src/apps/testapps/testGridDistance.c

/*
 * Copyright 2018-2020 Uber Technologies, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/** @file
 * @brief tests H3 distance function.
 *
 *  usage: `testGridDistance`
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "algos.h"
#include "baseCells.h"
#include "constants.h"
#include "h3Index.h"
#include "h3api.h"
#include "localij.h"
#include "test.h"
#include "utility.h"

SUITE(gridDistance) {
    // Some indexes that represent base cells. Base cells
    // are hexagons except for `pent1`.
    H3Index bc1 = H3_INIT;
    setH3Index(&bc1, 0, 15, 0);

    H3Index bc2 = H3_INIT;
    setH3Index(&bc2, 0, 8, 0);

    H3Index bc3 = H3_INIT;
    setH3Index(&bc3, 0, 31, 0);

    H3Index pent1 = H3_INIT;
    setH3Index(&pent1, 0, 4, 0);

    TEST(testIndexDistance) {
        H3Index bc = 0;
        setH3Index(&bc, 1, 17, 0);
        H3Index p = 0;
        setH3Index(&p, 1, 14, 0);
        H3Index p2;
        setH3Index(&p2, 1, 14, 2);
        H3Index p3;
        setH3Index(&p3, 1, 14, 3);
        H3Index p4;
        setH3Index(&p4, 1, 14, 4);
        H3Index p5;
        setH3Index(&p5, 1, 14, 5);
        H3Index p6;
        setH3Index(&p6, 1, 14, 6);

        int64_t distance;
        t_assertSuccess(H3_EXPORT(gridDistance)(bc, p, &distance));
        t_assert(distance == 3, "distance onto pentagon");
        t_assertSuccess(H3_EXPORT(gridDistance)(bc, p2, &distance));
        t_assert(distance == 2, "distance onto p2");
        t_assertSuccess(H3_EXPORT(gridDistance)(bc, p3, &distance));
        t_assert(distance == 3, "distance onto p3");
        // TODO works correctly but is rejected due to possible pentagon
        // distortion.
        // t_assertSuccess(H3_EXPORT(gridDistance)(bc, p4, &distance));
        // t_assert(distance == 3, "distance onto p4");
        // t_assertSuccess(H3_EXPORT(gridDistance)(bc, p5, &distance));
        // t_assert(distance == 4, "distance onto p5");
        t_assertSuccess(H3_EXPORT(gridDistance)(bc, p6, &distance));
        t_assert(distance == 2, "distance onto p6");
    }

    TEST(testIndexDistance2) {
        H3Index origin = 0x820c4ffffffffffL;
        // Destination is on the other side of the pentagon
        H3Index destination = 0x821ce7fffffffffL;

        // TODO doesn't work because of pentagon distortion. Both should be 5.
        int64_t distance;
        t_assert(H3_EXPORT(gridDistance)(destination, origin, &distance) !=
                     E_SUCCESS,
                 "distance in res 2 across pentagon");
        t_assert(H3_EXPORT(gridDistance)(origin, destination, &distance) !=
                     E_SUCCESS,
                 "distance in res 2 across pentagon (reversed)");
    }

    TEST(gridDistanceBaseCells) {
        int64_t distance;
        t_assertSuccess(H3_EXPORT(gridDistance)(bc1, pent1, &distance));
        t_assert(distance == 1, "distance to neighbor is 1 (15, 4)");
        t_assertSuccess(H3_EXPORT(gridDistance)(bc1, bc2, &distance));
        t_assert(distance == 1, "distance to neighbor is 1 (15, 8)");
        t_assertSuccess(H3_EXPORT(gridDistance)(bc1, bc3, &distance));
        t_assert(distance == 1, "distance to neighbor is 1 (15, 31)");
        t_assert(H3_EXPORT(gridDistance)(pent1, bc3, &distance) != E_SUCCESS,
                 "distance to neighbor is invalid");
    }

    TEST(gridDistanceResolutionMismatch) {
        int64_t distance;
        t_assert(H3_EXPORT(gridDistance)(0x832830fffffffffL, 0x822837fffffffffL,
                                         &distance) == E_RES_MISMATCH,
                 "cannot compare at different resolutions");
    }

    TEST(gridDistanceEdge) {
        H3Index origin = 0x832830fffffffffL;
        H3Index dest = 0x832834fffffffffL;
        H3Index edge;
        t_assertSuccess(H3_EXPORT(cellsToDirectedEdge)(origin, dest, &edge));

        t_assert(0 != edge, "test edge is valid");
        int64_t distance;
        t_assertSuccess(H3_EXPORT(gridDistance)(edge, origin, &distance));
        t_assert(distance == 0, "edge has zero distance to origin");
        t_assertSuccess(H3_EXPORT(gridDistance)(origin, edge, &distance));
        t_assert(distance == 0, "origin has zero distance to edge");

        t_assertSuccess(H3_EXPORT(gridDistance)(edge, dest, &distance));
        t_assert(distance == 1, "edge has distance to destination");
        t_assertSuccess(H3_EXPORT(gridDistance)(dest, edge, &distance));
        t_assert(distance == 1, "destination has distance to edge");
    }

    TEST(gridDistanceInvalid) {
        H3Index invalid = 0xffffffffffffffff;
        int64_t distance;
        t_assert(H3_EXPORT(gridDistance)(invalid, invalid, &distance) ==
                     E_CELL_INVALID,
                 "distance from invalid cell");

        t_assert(
            H3_EXPORT(gridDistance)(bc1, invalid, &distance) == E_RES_MISMATCH,
            "distance to invalid cell");
    }
}