name: Visual Studio shell
description: Set up Visual Studio paths and environment variables

inputs:
  arch:
    description: Target architecture
    required: false
    default: x64

runs:
  using: composite
  steps:
    - run: |
        function Locate-VSWhere {
            $path = Get-Command 'vswhere' -ErrorAction SilentlyContinue
            if ($path) {
                $path.Path
            } else {
                Join-Path ${env:ProgramFiles(x86)} 'Microsoft Visual Studio' 'Installer' 'vswhere'
            }
        }

        function Locate-VS {
            # vswhere doesn't search for Build Tools by default, God knows why.
            # https://github.com/microsoft/vswhere/issues/22
            $products = 'Community','Professional','Enterprise','BuildTools' | %{ "Microsoft.VisualStudio.Product.$_" }
            $vswhere = Locate-VSWhere
            & $vswhere -products $products -latest -format json | ConvertFrom-Json
        }

        function Import-PS {
            # VS 2019 includes Microsoft.VisualStudio.DevShell.dll, which does
            # what we want.
            #
            # It also includes Launch-VsDevShell.ps1, which sort of does the
            # same thing this function does, but it always sets up 32-bit
            # shell, which is stupid.  I use the same workaround as in
            # https://developercommunity.visualstudio.com/idea/943058/x64-developer-powershell-for-vs-2019.html

            param(
                [Parameter(Mandatory=$true)]
                [object] $info
            )

            $tools_path = Join-Path $info.installationPath 'Common7' 'Tools'
            $module_name = 'Microsoft.VisualStudio.DevShell.dll'
            $module_path = Join-Path $tools_path $module_name

            if (!(Test-Path $module_path -Type Leaf)) {
                $module_path = Join-Path $tools_path 'vsdevshell' $module_name
            }

            if (!(Test-Path $module_path -Type Leaf)) {
                throw "Couldn't find module '$module_name'"
            }

            Import-Module $module_path
            Enter-VsDevShell -VsInstanceId $info.instanceId -SkipAutomaticLocation -DevCmdArguments '-arch=${{ inputs.arch }} -no_logo'
        }

        function Import-CMD {
            # For Visual Studio 2017, there's no Microsoft.VisualStudio.DevShell.dll,
            # so we have to work around that.  One workaround I found here:
            # https://github.com/microsoft/vswhere/issues/150

            param(
                [Parameter(Mandatory=$true)]
                [object] $info
            )

            $tools_path = Join-Path $info.installationPath 'Common7' 'Tools'
            $script_name = 'VsDevCmd.bat'
            $script_path = Join-Path $tools_path $script_name

            if (!(Test-Path $script_path -Type Leaf)) {
                throw "Couldn't find script '$script_name'"
            }

            # OK, the following issue is royally stupid.  At one point, I
            # started getting errors like this:
            #
            #     Conversion from JSON failed with error: Unexpected character encountered while parsing value: W.
            #
            # They appeared out of nowhere, without any changes in the code.
            # Turns out, ConvertTo-Json is pretty much unusable by default.
            # See, it has a `-Depth` parameter, which has a default value of 2,
            # which is insanely low.  I don't know what it does if the input
            # exceeds the nesting depth of 2, but I do know that starting from
            # Powershell 7.1, ConvertTo-Json prints a "helpful" warning in this
            # case.  The warning looks like this:
            #
            #     WARNING: Resulting JSON is truncated as serialization has exceeded the set depth of 2.
            #
            # Apparently, PowerShell on windows-2016 images got upgraded, hence
            # the failure to parse the letter W.  I _accidentally_ fixed it by
            # adding "Select-Object Name,Value" to the pipeline, cutting the
            # nesting depth, so keeping that part in the pipeline is important.
            #
            # See also:
            #
            #     * https://github.com/PowerShell/PowerShell/issues/8393
            #     * https://stackoverflow.com/q/53583677/514684
            #     * https://stackoverflow.com/q/53562942/514684

            $json = $(& "${env:COMSPEC}" /s /c "`"$script_path`" -arch=${{ inputs.arch }} -no_logo && pwsh -Command `"Get-ChildItem env: | Select-Object Name,Value | ConvertTo-Json`"")
            if ($LASTEXITCODE -ne 0) {
                throw $json
            } else {
                try {
                    $json | ConvertFrom-Json | %{ Set-Content "env:$($_.Name)" $_.Value }
                } catch {
                    echo 'There was a problem with the following JSON:'
                    echo $json
                    throw
                }
            }
        }

        if ('${{ runner.os }}' -ne 'Windows') {
            echo 'Not going to set up a Visual Studio shell on ${{ runner.os }}'
        } else {
            $old_values = @{}
            Get-ChildItem env: | %{ $old_values.Add($_.Name, $_.Value) }

            $info = Locate-VS
            try {
                Import-PS $info
            } catch {
                echo $_
                Import-CMD $info
            }

            $new_values = @{}
            Get-ChildItem env: | %{ $new_values.Add($_.Name, $_.Value) }

            # Some diagnostics as to which exact variables were modified follows:
            echo '----------------------------------------------------------------'
            echo 'New variables'
            echo '----------------------------------------------------------------'
            $new_values.GetEnumerator() | where { -not $old_values.ContainsKey($_.Name) } | Format-List

            echo '----------------------------------------------------------------'
            echo 'Modified variables'
            echo '----------------------------------------------------------------'
            $new_values.GetEnumerator() | where { $old_values.ContainsKey($_.Name) -and $old_values[$_.Name] -ne $_.Value } | Format-List

            # Update the current environment:
            Get-ChildItem env: | %{ echo "$($_.Name)=$($_.Value)" >> $env:GITHUB_ENV }
        }
      shell: pwsh

branding:
  icon: star
  color: green