"use client";

import { AgentActivityStatus } from "@/components/agent-activity-status";
import { prefetchOnIdle } from "@/components/chat-chunk-prefetch";
import { ChatMessageContent } from "@/components/chat-message-content";
import { ConsultationRunTimeline } from "@/components/consultation-run-timeline";
import type { ChatMessageView } from "@/lib/chat-message-view";
import { memo, useEffect, useLayoutEffect, useRef, type ReactNode } from "react";

type GsapCore = typeof import("gsap")["gsap"];

const useEntryEffect = typeof window === "undefined" ? useEffect : useLayoutEffect;

let gsapCore: GsapCore | undefined;
let gsapRequest: Promise<GsapCore> | undefined;

function loadGsap() {
  gsapRequest ??= import("gsap").then((module) => {
    const core = module.gsap ?? module.default;
    gsapCore = (core as GsapCore & { gsap?: GsapCore }).gsap ?? core;
    return gsapCore;
  });
  return gsapRequest;
}

function motionPreferred() {
  return typeof window !== "undefined"
    && typeof window.matchMedia === "function"
    && !window.matchMedia("(prefers-reduced-motion: reduce)").matches;
}

if (motionPreferred()) prefetchOnIdle(loadGsap);

export const ChatMessageRow = memo(function ChatMessageRow({
  message,
  showActivity = message.state !== "settled",
  vargaSentence,
  afterAnswer,
  stoppedNotice,
}: Readonly<{
  message: ChatMessageView;
  showActivity?: boolean;
  vargaSentence?: string | null;
  afterAnswer?: ReactNode;
  stoppedNotice?: string;
}>) {
  const messageRow = useRef<HTMLElement>(null);
  const smalltalk = message.responseKind === "smalltalk";
  // Only a smalltalk reply is quiet. The wait before the server's first event
  // used to be quiet too, so nothing showed for the classification round trip
  // (BUG-1074); now the timeline's queued row is on screen from the send frame
  // and disappears when the run.completed event says the reply was smalltalk.
  const quiet = smalltalk;
  const assistantLabel = quiet ? "Jyotisha" : message.state === "thinking"
    ? "Jyotisha 正在分析"
    : message.state === "streaming"
      ? "Jyotisha 正在回答"
      : "Jyotisha";
  const activityState = message.activity
    ? ({
      received: "working",
      "loading-method": "searching",
      "chart-calculation": "solving",
      "compute-queue": "working",
      "evidence-validation": "working",
      "answer-composition": "composing",
    } as const)[message.activity.phase]
    : message.state === "thinking" ? "working" : "composing";
  const activityLabel = message.activity?.label
    ?? (message.state === "thinking" ? "正在处理…" : undefined);
  const hasAnswer = Boolean(message.text.trim());
  const consultTimeline = quiet ? undefined : message.timeline;
  // Rows with a step timeline (every consultation and rectification reply) render
  // `ConsultationRunTimeline`; the activity panel is the fallback for rows without one.
  const showLiveActivity = !quiet && showActivity && consultTimeline === undefined;
  const showThinkingPanel = !quiet && (showLiveActivity || (consultTimeline === undefined && Boolean(message.thinkingText?.trim())));
  const showSpokenAnswer = Boolean(message.text);
  const stackedThinkingAndAnswer = showThinkingPanel && showSpokenAnswer;

  useEntryEffect(() => {
    const row = messageRow.current;
    if (!row) return;
    if (!gsapCore) {
      if (motionPreferred()) void loadGsap();
      return;
    }
    const gsap = gsapCore;
    const motion = gsap.matchMedia();
    motion.add("(prefers-reduced-motion: no-preference)", () => {
      gsap.fromTo(row, {
        autoAlpha: 0,
        y: message.role === "user" ? 8 : 12,
      }, {
        autoAlpha: 1,
        clearProps: "opacity,transform,visibility",
        duration: 0.16,
        ease: "cubic-bezier(.22, 1, .36, 1)",
        y: 0,
      });
    });
    return () => motion.revert();
  }, [message.role]);

  const thinkingPanel = showThinkingPanel
    ? (
      <AgentActivityStatus
        state={activityState}
        label={activityLabel}
        startedAt={message.activity?.startedAt}
        completedTrail={message.activity?.completedTrail}
        thinkingText={message.thinkingText}
        vargaSentence={vargaSentence}
        hasAnswer={hasAnswer}
        showLive={showLiveActivity}
      />
    )
    : null;
  const spokenAnswer = showSpokenAnswer || (consultTimeline !== undefined && hasAnswer)
    ? (
      <ChatMessageContent
        text={message.text}
        auditRows={smalltalk ? undefined : message.agentExecutionReceipt?.techniqueAuditTable}
        streaming={message.state !== "settled"}
      />
    )
    : null;

  return (
    <article
      ref={messageRow}
      className={`message message-${message.role}`}
      aria-label={message.role === "assistant" ? assistantLabel : "你"}
    >
      <div className="message-content">
        <div className="message-bubble">
          {message.role === "assistant" ? (
            consultTimeline !== undefined ? (
              <div className="consultation-thinking-report">
                <ConsultationRunTimeline
                  rows={consultTimeline}
                  live={showActivity && message.state !== "settled" && !message.settling}
                  vargaSentence={vargaSentence}
                />
                {hasAnswer ? (
                  <section className="consultation-report-analysis" aria-label="回复">
                    {spokenAnswer}
                    {afterAnswer}
                  </section>
                ) : afterAnswer}
              </div>
            ) : (
              <>
                {stackedThinkingAndAnswer ? (
                  <div className="message-stage-and-answer">
                    {thinkingPanel}
                    <section className="consultation-report-analysis" aria-label="回复">
                      {spokenAnswer}
                      {afterAnswer}
                    </section>
                  </div>
                ) : (
                  <>
                    {thinkingPanel}
                    {spokenAnswer}
                    {afterAnswer}
                  </>
                )}
              </>
            )
          ) : <><p>{message.text}</p>{afterAnswer}</>}
          {stoppedNotice ? <p className="message-stopped-notice">{stoppedNotice}</p> : null}
        </div>
      </div>
    </article>
  );
});