From 924a759641bd382e80414db9e4b17beef2bba6a8 Mon Sep 17 00:00:00 2001
From: Adam Kewley <contact@adamkewley.com>
Date: Fri, 17 Jan 2025 15:10:28 +0100
Subject: [PATCH] Add ResourceLoader::resource_exists

---
 liboscar/Platform/FilesystemResourceLoader.cpp |  6 ++++++
 liboscar/Platform/FilesystemResourceLoader.h   |  1 +
 liboscar/Platform/IResourceLoader.h            |  2 ++
 liboscar/Platform/ResourceLoader.h             |  5 +++++
 liboscar/Platform/ResourceLoader.tests.cpp     | 15 +++++++++++++++
 5 files changed, 29 insertions(+)

diff --git a/liboscar/Platform/FilesystemResourceLoader.cpp b/liboscar/Platform/FilesystemResourceLoader.cpp
index 396558968b..6d24cb7e33 100644
--- a/liboscar/Platform/FilesystemResourceLoader.cpp
+++ b/liboscar/Platform/FilesystemResourceLoader.cpp
@@ -19,6 +19,12 @@ namespace
     }
 }
 
+bool osc::FilesystemResourceLoader::impl_resource_exists(const ResourcePath& resource_path)
+{
+    const std::filesystem::path full_path = calc_full_path(root_directory_, resource_path);
+    return std::filesystem::exists(full_path);
+}
+
 ResourceStream osc::FilesystemResourceLoader::impl_open(const ResourcePath& resource_path)
 {
     if (log_level() <= LogLevel::debug) {
diff --git a/liboscar/Platform/FilesystemResourceLoader.h b/liboscar/Platform/FilesystemResourceLoader.h
index 859f0e2edf..80d60f7508 100644
--- a/liboscar/Platform/FilesystemResourceLoader.h
+++ b/liboscar/Platform/FilesystemResourceLoader.h
@@ -18,6 +18,7 @@ namespace osc
         {}
 
     private:
+        bool impl_resource_exists(const ResourcePath&) final;
         ResourceStream impl_open(const ResourcePath&) final;
         std::function<std::optional<ResourceDirectoryEntry>()> impl_iterate_directory(const ResourcePath&) final;
 
diff --git a/liboscar/Platform/IResourceLoader.h b/liboscar/Platform/IResourceLoader.h
index 122c779c77..b84d93aac1 100644
--- a/liboscar/Platform/IResourceLoader.h
+++ b/liboscar/Platform/IResourceLoader.h
@@ -21,6 +21,7 @@ namespace osc
     public:
         virtual ~IResourceLoader() noexcept = default;
 
+        bool resource_exists(const ResourcePath& resource_path) { return impl_resource_exists(resource_path); }
         ResourceStream open(const ResourcePath& resource_path) { return impl_open(resource_path); }
         std::string slurp(const ResourcePath&);
 
@@ -30,6 +31,7 @@ namespace osc
         }
 
     private:
+        virtual bool impl_resource_exists(const ResourcePath&) = 0;
         virtual ResourceStream impl_open(const ResourcePath&) = 0;
         virtual std::function<std::optional<ResourceDirectoryEntry>()> impl_iterate_directory(const ResourcePath&)
         {
diff --git a/liboscar/Platform/ResourceLoader.h b/liboscar/Platform/ResourceLoader.h
index 39a140ca29..db46109e89 100644
--- a/liboscar/Platform/ResourceLoader.h
+++ b/liboscar/Platform/ResourceLoader.h
@@ -19,6 +19,11 @@ namespace osc
         operator IResourceLoader& () { return *impl_; }
         operator const IResourceLoader& () const { return *impl_; }
 
+        bool resource_exists(const ResourcePath& resource_path)
+        {
+            return impl_->resource_exists(resource_path);
+        }
+
         ResourceStream open(const ResourcePath& resource_path)
         {
             return impl_->open(prefix_ / resource_path);
diff --git a/liboscar/Platform/ResourceLoader.tests.cpp b/liboscar/Platform/ResourceLoader.tests.cpp
index 0ef6d5349d..e09d1b61f0 100644
--- a/liboscar/Platform/ResourceLoader.tests.cpp
+++ b/liboscar/Platform/ResourceLoader.tests.cpp
@@ -18,6 +18,7 @@ namespace
 {
     struct MockState final {
         std::optional<ResourcePath> last_open_call_path;
+        std::optional<ResourcePath> last_existence_check_path;
     };
 
     class MockResourceLoader : public IResourceLoader {
@@ -26,6 +27,12 @@ namespace
             state_{std::move(state_)}
         {}
     private:
+        bool impl_resource_exists(const ResourcePath& resource_path) final
+        {
+            state_->last_existence_check_path = resource_path;
+            return true;
+        }
+
         ResourceStream impl_open(const ResourcePath& resource_path) override
         {
             state_->last_open_call_path = resource_path;
@@ -64,3 +71,11 @@ TEST(ResourceLoader, WithPrefixCausesIResourceLoaderToBeCalledWithPrefixedPath)
     prefixed_loader.open(ResourcePath{"path"});
     ASSERT_EQ(mock_state->last_open_call_path, ResourcePath{"prefix/path"}) << "with_prefix should return a loader the prefixes each open call";
 }
+
+TEST(ResourceLoader, resource_exists_calls_underlying_impl_resource_exists)
+{
+    const auto mock_state = std::make_shared<MockState>();
+    ResourceLoader resource_loader = make_resource_loader<MockResourceLoader>(mock_state);
+    ASSERT_TRUE(resource_loader.resource_exists("should/exist"));
+    ASSERT_EQ(mock_state->last_existence_check_path, ResourcePath{"should/exist"});
+}