import { prisma } from "@/lib/prisma";

// НЕ "clean-pdf": так CopyButton логирует копирования — они не должны тратить лимит
export const PDF_TOOL_ID = "clean-pdf-generate";
export const BURST_LIMIT = 5; // успешных генераций в минуту
const BURST_WINDOW_MS = 60_000;

export function decidePaidAccess(input: {
  role: string;
  banned: boolean;
  enrollments: { courseSlug: string; expiresAt: Date | null }[];
  freeSlug: string;
  now?: Date;
}): boolean {
  const now = input.now ?? new Date();
  if (input.banned) return false;
  if (input.role === "admin" || input.role === "curator") return true;
  return input.enrollments.some(
    (e) => e.courseSlug !== input.freeSlug && (e.expiresAt === null || e.expiresAt > now),
  );
}

export async function hasPaidAccess(userId: string): Promise<boolean> {
  const user = await prisma.user.findUnique({
    where: { id: userId },
    select: {
      role: true,
      banned: true,
      enrollments: { select: { expiresAt: true, course: { select: { slug: true } } } },
    },
  });
  if (!user) return false;
  return decidePaidAccess({
    role: user.role,
    banned: user.banned ?? false,
    freeSlug: process.env.FREE_COURSE_SLUG ?? "obsidian-start",
    enrollments: user.enrollments.map((e) => ({ courseSlug: e.course.slug, expiresAt: e.expiresAt })),
  });
}

export function monthStartUtc(now: Date): Date {
  return new Date(Date.UTC(now.getUTCFullYear(), now.getUTCMonth(), 1));
}

export function getMonthlyLimit(): number {
  const n = Number(process.env.PDF_MONTHLY_LIMIT);
  return Number.isFinite(n) && n > 0 ? n : 100;
}

export async function getMonthlyUsage(userId: string): Promise<number> {
  return prisma.toolUsage.count({
    where: { userId, tool: PDF_TOOL_ID, createdAt: { gte: monthStartUtc(new Date()) } },
  });
}

export async function getBurstUsage(userId: string): Promise<number> {
  return prisma.toolUsage.count({
    where: { userId, tool: PDF_TOOL_ID, createdAt: { gte: new Date(Date.now() - BURST_WINDOW_MS) } },
  });
}