import { NextRequest, NextResponse } from "next/server";
import { sql } from "@/lib/db";
import { cacheGet, cacheSet, hashParams } from "@/lib/cache";
import type { CityStats } from "@transportationer/shared";

export const runtime = "nodejs";

export async function GET(req: NextRequest) {
  const city = req.nextUrl.searchParams.get("city") ?? "berlin";
  const mode = req.nextUrl.searchParams.get("mode") ?? "walking";
  const threshold = parseInt(
    req.nextUrl.searchParams.get("threshold") ?? "15",
    10,
  );

  const profile = req.nextUrl.searchParams.get("profile") ?? "universal";

  const cacheKey = `api:stats:${hashParams({ city, mode, threshold, profile })}`;
  const cached = await cacheGet<CityStats>(cacheKey);
  if (cached) {
    return NextResponse.json(cached, { headers: { "X-Cache": "HIT" } });
  }

  const [poiCounts, gridCount, percentiles] = await Promise.all([
    Promise.resolve(sql<{ category: string; count: number }[]>`
      SELECT category, COUNT(*)::int AS count
      FROM raw_pois
      WHERE city_slug = ${city}
      GROUP BY category
    `),
    Promise.resolve(sql<{ count: number }[]>`
      SELECT COUNT(*)::int AS count FROM grid_points WHERE city_slug = ${city}
    `),
    Promise.resolve(sql<{
      category: string;
      p10: number; p25: number; p50: number; p75: number; p90: number;
      coverage_pct: number;
    }[]>`
      SELECT
        gs.category,
        PERCENTILE_CONT(0.10) WITHIN GROUP (ORDER BY gs.score)::float AS p10,
        PERCENTILE_CONT(0.25) WITHIN GROUP (ORDER BY gs.score)::float AS p25,
        PERCENTILE_CONT(0.50) WITHIN GROUP (ORDER BY gs.score)::float AS p50,
        PERCENTILE_CONT(0.75) WITHIN GROUP (ORDER BY gs.score)::float AS p75,
        PERCENTILE_CONT(0.90) WITHIN GROUP (ORDER BY gs.score)::float AS p90,
        (COUNT(*) FILTER (WHERE gs.score >= 0.5) * 100.0 / COUNT(*))::float AS coverage_pct
      FROM grid_scores gs
      JOIN grid_points gp ON gp.id = gs.grid_point_id
      WHERE gp.city_slug = ${city}
        AND gs.travel_mode = ${mode}
        AND gs.threshold_min = ${threshold}
        AND gs.profile = ${profile}
      GROUP BY gs.category
    `),
  ]);

  const poisByCategory = Object.fromEntries(
    poiCounts.map((r) => [r.category, r.count]),
  );

  const stats: CityStats = {
    citySlug: city,
    totalPois: Object.values(poisByCategory).reduce((a, b) => a + b, 0),
    gridPointCount: gridCount[0]?.count ?? 0,
    categoryStats: percentiles.map((r) => ({
      category: r.category as any,
      poiCount: poisByCategory[r.category] ?? 0,
      p10: r.p10,
      p25: r.p25,
      p50: r.p50,
      p75: r.p75,
      p90: r.p90,
      coveragePct: r.coverage_pct,
    })),
  };

  await cacheSet(cacheKey, stats, "API_STATS");
  return NextResponse.json(stats);
}