Add support for exact version NuGet dependencies based on Maven dependency info from POM. (#770)

Directory.Build.targets

@@ -0,0 +1,18 @@
+<Project>
+  <!-- Enables "ExactVersion" attribute on "ProjectReference" to allow an exact NuGet reference version to be used.
+       https://github.com/NuGet/Home/issues/5556#issuecomment-1179526189  -->
+  <Target Name="UseExplicitPackageVersions" BeforeTargets="GenerateNuspec">
+    <ItemGroup>
+      <_ProjectReferenceWithExplicitPackageVersion Include="@(ProjectReference->'%(FullPath)')" Condition="'%(ProjectReference.PackageVersion)' != ''" />
+      <_ProjectReferenceWithExactPackageVersion Include="@(ProjectReference->'%(FullPath)')" Condition="'%(ProjectReference.ExactVersion)' == 'true'" />
+      <_ProjectReferenceWithReassignedVersion Include="@(_ProjectReferencesWithVersions)" Condition="'%(Identity)' != '' And '@(_ProjectReferenceWithExplicitPackageVersion)' == '@(_ProjectReferencesWithVersions)'">
+        <ProjectVersion>@(_ProjectReferenceWithExplicitPackageVersion->'%(PackageVersion)')</ProjectVersion>
+      </_ProjectReferenceWithReassignedVersion>
+      <_ProjectReferenceWithReassignedVersion Include="@(_ProjectReferencesWithVersions)" Condition="'%(Identity)' != '' And '@(_ProjectReferenceWithExactPackageVersion)' == '@(_ProjectReferencesWithVersions)'">
+        <ProjectVersion>[@(_ProjectReferencesWithVersions->'%(ProjectVersion)')]</ProjectVersion>
+      </_ProjectReferenceWithReassignedVersion>
+      <_ProjectReferencesWithVersions Remove="@(_ProjectReferenceWithReassignedVersion)" />
+      <_ProjectReferencesWithVersions Include="@(_ProjectReferenceWithReassignedVersion)" />
+    </ItemGroup>
+  </Target>
+</Project>

source/AndroidXProject.cshtml

@@ -173,8 +173,7 @@
     <!-- ProjectReference -->
     @foreach (var dep in @Model.NuGetDependencies) {
       if (dep.IsProjectReference) {
-        <ProjectReference Include="..\..\generated\@(dep.MavenArtifact.MavenGroupId).@(dep.MavenArtifact.MavenArtifactId)\@(dep.MavenArtifact.MavenGroupId).@(dep.MavenArtifact.MavenArtifactId).csproj" PrivateAssets="none" />
-
+        <ProjectReference Include="..\..\generated\@(dep.MavenArtifact.MavenGroupId).@(dep.MavenArtifact.MavenArtifactId)\@(dep.MavenArtifact.MavenGroupId).@(dep.MavenArtifact.MavenArtifactId).csproj" PrivateAssets="none" PackageVersion="@GetProjectVersionString(dep.MavenArtifact.MavenArtifactVersion, dep.NuGetVersion)" />
       }
     }
   </ItemGroup>
@@ -184,7 +183,7 @@
     <!-- PackageReference -->
     @foreach (var dep in @Model.NuGetDependencies) {
       if (!dep.IsProjectReference) {
-      <PackageReference Include="@(dep.NuGetPackageId)" Version="@(dep.NuGetVersion)" PrivateAssets="none" />
+      <PackageReference Include="@(dep.NuGetPackageId)" Version="@GetVersionString(dep.MavenArtifact.MavenArtifactVersion, dep.NuGetVersion)" PrivateAssets="none" />
       }
     }
   </ItemGroup>
@@ -205,4 +204,53 @@
     </PropertyGroup>
   }
 
+@{
+  string GetProjectVersionString (string mavenVersion, string nugetVersion)
+  {
+    var adjusted_string = GetVersionString (mavenVersion, nugetVersion);
+    
+    // If nothing changed, return empty string
+    if (adjusted_string == nugetVersion)
+      return null;
+      
+    return adjusted_string;
+  }
+  
+  string GetVersionString (string mavenVersion, string nugetVersion)
+  {
+    // If this isn't an exact version we don't use this code
+    if (!mavenVersion.StartsWith ('[') || !mavenVersion.EndsWith (']') || mavenVersion.Contains (','))
+      return nugetVersion;
+
+    // An exact version is requested like "1.2.0", however we want to let the revision (4th NuGet number) float,
+    // so that our updates that don't change the Java artifact can still be used.
+    // That is, if the POM specifies "1.2.0" and the dependency NuGet is already "1.2.0.4", we want to allow:
+    // 1.2.0.4 >= x < 1.2.1
+    // NuGet expresses that as "[1.2.0.4, 1.2.1)", so that's what we need to create.
+    var lower_bound = nugetVersion;
+
+    var nuget_first = 0;
+    var nuget_second = 0;
+    var nuget_third = 0;
+
+    var nuget_parts = nugetVersion.Split ('.');
+
+    if (nuget_parts.Length > 0 && int.TryParse (nuget_parts [0], out var p1))
+      nuget_first = p1;
+
+    if (nuget_parts.Length > 1 && int.TryParse (nuget_parts [1], out var p2))
+      nuget_second = p2;
+
+    if (nuget_parts.Length > 2 && int.TryParse (nuget_parts [2], out var p3))
+      nuget_third = p3;
+
+    // Bump the third number
+    nuget_third++;
+
+    var upper_bound = $"{nuget_first}.{nuget_second}.{nuget_third}";
+
+    // Put it all together
+    return $"[{lower_bound}, {upper_bound})";
+  }
+}
 </Project>