MSBuild: Copy files conditional output paths - msbuild

Question

I currently have a solution with the following project layout (simplified and condensed for this example)
src
├──2019
| └── Project.2019
| └── Input
| └── 1.txt
└──2020
└── Project.2020
└── Input
└── 1.txt
And I would like to copy all the input files to the following hierarchy
Input
├──2019
| └── 1.txt
└──2020
└── 1.txt
With [System.IO.Directory]::GetDirectories I am able to match the directories I want, but I'm not sure how to extract the year, and set DestinationFolder correctly using the Copy task

Answer 1

Does Project.2019 and Project.2020 include projects?
I have made the assumption that it does, following this structure:
directory.build.props
│
└───src
│ CopyFiles.sln
│
├───2019
│ └───Project.2019
│ │ Program.cs
│ │ Project.2019.csproj
│ │
│ └───input
│ 1.txt
│ 2.txt
│
└───2020
└───Project.2020
│ Program.cs
│ Project.2020.csproj
│
└───input
1.txt
2.txt
Having a project file in each of those folders, allows us to execute a custom build target, under the context of each project. This grants a simple way of building the list of files (includes) and allows us to go up a folder from the MSBuildProjectDirectory to get the year.
The final output path for the input files (InputOutputPath), assumes the existance of OutputRootPath and OutputPath is used to overwrite the default msbuild folders. I typically do this to have all output in \output. But you can customize these as you wish.
It also expects each project that needs files copied to have CopyInputFiles specified to true. This can also be done using a condition, in case you want it to always copy files if there are any in project\input*.txt
<PropertyGroup>
<CopyInputFiles>true</CopyInputFiles>
</PropertyGroup>
directory.build.props:
<Target Name="CopyFiles" Condition="'$(CopyInputFiles)' == 'true'" >
<ItemGroup>
<InputFiles Include="$(MSBuildProjectDirectory)\input\*.txt" />
</ItemGroup>
<PropertyGroup>
<Year>$([System.IO.Directory]::GetParent($(MSBuildProjectDirectory)).Name)</Year>
<InputOutputPath>$(OutputRootPath)\$(Configuration)\Input\$(Year)\</InputOutputPath>
</PropertyGroup>
<Copy SourceFiles="#(InputFiles)" DestinationFolder="$(InputOutputPath)" />
</Target>
Example output:
PS e:\repos\CopyFiles> msbuild .\src\CopyFiles.sln /t:copyfiles
Microsoft (R) Build Engine version 16.8.2+25e4d540b for .NET Framework
Copyright (C) Microsoft Corporation. All rights reserved.
Building the projects in this solution one at a time. To enable parallel build, please add the "-m" switch.
Build started 12/6/2020 12:56:07 PM.
Project "E:\repos\CopyFiles\src\CopyFiles.sln" on node 1 (copyfiles target(s)).
ValidateSolutionConfiguration:
Building solution configuration "Debug|Any CPU".
Project "E:\repos\CopyFiles\src\CopyFiles.sln" (1) is building "E:\repos\CopyFiles\src\2019\Project.2019\Project.2019.csproj" (2) on node 1 (copyfiles target(s)).
CopyFiles:
Creating directory "E:\repos\CopyFiles\Drops\Debug\Input\2019".
Creating directory "E:\repos\CopyFiles\Drops\Debug\Input\2019".
Copying file from "E:\repos\CopyFiles\src\2019\Project.2019\input\1.txt" to "E:\repos\CopyFiles\Drops\Debug\Input\2019\1.txt".
Copying file from "E:\repos\CopyFiles\src\2019\Project.2019\input\2.txt" to "E:\repos\CopyFiles\Drops\Debug\Input\2019\2.txt".
Done Building Project "E:\repos\CopyFiles\src\2019\Project.2019\Project.2019.csproj" (copyfiles target(s)).
Project "E:\repos\CopyFiles\src\CopyFiles.sln" (1) is building "E:\repos\CopyFiles\src\2020\Project.2020\Project.2020.csproj" (3) on node 1 (copyfiles target(s)).
CopyFiles:
Creating directory "E:\repos\CopyFiles\Drops\Debug\Input\2020".
Copying file from "E:\repos\CopyFiles\src\2020\Project.2020\input\1.txt" to "E:\repos\CopyFiles\Drops\Debug\Input\2020\1.txt".
Creating directory "E:\repos\CopyFiles\Drops\Debug\Input\2020".
Copying file from "E:\repos\CopyFiles\src\2020\Project.2020\input\2.txt" to "E:\repos\CopyFiles\Drops\Debug\Input\2020\2.txt".
Done Building Project "E:\repos\CopyFiles\src\2020\Project.2020\Project.2020.csproj" (copyfiles target(s)).
Done Building Project "E:\repos\CopyFiles\src\CopyFiles.sln" (copyfiles target(s)).
With the resulting structure:
Drops
└───Debug
├───AnyCPU
│ ├───Project.2019
│ │ └───netcoreapp3.1
│ └───Project.2020
│ └───netcoreapp3.1
└───Input
├───2019
│ 1.txt
│ 2.txt
│
└───2020
1.txt
2.txt
You can find a fully working example in: https://github.com/Kencdk/msbuild_copyfiles_example
You can hook it up to your build, by setting the target to execute after any other build target that is being executed in your projects.
eg:
<Target Name="CopyFiles" Condition="'$(CopyInputFiles)' == 'true'" AfterTargets="Build">