// Copyright 2018 Ulf Adams
//
// The contents of this file may be used under the terms of the Apache License,
// Version 2.0.
//
//    (See accompanying file LICENSE-Apache or copy at
//     http://www.apache.org/licenses/LICENSE-2.0)
//
// Alternatively, the contents of this file may be used under the terms of
// the Boost Software License, Version 1.0.
//    (See accompanying file LICENSE-Boost or copy at
//     https://www.boost.org/LICENSE_1_0.txt)
//
// Unless required by applicable law or agreed to in writing, this software
// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.

#include <math.h>

#include "ryu/ryu.h"
#include "third_party/gtest/gtest.h"

static float int32Bits2Float(uint32_t bits) {
  float f;
  memcpy(&f, &bits, sizeof(float));
  return f;
}

#define ASSERT_F2S(a, b) { char* result = f2s(b); ASSERT_STREQ(a, result); free(result); } while (0);

TEST(F2sTest, Basic) {
  ASSERT_F2S("0E0", 0.0);
  ASSERT_F2S("-0E0", -0.0);
  ASSERT_F2S("1E0", 1.0);
  ASSERT_F2S("-1E0", -1.0);
  ASSERT_F2S("NaN", NAN);
  ASSERT_F2S("Infinity", INFINITY);
  ASSERT_F2S("-Infinity", -INFINITY);
}

TEST(F2sTest, SwitchToSubnormal) {
  ASSERT_F2S("1.1754944E-38", 1.1754944E-38f);
}

TEST(F2sTest, MinAndMax) {
  ASSERT_F2S("3.4028235E38", int32Bits2Float(0x7f7fffff));
  ASSERT_F2S("1E-45", int32Bits2Float(1));
}

// Check that we return the exact boundary if it is the shortest
// representation, but only if the original floating point number is even.
TEST(F2sTest, BoundaryRoundEven) {
  ASSERT_F2S("3.355445E7", 3.355445E7f);
  ASSERT_F2S("9E9", 8.999999E9f);
  ASSERT_F2S("3.436672E10", 3.4366717E10f);
}

// If the exact value is exactly halfway between two shortest representations,
// then we round to even. It seems like this only makes a difference if the
// last two digits are ...2|5 or ...7|5, and we cut off the 5.
TEST(F2sTest, ExactValueRoundEven) {
  ASSERT_F2S("3.0540412E5", 3.0540412E5f);
  ASSERT_F2S("8.0990312E3", 8.0990312E3f);
}

TEST(F2sTest, LotsOfTrailingZeros) {
  // Pattern for the first test: 00111001100000000000000000000000
  ASSERT_F2S("2.4414062E-4", 2.4414062E-4f);
  ASSERT_F2S("2.4414062E-3", 2.4414062E-3f);
  ASSERT_F2S("4.3945312E-3", 4.3945312E-3f);
  ASSERT_F2S("6.3476562E-3", 6.3476562E-3f);
}

TEST(F2sTest, Regression) {
  ASSERT_F2S("4.7223665E21", 4.7223665E21f);
  ASSERT_F2S("8.388608E6", 8388608.0f);
  ASSERT_F2S("1.6777216E7", 1.6777216E7f);
  ASSERT_F2S("3.3554436E7", 3.3554436E7f);
  ASSERT_F2S("6.7131496E7", 6.7131496E7f);
  ASSERT_F2S("1.9310392E-38", 1.9310392E-38f);
  ASSERT_F2S("-2.47E-43", -2.47E-43f);
  ASSERT_F2S("1.993244E-38", 1.993244E-38f);
  ASSERT_F2S("4.1039004E3", 4103.9003f);
  ASSERT_F2S("5.3399997E9", 5.3399997E9f);
  ASSERT_F2S("6.0898E-39", 6.0898E-39f);
  ASSERT_F2S("1.0310042E-3", 0.0010310042f);
  ASSERT_F2S("2.882326E17", 2.8823261E17f);
#ifndef _WIN32
  // MSVC rounds this up to the next higher floating point number
  ASSERT_F2S("7.038531E-26", 7.038531E-26f);
#else
  ASSERT_F2S("7.038531E-26", 7.0385309E-26f);
#endif
  ASSERT_F2S("9.223404E17", 9.2234038E17f);
  ASSERT_F2S("6.710887E7", 6.7108872E7f);
  ASSERT_F2S("1E-44", 1.0E-44f);
  ASSERT_F2S("2.816025E14", 2.816025E14f);
  ASSERT_F2S("9.223372E18", 9.223372E18f);
  ASSERT_F2S("1.5846086E29", 1.5846085E29f);
  ASSERT_F2S("1.1811161E19", 1.1811161E19f);
  ASSERT_F2S("5.368709E18", 5.368709E18f);
  ASSERT_F2S("4.6143166E18", 4.6143165E18f);
  ASSERT_F2S("7.812537E-3", 0.007812537f);
  ASSERT_F2S("1E-45", 1.4E-45f);
  ASSERT_F2S("1.18697725E20", 1.18697724E20f);
  ASSERT_F2S("1.00014165E-36", 1.00014165E-36f);
  ASSERT_F2S("2E2", 200.0f);
  ASSERT_F2S("3.3554432E7", 3.3554432E7f);
}

TEST(F2sTest, LooksLikePow5) {
  // These numbers have a mantissa that is the largest power of 5 that fits,
  // and an exponent that causes the computation for q to result in 10, which is a corner
  // case for Ryu.
  ASSERT_F2S("6.7108864E17", int32Bits2Float(0x5D1502F9));
  ASSERT_F2S("1.3421773E18", int32Bits2Float(0x5D9502F9));
  ASSERT_F2S("2.6843546E18", int32Bits2Float(0x5E1502F9));
}

TEST(F2sTest, OutputLength) {
  ASSERT_F2S("1E0", 1.0f); // already tested in Basic
  ASSERT_F2S("1.2E0", 1.2f);
  ASSERT_F2S("1.23E0", 1.23f);
  ASSERT_F2S("1.234E0", 1.234f);
  ASSERT_F2S("1.2345E0", 1.2345f);
  ASSERT_F2S("1.23456E0", 1.23456f);
  ASSERT_F2S("1.234567E0", 1.234567f);
  ASSERT_F2S("1.2345678E0", 1.2345678f);
  ASSERT_F2S("1.23456735E-36", 1.23456735E-36f);
}