Public/Set-JiraIssueLabel.ps1

function Set-JiraIssueLabel {
    <#
    .Synopsis
        Modifies labels on an existing JIRA issue
    .DESCRIPTION
        This function modifies labels on an existing JIRA issue. There are
        four supported operations on labels:

        * Add: appends additional labels to the labels that an issue already has
        * Remove: Removes labels from an issue's current labels
        * Set: erases the existing labels on the issue and replaces them with
        the provided values
        * Clear: removes all labels from the issue
    .EXAMPLE
        Set-JiraIssueLabel -Issue TEST-01 -Set 'fixed'
        This example replaces all existing labels on issue TEST-01 with one
        label, "fixed".
    .EXAMPLE
        Get-JiraIssue -Query 'created >= -7d AND reporter in (joeSmith)' | Set-JiraIssueLabel -Add 'enhancement'
        This example adds the "enhancement" label to all issues matching the JQL - in this case,
        all issues created by user joeSmith in the last 7 days.
    .EXAMPLE
        Get-JiraIssue TEST-01 | Set-JiraIssueLabel -Clear
        This example removes all labels from the issue TEST-01.
    .INPUTS
       [JiraPS.Issue[]] The JIRA issue that should be modified
    .OUTPUTS
        If the -PassThru parameter is provided, this function will provide a reference
        to the JIRA issue modified. Otherwise, this function does not provide output.
    #>

    [CmdletBinding(
        SupportsShouldProcess = $true,
        DefaultParameterSetName = 'ReplaceLabels'
    )]
    param(
        # Issue key or JiraPS.Issue object returned from Get-JiraIssue
        [Parameter(Mandatory = $true,
            Position = 0,
            ValueFromPipeline = $true,
            ValueFromPipelineByPropertyName = $true)]
        [Alias('Key')]
        [Object[]] $Issue,

        # List of labels that will be set to the issue.
        # Any label that was already assigned to the issue will be removed.
        [Parameter(ParameterSetName = 'ReplaceLabels',
            Mandatory = $true)]
        [Alias('Label', 'Replace')]
        [String[]] $Set,

        # Existing labels to be added.
        [Parameter(ParameterSetName = 'ModifyLabels')]
        [String[]] $Add,

        # Existing labels to be removed.
        [Parameter(ParameterSetName = 'ModifyLabels')]
        [String[]] $Remove,

        # Remove all labels.
        [Parameter(ParameterSetName = 'ClearLabels')]
        [Switch] $Clear,

        # Credentials to use to connect to JIRA.
        # If not specified, this function will use anonymous access.
        [Parameter(Mandatory = $false)]
        [System.Management.Automation.PSCredential] $Credential,

        # Whether output should be provided after invoking this function.
        [Switch] $PassThru
    )

    begin {
    }

    process {
        foreach ($i in $Issue) {
            Write-Debug "[Set-JiraIssueLabel] Obtaining reference to issue"
            $issueObj = Get-JiraIssue -InputObject $i -Credential $Credential

            if ($issueObj) {
                $currentLabels = @($issueObj.labels)
                $url = $issueObj.RestURL
                $isDirty = $true

                # As of JIRA 6.4, the Add and Remove verbs in the REST API for
                # updating issues do not support arrays of parameters - you
                # need to pass a single label to add or remove per API call.

                # Instead, we'll do some fancy footwork with the existing
                # issue object and use the Set verb for everything, so we only
                # have to make one call to JIRA.

                if ($Clear) {
                    Write-Debug "[Set-JiraIssueLabel] Clearing all labels"
                    $newLabels = @()
                }
                elseif ($PSCmdlet.ParameterSetName -eq 'ReplaceLabels') {
                    Write-Debug "[Set-JiraIssueLabel] Set parameter was used; existing labels will be overwritten"
                    $newLabels = $Set
                }
                elseif ($null -eq $currentLabels -or $currentLabels.Count -eq 0) {
                    Write-Debug "[Set-JiraIssueLabel] Issue currently has no labels"
                    if ($Add) {
                        Write-Debug "[Set-JiraIssueLabel] Setting labels to Add parameter"
                        $newLabels = $Add
                    }
                    else {
                        Write-Debug "[Set-JiraIssueLabel] No labels were specified to be added; nothing to do"
                        $isDirty = $false
                    }
                }
                else {
                    Write-Debug "[Set-JiraIssueLabel] Calculating new labels"
                    # If $Add is not provided (null), this can end up with an
                    # extra $null being added to the array, so we need to
                    # account for that in the Where-Object as well as the
                    # Remove parameter.
                    $newLabels = $currentLabels + $Add | Where-Object -FilterScript {$_ -ne $null -and $Remove -notcontains $_}
                }

                if ($isDirty) {
                    Write-Debug "[Set-JiraIssueLabel] New labels for the issue: [$($newLabels -join ',')]"

                    $props = @{
                        'update' = @{
                            'labels' = @(
                                @{
                                    'set' = @($newLabels);
                                }
                            );
                        }
                    }

                    Write-Debug "[Set-JiraIssueLabel] Converting labels to JSON"
                    $json = ConvertTo-Json -InputObject $props -Depth 4

                    Write-Debug "[Set-JiraIssueLabel] JSON:`n$json"
                    Write-Debug "[Remove-JiraGroup] Checking for -WhatIf and Confirm"
                    if ($PSCmdlet.ShouldProcess($Issue, "Updating Issue [labels] from JIRA")) {
                        Write-Debug "[Set-JiraIssueLabel] Preparing for blastoff!"
                        # Should return no results
                        Invoke-JiraMethod -Method Put -URI $url -Body $json -Credential $Credential
                    }
                }
                else {
                    Write-Debug "[Set-JiraIssueLabel] No changes are necessary."
                }

                if ($PassThru) {
                    Write-Debug "[Set-JiraIssue] PassThru was specified. Obtaining updated reference to issue"
                    Get-JiraIssue -Key $issueObj.Key -Credential $Credential
                }
            }
            else {
                Write-Debug "[Set-JiraIssue] Unable to identify issue [$i]. Writing error message."
                Write-Error "Unable to identify issue [$i]"
            }
        }
    }

    end {
        Write-Debug "[Set-JiraIssueLabel] Complete"
    }
}