Converts a collection of projects from a SVN mono-repo to separate git repos.

convert-svn2git.ps1

# Where svn.exe can be found
$svnPath = 'C:\Data\svn'
# Where the resulting git repositories should be created
$gitRepoPath = 'C:\Data\svn\git'
# The branch that should become the default branch in the git repository
$defaultBranch = 'trunk'
$removeTempRepository = $true
# The URL to the SVN server (can be file:///)
$svnRepoUrl = 'file:///c:\Data\svn\SVNRepo'
# The relative paths of each project inside the SVN repository, where 'trunk', 'branches' and 'tags' folders can be found
# Note: If the project doesn't have a trunk folder, the script will not be able to clone the project.
$projectSvnPaths = 'Projects/ProjectA',
  'Projects/ProjectB',
  'Projects/ProjectC'

# git-svn uses a more strict unix url format, while svn.exe requires a Windows compatible format.
# If svn url is already a valid http:// or svn:// style url, this should not change it.
$svnRepoUrlForGit = $svnRepoUrl -replace ':\\','\\' -replace '\\','//' -replace ' ','%20'

If (-not (Test-Path "$gitRepoPath")) {
  md "$gitRepoPath" | Out-Null
}
$authorTransformFile = Join-Path $gitRepoPath "authors-transform.txt"
If (-not (Test-Path "$authorTransformFile")) {
  Write-Host "Extracting authors from the repository" -ForegroundColor Green
  & (Join-Path "$svnPath" 'svn.exe') log "$svnRepoUrl" -q | ?{ $_ -cmatch '^r.*?\|\s(.*?)\s\|' } | %{ "{0} = {0} <{0}>" -f $Matches[1] } | select -Unique | sc "$authorTransformFile"
  Write-Host "You can now edit the authors transform file '$authorTransformFile'"
  Read-Host -Prompt 'Press Enter when done' | Out-Null
}

Push-Location "$svnPath"

$projectSvnPaths | %{
  Write-Host
  Write-Host " Processing project '$_' " -ForegroundColor Black -BackgroundColor Green
  $projectPath = $_
  $projectCloneRootPath = Join-Path $gitRepoPath $projectPath
  $projectCloneTempPath = "$projectCloneRootPath.git-temp"
  $projectCloneBareGitPath = "$projectCloneRootPath.git"

  # Create folder if it doesn't exist
  # Skip project if it does and is not empty
  If (Test-Path "$projectCloneBareGitPath") {
    Write-Host "Project '$projectPath' already converted. Skipping project." -ForegroundColor Yellow
    Start-Sleep -Milliseconds 300
    return
  }
  If (-not (Test-Path "$projectCloneTempPath")) {
    md "$projectCloneTempPath" | Out-Null
  }
  ElseIf ((gci "$projectCloneTempPath" | measure).Count -gt 0) {
    Write-Host "Clone path not empty '$projectPath'. Skipping project" -ForegroundColor Yellow
    return
  }

  Write-Host "Creating temporary clone of SVN project '$projectPath' through Git" -ForegroundColor Green
  git svn clone "$svnRepoUrlForGit" --no-metadata -A "$authorTransformFile" --trunk="$projectPath/trunk" --tags="$projectPath/tags" --branches="$projectPath/branches" --prefix="origin/" "$projectCloneTempPath"

  Write-Host "Converting svn:ignore properties to .gitignore file" -ForegroundColor Green
  Push-Location "$projectCloneTempPath"
  git svn show-ignore --id=origin/trunk | sc .gitignore
  If (Test-Path '.gitignore') {
    git add .gitignore
    git commit -m 'Convert svn:ignore properties to .gitignore'
  }
  Pop-Location

  Write-Host "Creating new bare git repository" -ForegroundColor Green
  git init --bare "$projectCloneBareGitPath"
  Push-Location "$projectCloneBareGitPath"
  git symbolic-ref HEAD refs/heads/trunk
  Pop-Location

  Write-Host "Pushing to bare git repository" -ForegroundColor Green
  Push-Location "$projectCloneTempPath"
  git remote add bare "$projectCloneBareGitPath"
  git config remote.bare.push 'refs/remotes/*:refs/heads/*'
  git push bare
  Pop-Location

  Write-Host "Fixing tags and branch names in bare repository" -ForegroundColor Green
  Push-Location "$projectCloneBareGitPath"
  git for-each-ref --format='%(refname)' refs/heads/origin | %{
    $branch = $_ -replace '^refs/heads/origin/(.*)$','$1'
    if ($branch -like 'tags/*') {
      # If ref is a tag, create a real tag and remove the branch
      $tag = $branch -replace '^tags/(.*)$','$1'
      git tag "$tag" "refs/heads/origin/tags/$tag"
      Write-Host "  New tag '$tag'" -ForegroundColor DarkYellow
      git branch -D "origin/$branch"
    }
    Else {
      # Remove 'origin/' from all refs
      git branch -m "origin/$branch" "$branch"
    }
  }

  Write-Host "Setting default branch name in bare repository" -ForegroundColor Green
  $repoDefaultBranch = $defaultBranch
  Do {
    If (-not $repoDefaultBranch) {
      Write-Host "Branch '$repoDefaultBranch' not found. Please select one from above list: " -ForegroundColor Yellow -NoNewline
      $repoDefaultBranch = Read-Host
    }
    $repoDefaultBranch = git branch -l | %{
      If ($_ -cmatch "^.*\s($repoDefaultBranch)$") {
        Write-Host $_ -ForegroundColor Cyan
        return $Matches[1]
      }
      Write-Host $_ -ForegroundColor DarkYellow
      # returning anything at all (including empty string and even $null) results in weird output
      return
    }
  } Until ($repoDefaultBranch)
  git branch -m "$repoDefaultBranch" master
  git symbolic-ref HEAD refs/heads/master
  Pop-Location

  If ($removeTempRepository) {
    Write-Host "Removing temporary clone" -ForegroundColor Green
    del "$projectCloneTempPath" -Recurse -Force | Out-Null
  }
}

Pop-Location