//
//  ToastCenter.swift
//  suixinkan
//
//  Created by Codex on 2026/6/18.
//

import Observation
import SwiftUI

@MainActor
@Observable
/// 全局 Toast 状态中心，负责保存和清除当前提示文案。
final class ToastCenter {
    fileprivate var message: String?

    /// 显示一条全局 Toast 文案。
    func show(_ message: String) {
        self.message = message
    }

    /// 清除当前 Toast 文案。
    func dismiss() {
        message = nil
    }
}

/// 全局 Toast 叠加层修饰器，负责把 Toast 展示到页面顶部。
private struct GlobalToastOverlay: ViewModifier {
    @Environment(ToastCenter.self) private var toastCenter

    func body(content: Content) -> some View {
        content
            .overlay(alignment: .top) {
                if let message = toastCenter.message {
                    HStack(spacing: 10) {
                        Image(systemName: "exclamationmark.triangle.fill")
                            .font(.system(size: 14, weight: .semibold))

                        Text(message)
                            .font(.system(size: 13, weight: .medium))
                            .lineLimit(2)

                        Spacer(minLength: 0)

                        Button("关闭") {
                            toastCenter.dismiss()
                        }
                        .font(.system(size: 13, weight: .semibold))
                    }
                    .foregroundStyle(.white)
                    .padding(.horizontal, 14)
                    .padding(.vertical, 10)
                    .background(Color.black.opacity(0.78), in: RoundedRectangle(cornerRadius: 12))
                    .padding(.horizontal, 16)
                    .padding(.top, 10)
                    .transition(.move(edge: .top).combined(with: .opacity))
                }
            }
            .animation(.easeInOut(duration: 0.18), value: toastCenter.message)
    }
}

extension View {
    /// 给任意根视图追加全局 Toast 展示能力。
    func globalToastOverlay() -> some View {
        modifier(GlobalToastOverlay())
    }
}