Functions/Set-GitHead.ps1

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

function Set-GitHead {
    <#
    .SYNOPSIS
    Updates the working directory of a Git repository to a specific commit.

    .DESCRIPTION
    The `Set-GitHead` function updates a Git repository to a specific commit, i.e. it checks out a specific commit.

    The default target is "HEAD". Use the `Revision` parameter to specifiy a different branch, tag, commit, etc. If you specify a branch name, and there isn't a local branch by that name, but there is a remote branch, this function creates a new local branch that tracks the remote branch.

    It defaults to the current repository. Use the `RepoRoot` parameter to specify an explicit path to another repo.

    Use the `Force` switch to remove any uncommitted/unstaged changes during the checkout. Otherwise, the update will fail.

    This function implements the `git checkout <target>` command.

    .INPUTS
    PSGitHub.PullRequest. You can pipe in the output of PSGitHub's Get-GitHubPullRequest.

    .EXAMPLE
    Set-GitHead -RepoRoot 'C:\Projects\PowerGit' -Revision 'feature/ticket'

    Demonstrates how to checkout the 'feature/ticket' branch of the given repository.

    .EXAMPLE
    Set-GitHead -RepoRoot 'C:\Projects\PowerGit' -Revision 'refs/tags/tag1'

    Demonstrates how to create a detached head at the tag 'tag1'.

    .EXAMPLE
    Set-GitHead -RepoRoot 'C:\Projects\PowerGit' -Revision 'develop' -Force

    Demonstrates how to remove any uncommitted changes during the checkout by using the `Force` switch.
    #>


    [CmdletBinding()]
    [OutputType([LibGit2Sharp.Branch])]
    param(
        # Specifies which git repository to update. Defaults to the current directory.
        [string] $RepoRoot = (Get-Location).ProviderPath,

        # The revision checkout, i.e. update the repository HEAD to.
        # A revision can be a specific commit ID/sha (short or long), branch name, tag name, etc.
        # Run git help gitrevisions or go to https://git-scm.com/docs/gitrevisions for full documentation on Git's revision syntax.
        [Parameter(Position = 0, Mandatory, ValueFromPipelineByPropertyName)]
        [Alias('FriendlyName')]
        [Alias('HeadRef')] # PSGitHub.PullRequest
        [string] $Revision,

        # Remove any uncommitted changes when checking out/updating to `Revision`.
        [Switch] $Force
    )

    Set-StrictMode -Version 'Latest'

    $repo = Find-GitRepository -Path $RepoRoot -Verify
    if (-not $repo) {
        return
    }

    $cancel = $false
    try {
        $checkoutOptions = [LibGit2Sharp.CheckoutOptions]::new()
        $checkoutOptions.OnCheckoutNotify = {
            param([string]$Path, [LibGit2Sharp.CheckoutNotifyFlags]$NotifyFlags)
            Write-Information "$($NotifyFlags): $Path"
            return -not $cancel -and -not $PSCmdlet.Stopping
        }
        $checkoutOptions.OnCheckoutProgress = {
            param([string]$Path, [int]$CompletedSteps, [int]$TotalSteps)
            if ($ProgressPreference -ne 'SilentlyContinue' -and $TotalSteps -ne 0) {
                $progressParams = @{
                    Activity = 'Checking files out'
                }
                if ($TotalSteps -ne 0) {
                    $progressParams.PercentComplete = (($CompletedSteps / $TotalSteps) * 100)
                }
                if ($Path) {
                    $progressParams.Status = $Path
                }
                Write-Progress @progressParams
            }
        }
        if ($Force) {
            $checkoutOptions.CheckoutModifiers = [LibGit2Sharp.CheckoutModifiers]::Force
        }

        $branch = $repo.Branches[$Revision]
        if (-not $branch) {
            [LibGit2Sharp.Branch]$remoteBranch = $repo.Branches | Where-Object { $_.UpstreamBranchCanonicalName -eq ('refs/heads/{0}' -f $Revision) }
            if ($remoteBranch) {
                $branch = $repo.Branches.Add($Revision, $remoteBranch.Tip.Sha)
                $repo.Branches.Update($branch, {
                    param([LibGit2Sharp.BranchUpdater] $Updater)

                    $Updater.TrackedBranch = $remoteBranch.CanonicalName
                }) | Out-Null
            }
        }

        [LibGit2Sharp.Commands]::Checkout($repo, $Revision, $checkoutOptions)
    } finally {
        $cancel = $true
        $repo.Dispose()
    }
}