// Résumés intelligents : générés depuis les sources du cours (RAG), avec citations validées.
import { NextResponse } from "next/server";
import { z } from "zod";
import { apiError, parseBody, requireEnrollment } from "@/lib/api.ts";
import { assertSameOrigin, requireUser } from "@/lib/auth/session.ts";
import { all, run } from "@/lib/db/index.ts";
import { normalizeCourse } from "@/lib/learning/helpers.ts";
import { getPrompt } from "@/lib/prompts.ts";
import { completeChat } from "@/lib/openrouter/client.ts";
import { resolvePreset, getModel, estimateCost } from "@/lib/openrouter/registry.ts";
import { buildContext, type RetrievedChunk } from "@/lib/rag/search.ts";
import { resolveCitations } from "@/lib/rag/citations.ts";
import { checkBudget, logActivity, logUsage } from "@/lib/usage.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 summaries = all(
      `SELECT id, scope, ref, title, content, citations, created_by, created_at FROM summaries
       WHERE course_code = ? AND (owner_user_id IS NULL OR owner_user_id = ?) ORDER BY id DESC LIMIT 100`,
      course, user.id
    );
    return NextResponse.json({ summaries });
  } catch (e) {
    return apiError(e);
  }
}

const schema = z.object({
  scope: z.enum(["week", "concept", "exam-prep"]),
  week: z.number().int().min(1).max(14).optional(),
  conceptSlug: z.string().max(120).optional(),
  style: z.enum(["ultra-court", "detaille", "avec-formules"]).default("detaille"),
});

export async function POST(req: Request, ctx: { params: Promise<{ course: string }> }) {
  try {
    await assertSameOrigin();
    const user = await requireUser();
    const course = normalizeCourse((await ctx.params).course);
    requireEnrollment(user.id, course);
    const body = await parseBody(req, schema);
    const budget = checkBudget(user.id);
    if (!budget.ok) return NextResponse.json({ error: budget.reason }, { status: 429 });

    // Sélection directe des fragments (pas de recherche : on veut la couverture du scope).
    let chunks: RetrievedChunk[] = [];
    let title = "";
    let ref = "";
    if (body.scope === "week") {
      if (!body.week) return NextResponse.json({ error: "Semaine requise." }, { status: 400 });
      chunks = all<RetrievedChunk>(
        `SELECT c.id, c.document_id, c.course_code, c.space, c.ref_type, c.ref_number, c.ref_label,
                c.section_title, c.title, c.content, c.box_types, c.week,
                d.title as doc_title, d.path as doc_path, d.filename, 1.0 as score
         FROM chunks c JOIN documents d ON d.id = c.document_id
         WHERE c.course_code = ? AND c.space = ? AND c.week = ? AND c.ref_type = 'slide'
         ORDER BY c.ref_number LIMIT 90`,
        course, `official-${course.toLowerCase()}`, body.week
      );
      title = `Résumé — Séance ${body.week}`;
      ref = `semaine-${body.week}`;
    } else if (body.scope === "concept") {
      if (!body.conceptSlug) return NextResponse.json({ error: "Concept requis." }, { status: 400 });
      const { hybridSearch } = await import("@/lib/rag/search.ts");
      const concept = all<{ name: string; description: string }>(
        "SELECT name, description FROM concepts WHERE course_code = ? AND slug = ?", course, body.conceptSlug
      )[0];
      if (!concept) return NextResponse.json({ error: "Concept inconnu." }, { status: 404 });
      chunks = await hybridSearch({ query: concept.name + ". " + concept.description, spaces: [`official-${course.toLowerCase()}`], k: 12 });
      title = `Résumé — ${concept.name}`;
      ref = body.conceptSlug;
    } else {
      chunks = all<RetrievedChunk>(
        `SELECT c.id, c.document_id, c.course_code, c.space, c.ref_type, c.ref_number, c.ref_label,
                c.section_title, c.title, c.content, c.box_types, c.week,
                d.title as doc_title, d.path as doc_path, d.filename, 1.0 as score
         FROM chunks c JOIN documents d ON d.id = c.document_id
         WHERE c.course_code = ? AND c.space = ? AND c.box_types != '' AND c.ref_type = 'slide'
         ORDER BY c.week, c.ref_number LIMIT 80`,
        course, `official-${course.toLowerCase()}`
      );
      title = "Résumé de préparation à l'examen";
      ref = "exam-prep";
    }
    if (!chunks.length) return NextResponse.json({ error: "Aucun contenu trouvé pour ce choix." }, { status: 404 });

    const context = buildContext(chunks, 26_000);
    const styleInstr = {
      "ultra-court": "Résumé ULTRA-COURT : une page maximum, uniquement l'essentiel en listes serrées.",
      detaille: "Résumé DÉTAILLÉ : structuré par sous-thèmes, avec exemples brefs et erreurs fréquentes.",
      "avec-formules": "Résumé AXÉ FORMULES : chaque formule en LaTeX avec ses variables définies, ses conditions d'application et un mini-exemple chiffré.",
    }[body.style];
    const model = await resolvePreset("recommande");
    const t0 = Date.now();
    const { text, promptTokens, completionTokens } = await completeChat({
      model,
      messages: [
        {
          role: "system",
          content: [getPrompt("base-system"), course === "IMM1003" ? getPrompt("course-imm1003") : getPrompt("course-imm1033"), getPrompt("rag-grounding"), getPrompt("citation-policy")].join("\n\n---\n\n"),
        },
        {
          role: "user",
          content: `Produis « ${title} » pour le cours ${course}. ${styleInstr}\nTermine par une section « Questions d'auto-vérification » (3 questions sans réponse).\n\nMatériel du cours :\n${context.text}`,
        },
      ],
      maxTokens: 4000,
      temperature: 0.3,
    });
    const mi = await getModel(model);
    logUsage({ userId: user.id, model, kind: "summary", tokensIn: promptTokens, tokensOut: completionTokens, cost: mi ? estimateCost(mi, promptTokens, completionTokens) : 0, latencyMs: Date.now() - t0 });

    const { cleaned, citations } = resolveCitations(text, context);
    const r = run(
      `INSERT INTO summaries (course_code, scope, ref, title, content, citations, owner_user_id, created_by)
       VALUES (?, ?, ?, ?, ?, ?, ?, 'ai')`,
      course, body.scope, ref, title, cleaned, JSON.stringify(citations), user.id
    );
    logActivity(user.id, "summary", course, 120);
    return NextResponse.json({ ok: true, id: Number(r.lastInsertRowid), title, content: cleaned, citations });
  } catch (e) {
    return apiError(e);
  }
}