"use client";

/**
 * 扫描批改页 - 客户端组件（ARCHITECTURE.md §7.3 工作台页 / §9.1 / §10 P2）
 *
 * 数据契约：
 * - 单查 submissionDetail(submissionId)：❌ schema 无此字段 → MSW 兜底（@contract-pending）
 * - mutation saveScanGrading(input)：❌ schema 无 Mutation → MSW 兜底（@contract-pending）
 *
 * 三态规范（§11.3 DoD）：
 * - loading：WorkbenchPageSkeleton（loading=true）
 * - error：errorNode 局部降级
 * - 局部加载：左/中/右各自支持独立 loading（本页用整体 loading）
 *
 * 关联：ARCHITECTURE.md §5.3 / §5.4 / §7.3 / §9.1 / §10 P2 / §11.3 / §11.4
 *
 * 注：WorkbenchPageShell 没有 emptyNode 属性；notFound 由 errorNode 节点呈现。
 */
import { ScanLine } from "lucide-react";
import { useParams } from "next/navigation";
import { useMemo, useState } from "react";
import { useTranslations } from "next-intl";

import {
  useSubmissionDetail,
  useSaveScanGrading,
  type SubmissionAnswer,
} from "@/lib/api";
import { Button } from "@/shared/components/ui/button";
import {
  WorkbenchPageShell,
  WorkbenchPanel,
  WorkbenchPageSkeleton,
} from "@/shared/components/page-templates";
import { notify } from "@/shared/lib/notify";
import {
  confidenceToColorClass,
  formatConfidence,
} from "@/features/teacher/homework/transformations";

/**
 * 扫描批改客户端主体。需由 server page 包裹在 <Suspense> 中。
 */
export function ScanGradingClient(): React.ReactElement {
  const t = useTranslations("homework");
  const tCommon = useTranslations("common");
  const params = useParams<{ submissionId: string }>();
  const submissionId = params?.submissionId ?? "";

  // @contract-pending：MSW 兜底
  const { data, loading, error } = useSubmissionDetail(submissionId);

  const errorNode = error ? (
    <div className="rounded-xl border border-destructive/30 bg-destructive/5 p-6 text-center">
      <p className="text-sm text-destructive">
        {tCommon("error.loadFailed", { message: String(error) })}
      </p>
    </div>
  ) : undefined;

  const notFoundNode =
    !loading && !error && !data ? (
      <div className="rounded-xl border p-6 text-center text-muted-foreground">
        {t("scan.notFound")}
      </div>
    ) : undefined;

  return (
    <WorkbenchPageShell
      title={
        data
          ? t("scan.title", { name: data.submission.studentName })
          : t("scan.titleLoading")
      }
      description={
        data
          ? t("scan.subtitle", {
              homework: data.submission.homeworkTitle,
            })
          : undefined
      }
      icon={<ScanLine className="size-6" />}
      loading={loading}
      loadingNode={<WorkbenchPageSkeleton />}
      errorNode={errorNode ?? notFoundNode}
      left={
        data ? (
          <WorkbenchPanel title={t("scan.scanPreview")}>
            <ScanPreviewPanel submissionId={data.submission.id} />
          </WorkbenchPanel>
        ) : null
      }
      center={
        data ? (
          <WorkbenchPanel title={t("scan.recognizedAnswers")}>
            <RecognizedAnswersPanel answers={data.answers} />
          </WorkbenchPanel>
        ) : null
      }
      right={
        data ? (
          <WorkbenchPanel title={t("scan.gradingForm")}>
            <ScanGradingForm
              submissionId={data.submission.id}
              answers={data.answers}
              maxScore={data.submission.maxScore}
            />
          </WorkbenchPanel>
        ) : null
      }
    />
  );
}

/**
 * 扫描图片预览面板（左栏）。
 * 注：当前无真实扫描图片，使用占位符 + 提示。
 */
function ScanPreviewPanel({
  submissionId,
}: {
  submissionId: string;
}): React.ReactElement {
  const t = useTranslations("homework");
  return (
    <div className="flex h-full flex-col gap-3">
      <div className="flex flex-1 items-center justify-center rounded-md border bg-muted/30 p-4">
        <div className="text-center">
          <ScanLine className="mx-auto size-12 text-muted-foreground" />
          <p className="mt-2 text-xs text-muted-foreground">
            {t("scan.imagePlaceholder", { id: submissionId })}
          </p>
        </div>
      </div>
      <p className="text-xs text-muted-foreground">
        {t("scan.imageContractPending")}
      </p>
    </div>
  );
}

/**
 * 已识别答案面板（中栏）。
 */
function RecognizedAnswersPanel({
  answers,
}: {
  answers: SubmissionAnswer[];
}): React.ReactElement {
  const t = useTranslations("homework");
  return (
    <div className="space-y-3">
      {answers.map((a, idx) => (
        <div key={a.id} className="rounded-md border p-3">
          <div className="mb-1 flex items-start justify-between gap-2">
            <p className="text-sm font-medium">
              {idx + 1}. {a.questionTitle}
            </p>
            <span className="text-xs text-muted-foreground">
              {a.maxScore} {t("scan.unitScore")}
            </span>
          </div>
          <p className="text-xs text-muted-foreground">
            {t("scan.questionType")}: {a.questionType}
          </p>
          <div className="mt-2 rounded-md bg-muted/30 p-2">
            <p className="text-xs text-muted-foreground">
              {t("scan.recognizedAnswer")}
            </p>
            <p className="mt-1 text-sm">{a.answer}</p>
          </div>
          {a.aiSuggestion ? (
            <p className="mt-2 text-xs">
              <span className="font-medium text-muted-foreground">
                {t("scan.aiSuggestionLabel")}
              </span>
              <span className="ml-1">{a.aiSuggestion}</span>
            </p>
          ) : null}
          {a.isCorrect !== null ? (
            <p
              className={`mt-1 text-xs ${a.isCorrect ? "text-emerald-600" : "text-destructive"}`}
            >
              {a.isCorrect
                ? t("scan.recognizedCorrect")
                : t("scan.recognizedIncorrect")}
            </p>
          ) : null}
        </div>
      ))}
      {answers.length === 0 ? (
        <p className="text-sm text-muted-foreground">{t("scan.noAnswers")}</p>
      ) : null}
    </div>
  );
}

