import 'package:flutter/material.dart';

import '../model/msg.dart';
import '../util/ToastUtil.dart';

/// 聊天页面
class ChatPage extends StatefulWidget {
  const ChatPage({super.key});

  @override
  State<StatefulWidget> createState() {
    return ChatPageState();
  }
}

class ChatPageState extends State<ChatPage> {
  /// TextField操作控制器
  final TextEditingController _editingController = TextEditingController();

  /// ListView的滚动控制器
  final ScrollController _scrollController = ScrollController();

  /// 输入框焦点
  final _inputFocusNode = FocusNode();

  /// 消息列表
  final List<Msg> _msgList = [];

  /// 添加消息到消息列表中
  void _addMsg2List(String msg, bool isMe) {
    setState(() {
      String msgText;
      if (isMe) {
        msgText = "我：$msg";
      } else {
        msgText = "对方：$msg";
      }
      _msgList.add(
        Msg(isMe: isMe, msg: msgText, createTime: DateTime.now().millisecond),
      );
    });
    Future.delayed(const Duration(milliseconds: 300), () {
      //延迟300毫秒，再滚动到列表底部
      _scrollController.jumpTo(_scrollController.position.maxScrollExtent);
    });
  }

  /// 发送消息
  void _sendMsg(String msg) {
    if (msg.isEmpty) {
      ToastUtil.showToast("请输入要发送的消息内容");
      return;
    }
    //添加消息到列表中
    _addMsg2List(msg, true);
    // 延迟生成对方的回复消息
    Future.delayed(const Duration(milliseconds: 150), () {
      //添加消息到列表中
      _addMsg2List(replyMessage2Client(msg), false);
    });
    //清除输入框的内容
    _editingController.clear();
  }

  /// 生成回复消息
  String replyMessage2Client(String clientMsg) {
    return clientMsg
        .replaceAll("我", "你")
        .replaceAll("吗", "")
        .replaceAll("?", "!")
        .replaceAll("？", "！");
  }

  /// 构建聊天气泡
  Widget _buildMsgBubble(Msg msg) {
    return Container(
      padding: const EdgeInsets.all(15.0),
      decoration: BoxDecoration(
        color:
            msg.isMe
                ? const Color.fromARGB(255, 164, 208, 238)
                : const Color.fromARGB(255, 153, 231, 169),
        borderRadius: BorderRadius.circular(12),
      ),
      // 消息文本
      child: Text(msg.msg),
    );
  }

  /// 构建聊天消息列表项
  Widget _buildMsgItem(Msg msg) {
    Widget content;
    // 自己发的
    if (msg.isMe) {
      content = Row(
        // 如果是自己发的，则在右边
        mainAxisAlignment: MainAxisAlignment.end,
        children: [
          // 聊天气泡
          _buildMsgBubble(msg),
          // 头像
          _buildAvatar(msg),
        ],
      );
    } else {
      // 对方发的
      content = Row(
        // 如果是自己发的，则在右边
        mainAxisAlignment: MainAxisAlignment.start,
        children: [
          // 头像
          _buildAvatar(msg),
          // 聊天气泡
          _buildMsgBubble(msg),
        ],
      );
    }
    return Container(padding: const EdgeInsets.all(8.0), child: content);
  }

  /// 构建头像
  Widget _buildAvatar(Msg msg) {
    return Container(
      margin: const EdgeInsets.symmetric(horizontal: 8.0),
      child: CircleAvatar(
        radius: 20,
        backgroundColor: Colors.grey,
        child: Text(
          msg.isMe ? "我" : "对方",
          style: const TextStyle(color: Colors.white),
        ),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        leading: IconButton(
          onPressed: () {
            Navigator.pop(context, null);
          },
          icon: const Icon(Icons.arrow_back),
        ),
        title: const Text("聊天页"),
      ),
      body: Column(
        children: [
          Expanded(
            flex: 1,
            child: ListView.builder(
              controller: _scrollController,
              itemCount: _msgList.length,
              itemBuilder: (BuildContext context, int index) {
                return _buildMsgItem(_msgList[index]);
              },
            ),
          ),
          Center(
            child: Column(
              children: [
                Container(height: 0.3, color: Colors.grey),
                Padding(
                  padding: const EdgeInsets.symmetric(
                    vertical: 15.0,
                    horizontal: 18.0,
                  ),
                  child: Row(
                    mainAxisAlignment: MainAxisAlignment.start,
                    children: [
                      Expanded(
                        flex: 1,
                        child: TextField(
                          // 输入框焦点
                          focusNode: _inputFocusNode,
                          // 点击外部区域，关闭软键盘
                          onTapUpOutside: (event) {
                            _inputFocusNode.unfocus();
                          },
                          controller: _editingController,
                          decoration: const InputDecoration(
                            //提示文字
                            hintText: "请输入要发送的消息",
                            //边框
                            border: OutlineInputBorder(),
                          ),
                        ),
                      ),
                      Container(
                        margin: const EdgeInsets.only(left: 5.0),
                        child: ElevatedButton(
                          child: const Text("发送"),
                          onPressed: () {
                            var msg = _editingController.text;
                            _sendMsg(msg);
                          },
                        ),
                      ),
                    ],
                  ),
                ),
              ],
            ),
          ),
        ],
      ),
    );
  }
}