// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <utility>

#include "base/functional/callback.h"
#include "base/functional/callback_helpers.h"
#include "components/services/app_service/public/cpp/app_types.h"
#include "components/services/app_service/public/cpp/icon_cache.h"
#include "components/services/app_service/public/cpp/icon_types.h"
#include "testing/gtest/include/gtest/gtest.h"
#include "ui/gfx/geometry/size.h"
#include "ui/gfx/image/image_skia_rep.h"

class AppsIconCacheTest : public testing::Test {
 protected:
  enum class HitOrMiss {
    kHit,
    kMiss,
  };

  using UniqueReleaser = std::unique_ptr<apps::IconLoader::Releaser>;
  static constexpr HitOrMiss kHit = HitOrMiss::kHit;
  static constexpr HitOrMiss kMiss = HitOrMiss::kMiss;

  class FakeIconLoader : public apps::IconLoader {
   public:
    int NumLoadIconFromIconKeyCalls() { return num_load_calls_; }

    void SetReturnPlaceholderIcons(bool b) { return_placeholder_icons_ = b; }

   private:
    std::unique_ptr<Releaser> LoadIconFromIconKey(
        const std::string& id,
        const apps::IconKey& icon_key,
        apps::IconType icon_type,
        int32_t size_hint_in_dip,
        bool allow_placeholder_icon,
        apps::LoadIconCallback callback) override {
      num_load_calls_++;

      auto iv = std::make_unique<apps::IconValue>();
      if (icon_type == apps::IconType::kUncompressed) {
        iv->icon_type = apps::IconType::kUncompressed;
        iv->uncompressed =
            gfx::ImageSkia(gfx::ImageSkiaRep(gfx::Size(1, 1), 1.0f));
        iv->is_placeholder_icon = return_placeholder_icons_;
      }

      std::move(callback).Run(std::move(iv));
      return nullptr;
    }

    int num_load_calls_ = 0;
    bool return_placeholder_icons_ = false;
  };

  UniqueReleaser LoadIcon(apps::IconLoader* loader,
                          FakeIconLoader* fake,
                          const std::string& app_id,
                          HitOrMiss expect_hom,
                          bool allow_placeholder_icon = false) {
    int before = fake->NumLoadIconFromIconKeyCalls();

    UniqueReleaser releaser;
    releaser = loader->LoadIcon(app_id, apps::IconType::kUncompressed,
                                /*size_hint_in_dip=*/1, allow_placeholder_icon,
                                base::DoNothing());

    int after = fake->NumLoadIconFromIconKeyCalls();
    HitOrMiss actual_hom = (after == before) ? kHit : kMiss;
    EXPECT_EQ(expect_hom, actual_hom);

    return releaser;
  }

  void TestBasics(apps::IconCache::GarbageCollectionPolicy gc_policy,
                  bool remove_icon = false) {
    FakeIconLoader fake;
    apps::IconCache cache(&fake, gc_policy);

    UniqueReleaser a0 = LoadIcon(&cache, &fake, "apricot", kMiss);
    a0.reset();

    UniqueReleaser b0 = LoadIcon(&cache, &fake, "banana", kMiss);
    UniqueReleaser b1 = LoadIcon(&cache, &fake, "banana", kHit);
    b0.reset();
    b1.reset();

    UniqueReleaser c0 = LoadIcon(&cache, &fake, "cherry", kMiss);
    UniqueReleaser c1 = LoadIcon(&cache, &fake, "cherry", kHit);
    UniqueReleaser c2 = LoadIcon(&cache, &fake, "cherry", kHit);
    c2.reset();
    c1.reset();

    UniqueReleaser d0 = LoadIcon(&cache, &fake, "durian", kMiss);
    d0.reset();

    UniqueReleaser c3 = LoadIcon(&cache, &fake, "cherry", kHit);
    c3.reset();

    HitOrMiss expect_hom = kHit;
    if (gc_policy == apps::IconCache::GarbageCollectionPolicy::kExplicit) {
      if (remove_icon) {
        cache.RemoveIcon("cherry");
        cache.RemoveIcon("apricot");
        expect_hom = kMiss;
      } else {
        cache.SweepReleasedIcons();
      }
    }

