// Copyright 2021 The PDFium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "core/fxcrt/span_util.h"

#include <array>
#include <vector>

#include "testing/gmock/include/gmock/gmock.h"
#include "testing/gtest/include/gtest/gtest.h"

TEST(Spancpy, FitsEntirely) {
  std::vector<char> src(4, 'A');
  std::vector<char> dst(4, 'B');
  auto remain = fxcrt::spancpy(pdfium::span(dst), pdfium::span(src));
  EXPECT_EQ(dst[0], 'A');
  EXPECT_EQ(dst[1], 'A');
  EXPECT_EQ(dst[2], 'A');
  EXPECT_EQ(dst[3], 'A');
  EXPECT_TRUE(remain.empty());
}

TEST(Spancpy, FitsWithin) {
  std::vector<char> src(2, 'A');
  std::vector<char> dst(4, 'B');
  // Also show that a const src argument is acceptable.
  auto remain = fxcrt::spancpy(pdfium::span(dst).subspan<1u>(),
                               pdfium::span<const char>(src));
  EXPECT_EQ(dst[0], 'B');
  EXPECT_EQ(dst[1], 'A');
  EXPECT_EQ(dst[2], 'A');
  EXPECT_EQ(dst[3], 'B');
  EXPECT_EQ(remain.size(), 1u);
  EXPECT_EQ(remain.data(), &dst[3]);
}

TEST(Spancpy, EmptyCopyWithin) {
  std::vector<char> src(2, 'A');
  std::vector<char> dst(4, 'B');
  auto remain = fxcrt::spancpy(pdfium::span(dst).subspan<1u>(),
                               pdfium::span(src).subspan<2u>());
  EXPECT_EQ(dst[0], 'B');
  EXPECT_EQ(dst[1], 'B');
  EXPECT_EQ(dst[2], 'B');
  EXPECT_EQ(dst[3], 'B');
  EXPECT_EQ(remain.size(), 3u);
  EXPECT_EQ(remain.data(), &dst[1]);
}

TEST(Spancpy, EmptyCopyToEmpty) {
  std::vector<char> src(2, 'A');
  std::vector<char> dst(4, 'B');
  auto remain = fxcrt::spancpy(pdfium::span(dst).subspan<4u>(),
                               pdfium::span(src).subspan<2u>());
  EXPECT_EQ(dst[0], 'B');
  EXPECT_EQ(dst[1], 'B');
  EXPECT_EQ(dst[2], 'B');
  EXPECT_EQ(dst[3], 'B');
  EXPECT_TRUE(remain.empty());
}

TEST(Spancpy, TryFitsEntirely) {
  std::vector<char> src(4, 'A');
  std::vector<char> dst(4, 'B');
  EXPECT_TRUE(fxcrt::try_spancpy(pdfium::span(dst), pdfium::span(src)));
  EXPECT_EQ(dst[0], 'A');
  EXPECT_EQ(dst[1], 'A');
  EXPECT_EQ(dst[2], 'A');
  EXPECT_EQ(dst[3], 'A');
}

TEST(Spancpy, TryDoesNotFit) {
  std::vector<char> src(4, 'A');
  std::vector<char> dst(3, 'B');
  EXPECT_FALSE(fxcrt::try_spancpy(pdfium::span(dst), pdfium::span(src)));
  EXPECT_EQ(dst[0], 'B');
  EXPECT_EQ(dst[1], 'B');
  EXPECT_EQ(dst[2], 'B');
}

TEST(Spanmove, FitsWithin) {
  std::vector<char> src(2, 'A');
  std::vector<char> dst(4, 'B');
  // Also show that a const src argument is acceptable.
  auto remain = fxcrt::spanmove(pdfium::span(dst).subspan<1u>(),
                                pdfium::span<const char>(src));
  EXPECT_EQ(dst[0], 'B');
  EXPECT_EQ(dst[1], 'A');
  EXPECT_EQ(dst[2], 'A');
  EXPECT_EQ(dst[3], 'B');
  EXPECT_EQ(remain.size(), 1u);
  EXPECT_EQ(remain.data(), &dst[3]);
}

TEST(Spanmove, TryFitsEntirely) {
  std::vector<char> src(4, 'A');
  std::vector<char> dst(4, 'B');
  EXPECT_TRUE(fxcrt::try_spanmove(pdfium::span(dst), pdfium::span(src)));
  EXPECT_EQ(dst[0], 'A');
  EXPECT_EQ(dst[1], 'A');
  EXPECT_EQ(dst[2], 'A');
  EXPECT_EQ(dst[3], 'A');
}

