import { useEffect, useRef, useState } from "react";
import {
  Avatar,
  Button,
  Card,
  CardBody,
  CardHeader,
  Divider,
  ScrollShadow,
  Spinner,
  Textarea,
} from "@heroui/react";
import { requestBotReply } from "./dsAPI";

export default function App() {
  const [messages, setMessages] = useState([
    {
      role: "assistant",
      content: "你好，有什么可以帮你？",
    },
  ]);

  const [inputText, setInputText] = useState("");

  const [isSending, setIsSending] = useState(false);
  const [isBotTyping, setIsBotTyping] = useState(false);

  const bottomRef = useRef(null);

  useEffect(() => {
    bottomRef.current?.scrollIntoView({ behavior: "smooth" });
  }, [messages, isBotTyping]);

  async function handleSend() {
    const text = inputText.trim();
    if (!text || isSending) return;

    const userMessage = {
      role: "user",
      content: text,
    };

    const nextMessages = [...messages, userMessage];
    setMessages(nextMessages);
    setInputText("");
    setIsSending(true);
    setIsBotTyping(true);

    // 给模型的上下文
    const historyForModel = [
      { role: "system", content: "你是一个简洁的助手，用中文回答。" },
      ...nextMessages.map(({ role, content }) => ({ role, content })),
    ];

    let reply = "";
    try {
      reply = await requestBotReply(historyForModel);
    } catch (e) {
      reply = "出错了，请稍后再试。";
    }

    const botMessage = {
      role: "assistant",
      content: reply,
    };

    setMessages((prev) => [...prev, botMessage]);
    setIsBotTyping(false);
    setIsSending(false);
  }

  function handleKeyDown(e) {
    if (e.key === "Enter" && !e.shiftKey) {
      e.preventDefault();
      handleSend();
    }
  }

  return (
    <div className="min-h-screen bg-gradient-to-b from-background to-content2/50 p-4">
      <div className="mx-auto max-w-3xl">
        <Card className="shadow-xl">
          {/* 顶部 */}
          <CardHeader className="flex items-center gap-3">
            <Avatar name="Bot" />
            <div className="flex flex-col">
              <span className="font-semibold">Chatbot Demo</span>
              <span className="text-xs text-default-500">
              </span>
            </div>
          </CardHeader>

          <Divider />

          {/* 聊天区域 */}
          <CardBody className="p-0">
            <ScrollShadow className="h-[520px] px-4 py-4">
              <div className="flex flex-col gap-3">
                {messages.map((m) => {
                  const isUser = m.role === "user";
                  return (
                    <div
                      className={`flex ${isUser ? "justify-end" : "justify-start"}`}
                    >
                      <div
                        className={`flex max-w-[80%] items-end gap-2 ${isUser ? "flex-row-reverse" : ""}`}
                      >
                        <Avatar
                          size="sm"
                          name={isUser ? "You" : "Bot"}
                        />
                        <div
                          className={`rounded-2xl px-4 py-3 text-sm leading-relaxed ${isUser
                            ? "bg-primary text-primary-foreground"
                            : "bg-content2 text-foreground"
                            }`}
                        >
                          {m.content}
                        </div>
                      </div>
                    </div>
                  );
                })}

                {isBotTyping && (
                  <div className="flex justify-start">
                    <div className="flex items-center gap-2">
                      <Avatar size="sm" name="Bot" />
                      <div className="flex items-center gap-2 rounded-2xl bg-content2 px-4 py-2 text-sm text-default-600">
                        <Spinner size="sm" />
                        正在回复…
                      </div>
                    </div>
                  </div>
                )}

                <div ref={bottomRef} />
              </div>
            </ScrollShadow>

            <Divider />

            {/* 输入区 */}
            <div className="p-4">
              <div className="flex items-end gap-3">
                <Textarea
                  value={inputText}
                  onValueChange={setInputText}
                  onKeyDown={handleKeyDown}
                  placeholder="输入消息，Enter 发送，Shift+Enter 换行"
                  minRows={2}
                  maxRows={6}
                  isDisabled={isSending}
                  variant="bordered"
                  className="flex-1"
                />
                <Button
                  color="primary"
                  onPress={handleSend}
                  isDisabled={isSending || !inputText.trim()}
                >
                  {isSending ? "发送中…" : "发送"}
                </Button>
              </div>
            </div>
          </CardBody>
        </Card>
      </div>
    </div>
  );
}