import { NextRequest, NextResponse } from "next/server";
import { sql } from "@/lib/db";
import { PROFILE_IDS } from "@transportationer/shared";

export const runtime = "nodejs";

const VALID_MODES = ["walking", "cycling", "driving", "transit", "fifteen"];
const VALID_THRESHOLDS = [5, 8, 10, 12, 15, 20, 25, 30];

export async function GET(
  req: NextRequest,
  { params }: { params: Promise<{ tile: string[] }> },
) {
  const { tile } = await params;
  if (tile.length !== 3) {
    return new NextResponse("Invalid tile path", { status: 400 });
  }
  const z = parseInt(tile[0], 10);
  const x = parseInt(tile[1], 10);
  const y = parseInt(tile[2], 10);

  if ([z, x, y].some(isNaN)) {
    return new NextResponse("Invalid tile coordinates", { status: 400 });
  }

  const p = req.nextUrl.searchParams;
  const city = p.get("city") ?? "";
  const mode = p.get("mode") ?? "walking";
  const threshold = parseInt(p.get("threshold") ?? "15", 10);
  const profile = p.get("profile") ?? "universal";

  if (!city) return new NextResponse("Missing city", { status: 400 });
  if (!VALID_MODES.includes(mode)) return new NextResponse("Invalid mode", { status: 400 });
  const validProfile = (PROFILE_IDS as readonly string[]).includes(profile) ? profile : "universal";

  const closestThreshold = VALID_THRESHOLDS.reduce((prev, curr) =>
    Math.abs(curr - threshold) < Math.abs(prev - threshold) ? curr : prev,
  );

  try {
    const rows = await Promise.resolve(sql<{ mvt: Uint8Array }[]>`
      WITH
        envelope  AS (SELECT ST_TileEnvelope(${z}, ${x}, ${y}) AS env),
        city_info AS (SELECT COALESCE(resolution_m, 200) AS resolution_m FROM cities WHERE slug = ${city})
      SELECT ST_AsMVT(t, 'grid', 4096, 'geom') AS mvt
      FROM (
        SELECT
          ST_AsMVTGeom(
            ST_Expand(ST_Transform(gp.geom, 3857), ci.resolution_m::float / 2),
            e.env,
            4096, 0, true
          ) AS geom,
          MAX(gs.score) FILTER (WHERE gs.category = 'service_trade')    AS score_service_trade,
          MAX(gs.score) FILTER (WHERE gs.category = 'transport')         AS score_transport,
          MAX(gs.score) FILTER (WHERE gs.category = 'work_school')       AS score_work_school,
          MAX(gs.score) FILTER (WHERE gs.category = 'culture_community') AS score_culture_community,
          MAX(gs.score) FILTER (WHERE gs.category = 'recreation')        AS score_recreation
        FROM grid_points gp
        JOIN grid_scores gs ON gs.grid_point_id = gp.id
        CROSS JOIN envelope e
        CROSS JOIN city_info ci
        WHERE gp.city_slug = ${city}
          AND gs.travel_mode = ${mode}
          AND gs.threshold_min = ${closestThreshold}
          AND gs.profile = ${validProfile}
          AND ST_Intersects(
            ST_Transform(gp.geom, 3857),
            ST_Expand(e.env, ci.resolution_m::float / 2)
          )
        GROUP BY gp.id, gp.geom, e.env, ci.resolution_m
      ) t
      WHERE t.geom IS NOT NULL
    `);

    const buf = rows[0]?.mvt;
    const data = buf ? new Uint8Array(buf) : new Uint8Array(0);

    return new NextResponse(data, {
      headers: {
        "Content-Type": "application/x-protobuf",
        "Cache-Control": "public, max-age=300",
        "Access-Control-Allow-Origin": "*",
      },
    });
  } catch (err) {
    console.error("[tiles/grid] Error:", err);
    return new NextResponse("Internal Server Error", { status: 500 });
  }
}