/*
 * Copyright (C) 2018 The Android Open Source Project
 *
 * 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.
 */

#include "optimize/Obfuscator.h"

#include <memory>
#include <string>

#include "ResourceTable.h"
#include "test/Test.h"

using ::aapt::test::GetValue;
using ::testing::Eq;
using ::testing::Not;
using ::testing::NotNull;

android::StringPiece GetExtension(android::StringPiece path) {
  auto iter = std::find(path.begin(), path.end(), '.');
  return android::StringPiece(iter, path.end() - iter);
}

void FillTable(aapt::test::ResourceTableBuilder& builder, int start, int end) {
  for (int i = start; i < end; i++) {
    builder.AddFileReference("android:drawable/xmlfile" + std::to_string(i),
                             "res/drawable/xmlfile" + std::to_string(i) + ".xml");
  }
}

namespace aapt {

TEST(ObfuscatorTest, FileRefPathsChangedInResourceTable) {
  std::unique_ptr<IAaptContext> context = test::ContextBuilder().Build();

  std::unique_ptr<ResourceTable> table =
      test::ResourceTableBuilder()
          .AddFileReference("android:drawable/xmlfile", "res/drawables/xmlfile.xml")
          .AddFileReference("android:drawable/xmlfile2", "res/drawables/xmlfile2.xml")
          .AddString("android:string/string", "res/should/still/be/the/same.png")
          .Build();

  std::map<std::string, std::string> path_map;
  ASSERT_TRUE(Obfuscator(path_map).Consume(context.get(), table.get()));

  // Expect that the path map is populated
  ASSERT_THAT(path_map.find("res/drawables/xmlfile.xml"), Not(Eq(path_map.end())));
  ASSERT_THAT(path_map.find("res/drawables/xmlfile2.xml"), Not(Eq(path_map.end())));

  // The file paths were changed
  EXPECT_THAT(path_map.at("res/drawables/xmlfile.xml"), Not(Eq("res/drawables/xmlfile.xml")));
  EXPECT_THAT(path_map.at("res/drawables/xmlfile2.xml"), Not(Eq("res/drawables/xmlfile2.xml")));

  // Different file paths should remain different
  EXPECT_THAT(path_map["res/drawables/xmlfile.xml"],
              Not(Eq(path_map["res/drawables/xmlfile2.xml"])));

  FileReference* ref = GetValue<FileReference>(table.get(), "android:drawable/xmlfile");
  ASSERT_THAT(ref, NotNull());
  // The map correctly points to the new location of the file
  EXPECT_THAT(path_map["res/drawables/xmlfile.xml"], Eq(*ref->path));

  // Strings should not be affected, only file paths
  EXPECT_THAT(*GetValue<String>(table.get(), "android:string/string")->value,
              Eq("res/should/still/be/the/same.png"));
  EXPECT_THAT(path_map.find("res/should/still/be/the/same.png"), Eq(path_map.end()));
}

TEST(ObfuscatorTest, SkipColorFileRefPaths) {
  std::unique_ptr<IAaptContext> context = test::ContextBuilder().Build();

  std::unique_ptr<ResourceTable> table =
      test::ResourceTableBuilder()
          .AddFileReference("android:color/colorlist", "res/color/colorlist.xml")
          .AddFileReference("android:color/colorlist", "res/color-mdp-v21/colorlist.xml",
                            test::ParseConfigOrDie("mdp-v21"))
          .Build();

  std::map<std::string, std::string> path_map;
  ASSERT_TRUE(Obfuscator(path_map).Consume(context.get(), table.get()));

  // Expect that the path map to not contain the ColorStateList
  ASSERT_THAT(path_map.find("res/color/colorlist.xml"), Eq(path_map.end()));
  ASSERT_THAT(path_map.find("res/color-mdp-v21/colorlist.xml"), Eq(path_map.end()));
}

TEST(ObfuscatorTest, KeepExtensions) {
  std::unique_ptr<IAaptContext> context = test::ContextBuilder().Build();

  std::string original_xml_path = "res/drawable/xmlfile.xml";
  std::string original_png_path = "res/drawable/pngfile.png";

  std::unique_ptr<ResourceTable> table =
      test::ResourceTableBuilder()
          .AddFileReference("android:color/xmlfile", original_xml_path)
          .AddFileReference("android:color/pngfile", original_png_path)
          .Build();

  std::map<std::string, std::string> path_map;
  ASSERT_TRUE(Obfuscator(path_map).Consume(context.get(), table.get()));

  // Expect that the path map is populated
  ASSERT_THAT(path_map.find("res/drawable/xmlfile.xml"), Not(Eq(path_map.end())));
  ASSERT_THAT(path_map.find("res/drawable/pngfile.png"), Not(Eq(path_map.end())));

  auto shortend_xml_path = path_map[original_xml_path];
  auto shortend_png_path = path_map[original_png_path];

  EXPECT_THAT(GetExtension(path_map[original_xml_path]), Eq(android::StringPiece(".xml")));
  EXPECT_THAT(GetExtension(path_map[original_png_path]), Eq(android::StringPiece(".png")));
}

TEST(ObfuscatorTest, DeterministicallyHandleCollisions) {
  std::unique_ptr<IAaptContext> context = test::ContextBuilder().Build();

  // 4000 resources is the limit at which the hash space is expanded to 3
  // letters to reduce collisions, we want as many collisions as possible thus
  // N-1.
  const auto kNumResources = 3999;
  const auto kNumTries = 5;

  test::ResourceTableBuilder builder1;
  FillTable(builder1, 0, kNumResources);
  std::unique_ptr<ResourceTable> table1 = builder1.Build();
  std::map<std::string, std::string> expected_mapping;
  ASSERT_TRUE(Obfuscator(expected_mapping).Consume(context.get(), table1.get()));

  // We are trying to ensure lack of non-determinism, it is not simple to prove
  // a negative, thus we must try the test a few times so that the test itself
  // is non-flaky. Basically create the pathmap 5 times from the same set of
  // resources but a different order of addition and then ensure they are always
  // mapped to the same short path.
  for (int i = 0; i < kNumTries; i++) {
    test::ResourceTableBuilder builder2;
    // This loop adds resources to the resource table in the range of
    // [0:kNumResources).  Adding the file references in different order makes
    // non-determinism more likely to surface. Thus we add resources
    // [start_index:kNumResources) first then [0:start_index). We also use a
    // different start_index each run.
    int start_index = (kNumResources / kNumTries) * i;
    FillTable(builder2, start_index, kNumResources);
    FillTable(builder2, 0, start_index);
    std::unique_ptr<ResourceTable> table2 = builder2.Build();

    std::map<std::string, std::string> actual_mapping;
    ASSERT_TRUE(Obfuscator(actual_mapping).Consume(context.get(), table2.get()));

    for (auto& item : actual_mapping) {
      ASSERT_THAT(expected_mapping[item.first], Eq(item.second));
    }
  }
}

}  // namespace aapt