/**
 * Admin Lesson Plans 数据变换工具（ARCHITECTURE.md §11.3 DoD - 纯函数单测）
 *
 * 所有格式化/映射函数均为纯函数，便于 vitest 单测。
 * 关联：ARCHITECTURE.md §11.3 DoD "数据变换/权限判断等纯函数有 vitest 单测"
 */

import type { AdminLessonPlanListItem } from "@/lib/api/admin-p5";

/** 教案状态中文标签映射 */
export const LESSON_PLAN_STATUS_LABEL: Record<string, string> = {
  DRAFT: "草稿",
  PUBLISHED: "已发布",
  ARCHIVED: "已归档",
  SUBMITTED: "已提交",
};

/**
 * 将教案状态枚举值映射为中文标签。
 * 未知状态回退为原始值。
 */
export function formatLessonPlanStatus(status: string): string {
  return LESSON_PLAN_STATUS_LABEL[status] ?? status;
}

/**
 * 格式化 ISO 日期字符串为本地化展示（zh-CN，含年月日时分）。
 * 输入无效（null/undefined/空/非法）时返回占位符 "--"。
 */
export function formatLessonPlanDate(
  isoDate: string | null | undefined,
): string {
  if (!isoDate) return "--";
  const d = new Date(isoDate);
  if (Number.isNaN(d.getTime())) return "--";
  return d.toLocaleString("zh-CN", {
    year: "numeric",
    month: "2-digit",
    day: "2-digit",
    hour: "2-digit",
    minute: "2-digit",
  });
}

/**
 * 判断教案是否可编辑（草稿与已发布状态允许编辑，归档后不可编辑）。
 */
export function isLessonPlanEditable(status: string): boolean {
  return status === "DRAFT" || status === "PUBLISHED";
}

/**
 * 判断教案是否已发布（PUBLISHED）。
 */
export function isLessonPlanPublished(status: string): boolean {
  return status === "PUBLISHED";
}

/**
 * 判断教案是否已归档（ARCHIVED）。
 */
export function isLessonPlanArchived(status: string): boolean {
  return status === "ARCHIVED";
}

/**
 * 从教案详情中提取列表项视图模型（裁剪字段）。
 *
 * 用于详情→列表裁剪场景；详情字段（textbookId/chapterId/content 等）被剥离。
 */
export function toAdminLessonPlanListItem(detail: {
  id: string;
  title: string;
  subjectId: string;
  subjectName: string;
  teacherId: string;
  teacherName: string;
  classId: string;
  className: string;
  status: string;
  createdAt: string;
  updatedAt: string;
}): AdminLessonPlanListItem {
  return {
    id: detail.id,
    title: detail.title,
    subjectId: detail.subjectId,
    subjectName: detail.subjectName,
    teacherId: detail.teacherId,
    teacherName: detail.teacherName,
    classId: detail.classId,
    className: detail.className,
    status: detail.status,
    createdAt: detail.createdAt,
    updatedAt: detail.updatedAt,
  };
}

/**
 * 格式化数量为展示字符串。
 * 输入无效（null/undefined/NaN/负数）返回 "0"。
 */
export function formatCount(count: number | null | undefined): string {
  if (count === null || count === undefined) return "0";
  if (!Number.isFinite(count) || count < 0) return "0";
  return `${count}`;
}

/**
 * 根据教案状态返回 Tailwind 徽章语义类名。
 */
export function lessonPlanStatusToBadgeClass(status: string): string {
  switch (status) {
    case "DRAFT":
      return "bg-muted text-muted-foreground";
    case "PUBLISHED":
      return "bg-primary/10 text-primary";
    case "ARCHIVED":
      return "bg-muted text-muted-foreground";
    case "SUBMITTED":
      return "bg-amber-500/10 text-amber-600 dark:text-amber-400";
    default:
      return "bg-muted text-muted-foreground";
  }
}