/**
 * Questions 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 { Question, QuestionListItem } from "@/lib/api";

/** 题型中文标签映射（对齐 schema Question.type 字符串语义） */
export const QUESTION_TYPE_LABEL: Record<string, string> = {
  single_choice: "单选题",
  multiple_choice: "多选题",
  fill_blank: "填空题",
  short_answer: "简答题",
  essay: "论述题",
  true_false: "判断题",
};

/** 题目状态中文标签映射 */
export const QUESTION_STATUS_LABEL: Record<string, string> = {
  DRAFT: "草稿",
  PUBLISHED: "已发布",
  ARCHIVED: "已归档",
};

/**
 * 将题型映射为中文标签。未知题型回退为原始值。
 */
export function formatQuestionType(type: string): string {
  return QUESTION_TYPE_LABEL[type] ?? type;
}

/**
 * 将题目状态映射为中文标签。未知状态回退为原始值。
 */
export function formatQuestionStatus(status: string): string {
  return QUESTION_STATUS_LABEL[status] ?? status;
}

/**
 * 格式化难度。
 *
 * schema Question.difficulty 是 Float，但业务列表 mock 数据常用字符串枚举
 * （easy/medium/hard）。本函数同时支持两种输入：
 * - 字符串枚举：直接映射（"easy" → "简单"）
 * - 数值：0~0.4 → 简单，0.4~0.7 → 中等，0.7~1.0 → 困难
 * - 其他：回退原始字符串
 */
export function formatDifficulty(difficulty: string | number): string {
  if (typeof difficulty === "number") {
    if (!Number.isFinite(difficulty)) return "--";
    if (difficulty <= 0.4) return "简单";
    if (difficulty <= 0.7) return "中等";
    return "困难";
  }
  switch (difficulty) {
    case "easy":
      return "简单";
    case "medium":
      return "中等";
    case "hard":
      return "困难";
    default:
      return difficulty;
  }
}

/**
 * 格式化 ISO 日期字符串为本地化展示（zh-CN，含年月日时分）。
 * 输入无效时返回占位符。
 */
export function formatQuestionDate(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",
  });
}

/**
 * 截断题干文本用于列表展示。
 * - 超过 maxLen 字符时截断并加省略号
 * - 移除换行符（列表单行展示）
 * - maxLen 默认 60
 */
export function truncateContent(content: string, maxLen = 60): string {
  const text = content.replace(/\s+/g, " ").trim();
  if (text.length <= maxLen) return text;
  return `${text.slice(0, maxLen)}...`;
}

/**
 * 从题目详情中提取列表项视图模型（裁剪字段）。
 *
 * 注：Question 详情无 subjectId/textbookId 字段（schema 未提供），
 * 列表项的这两个字段由 MSW mock 扩展，详情→列表裁剪时置为 null。
 */
export function toQuestionListItem(question: Question): QuestionListItem {
  return {
    id: question.id,
    type: question.type,
    content: question.content,
    difficulty: String(question.difficulty),
    status: question.status,
    source: question.source,
    knowledgePointId: question.knowledgePointId,
    subjectId: null,
    textbookId: null,
    createdAt: question.createdAt,
  };
}

/**
 * 根据题型返回 Tailwind 徽章语义类名。
 */
export function questionTypeToBadgeClass(type: string): string {
  switch (type) {
    case "single_choice":
    case "multiple_choice":
      return "bg-blue-500/10 text-blue-600 dark:text-blue-400";
    case "fill_blank":
      return "bg-emerald-500/10 text-emerald-600 dark:text-emerald-400";
    case "short_answer":
    case "essay":
      return "bg-amber-500/10 text-amber-600 dark:text-amber-400";
    case "true_false":
      return "bg-purple-500/10 text-purple-600 dark:text-purple-400";
    default:
      return "bg-muted text-muted-foreground";
  }
}

/**
 * 根据难度返回 Tailwind 文本语义类名。
 * 支持字符串枚举与数值输入。
 */
export function difficultyToColorClass(difficulty: string | number): string {
  const label = formatDifficulty(difficulty);
  switch (label) {
    case "简单":
      return "text-emerald-600";
    case "中等":
      return "text-amber-600";
    case "困难":
      return "text-destructive";
    default:
      return "text-muted-foreground";
  }
}

/**
 * 根据题目状态返回 Tailwind 徽章语义类名。
 */
export function questionStatusToBadgeClass(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";
    default:
      return "bg-muted text-muted-foreground";
  }
}

/**
 * 判断题目是否处于可编辑状态（DRAFT）。
 */
export function isQuestionEditable(status: string): boolean {
  return status === "DRAFT";
}

/**
 * 判断题目是否已发布（PUBLISHED）。
 */
export function isQuestionPublished(status: string): boolean {
  return status === "PUBLISHED";
}