/**
 * Toast 通知组件
 * 
 * 包含单个 Toast 条目渲染 + ToastProvider 全局容器
 * 右上角堆叠显示，支持入场/退场动画
 */

import { useEffect, useState, useCallback } from 'react'
import { useTranslation } from 'react-i18next'
import { CheckCircle, XCircle, AlertTriangle, Info, X } from 'lucide-react'
import { useToastStore, type ToastItem, type ToastType } from '../../stores/toastStore'

/** 类型 → 图标映射 */
const iconMap: Record<ToastType, typeof CheckCircle> = {
  success: CheckCircle,
  error: XCircle,
  warning: AlertTriangle,
  info: Info,
}

/** 类型 → 颜色样式映射（theme tokens，浅色/深色都可读） */
const colorMap: Record<ToastType, { bg: string; border: string; icon: string; text: string }> = {
  success: {
    bg: 'bg-feedback-success-bg',
    border: 'border-feedback-success/35',
    icon: 'text-feedback-success',
    text: 'text-content-primary',
  },
  error: {
    bg: 'bg-feedback-error-bg',
    border: 'border-feedback-error/35',
    icon: 'text-feedback-error',
    text: 'text-content-primary',
  },
  warning: {
    bg: 'bg-feedback-warning-bg',
    border: 'border-feedback-warning/35',
    icon: 'text-feedback-warning',
    text: 'text-content-primary',
  },
  info: {
    bg: 'bg-feedback-info-bg',
    border: 'border-feedback-info/35',
    icon: 'text-feedback-info',
    text: 'text-content-primary',
  },
}

interface ToastItemProps {
  toast: ToastItem
  onClose: (id: string) => void
}

/**
 * 单个 Toast 条目
 * 
 * 支持自动消失和手动关闭，带入场/退场动画
 */
function ToastItemView({ toast, onClose }: ToastItemProps) {
  const { t } = useTranslation('common')
  const [visible, setVisible] = useState(false)
  const Icon = iconMap[toast.type]
  const colors = colorMap[toast.type]

  // 入场动画：挂载后下一帧设为可见
  useEffect(() => {
    const raf = requestAnimationFrame(() => setVisible(true))
    return () => cancelAnimationFrame(raf)
  }, [])

  // 自动关闭
  const handleClose = useCallback(() => {
    setVisible(false)
    // 等待退场动画结束后再移除
    setTimeout(() => onClose(toast.id), 200)
  }, [onClose, toast.id])

  useEffect(() => {
    if (toast.duration <= 0) return
    const timer = setTimeout(() => {
      handleClose()
    }, toast.duration)
    return () => clearTimeout(timer)
  }, [toast.duration, handleClose])

  return (
    <div
      className={`
        flex items-start gap-3 w-80 px-4 py-3 rounded-lg border
        shadow-lg backdrop-blur-sm
        transition-all duration-200 ease-out
        ${colors.bg} ${colors.border}
        ${visible
          ? 'translate-x-0 opacity-100'
          : 'translate-x-4 opacity-0'
        }
      `}
      role="alert"
    >
      {/* 图标 */}
      <Icon className={`w-5 h-5 mt-0.5 shrink-0 ${colors.icon}`} />

      {/* 消息 */}
      <p className={`flex-1 text-sm font-medium ${colors.text}`}>
        {toast.message}
      </p>

      {/* 关闭按钮 */}
      <button
        onClick={handleClose}
        className="p-0.5 rounded hover:bg-white/10 transition-colors shrink-0"
        aria-label={t('toast.closeAria')}
      >
        <X className="w-4 h-4 text-txt-muted hover:text-content-primary" />
      </button>
    </div>
  )
}

/**
 * Toast 通知容器（Provider）
 * 
 * 在应用根节点中使用，渲染右上角通知堆叠
 * 
 * @example
 * // 在 App.tsx 中
 * <ToastProvider>
 *   <Router />
 * </ToastProvider>
 */
export function ToastProvider({ children }: { children: React.ReactNode }) {
  const toasts = useToastStore((s) => s.toasts)
  const removeToast = useToastStore((s) => s.removeToast)

  return (
    <>
      {children}
      <div
        className="fixed top-4 right-4 z-50 flex flex-col gap-2 pointer-events-none"
        aria-live="polite"
      >
        {toasts.map((toast) => (
          <div key={toast.id} className="pointer-events-auto">
            <ToastItemView toast={toast} onClose={removeToast} />
          </div>
        ))}
      </div>
    </>
  )
}

export default ToastProvider