'use client';

/**
 * @file ToastProvider.tsx
 * @description Lightweight global Toast/Notification system.
 * Uses React Context + Zustand-like imperative API via a singleton store.
 * 
 * Usage:
 * 1. Wrap your layout with <ToastProvider>
 * 2. Call toast.success('Mensaje') anywhere in the app
 */

import React, { createContext, useCallback, useContext, useReducer, useRef } from 'react';
import { createPortal } from 'react-dom';
import { CheckCircle, AlertCircle, Info, X, AlertTriangle } from 'lucide-react';

// ─────────────────────────────────────────────
// TYPES
// ─────────────────────────────────────────────

export type ToastVariant = 'success' | 'error' | 'warning' | 'info';

export interface Toast {
  id: string;
  message: string;
  variant: ToastVariant;
  duration?: number;
}

type ToastAction =
  | { type: 'ADD'; toast: Toast }
  | { type: 'REMOVE'; id: string };

interface ToastContextValue {
  toasts: Toast[];
  addToast: (message: string, variant?: ToastVariant, duration?: number) => void;
  removeToast: (id: string) => void;
}

// ─────────────────────────────────────────────
// CONTEXT
// ─────────────────────────────────────────────

const ToastContext = createContext<ToastContextValue | null>(null);

function toastReducer(state: Toast[], action: ToastAction): Toast[] {
  switch (action.type) {
    case 'ADD': return [action.toast, ...state].slice(0, 5); // Max 5 toasts
    case 'REMOVE': return state.filter((t) => t.id !== action.id);
    default: return state;
  }
}

// ─────────────────────────────────────────────
// PROVIDER
// ─────────────────────────────────────────────

export function ToastProvider({ children }: { children: React.ReactNode }) {
  const [toasts, dispatch] = useReducer(toastReducer, []);
  const counterRef = useRef(0);

  const removeToast = useCallback((id: string) => {
    dispatch({ type: 'REMOVE', id });
  }, []);

  const addToast = useCallback((
    message: string,
    variant: ToastVariant = 'info',
    duration = 4000
  ) => {
    const id = `toast-${Date.now()}-${++counterRef.current}`;
    dispatch({ type: 'ADD', toast: { id, message, variant, duration } });

    if (duration > 0) {
      setTimeout(() => dispatch({ type: 'REMOVE', id }), duration);
    }
  }, []);

  return (
    <ToastContext.Provider value={{ toasts, addToast, removeToast }}>
      {children}
      <ToastContainer toasts={toasts} onRemove={removeToast} />
    </ToastContext.Provider>
  );
}

// ─────────────────────────────────────────────
// HOOK
// ─────────────────────────────────────────────

export function useToast() {
  const ctx = useContext(ToastContext);
  if (!ctx) throw new Error('useToast must be used inside <ToastProvider>');

  return {
    success: (msg: string, duration?: number) => ctx.addToast(msg, 'success', duration),
    error:   (msg: string, duration?: number) => ctx.addToast(msg, 'error', duration),
    warning: (msg: string, duration?: number) => ctx.addToast(msg, 'warning', duration),
    info:    (msg: string, duration?: number) => ctx.addToast(msg, 'info', duration),
    remove:  ctx.removeToast,
  };
}

// ─────────────────────────────────────────────
// TOAST ITEM
// ─────────────────────────────────────────────

const variantStyles: Record<ToastVariant, { bg: string; border: string; icon: React.ReactNode }> = {
  success: {
    bg: 'bg-emerald-950/90',
    border: 'border-emerald-500/40',
    icon: <CheckCircle size={16} className="text-emerald-400 shrink-0" />,
  },
  error: {
    bg: 'bg-red-950/90',
    border: 'border-red-500/40',
    icon: <AlertCircle size={16} className="text-red-400 shrink-0" />,
  },
  warning: {
    bg: 'bg-amber-950/90',
    border: 'border-amber-500/40',
    icon: <AlertTriangle size={16} className="text-amber-400 shrink-0" />,
  },
  info: {
    bg: 'bg-slate-900/90',
    border: 'border-cyan-500/30',
    icon: <Info size={16} className="text-cyan-400 shrink-0" />,
  },
};

const ToastItem = React.memo(function ToastItem({
  toast,
  onRemove,
}: {
  toast: Toast;
  onRemove: (id: string) => void;
}) {
  const styles = variantStyles[toast.variant];

  return (
    <div
      role="alert"
      aria-live="assertive"
      className={`
        flex items-start gap-3 px-4 py-3 rounded-xl border shadow-2xl
        backdrop-blur-xl min-w-[280px] max-w-[400px]
        animate-in slide-in-from-right-4 fade-in duration-300
        ${styles.bg} ${styles.border}
      `}
    >
      {styles.icon}
      <p className="text-sm font-medium text-white flex-1 leading-snug">{toast.message}</p>
      <button
        type="button"
        onClick={() => onRemove(toast.id)}
        className="text-slate-500 hover:text-white transition-colors ml-1 shrink-0"
        aria-label="Cerrar notificación"
      >
        <X size={14} />
      </button>
    </div>
  );
});

// ─────────────────────────────────────────────
// TOAST CONTAINER (Portal)
// ─────────────────────────────────────────────

function ToastContainer({
  toasts,
  onRemove,
}: {
  toasts: Toast[];
  onRemove: (id: string) => void;
}) {
  if (typeof document === 'undefined' || toasts.length === 0) return null;

  return createPortal(
    <div
      className="fixed bottom-6 right-6 z-[99999] flex flex-col gap-3"
      aria-label="Notificaciones"
    >
      {toasts.map((t) => (
        <ToastItem key={t.id} toast={t} onRemove={onRemove} />
      ))}
    </div>,
    document.body
  );
}