// Diapositives d'une séance (contenu structuré) — et PDF original via ?pdf=1.
import { NextResponse } from "next/server";
import { createReadStream, existsSync, statSync } from "node:fs";
import { Readable } from "node:stream";
import { resolve } from "node:path";
import { apiError, requireEnrollment } from "@/lib/api.ts";
import { AuthError, requireUser } from "@/lib/auth/session.ts";
import { all, get } from "@/lib/db/index.ts";
import { normalizeCourse } from "@/lib/learning/helpers.ts";

export async function GET(req: Request, ctx: { params: Promise<{ course: string; week: string }> }) {
  try {
    const user = await requireUser();
    const params = await ctx.params;
    const course = normalizeCourse(params.course);
    requireEnrollment(user.id, course);
    const week = parseInt(params.week, 10);
    if (!Number.isInteger(week) || week < 1 || week > 14) throw new AuthError(404, "Séance inconnue.");

    const doc = get<{ id: number; title: string; path: string }>(
      "SELECT id, title, path FROM documents WHERE course_code = ? AND doc_type = 'slides' AND week = ? AND visible_to_students = 1",
      course, week
    );
    if (!doc) throw new AuthError(404, "Séance introuvable.");

    // PDF original compilé (même chemin que la source .tex)
    if (new URL(req.url).searchParams.get("pdf") === "1") {
      const pdfPath = resolve(process.cwd(), "..", doc.path.replace(/\.tex$/, ".pdf"));
      if (!existsSync(pdfPath)) return NextResponse.json({ error: "PDF non disponible pour cette séance." }, { status: 404 });
      const size = statSync(pdfPath).size;
      const stream = Readable.toWeb(createReadStream(pdfPath)) as ReadableStream;
      return new Response(stream, {
        headers: {
          "Content-Type": "application/pdf",
          "Content-Length": String(size),
          "Content-Disposition": `inline; filename="${course}-seance${String(week).padStart(2, "0")}.pdf"`,
          "Cache-Control": "private, max-age=3600",
        },
      });
    }

    const slides = all<{ ref_number: number; title: string; section_title: string; display_content: string; box_types: string }>(
      `SELECT ref_number, title, section_title, display_content, box_types
       FROM chunks WHERE document_id = ? AND ref_type = 'slide' ORDER BY ref_number, seq`,
      doc.id
    );
    return NextResponse.json({ deck: { week, title: doc.title }, slides });
  } catch (e) {
    return apiError(e);
  }
}