import { and, eq, sql } from "drizzle-orm";
import { db } from "@/db";
import { grammarPoints, grammarProgress, taskInstances } from "@/db/schema";
import { todayStr } from "@/lib/dates";
import { extractQuiz, type QuizQ } from "@/lib/quiz-parse";

export { extractQuiz, type QuizQ };

// 三档级别元信息(展示用)
export const LEVELS = [
  { id: "starter", name: "入门", stars: 1, desc: "打地基:词与句子、四种句类、名词、代词、冠词、be 动词等。" },
  { id: "base", name: "基础", stars: 2, desc: "时态、情态、比较级、介词、连词等核心用法。" },
  { id: "pro", name: "进阶", stars: 3, desc: "复合句、非谓语、被动、虚拟等综合提升。" },
] as const;

export type PointRow = {
  pointId: string;
  level: string;
  levelName: string;
  title: string;
  difficulty: number;
  seq: number;
};

// 全部知识点(按展示顺序)
export async function listPoints(): Promise<PointRow[]> {
  return db
    .select({
      pointId: grammarPoints.pointId,
      level: grammarPoints.level,
      levelName: grammarPoints.levelName,
      title: grammarPoints.title,
      difficulty: grammarPoints.difficulty,
      seq: grammarPoints.seq,
    })
    .from(grammarPoints)
    .orderBy(grammarPoints.seq);
}

export async function totalPoints(): Promise<number> {
  const [r] = await db.select({ n: sql<number>`COUNT(*)` }).from(grammarPoints);
  return r.n;
}

// 单个知识点全文
export async function getPoint(pointId: string) {
  const [row] = await db.select().from(grammarPoints).where(eq(grammarPoints.pointId, pointId)).limit(1);
  return row ?? null;
}

// 已通过知识点集合
export async function passedByPoint(childId: number): Promise<Set<string>> {
  const rows = await db
    .select({ pointId: grammarProgress.pointId })
    .from(grammarProgress)
    .where(and(eq(grammarProgress.childUserId, childId), eq(grammarProgress.passed, true)));
  return new Set(rows.map((r) => r.pointId));
}

export async function passedCount(childId: number): Promise<number> {
  return (await passedByPoint(childId)).size;
}

const norm = (s: unknown) => String(s ?? "").trim().toLowerCase();

// 服务端判分:六种题型 choice/judge/fill/order/match/solve(solve 不在此处判,走 AI)
export type AnswerValue = number | string | string[];

// xuchao: 单题客观判分(solve 返回 false,由 AI 判分链路单独处理)
export function gradeOne(q: QuizQ, a: AnswerValue | null | undefined): boolean {
  if (q.type === "fill") return (q.answers ?? []).some((x) => norm(x) === norm(a));
  if (q.type === "order") return Array.isArray(a) && a.join(" ").trim() === (q.answer as string[]).join(" ").trim();
  if (q.type === "match") return Array.isArray(a) && (q.pairs ?? []).every((p, pi) => norm(a[pi]) === norm(p[1]));
  if (q.type === "solve") return false;
  return Number(a) === (q.answer as number);
}

export function gradeAnswers(questions: QuizQ[], answers: AnswerValue[]) {
  let correct = 0;
  const detail = questions.map((q, i) => {
    const ok = gradeOne(q, answers[i]);
    if (ok) correct++;
    return ok;
  });
  const score = questions.length ? Math.round((correct / questions.length) * 100) : 0;
  return { score, passed: score >= 80, correct, total: questions.length, detail };
}

// 记录结果;通过则同步完成当天英语打卡
export async function completePoint(
  childId: number,
  pointId: string,
  title: string,
  score: number,
  passed: boolean,
) {
  await db
    .insert(grammarProgress)
    .values({ childUserId: childId, pointId, score, passed })
    .onDuplicateKeyUpdate({ set: { score, passed, completedAt: sql`CURRENT_TIMESTAMP` } });

  if (!passed) return;
  const today = todayStr();
  const ckTitle = `英语语法 · ${title}`;
  const [existing] = await db
    .select({ id: taskInstances.id, status: taskInstances.status })
    .from(taskInstances)
    .where(
      and(eq(taskInstances.childUserId, childId), eq(taskInstances.date, today), eq(taskInstances.title, ckTitle)),
    )
    .limit(1);
  if (existing) {
    if (existing.status !== "done")
      await db
        .update(taskInstances)
        .set({ status: "done", doneAt: sql`CURRENT_TIMESTAMP` })
        .where(eq(taskInstances.id, existing.id));
  } else {
    await db.insert(taskInstances).values({
      childUserId: childId,
      date: today,
      title: ckTitle,
      subject: "english",
      status: "done",
      doneAt: new Date(),
      sortOrder: 99,
    });
  }
}