// pangolin_toast.dart — 统一轻提示(toast)。真相源规格见 design/CONTRACT.md §2「Toast/SnackBar」。
//
// 用 Overlay 实现(非 Material SnackBar),以完全控制布局:
//   · 只在主显示区内(避开左侧栏:desktop 204 / tablet 232 / mobile 0)。
//   · 宽度自适应内容,上限为主显示区的 80%;超长则文本多行、居中。
//   · 跟随明暗主题:surface 底 + fg1 字 + border 描边 + md 圆角 + 柔和暖阴影,淡入轻起。
import 'dart:async';

import 'package:flutter/material.dart';

import '../core/responsive/form_factor.dart';
import '../pangolin_theme.dart';

/// 在主显示区底部居中弹一条 toast(默认 3 秒)。需要一个能拿到 Overlay/主题的 context。
void showPangolinToast(BuildContext context, String message,
    {Duration duration = const Duration(seconds: 3)}) {
  final overlay = Overlay.maybeOf(context, rootOverlay: true);
  if (overlay == null) return;
  late final OverlayEntry entry;
  entry = OverlayEntry(builder: (_) => _PangolinToast(message: message));
  overlay.insert(entry);
  Timer(duration, () {
    if (entry.mounted) entry.remove();
  });
}

class _PangolinToast extends StatelessWidget {
  const _PangolinToast({required this.message});
  final String message;

  @override
  Widget build(BuildContext context) {
    final c = context.pangolin;
    // 侧栏宽度(避开它):取自各 shell 的 NavSidebar 宽度。
    final sidebar = switch (context.formFactor) {
      FormFactor.desktop => 204.0,
      FormFactor.tablet => 232.0,
      FormFactor.mobile => 0.0,
    };
    final w = MediaQuery.sizeOf(context).width;
    final contentW = (w - sidebar).clamp(0.0, w);
    return Positioned(
      left: sidebar,
      right: 0,
      bottom: 28,
      child: IgnorePointer(
        child: TweenAnimationBuilder<double>(
          tween: Tween(begin: 0, end: 1),
          duration: const Duration(milliseconds: 240),
          curve: Curves.easeOut,
          builder: (_, t, child) =>
              Opacity(opacity: t, child: Transform.translate(offset: Offset(0, (1 - t) * 8), child: child)),
          child: Center(
            child: ConstrainedBox(
              constraints: BoxConstraints(maxWidth: contentW * 0.8),
              child: Container(
                padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
                decoration: BoxDecoration(
                  color: c.surface,
                  borderRadius: BorderRadius.circular(PangolinRadius.md),
                  border: Border.all(color: c.border),
                  boxShadow: PangolinShadow.sm,
                ),
                child: Text(
                  message,
                  textAlign: TextAlign.center,
                  style: PangolinText.sm.copyWith(color: c.fg1, fontWeight: FontWeight.w600),
                ),
              ),
            ),
          ),
        ),
      ),
    );
  }
}