"use client";

import { useState } from "react";
import { sendChatMessage, fetchExpression, type TachieExpressionResponse } from "../../lib/api";
import { EMOTION_LABELS } from "../../lib/emotion-labels";
import { ChatBubble } from "../../components/ChatBubble";
import { HeartbeatWave } from "../../components/HeartbeatWave";
import { TachieStage } from "../../components/TachieStage";
import type { EmotionTag } from "@kokorone/shared";

// O-2 表情演出時機：表情差分要在文字回覆出現前先變化——順序要對才有真實感。
const EXPRESSION_LEAD_MS = 220;

const CHARACTER_ID = "seed-character-genki";
const USER_ID = "seed-user-primary";

interface Message {
  role: "user" | "character";
  text: string;
}

export function ChatView() {
  const [sessionId] = useState(() => crypto.randomUUID());
  const [messages, setMessages] = useState<Message[]>([]);
  const [input, setInput] = useState("");
  const [sending, setSending] = useState(false);
  const [dominant, setDominant] = useState<EmotionTag>("CALM");
  const [intimacy, setIntimacy] = useState(0);
  const [expression, setExpression] = useState<TachieExpressionResponse | null>(null);
  const [error, setError] = useState<string | null>(null);

  async function handleSend() {
    const text = input.trim();
    if (!text || sending) {
      return;
    }
    setSending(true);
    setError(null);
    setInput("");
    setMessages((prev) => [...prev, { role: "user", text }]);

    try {
      const result = await sendChatMessage(CHARACTER_ID, USER_ID, sessionId, text);
      if (result.availability === "NO_REPLY") {
        // I-2：作息狀態為睡眠且未破例時，這輪不會有真的回覆。
        return;
      }
      if (result.context) {
        setDominant(result.context.emotion.dominant);
        setIntimacy(result.context.relationship.intimacy);
      }
      // O-2：情緒引擎在文字生成前就已經更新完畢，這裡先套用新表情，文字訊息延後一小段時間才出現。
      try {
        setExpression(await fetchExpression(CHARACTER_ID, USER_ID));
      } catch {
        // 表情查詢失敗不影響對話本身。
      }
      await new Promise((resolve) => setTimeout(resolve, EXPRESSION_LEAD_MS));
      setMessages((prev) => [...prev, { role: "character", text: result.text }]);
    } catch {
      setError("訊息傳送失敗，請確認 api 服務是否已啟動");
    } finally {
      setSending(false);
    }
  }

  return (
    <div className="flex h-dvh flex-col md:flex-row">
      <div
        className="relative flex h-[38vh] shrink-0 items-end justify-center overflow-hidden md:order-2 md:h-auto md:w-[38%] md:min-w-[280px]"
        style={{ background: "linear-gradient(180deg, var(--bg-soft), var(--card))" }}
      >
        <span className="absolute top-3.5 left-3.5 text-[11px]" style={{ color: "var(--ink-soft)" }}>
          親密度 <b style={{ color: "var(--accent)" }}>{intimacy}</b>
        </span>
        <span
          className="absolute top-3.5 right-3.5 rounded-full px-3 py-1 text-xs font-bold"
          style={{ background: "var(--chip-bg)", color: "var(--accent)" }}
        >
          {EMOTION_LABELS[dominant]}
        </span>
        <div className="mb-6 flex flex-col items-center gap-2">
          <TachieStage expression={expression} />
          <p className="text-xs" style={{ color: "var(--ink-soft)" }}>
            立繪（表情差分即時變化）
          </p>
        </div>
      </div>

      <div
        className="flex flex-1 flex-col gap-2.5 overflow-y-auto p-4 md:order-1 md:border-r"
        style={{ borderColor: "var(--line)" }}
      >
        <div className="mb-2 flex items-center gap-3">
          <HeartbeatWave amplitude={intimacy} className="h-6 w-24" />
          <h1 className="text-sm font-bold" style={{ color: "var(--accent)" }}>
            心音 Kokorone
          </h1>
        </div>

        <div className="flex flex-1 flex-col gap-2.5 overflow-y-auto">
          {messages.length === 0 && (
            <p className="text-sm" style={{ color: "var(--ink-soft)" }}>
              傳個訊息，開始今天的對話吧。
            </p>
          )}
          {messages.map((message, index) => (
            <ChatBubble key={index} role={message.role} text={message.text} />
          ))}
        </div>

        {error && (
          <p className="text-xs" style={{ color: "var(--accent)" }}>
            {error}
          </p>
        )}

        <div
          className="mt-2 flex items-center justify-between gap-2 rounded-full border px-4 py-2 text-sm"
          style={{ borderColor: "var(--line)" }}
        >
          <input
            value={input}
            onChange={(event) => setInput(event.target.value)}
            onKeyDown={(event) => {
              if (event.key === "Enter") {
                void handleSend();
              }
            }}
            placeholder="輸入訊息……"
            className="flex-1 bg-transparent outline-none"
            style={{ color: "var(--ink)" }}
            disabled={sending}
          />
          <button
            type="button"
            onClick={() => void handleSend()}
            disabled={sending}
            className="font-bold disabled:opacity-50"
            style={{ color: "var(--accent)" }}
          >
            送出
          </button>
        </div>
      </div>
    </div>
  );
}