/**
 * 扫描批改表单（右栏）：每题分数 + 评语 + 总反馈 + 保存。
 */
function ScanGradingForm({
  submissionId,
  answers,
  maxScore,
}: {
  submissionId: string;
  answers: SubmissionAnswer[];
  maxScore: number;
}): React.ReactElement {
  const t = useTranslations("homework");
  const { run: saveScanGrading, loading: submitting } = useSaveScanGrading();

  const initialScores = useMemo<Record<string, string>>(() => {
    const m: Record<string, string> = {};
    for (const a of answers) {
      m[a.questionId] = a.score === null ? "" : String(a.score);
    }
    return m;
  }, [answers]);

  const [scores, setScores] = useState<Record<string, string>>(initialScores);
  const [feedback, setFeedback] = useState("");
  const [error, setError] = useState<string | null>(null);

  const applyAllAi = (): void => {
    const next: Record<string, string> = { ...scores };
    let applied = 0;
    for (const a of answers) {
      if (!a.aiSuggestion) continue;
      if (a.aiSuggestion.includes("满分")) {
        next[a.questionId] = String(a.maxScore);
        applied += 1;
      }
    }
    setScores(next);
    notify.info(t("scan.aiAppliedCount", { count: applied }));
  };

  const totalScore = answers.reduce((sum, a) => {
    const raw = scores[a.questionId] ?? "";
    const num = Number(raw);
    return Number.isFinite(num) ? sum + num : sum;
  }, 0);

  const handleSubmit = async (): Promise<void> => {
    setError(null);
    const payload = answers.map((a) => {
      const raw = scores[a.questionId] ?? "";
      const num = Number(raw);
      if (raw === "" || !Number.isFinite(num)) {
        throw new Error(t("scan.errorScoreInvalid", { qid: a.questionId }));
      }
      return {
        questionId: a.questionId,
        score: num,
      };
    });

    try {
      await saveScanGrading({
        submissionId,
        answers: payload,
        feedback: feedback.trim() || undefined,
      });
      notify.success(t("scan.saveSuccess"));
    } catch (err) {
      const msg = err instanceof Error ? err.message : String(err);
      setError(msg);
      notify.error(`${t("scan.saveError")}: ${msg}`);
    }
  };

  return (
    <div className="flex h-full flex-col gap-3">
      <div className="flex items-center justify-between">
        <span className="text-xs text-muted-foreground">
          {t("scan.totalScore")}: {totalScore} / {maxScore}
        </span>
        <Button type="button" variant="ghost" size="sm" onClick={applyAllAi}>
          {t("scan.applyAllAi")}
        </Button>
      </div>

      <div className="space-y-3 overflow-y-auto">
        {answers.map((a, idx) => {
          const raw = scores[a.questionId] ?? "";
          const aiConf = a.aiSuggestion
            ? a.aiSuggestion.includes("满分")
              ? 0.95
              : 0.7
            : null;
          return (
            <div key={a.id} className="space-y-1 rounded-md border p-2">
              <p className="text-xs font-medium">
                {idx + 1}. {a.questionTitle}
              </p>
              <div className="flex items-center gap-2">
                <input
                  type="number"
                  min={0}
                  max={a.maxScore}
                  value={raw}
                  onChange={(e) =>
                    setScores((prev) => ({
                      ...prev,
                      [a.questionId]: e.target.value,
                    }))
                  }
                  className="h-8 w-20 rounded-md border border-input bg-background px-2 text-sm"
                  aria-label={t("scan.scoreLabel", { qid: a.questionId })}
                />
                <span className="text-xs text-muted-foreground">
                  / {a.maxScore}
                </span>
                {aiConf !== null ? (
                  <span
                    className={`ml-auto text-xs ${confidenceToColorClass(aiConf)}`}
                  >
                    {t("scan.confidence")}: {formatConfidence(aiConf)}
                  </span>
                ) : null}
              </div>
            </div>
          );
        })}
      </div>

      <div className="space-y-1">
        <label className="text-xs font-medium">
          {t("scan.overallFeedback")}
        </label>
        <textarea
          value={feedback}
          onChange={(e) => setFeedback(e.target.value)}
          rows={3}
          className="w-full rounded-md border border-input bg-background px-2 py-1 text-sm"
          placeholder={t("scan.overallFeedbackPlaceholder")}
        />
      </div>

      {error ? <p className="text-xs text-destructive">{error}</p> : null}

      <Button
        type="button"
        onClick={() => void handleSubmit()}
        disabled={submitting}
      >
        {submitting ? t("scan.saving") : t("scan.save")}
      </Button>

      <p className="text-xs text-muted-foreground">
        {t("scan.contractPending")}
      </p>
    </div>
  );
}