import 'package:flutter/material.dart';

/// 助手页（占位）。
///
/// 现在是骨架里预留的位置 —— 先让布局一次到位，阶段 B 接 AI 时只填内容、
/// 不再动导航结构。同时它也是首页那个输入框的落地页。
class AssistantPage extends StatelessWidget {
  const AssistantPage({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(
        width: double.infinity,
        height: double.infinity,
        decoration: const BoxDecoration(
          gradient: LinearGradient(
            begin: Alignment.topLeft,
            end: Alignment.bottomRight,
            colors: [Color(0xFFFFE5CC), Color(0xFFFFD4A8), Color(0xFFFFC08A)],
          ),
        ),
        child: SafeArea(
          child: Column(
            children: [
              _header(context),
              Expanded(
                child: ListView(
                  physics: const AlwaysScrollableScrollPhysics(),
                  padding: const EdgeInsets.fromLTRB(24, 40, 24, 0),
                  children: [
                    const Center(child: Text('✨', style: TextStyle(fontSize: 46))),
                    const SizedBox(height: 16),
                    const Center(
                      child: Text(
                        'AI 助手正在建设中',
                        style: TextStyle(
                          fontSize: 17,
                          fontWeight: FontWeight.w600,
                          color: Color(0xFF5D4037),
                        ),
                      ),
                    ),
                    const SizedBox(height: 8),
                    const Center(
                      child: Text(
                        '位置已经预留好，接入后不用再改布局',
                        style: TextStyle(fontSize: 12.5, color: Color(0xFF8D6E63)),
                      ),
                    ),
                    const SizedBox(height: 28),
                    _planCard(),
                    const SizedBox(height: 90),
                  ],
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }

  /// 用 Tab 打开时没有上一页，就不显示返回箭头
  Widget _header(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.fromLTRB(10, 6, 16, 6),
      child: Row(
        children: [
          if (Navigator.of(context).canPop())
            InkWell(
              onTap: () => Navigator.of(context).pop(),
              borderRadius: BorderRadius.circular(20),
              child: const Padding(
                padding: EdgeInsets.all(6),
                child: Icon(Icons.arrow_back, size: 22, color: Color(0xFF5D4037)),
              ),
            ),
          const Padding(
            padding: EdgeInsets.only(left: 6),
            child: Text(
              '助手',
              style: TextStyle(
                fontSize: 20,
                fontWeight: FontWeight.bold,
                color: Color(0xFF5D4037),
              ),
            ),
          ),
        ],
      ),
    );
  }

  Widget _planCard() {
    const items = [
      ('一句话记账', '「昨天买咖啡 32」→ 自动填好分类和金额'),
      ('笔记问答', '从你的知识库里找答案，而不是重读一遍'),
      ('服务器状态', '查状态、看日志 —— 只走预定义动作，不给任意 shell'),
      ('跨模块查询', '「上周服务器相关的花费」这类要跨模块的问题'),
    ];

    return Container(
      padding: const EdgeInsets.fromLTRB(18, 16, 18, 8),
      decoration: BoxDecoration(
        color: Colors.white,
        borderRadius: BorderRadius.circular(16),
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          const Text(
            '规划中的能力',
            style: TextStyle(
              fontSize: 13,
              fontWeight: FontWeight.w600,
              color: Color(0xFF5D4037),
            ),
          ),
          const SizedBox(height: 12),
          for (final (title, desc) in items) ...[
            Row(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                const Padding(
                  padding: EdgeInsets.only(top: 5),
                  child: Icon(Icons.circle, size: 5, color: Color(0xFFC8956E)),
                ),
                const SizedBox(width: 10),
                Expanded(
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Text(
                        title,
                        style: const TextStyle(
                          fontSize: 13.5,
                          fontWeight: FontWeight.w600,
                          color: Color(0xFF5D4037),
                        ),
                      ),
                      const SizedBox(height: 2),
                      Text(
                        desc,
                        style: const TextStyle(fontSize: 12, color: Color(0xFF8D6E63)),
                      ),
                    ],
                  ),
                ),
              ],
            ),
            const SizedBox(height: 14),
          ],
          const Divider(height: 1, color: Color(0xFFF0E6D8)),
          const SizedBox(height: 10),
          const Text(
            '隐私：涉及你笔记里的服务器信息时，会在请求发出前先脱敏。',
            style: TextStyle(fontSize: 11.5, color: Color(0xFFBCAAA4), height: 1.5),
          ),
          const SizedBox(height: 8),
        ],
      ),
    );
  }
}