import { NextRequest, NextResponse } from "next/server";
import { sql } from "@/lib/db";
import type { CategoryId, ProfileId } from "@transportationer/shared";
import {
  CATEGORY_IDS,
  PROFILE_IDS,
  TRAVEL_MODES,
  VALID_THRESHOLDS,
} from "@transportationer/shared";

export const runtime = "nodejs";

export async function GET(req: NextRequest) {
  const p = req.nextUrl.searchParams;
  const lat = parseFloat(p.get("lat") ?? "");
  const lng = parseFloat(p.get("lng") ?? "");
  const city = p.get("city") ?? "";
  const mode = p.get("mode") ?? "walking";
  const threshold = parseInt(p.get("threshold") ?? "15", 10);
  const profileId = (PROFILE_IDS as readonly string[]).includes(p.get("profile") ?? "")
    ? (p.get("profile") as ProfileId)
    : "universal" as ProfileId;

  if (isNaN(lat) || isNaN(lng)) {
    return NextResponse.json({ error: "Invalid lat/lng" }, { status: 400 });
  }
  if (!city) return NextResponse.json({ error: "Missing city" }, { status: 400 });
  if (!(TRAVEL_MODES as readonly string[]).includes(mode)) {
    return NextResponse.json({ error: "Invalid mode" }, { status: 400 });
  }

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

  const rows = await Promise.resolve(sql<{
    grid_point_id: string;
    grid_lat: number;
    grid_lng: number;
    score_service_trade: number | null;
    score_transport: number | null;
    score_work_school: number | null;
    score_culture_community: number | null;
    score_recreation: number | null;
    dist_service_trade: number | null;
    dist_transport: number | null;
    dist_work_school: number | null;
    dist_culture_community: number | null;
    dist_recreation: number | null;
    time_service_trade: number | null;
    time_transport: number | null;
    time_work_school: number | null;
    time_culture_community: number | null;
    time_recreation: number | null;
  }[]>`
    WITH nearest AS (
      SELECT gp.id,
             gp.id::text AS grid_point_id,
             ST_Y(gp.geom)::float AS grid_lat,
             ST_X(gp.geom)::float AS grid_lng
      FROM grid_points gp
      WHERE gp.city_slug = ${city}
      ORDER BY gp.geom <-> ST_SetSRID(ST_MakePoint(${lng}, ${lat}), 4326)
      LIMIT 1
    )
    SELECT
      n.grid_point_id,
      n.grid_lat, n.grid_lng,
      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,
      MAX(gs.distance_m)  FILTER (WHERE gs.category = 'service_trade')     AS dist_service_trade,
      MAX(gs.distance_m)  FILTER (WHERE gs.category = 'transport')          AS dist_transport,
      MAX(gs.distance_m)  FILTER (WHERE gs.category = 'work_school')        AS dist_work_school,
      MAX(gs.distance_m)  FILTER (WHERE gs.category = 'culture_community')  AS dist_culture_community,
      MAX(gs.distance_m)  FILTER (WHERE gs.category = 'recreation')         AS dist_recreation,
      MAX(gs.travel_time_s) FILTER (WHERE gs.category = 'service_trade')    AS time_service_trade,
      MAX(gs.travel_time_s) FILTER (WHERE gs.category = 'transport')         AS time_transport,
      MAX(gs.travel_time_s) FILTER (WHERE gs.category = 'work_school')       AS time_work_school,
      MAX(gs.travel_time_s) FILTER (WHERE gs.category = 'culture_community') AS time_culture_community,
      MAX(gs.travel_time_s) FILTER (WHERE gs.category = 'recreation')        AS time_recreation
    FROM nearest n
    JOIN grid_scores gs ON gs.grid_point_id = n.id
    WHERE gs.travel_mode = ${mode}
      AND gs.threshold_min = ${closestThreshold}
      AND gs.profile = ${profileId}
    GROUP BY n.grid_point_id, n.grid_lat, n.grid_lng
  `);

  if (rows.length === 0) {
    return NextResponse.json(
      { error: "No grid data for this location" },
      { status: 404 },
    );
  }

  const r = rows[0];

  const categoryScores: Record<CategoryId, number> = {
    service_trade:     r.score_service_trade     ?? 0,
    transport:         r.score_transport          ?? 0,
    work_school:       r.score_work_school        ?? 0,
    culture_community: r.score_culture_community  ?? 0,
    recreation:        r.score_recreation         ?? 0,
  };

  const distancesM: Partial<Record<CategoryId, number>> = {
    service_trade:     r.dist_service_trade     ?? undefined,
    transport:         r.dist_transport          ?? undefined,
    work_school:       r.dist_work_school        ?? undefined,
    culture_community: r.dist_culture_community  ?? undefined,
    recreation:        r.dist_recreation         ?? undefined,
  };

  const travelTimesS: Partial<Record<CategoryId, number>> = {
    service_trade:     r.time_service_trade     ?? undefined,
    transport:         r.time_transport          ?? undefined,
    work_school:       r.time_work_school        ?? undefined,
    culture_community: r.time_culture_community  ?? undefined,
    recreation:        r.time_recreation         ?? undefined,
  };

  // "fifteen" is synthetic — grid_poi_details only stores the raw modes
  // (walking, cycling, transit, driving). For fifteen we query all three
  // contributing modes and pick the best (minimum travel_time_s) per subcategory.
  const detailModes = mode === "fifteen" ? ["walking", "cycling", "transit"] : [mode];

  // Fetch nearest POI per subcategory for this grid point and mode.
  const detailRows = await Promise.resolve(sql<{
    category: string;
    subcategory: string;
    nearest_poi_name: string | null;
    distance_m: number | null;
    travel_time_s: number | null;
  }[]>`
    SELECT DISTINCT ON (category, subcategory)
      category, subcategory, nearest_poi_name, distance_m, travel_time_s
    FROM grid_poi_details
    WHERE grid_point_id = ${r.grid_point_id}::bigint
      AND travel_mode = ANY(${detailModes})
    ORDER BY category, subcategory, travel_time_s ASC NULLS LAST
  `);

  type SubcategoryDetail = {
    subcategory: string;
    name: string | null;
    distanceM: number | null;
    travelTimeS: number | null;
  };

  const subcategoryDetails: Partial<Record<CategoryId, SubcategoryDetail[]>> = {};
  for (const cat of CATEGORY_IDS) {
    subcategoryDetails[cat] = [];
  }
  for (const row of detailRows) {
    const cat = row.category as CategoryId;
    if (subcategoryDetails[cat]) {
      subcategoryDetails[cat]!.push({
        subcategory: row.subcategory,
        name: row.nearest_poi_name,
        distanceM: row.distance_m,
        travelTimeS: row.travel_time_s,
      });
    }
  }

  return NextResponse.json({
    lat: r.grid_lat,
    lng: r.grid_lng,
    categoryScores,
    distancesM,
    travelTimesS,
    subcategoryDetails,
    profile: profileId,
  });
}