// Author: Simon-Pierre Boucher
// Contact: contact@spboucher.ai
// Project: chat.spboucher.ai

import { NextResponse, type NextRequest } from "next/server";
import { requireSession } from "@/lib/auth/guard";
import { getDb } from "@/lib/db/database";

export const runtime = "nodejs";

const PERIODS: Record<string, number | null> = {
  today: 1000 * 60 * 60 * 24,
  "7d": 1000 * 60 * 60 * 24 * 7,
  "30d": 1000 * 60 * 60 * 24 * 30,
  all: null,
};

export async function GET(req: NextRequest) {
  const { unauthorized } = await requireSession();
  if (unauthorized) return unauthorized;

  const period = req.nextUrl.searchParams.get("period") ?? "7d";
  const windowMs = PERIODS[period] ?? PERIODS["7d"];
  const since = windowMs === null ? 0 : Date.now() - windowMs;
  const db = getDb();

  const totals = db
    .prepare(
      `SELECT COUNT(*) AS requests,
              COALESCE(SUM(prompt_tokens), 0) AS prompt_tokens,
              COALESCE(SUM(completion_tokens), 0) AS completion_tokens,
              COALESCE(SUM(reasoning_tokens), 0) AS reasoning_tokens,
              COALESCE(SUM(total_tokens), 0) AS total_tokens,
              COALESCE(SUM(COALESCE(reported_cost_usd, estimated_cost_usd)), 0) AS cost_usd
       FROM generation_usage WHERE created_at >= ?`
    )
    .get(since) as Record<string, number>;

  const byModel = db
    .prepare(
      `SELECT gu.model_id,
              COALESCE(m.name, gu.model_id) AS model_name,
              m.provider,
              COUNT(*) AS requests,
              COALESCE(SUM(gu.total_tokens), 0) AS total_tokens,
              COALESCE(SUM(COALESCE(gu.reported_cost_usd, gu.estimated_cost_usd)), 0) AS cost_usd
       FROM generation_usage gu
       LEFT JOIN models m ON m.openrouter_model_id = gu.model_id
       WHERE gu.created_at >= ?
       GROUP BY gu.model_id
       ORDER BY cost_usd DESC, requests DESC
       LIMIT 25`
    )
    .all(since);

  const byDay = db
    .prepare(
      `SELECT date(created_at / 1000, 'unixepoch', 'localtime') AS day,
              COUNT(*) AS requests,
              COALESCE(SUM(total_tokens), 0) AS total_tokens,
              COALESCE(SUM(COALESCE(reported_cost_usd, estimated_cost_usd)), 0) AS cost_usd
       FROM generation_usage WHERE created_at >= ?
       GROUP BY day ORDER BY day`
    )
    .all(since);

  return NextResponse.json({ period, totals, byModel, byDay });
}