    UniqueReleaser c4 = LoadIcon(&cache, &fake, "cherry", expect_hom);
    c4.reset();
    c0.reset();

    if (gc_policy == apps::IconCache::GarbageCollectionPolicy::kExplicit) {
      if (remove_icon) {
        cache.RemoveIcon("cherry");
      } else {
        cache.SweepReleasedIcons();
      }
    }

    UniqueReleaser c5 = LoadIcon(&cache, &fake, "cherry", kMiss);
    c5.reset();
  }

  void TestPlaceholder(apps::IconCache::GarbageCollectionPolicy gc_policy) {
    FakeIconLoader fake;
    apps::IconCache cache(&fake, gc_policy);
    bool allow_placeholder_icon;

    fake.SetReturnPlaceholderIcons(true);

    allow_placeholder_icon = true;
    UniqueReleaser f0 =
        LoadIcon(&cache, &fake, "fig", kMiss, allow_placeholder_icon);

    fake.SetReturnPlaceholderIcons(false);

    // The next LoadIcon call is a kMiss, even though there is a cache entry,
    // because the cache entry holds a placeholder icon, but we have
    // allow_placeholder_icon == false.
    //
    // A side effect of the next LoadIcon call is to prime the cache with the
    // real (non-placeholder) icon.

    allow_placeholder_icon = false;
    UniqueReleaser f1 =
        LoadIcon(&cache, &fake, "fig", kMiss, allow_placeholder_icon);

    // The next two LoadIcons are all both kHit's. The real icon can be served
    // from the cache, regardless of allow_placeholder_icon's value.

    allow_placeholder_icon = false;
    UniqueReleaser f2 =
        LoadIcon(&cache, &fake, "fig", kHit, allow_placeholder_icon);

    allow_placeholder_icon = true;
    UniqueReleaser f3 =
        LoadIcon(&cache, &fake, "fig", kHit, allow_placeholder_icon);
  }

  void TestAfterZeroRefcount(apps::IconCache::GarbageCollectionPolicy gc_policy,
                             bool remove_icon = false) {
    FakeIconLoader fake;
    apps::IconCache cache(&fake, gc_policy);

    UniqueReleaser w0 = LoadIcon(&cache, &fake, "watermelon", kMiss);
    w0.reset();

    // We now have a zero ref-count. Whether the next LoadIcon call is kHit or
    // kMiss depends on our gc_policy.

    HitOrMiss expect_hom;
    switch (gc_policy) {
      case apps::IconCache::GarbageCollectionPolicy::kEager:
        expect_hom = kMiss;
        break;
      case apps::IconCache::GarbageCollectionPolicy::kExplicit:
        expect_hom = kHit;
        break;
    }

    UniqueReleaser w1 = LoadIcon(&cache, &fake, "watermelon", expect_hom);
    w1.reset();

    // Once again, we have a zero ref-count, but for a kExplicit gc_policy, we
    // also explicitly SweepReleasedIcons(), so the next LoadIcon call should
    // get kMiss.

    if (gc_policy == apps::IconCache::GarbageCollectionPolicy::kExplicit) {
      if (remove_icon) {
        cache.RemoveIcon("watermelon");
      } else {
        cache.SweepReleasedIcons();
      }
    }

    UniqueReleaser w2 = LoadIcon(&cache, &fake, "watermelon", kMiss);
    w2.reset();
  }
};

TEST_F(AppsIconCacheTest, Eager) {
  static constexpr apps::IconCache::GarbageCollectionPolicy gc_policy =
      apps::IconCache::GarbageCollectionPolicy::kEager;

  TestBasics(gc_policy);
  TestPlaceholder(gc_policy);
  TestAfterZeroRefcount(gc_policy);
}

TEST_F(AppsIconCacheTest, ExplicitSweepReleasedIcons) {
  static constexpr apps::IconCache::GarbageCollectionPolicy gc_policy =
      apps::IconCache::GarbageCollectionPolicy::kExplicit;

  TestBasics(gc_policy);
  TestPlaceholder(gc_policy);
  TestAfterZeroRefcount(gc_policy);
}

TEST_F(AppsIconCacheTest, ExplicitRemoveIcons) {
  static constexpr apps::IconCache::GarbageCollectionPolicy gc_policy =
      apps::IconCache::GarbageCollectionPolicy::kExplicit;

  TestBasics(gc_policy, true /* remove_icon */);
  TestPlaceholder(gc_policy);
  TestAfterZeroRefcount(gc_policy, true /* remove_icon */);
}