const [cart, setCart] = useState<Map<number, CartEntry>>(new Map())
  const [busy, setBusy] = useState(false)
  const [error, setError] = useState<string | null>(null)

  const total = useMemo(
    () => Math.round([...cart.values()].reduce((s, e) => s + e.item.price * e.qty, 0) * 100) / 100,
    [cart],
  )

  // Catálogo aplanado y paginado: 4 objetos por fila, 2 filas (8) por página.
  const PAGE_SIZE = 8
  const allItems = useMemo(
    () => catalog.flatMap((c) => c.items.map((it) => ({ ...it, category: c.name }))),
    [catalog],
  )
  const [page, setPage] = useState(1)
  const totalPages = Math.max(1, Math.ceil(allItems.length / PAGE_SIZE))
  const currentPage = Math.min(page, totalPages)
  const pageItems = allItems.slice((currentPage - 1) * PAGE_SIZE, currentPage * PAGE_SIZE)

  function addItem(item: GiftItem) {
    setCart((prev) => {
      const next = new Map(prev)
      const cur = next.get(item.id)
      next.set(item.id, { item, qty: Math.min(MAX_QTY, (cur?.qty ?? 0) + 1) })
      return next
    })
  }
  function setQty(id: number, qty: number) {
    setCart((prev) => {
      const next = new Map(prev)
      const cur = next.get(id)
      if (!cur) return prev
      const q = Math.max(1, Math.min(MAX_QTY, Math.floor(qty) || 1))
      next.set(id, { ...cur, qty: q })
      return next
    })
  }
  function removeItem(id: number) {
    setCart((prev) => {
      const next = new Map(prev)
      next.delete(id)
      return next
    })
  }

  async function handleSubmit(e: React.FormEvent) {
    e.preventDefault()
    if (busy) return
    if (!source || !destination.trim() || !token.trim()) {
      setError('Completa el personaje de origen, el de destino y el token de seguridad.')
      return
    }
    if (cart.size === 0) {
      setError('Añade al menos un objeto al carrito.')
      return
    }
    if (
      !window.confirm(
        `¿Enviar el regalo a "${destination.trim()}" por ${total} ${currency} (SumUp)? Esta acción no es reversible.`,
      )
    )
      return
    setBusy(true)
    setError(null)
    try {
      const res = await fetch('/api/gift/checkout', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        credentials: 'same-origin',
        body: JSON.stringify({
          source,
          destination: destination.trim(),
          security_token: token.trim(),
          cart: [...cart.values()].map((e) => ({ id: e.item.id, qty: e.qty })),
          provider: 'sumup',
        }),
      })
      const data: { success?: boolean; url?: string; message?: string } = await res.json()
      if (data.success && data.url) window.location.href = data.url
      else {
        setError(data.message || 'No se pudo iniciar el pago. Inténtalo de nuevo.')
        setBusy(false)
      }
    } catch {
      setError('Algo ha salido mal. Inténtalo más tarde.')
      setBusy(false)
    }
  }

  if (characters.length === 0) return <p className="second-brown">No tienes personajes disponibles.</p>
  if (catalog.length === 0) return <p className="second-brown">No hay objetos disponibles para regalar por ahora.</p>

  return (
    <div className="centered">
      <form onSubmit={handleSubmit} acceptCharset="utf-8">
        <p>Escoge desde qué personaje se envía el regalo:</p>
        <CharacterSelect characters={characters} value={source} onChange={setSource} placeholder="Personaje de origen" />
        <br />
        <p>Nombre del personaje que recibirá el regalo:</p>
        <input
          type="text"
          maxLength={12}
          placeholder="Personaje de destino"
          value={destination}
          onChange={(e) => setDestination(e.target.value)}
          required
        />
        <br />
        <p>Token de seguridad:</p>
        <SecretInput value={token} onChange={setToken} placeholder="Token de seguridad" />
        <hr />

        {/* Catálogo de objetos: cuadrícula centrada de 4 por fila + paginación */}
        <h3 className="first-brown centered">Objetos disponibles</h3>
        <div className="gift-grid">
          {pageItems.map((it) => (
            <div className="item-box" key={it.id}>
              <a href={`https://www.wowhead.com/wotlk/item=${it.itemId}`} target="_blank" rel="noreferrer noopener">
                <img className="item-img-box" src={it.imageUrl} alt={it.name} />
              </a>
              <div className="third-brown" style={{ fontSize: '12px' }}>{it.category}</div>
              <div className="item-name second-brown">{it.name}</div>
              <div className="yellow-info">
                {it.price} {currency}
              </div>
              <button type="button" className="store-add-button" onClick={() => addItem(it)}>
                Añadir
              </button>
            </div>
          ))}
        </div>
        {totalPages > 1 && (
          <div className="gift-pagination">
            <button type="button" onClick={() => setPage((p) => Math.max(1, Math.min(totalPages, p) - 1))} disabled={currentPage === 1}>
              Atrás
            </button>
            {Array.from({ length: totalPages }, (_, i) => i + 1).map((n) => (
              <button
                type="button"
                key={n}
                className={n === currentPage ? 'active-page' : ''}
                onClick={() => setPage(n)}
              >
                {n}
              </button>
            ))}
            <button type="button" onClick={() => setPage((p) => Math.min(totalPages, Math.min(totalPages, p) + 1))} disabled={currentPage === totalPages}>
              Siguiente
            </button>
          </div>
        )}
        <hr />

        {/* Carrito */}
        <h3 className="first-brown">Carrito</h3>
        {cart.size === 0 ? (
          <p className="second-brown">Aún no has añadido objetos.</p>
        ) : (
          <table className="cart-list max-center-table">
            <tbody>
              {[...cart.values()].map((e) => (
                <tr key={e.item.id}>
                  <td>
                    <img className="item-img-box" src={e.item.imageUrl} alt={e.item.name} />
                  </td>
                  <td className="second-brown">{e.item.name}</td>
                  <td>
                    <input
                      type="number"
                      min={1}
                      max={MAX_QTY}
                      value={e.qty}
                      onChange={(ev) => setQty(e.item.id, Number(ev.target.value))}
                      style={{ width: '4em' }}
                    />
                  </td>
                  <td className="yellow-info">{Math.round(e.item.price * e.qty * 100) / 100} {currency}</td>
                  <td>
                    <button type="button" className="store-remove-button" onClick={() => removeItem(e.item.id)}>
                      <i className="fas fa-trash" />
                    </button>
                  </td>
                </tr>
              ))}
            </tbody>
          </table>
        )}

        <div className="centered">
          <br />
          <p>
            Total: <span className="yellow-info">{total} {currency}</span> (SumUp)
          </p>
          <br />
          <button
            type="submit"
            className="store-send-button"
            disabled={busy || cart.size === 0 || !source || !destination.trim() || !token.trim()}
          >
            {busy ? 'Enviando regalo' : 'ENVIAR REGALO'}
          </button>
        </div>
      </form>
      <hr />
      <div className="alert-message" style={{ display: error ? 'block' : 'none' }}>
        {error && <span className="red-form-response">{error}</span>}
      </div>
    </div>
  )
}