TEST(Spanmove, TrySelfIntersect) {
  {
    std::vector<char> vec = {'A', 'B', 'C', 'D'};
    EXPECT_TRUE(fxcrt::try_spanmove(pdfium::span(vec).first(3u),
                                    pdfium::span(vec).last(3u)));
    EXPECT_EQ(vec[0], 'B');
    EXPECT_EQ(vec[1], 'C');
    EXPECT_EQ(vec[2], 'D');
    EXPECT_EQ(vec[3], 'D');
  }
  {
    std::vector<char> vec = {'A', 'B', 'C', 'D'};
    EXPECT_TRUE(fxcrt::try_spanmove(pdfium::span(vec).last(3u),
                                    pdfium::span(vec).first(3u)));
    EXPECT_EQ(vec[0], 'A');
    EXPECT_EQ(vec[1], 'A');
    EXPECT_EQ(vec[2], 'B');
    EXPECT_EQ(vec[3], 'C');
  }
}

TEST(Spanmove, TryDoesNotFit) {
  std::vector<char> src(4, 'A');
  std::vector<char> dst(3, 'B');
  EXPECT_FALSE(fxcrt::try_spanmove(pdfium::span(dst), pdfium::span(src)));
  EXPECT_EQ(dst[0], 'B');
  EXPECT_EQ(dst[1], 'B');
  EXPECT_EQ(dst[2], 'B');
}

TEST(Span, AssignOverOnePastEnd) {
  std::vector<char> src(2, 'A');
  pdfium::span<char> span = pdfium::span(src);
  span = span.subspan<2u>();
  span = pdfium::span(src);
  EXPECT_EQ(span.size(), 2u);
}

TEST(ReinterpretSpan, Empty) {
  pdfium::span<uint8_t> empty;
  pdfium::span<uint32_t> converted = fxcrt::reinterpret_span<uint32_t>(empty);
  EXPECT_EQ(converted.data(), nullptr);
  EXPECT_EQ(converted.size(), 0u);
}

TEST(ReinterpretSpan, LegalConversions) {
  uint8_t aaaabbbb[8] = {0x61, 0x61, 0x61, 0x61, 0x62, 0x62, 0x62, 0x62};
  pdfium::span<uint8_t> original = pdfium::span(aaaabbbb);
  pdfium::span<uint32_t> converted =
      fxcrt::reinterpret_span<uint32_t>(original);
  ASSERT_NE(converted.data(), nullptr);
  ASSERT_EQ(converted.size(), 2u);
  EXPECT_EQ(converted[0], 0x61616161u);
  EXPECT_EQ(converted[1], 0x62626262u);
}

TEST(ReinterpretSpan, BadAlignment) {
  uint8_t abcabc[6] = {0x61, 0x62, 0x63, 0x61, 0x62, 0x63};
  EXPECT_DEATH(
      fxcrt::reinterpret_span<uint32_t>(pdfium::span(abcabc).subspan<1u, 4u>()),
      "");
}

TEST(ReinterpretSpan, FlattenMultiDimension) {
  struct Pt {
    float x;
    float y;
  };
  using Line = std::array<Pt, 4>;
  using Plane = std::array<Line, 4>;
  using Volume = std::array<Plane, 4>;
  Volume box = {{{{{{}}}}}};
  auto flat = fxcrt::reinterpret_span<Pt>(pdfium::span(box));
  EXPECT_EQ(64u, flat.size());

  float ctr = 0.0f;
  for (auto& pt : flat) {
    pt.x = ctr++;
    pt.y = ctr++;
  }
  EXPECT_EQ(box[3][3][3].x, 126.0f);
  EXPECT_EQ(box[3][3][3].y, 127.0f);
}

TEST(Spanpos, Empty) {
  pdfium::span<const uint32_t> kEmpty;
  const uint32_t kHaystack[] = {0, 1, 2, 3, 4, 5};
  const uint32_t kNeedle[] = {1, 2};
  EXPECT_FALSE(fxcrt::spanpos(kEmpty, kEmpty));
  EXPECT_FALSE(fxcrt::spanpos(pdfium::span(kHaystack), kEmpty));
  EXPECT_FALSE(fxcrt::spanpos(kEmpty, pdfium::span(kNeedle)));
}

TEST(Spanpos, NotEmpty) {
  const uint32_t kHaystack[] = {0, 1, 2, 3, 4, 5};
  const uint32_t kStartMatch[] = {0, 1};
  const uint32_t kEndMatch[] = {4, 5};
  const uint32_t kNotFound[] = {256, 512};  // test byte-shifted {1,2}.
  const uint32_t kTooLong[] = {0, 1, 2, 3, 4, 5, 6};
  EXPECT_THAT(
      fxcrt::spanpos(pdfium::span(kHaystack), pdfium::span(kStartMatch)),
      testing::Optional(0u));
  EXPECT_THAT(fxcrt::spanpos(pdfium::span(kHaystack), pdfium::span(kEndMatch)),
              testing::Optional(4u));
  EXPECT_FALSE(
      fxcrt::spanpos(pdfium::span(kHaystack), pdfium::span(kNotFound)));
  EXPECT_FALSE(fxcrt::spanpos(pdfium::span(kHaystack), pdfium::span(kTooLong)));
}