pangolin/client/lib/screens/purchase_page.dart

// purchase_page.dart — 购买套餐(三档 pro:月/季/年,pay v2 通道)。
// 档位数据来自 GET /v1/pay/catalog(server 单源);金额仅展示,扣款以 pay 为准。
// 支付渠道即币种即方式(USDT→加密货币 默认 / 人民币→支付宝),顶部 SegSwitch 选定,
// 套餐价随渠道币种刷新;点「立即购买」直接下单进支付页(不再底部弹窗选方式)。
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../l10n/app_text.dart';
import '../models/payment.dart';
import '../pangolin_theme.dart';
import '../state/payment_provider.dart';
import '../widgets/pangolin_icons.dart';
import '../widgets/plan_card.dart';
import '../widgets/seg_switch.dart';

class PurchaseScreen extends ConsumerStatefulWidget {
  const PurchaseScreen({super.key, required this.t, this.onBack, this.onOrderCreated, this.embedded = false});

  final AppText t;
  final VoidCallback? onBack;
  /// 下单成功(进入 awaitingPayment)后由壳导航到支付页。
  final VoidCallback? onOrderCreated;
  final bool embedded;

  @override
  ConsumerState<PurchaseScreen> createState() => _PurchaseScreenState();
}

class _PurchaseScreenState extends ConsumerState<PurchaseScreen> {
  AppText get t => widget.t;

  // 支付渠道:默认 USDT·加密货币。切换即刷新套餐卡显价币种。
  PayChannel _channel = PayChannel.usdt;

  String _name(String sku) => switch (sku) {
        'pro_month' => t.proMonthly,
        'pro_quarter' => t.proQuarterly,
        'pro_year' => t.proYearly,
        _ => sku,
      };

  Future<void> _buy(PayCatalogItem item) async {
    await ref.read(paymentFlowProvider.notifier).start(item, _channel.method);
    if (!mounted) return;
    if (ref.read(paymentFlowProvider).phase == PaymentPhase.awaitingPayment) {
      widget.onOrderCreated?.call();
    }
  }

  @override
  Widget build(BuildContext context) {
    final c = context.pangolin;
    final catalog = ref.watch(payCatalogProvider);

    final body = catalog.when(
      loading: () => const Center(
          child: Padding(padding: EdgeInsets.all(40), child: CircularProgressIndicator())),
      error: (_, __) => Center(
        child: Padding(
          padding: const EdgeInsets.all(40),
          child: Text(t.lang == AppLang.zh ? '加载失败,请重试' : 'Failed to load, retry',
              style: PangolinText.body.copyWith(color: c.fg3)),
        ),
      ),
      data: (items) => ListView(
        padding: const EdgeInsets.fromLTRB(20, 14, 20, 24),
        children: [
          // 支付渠道 SegSwitch(默认 USDT;人民币走支付宝)→ 套餐价随之刷新
          Padding(
            padding: const EdgeInsets.only(left: 2, bottom: 8),
            child: Text(t.payChannel.toUpperCase(),
                style: PangolinText.caption.copyWith(
                    color: c.fg3, fontWeight: FontWeight.w700, letterSpacing: 0.6)),
          ),
          SegSwitch(
            options: [
              (icon: PangolinIcons.globe, label: t.payChannelUsdt),
              (icon: PangolinIcons.creditCard, label: t.payChannelCny),
            ],
            selectedIndex: _channel == PayChannel.usdt ? 0 : 1,
            onChanged: (i) => setState(
                () => _channel = i == 0 ? PayChannel.usdt : PayChannel.cny),
          ),
          const SizedBox(height: 18),
          for (final it in items)
            Padding(
              padding: EdgeInsets.only(bottom: 14, top: it.sku == 'pro_year' ? 12 : 0),
              child: PlanCard(
                name: _name(it.sku),
                price: it.priceLabel(_channel),
                period: '${it.perMonthLabel(_channel)}${t.perMonthSuffix}',
                features: t.featsPro,
                ctaLabel: t.buyNow,
                featured: it.sku == 'pro_year',
                popularLabel: it.sku == 'pro_year' ? t.mostPopular : null,
                onPressed: () => _buy(it),
              ),
            ),
        ],
      ),
    );

    if (widget.embedded) return body;
    return Scaffold(
      backgroundColor: c.bg,
      body: SafeArea(
        child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
          Padding(
            padding: const EdgeInsets.fromLTRB(8, 6, 16, 10),
            child: Row(children: [
              IconButton(
                onPressed: widget.onBack ?? () => Navigator.of(context).maybePop(),
                icon: Icon(PangolinIcons.arrowLeft, size: 22, color: c.fg1),
              ),
              Text(t.purchaseTitle,
                  style: PangolinText.h3.copyWith(color: c.fg1, fontWeight: FontWeight.w700)),
            ]),
          ),
          Expanded(child: body),
        ]),
      ),
    );
  }
}