1  <#
 2  .SYNOPSIS
 3      Retrieves the unified diff patch for a specific file in a GitHub pull request.
 4  
 5  .DESCRIPTION
 6      This script fetches the patch content (unified diff format) for a specified file
 7      within a pull request. It uses the GitHub CLI (gh) to query the GitHub API and
 8      retrieve file change information.
 9  
10  .PARAMETER PullRequestNumber
11      The pull request number to query.
12  
13  .PARAMETER FilePath
14      The relative path to the file in the repository (e.g., "src/modules/main.cpp").
15  
16  .PARAMETER RepositoryOwner
17      The GitHub repository owner. Defaults to "microsoft".
18  
19  .PARAMETER RepositoryName
20      The GitHub repository name. Defaults to "PowerToys".
21  
22  .EXAMPLE
23      .\Get-GitHubPrFilePatch.ps1 -PullRequestNumber 42374 -FilePath "src/modules/cmdpal/main.cpp"
24      Retrieves the patch for main.cpp in PR #42374.
25  
26  .EXAMPLE
27      .\Get-GitHubPrFilePatch.ps1 -PullRequestNumber 42374 -FilePath "README.md" -RepositoryOwner "myorg" -RepositoryName "myrepo"
28      Retrieves the patch from a different repository.
29  
30  .NOTES
31      Requires GitHub CLI (gh) to be installed and authenticated.
32      Run 'gh auth login' if not already authenticated.
33  
34  .LINK
35      https://cli.github.com/
36  #>
37  
38  [CmdletBinding()]
39  param(
40      [Parameter(Mandatory = $true, HelpMessage = "Pull request number")]
41      [int]$PullRequestNumber,
42  
43      [Parameter(Mandatory = $true, HelpMessage = "Relative path to the file in the repository")]
44      [string]$FilePath,
45  
46      [Parameter(Mandatory = $false, HelpMessage = "Repository owner")]
47      [string]$RepositoryOwner = "microsoft",
48  
49      [Parameter(Mandatory = $false, HelpMessage = "Repository name")]
50      [string]$RepositoryName = "PowerToys"
51  )
52  
53  # Construct GitHub API path for pull request files
54  $apiPath = "repos/$RepositoryOwner/$RepositoryName/pulls/$PullRequestNumber/files?per_page=250"
55  
56  # Query GitHub API to get all files in the pull request
57  try {
58      $pullRequestFiles = gh api $apiPath | ConvertFrom-Json
59  } catch {
60      Write-Error "Failed to query GitHub API for PR #$PullRequestNumber. Ensure gh CLI is authenticated. Details: $_"
61      exit 1
62  }
63  
64  # Find the matching file in the pull request
65  $matchedFile = $pullRequestFiles | Where-Object { $_.filename -eq $FilePath }
66  
67  if (-not $matchedFile) {
68      Write-Error "File '$FilePath' not found in PR #$PullRequestNumber."
69      exit 1
70  }
71  
72  # Check if patch content exists
73  if (-not $matchedFile.patch) {
74      Write-Warning "File '$FilePath' has no patch content (possibly binary or too large)."
75      return
76  }
77  
78  # Output the patch content
79  $matchedFile.patch