// Plan d'étude personnalisé : génération, consultation, progression (items cochés).
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 { get, run } from "@/lib/db/index.ts";
import { generatePlan } from "@/lib/learning/plan.ts";
import { normalizeCourse } from "@/lib/learning/helpers.ts";
import { logActivity } 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 plan = get<{ id: number; exam_date: string; config: string; plan: string; created_at: string }>(
      "SELECT id, exam_date, config, plan, created_at FROM study_plans WHERE user_id = ? AND course_code = ? AND active = 1 ORDER BY id DESC LIMIT 1",
      user.id, course
    );
    return NextResponse.json({
      plan: plan ? { id: plan.id, examDate: plan.exam_date, config: JSON.parse(plan.config), days: JSON.parse(plan.plan), createdAt: plan.created_at } : null,
    });
  } catch (e) {
    return apiError(e);
  }
}

const createSchema = z.object({
  action: z.literal("create"),
  examDate: z.string().regex(/^\d{4}-\d{2}-\d{2}$/),
  weekdays: z.array(z.number().int().min(0).max(6)).min(1),
  minutesPerSession: z.number().int().min(20).max(360),
  weeksScope: z.tuple([z.number().int().min(1).max(14), z.number().int().min(1).max(14)]),
});
const toggleSchema = z.object({
  action: z.literal("toggle"),
  planId: z.number().int().positive(),
  date: z.string(),
  itemIndex: z.number().int().min(0),
  done: z.boolean(),
});

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, z.discriminatedUnion("action", [createSchema, toggleSchema]));

    if (body.action === "create") {
      if (new Date(body.examDate) <= new Date()) {
        return NextResponse.json({ error: "La date d'examen doit être dans le futur." }, { status: 400 });
      }
      const days = generatePlan(user.id, course, {
        examDate: body.examDate,
        weekdays: body.weekdays,
        minutesPerSession: body.minutesPerSession,
        weeksScope: body.weeksScope,
      });
      if (!days.length) return NextResponse.json({ error: "Aucun jour disponible avant l'examen avec ces choix." }, { status: 400 });
      run("UPDATE study_plans SET active = 0 WHERE user_id = ? AND course_code = ?", user.id, course);
      const r = run(
        "INSERT INTO study_plans (user_id, course_code, exam_date, config, plan, active) VALUES (?, ?, ?, ?, ?, 1)",
        user.id, course, body.examDate,
        JSON.stringify({ weekdays: body.weekdays, minutesPerSession: body.minutesPerSession, weeksScope: body.weeksScope }),
        JSON.stringify(days)
      );
      logActivity(user.id, "plan", course, 60);
      return NextResponse.json({ ok: true, planId: Number(r.lastInsertRowid), days });
    }

    // toggle
    const plan = get<{ id: number; plan: string }>(
      "SELECT id, plan FROM study_plans WHERE id = ? AND user_id = ? AND course_code = ?",
      body.planId, user.id, course
    );
    if (!plan) return NextResponse.json({ error: "Plan introuvable." }, { status: 404 });
    const days = JSON.parse(plan.plan) as { date: string; items: { done?: boolean }[] }[];
    const day = days.find((d) => d.date === body.date);
    if (!day || !day.items[body.itemIndex]) return NextResponse.json({ error: "Élément introuvable." }, { status: 404 });
    day.items[body.itemIndex].done = body.done;
    run("UPDATE study_plans SET plan = ? WHERE id = ?", JSON.stringify(days), plan.id);
    return NextResponse.json({ ok: true });
  } catch (e) {
    return apiError(e);
  }
}