import {bench, describe} from 'vitest';
import Point from '@mapbox/point-geometry';
import {LngLat} from '../lng_lat.ts';
import {MercatorCoordinate} from '../mercator_coordinate.ts';
import {MercatorTransform} from './mercator_transform.ts';
import {OverscaledTileID} from '../../tile/tile_id.ts';
import {createDEM, createDEMTerrain} from '../../util/test/util.ts';
import type {Terrain} from '../../render/terrain.ts';

const DEM_DIM = 256;

function createScene(zoom: number, heightFn: (x: number, y: number) => number, pitch: number): {terrain: Terrain; transform: MercatorTransform} {
    const transform = new MercatorTransform({minZoom: 0, maxZoom: 22, minPitch: 0, maxPitch: 85, renderWorldCopies: true});
    transform.resize(1024, 1024);
    transform.setCenter(new LngLat(11.4, 47.3));
    transform.setZoom(zoom);
    transform.setPitch(pitch);

    const tileZoom = Math.max(Math.floor(zoom) - 1, 0);
    const scale = 1 << tileZoom;
    const center = MercatorCoordinate.fromLngLat(transform.center);
    const centerX = Math.floor(center.x * scale);
    const centerY = Math.floor(center.y * scale);
    const tileIDs: OverscaledTileID[] = [];
    for (let dy = -2; dy <= 2; dy++) {
        for (let dx = -2; dx <= 2; dx++) {
            const x = centerX + dx;
            const y = centerY + dy;
            if (x < 0 || y < 0 || x >= scale || y >= scale) continue;
            tileIDs.push(new OverscaledTileID(tileZoom, 0, tileZoom, x, y));
        }
    }

    const terrain = createDEMTerrain(tileIDs, createDEM(heightFn, DEM_DIM));
    return {terrain, transform};
}

describe('terrain raycast', () => {
    for (const zoom of [2, 10, 16]) {
        const flatScene = createScene(zoom, () => 800, 50);
        bench(`flat hit z${zoom}`, () => {
            flatScene.transform.screenTerrainPointToMercatorCoordinate(new Point(512, 600), flatScene.terrain);
        });

        const slopedScene = createScene(zoom, (x, y) => 400 + 8 * x + 6 * y, 50);
        bench(`sloped hit z${zoom}`, () => {
            slopedScene.transform.screenTerrainPointToMercatorCoordinate(new Point(512, 600), slopedScene.terrain);
        });

        const skyScene = createScene(zoom, () => 0, 80);
        bench(`sky miss z${zoom}`, () => {
            skyScene.transform.screenTerrainPointToMercatorCoordinate(new Point(512, 20), skyScene.terrain);
        });
    }
});