// 考试列表页面（家长查看子女考试）
// 依据：02-architecture-design.md §3.1 路由结构
// 路由：/parent/exams
// 对标 student-portal /my-exams（家长只读视角）

"use client";

import Link from "next/link";
import { useChildExams } from "@/hooks/useChildExams";
import { useChildSwitcher } from "@/hooks/useChildSwitcher";
import { formatDate, cn } from "@/lib/utils";
import type { ExamListItem, ExamStatus } from "@/types";

const STATUS_GROUPS: Array<{
  key: ExamStatus;
  label: string;
  description: string;
}> = [
  { key: "in_progress", label: "进行中", description: "子女正在作答" },
  { key: "not_started", label: "未开始", description: "等待开考" },
  { key: "submitted", label: "已提交", description: "等待批改" },
  { key: "graded", label: "已批改", description: "可查看成绩" },
  { key: "expired", label: "已结束", description: "考试已结束" },
];

const STATUS_BADGE_STYLES: Record<ExamStatus, string> = {
  not_started: "text-ink-muted",
  in_progress: "text-warning",
  submitted: "text-ink-muted",
  graded: "text-success",
  expired: "text-ink-muted",
};

const STATUS_LABELS: Record<ExamStatus, string> = {
  not_started: "未开始",
  in_progress: "进行中",
  submitted: "已提交",
  graded: "已批改",
  expired: "已结束",
};

function formatDuration(seconds: number): string {
  return `${Math.round(seconds / 60)} 分钟`;
}

export default function ExamsPage(): JSX.Element {
  const { currentChild } = useChildSwitcher();
  const { exams, loading, error } = useChildExams();

  if (loading) {
    return (
      <div className="space-y-4" role="status" aria-live="polite">
        <span className="skeleton h-8 w-48 rounded" aria-hidden="true" />
        <span className="skeleton h-40 w-full rounded" aria-hidden="true" />
        <span className="skeleton h-40 w-full rounded" aria-hidden="true" />
        <span className="sr-only">加载考试列表中...</span>
      </div>
    );
  }

  if (error) {
    return (
      <div
        role="alert"
        className="rounded border border-danger p-4 text-sm text-danger"
      >
        加载失败：{error.message}
      </div>
    );
  }

  const grouped = STATUS_GROUPS.map((g) => ({
    ...g,
    items: exams.filter((e) => e.status === g.key),
  }));

  return (
    <div className="space-y-6">
      <h1 className="font-serif text-2xl">{currentChild?.name}的考试</h1>

      {exams.length === 0 ? (
        <p className="text-sm text-ink-muted">暂无考试安排</p>
      ) : (
        <div className="space-y-8">
          {grouped.map((group) =>
            group.items.length > 0 ? (
              <section key={group.key} aria-label={group.label}>
                <div className="mb-3 flex items-baseline gap-3">
                  <h2 className="font-serif text-base">{group.label}</h2>
                  <span className="text-xs text-ink-muted">
                    {group.items.length} 场 · {group.description}
                  </span>
                </div>
                <ul className="grid grid-cols-1 gap-4 lg:grid-cols-2">
                  {group.items.map((exam) => (
                    <li key={exam.id}>
                      <ExamCard exam={exam} />
                    </li>
                  ))}
                </ul>
              </section>
            ) : null,
          )}
        </div>
      )}
    </div>
  );
}

function ExamCard({ exam }: { exam: ExamListItem }): JSX.Element {
  const isResult = exam.status === "submitted" || exam.status === "graded";
  const linkHref = isResult ? `/parent/exams/${exam.id}/result` : null;

  const inner = (
    <article
      className={cn(
        "h-full rounded border border-rule bg-paper-elevated p-4",
        linkHref && "transition-shadow hover:shadow-md",
      )}
      aria-label={`${exam.name} - ${STATUS_LABELS[exam.status]}`}
    >
      <div className="flex items-start justify-between gap-3">
        <div className="min-w-0 flex-1">
          <p className="text-xs text-ink-muted">{exam.subject}</p>
          <h3 className="mt-1 font-serif text-base">{exam.name}</h3>
        </div>
        <span
          className={cn(
            "flex-shrink-0 text-xs font-medium",
            STATUS_BADGE_STYLES[exam.status],
          )}
        >
          {STATUS_LABELS[exam.status]}
        </span>
      </div>

      <div className="mt-3 border-t border-rule pt-3">
        <dl className="grid grid-cols-2 gap-y-2 text-xs">
          <div>
            <dt className="text-ink-muted">开考时间</dt>
            <dd className="mt-1">{formatDate(exam.startsAt)}</dd>
          </div>
          <div>
            <dt className="text-ink-muted">截止时间</dt>
            <dd className="mt-1">{formatDate(exam.expiresAt)}</dd>
          </div>
          <div>
            <dt className="text-ink-muted">时长</dt>
            <dd className="mt-1">{formatDuration(exam.durationSeconds)}</dd>
          </div>
          <div>
            <dt className="text-ink-muted">题量</dt>
            <dd className="mt-1">{exam.questionCount} 题</dd>
          </div>
          <div>
            <dt className="text-ink-muted">满分</dt>
            <dd className="mt-1">{exam.totalScore} 分</dd>
          </div>
        </dl>
      </div>

      {linkHref && <p className="mt-3 text-xs text-accent">查看结果 →</p>}
    </article>
  );

  if (!linkHref) return inner;
  return (
    <Link
      href={linkHref}
      className="block h-full focus-visible:outline-2"
      aria-label={`${exam.name} - 查看结果`}
    >
      {inner}
    </Link>
  );
}