// Tableau de progression : maîtrise par concept/semaine, activité, série, statistiques.
import { NextResponse } from "next/server";
import { apiError, requireEnrollment } from "@/lib/api.ts";
import { requireUser } from "@/lib/auth/session.ts";
import { all, get } from "@/lib/db/index.ts";
import { masteryForCourse, LEVEL_LABELS } from "@/lib/learning/mastery.ts";
import { recommendations } from "@/lib/learning/recommend.ts";
import { normalizeCourse } from "@/lib/learning/helpers.ts";

export async function GET(_req: Request, ctx: { params: Promise<{ course: string }> }) {
  try {
    const user = await requireUser();
    const course = normalizeCourse((await ctx.params).course);
    requireEnrollment(user.id, course);

    const mastery = masteryForCourse(user.id, course);
    const practiced = mastery.filter((m) => m.observations > 0);
    const globalScore = mastery.length
      ? mastery.reduce((s, m) => s + m.score * m.importance, 0) / mastery.reduce((s, m) => s + m.importance, 0)
      : 0;

    // Par semaine
    const weeks = new Map<number, { score: number; n: number }>();
    for (const m of mastery) {
      const w = m.week ?? 0;
      const e = weeks.get(w) ?? { score: 0, n: 0 };
      e.score += m.score;
      e.n++;
      weeks.set(w, e);
    }

    // Série de jours actifs
    const days = all<{ d: string }>(
      "SELECT DISTINCT date(created_at) as d FROM activity_log WHERE user_id = ? ORDER BY d DESC LIMIT 60",
      user.id
    ).map((r) => r.d);
    let streak = 0;
    const today = new Date();
    for (let i = 0; i < 60; i++) {
      const d = new Date(today);
      d.setDate(d.getDate() - i);
      const iso = d.toISOString().slice(0, 10);
      if (days.includes(iso)) streak++;
      else if (i > 0) break; // aujourd'hui pas encore actif ne casse pas la série d'hier
    }

    const stats = {
      cardsReviewed: get<{ n: number }>(
        `SELECT COUNT(*) as n FROM review_log rl JOIN flashcards f ON f.id = rl.card_id WHERE rl.user_id = ? AND f.course_code = ?`,
        user.id, course
      )?.n ?? 0,
      quizAnswered: get<{ n: number }>(
        `SELECT COUNT(*) as n FROM quiz_answers qa JOIN quiz_sessions qs ON qs.id = qa.session_id WHERE qs.user_id = ? AND qs.course_code = ?`,
        user.id, course
      )?.n ?? 0,
      quizAccuracy: get<{ p: number }>(
        `SELECT ROUND(AVG(qa.correct)*100) as p FROM quiz_answers qa JOIN quiz_sessions qs ON qs.id = qa.session_id WHERE qs.user_id = ? AND qs.course_code = ?`,
        user.id, course
      )?.p ?? null,
      examAttempts: get<{ n: number }>(
        `SELECT COUNT(*) as n FROM exam_attempts ea JOIN mock_exams me ON me.id = ea.exam_id WHERE ea.user_id = ? AND me.course_code = ? AND ea.finished_at IS NOT NULL`,
        user.id, course
      )?.n ?? 0,
      studyMinutes: Math.round((get<{ s: number }>(
        "SELECT COALESCE(SUM(duration_s),0) as s FROM activity_log WHERE user_id = ? AND course_code = ?",
        user.id, course
      )?.s ?? 0) / 60),
      errorsToReview: get<{ n: number }>(
        "SELECT COUNT(*) as n FROM error_notebook WHERE user_id = ? AND course_code = ? AND status = 'a-revoir'",
        user.id, course
      )?.n ?? 0,
      cardsDue: get<{ n: number }>(
        `SELECT COUNT(*) as n FROM card_states cs JOIN flashcards f ON f.id = cs.card_id
         WHERE cs.user_id = ? AND f.course_code = ? AND cs.suspended = 0 AND cs.due_at <= datetime('now')`,
        user.id, course
      )?.n ?? 0,
    };

    const recent = all(
      `SELECT kind, meta, created_at FROM activity_log WHERE user_id = ? AND course_code = ? ORDER BY id DESC LIMIT 10`,
      user.id, course
    );

    return NextResponse.json({
      globalScore,
      levels: LEVEL_LABELS,
      concepts: mastery,
      practicedCount: practiced.length,
      weekScores: [...weeks.entries()].map(([week, v]) => ({ week, score: v.score / v.n })).sort((a, b) => a.week - b.week),
      streak,
      stats,
      recent,
      recommendations: recommendations(user.id, course),
    });
  } catch (e) {
    return apiError(e);
  }
}