/*

 * Copyright 2023 Google LLC

 *

 * Use of this source code is governed by a BSD-style license that can be

 * found in the LICENSE file.

 */

#include "fuzz/Fuzz.h"

#include "include/private/base/SkAssert.h"

#include "include/private/base/SkFloatingPoint.h"

#include "src/base/SkCubics.h"

#include "src/base/SkQuads.h"

#include "src/base/SkUtils.h"

#include <cmath>

static void fuzz_cubic_real_roots(double A, double B, double C, double D) {

    double roots[3];

    const int numSolutions = SkCubics::RootsReal(A, B, C, D, roots);

    SkASSERT_RELEASE(numSolutions >= 0 && numSolutions <= 3);

    for (int i = 0; i < numSolutions; i++) {

        SkASSERT_RELEASE(std::isfinite(roots[i]));

    }

    // Roots should not be duplicated

    if (numSolutions >= 2) {

        SkASSERT_RELEASE(!sk_doubles_nearly_equal_ulps(roots[0], roots[1]));

    }

    if (numSolutions == 3) {

        SkASSERT_RELEASE(!sk_doubles_nearly_equal_ulps(roots[1], roots[2]));

        SkASSERT_RELEASE(!sk_doubles_nearly_equal_ulps(roots[0], roots[2]));

    }

}

static void fuzz_cubic_roots_valid_t(double A, double B, double C, double D) {

    double roots[3];

    const int numSolutions = SkCubics::RootsValidT(A, B, C, D, roots);

    SkASSERT_RELEASE(numSolutions >= 0 && numSolutions <= 3);

    for (int i = 0; i < numSolutions; i++) {

        SkASSERT_RELEASE(std::isfinite(roots[i]));

        SkASSERT_RELEASE(roots[i] >= 0.0);

        SkASSERT_RELEASE(roots[i] <= 1.0);

    }

    // Roots should not be duplicated

    if (numSolutions >= 2) {

        SkASSERT_RELEASE(!sk_doubles_nearly_equal_ulps(roots[0], roots[1]));

    }

    if (numSolutions == 3) {

        SkASSERT_RELEASE(!sk_doubles_nearly_equal_ulps(roots[1], roots[2]));

        SkASSERT_RELEASE(!sk_doubles_nearly_equal_ulps(roots[0], roots[2]));

    }

}

static void fuzz_cubic_roots_binary_search(double A, double B, double C, double D) {

    double roots[3];

    const int numSolutions = SkCubics::BinarySearchRootsValidT(A, B, C, D, roots);

    SkASSERT_RELEASE(numSolutions >= 0 && numSolutions <= 3);

    for (int i = 0; i < numSolutions; i++) {

        SkASSERT_RELEASE(std::isfinite(roots[i]));

        SkASSERT_RELEASE(roots[i] >= 0.0);

        SkASSERT_RELEASE(roots[i] <= 1.0);

        double actual = SkCubics::EvalAt(A, B, C, D, roots[i]);

        // The binary search algorithm *should* be accurate regardless of the inputs.

        SkASSERT_RELEASE(std::abs(actual) < 0.001);

    }

    // Roots should not be duplicated

    if (numSolutions >= 2) {

        SkASSERT_RELEASE(!sk_doubles_nearly_equal_ulps(roots[0], roots[1]));

    }

    if (numSolutions == 3) {

        SkASSERT_RELEASE(!sk_doubles_nearly_equal_ulps(roots[1], roots[2]));

        SkASSERT_RELEASE(!sk_doubles_nearly_equal_ulps(roots[0], roots[2]));

    }

}

DEF_FUZZ(CubicRoots, fuzz) {

    double A, B, C, D;

    fuzz->next(&A);

    fuzz->next(&B);

    fuzz->next(&C);

    fuzz->next(&D);

    // Uncomment for easy test case creation

//    SkDebugf("A %16e (0x%lx) B %16e (0x%lx) C %16e (0x%lx) D %16e (0x%lx)\n",

//             A, sk_bit_cast<uint64_t>(A), B, sk_bit_cast<uint64_t>(B),

//             C, sk_bit_cast<uint64_t>(C), D, sk_bit_cast<uint64_t>(D));

    fuzz_cubic_real_roots(A, B, C, D);

    fuzz_cubic_roots_valid_t(A, B, C, D);

    fuzz_cubic_roots_binary_search(A, B, C, D);

}