function Add-PoshGitToProfile {

    [CmdletBinding(SupportsShouldProcess)]

    param(

        [Parameter()]

        [switch]

        $AllHosts,

        [Parameter()]

        [switch]

        $AllUsers,

        [Parameter()]

        [switch]

        $Force,

        [Parameter(ValueFromRemainingArguments)]

        [psobject[]]

        $TestParams

    )

    if ($AllUsers -and !(Test-Administrator)) {

        throw 'Adding posh-git to an AllUsers profile requires an elevated host.'

    }

    $underTest = $false

    $profileName = $(if ($AllUsers) { 'AllUsers' } else { 'CurrentUser' }) `

                 + $(if ($AllHosts) { 'AllHosts' } else { 'CurrentHost' })

    Write-Verbose "`$profileName = '$profileName'"

    $profilePath = $PROFILE.$profileName

    Write-Verbose "`$profilePath = '$profilePath'"

    # Under test, we override some variables using $args as a backdoor.

    if (($TestParams.Count -gt 0) -and ($TestParams[0] -is [string])) {

        $profilePath = [string]$TestParams[0]

        $underTest = $true

        if ($TestParams.Count -gt 1) {

            $ModuleBasePath = [string]$TestParams[1]

        }

    }

    if (!$profilePath) { $profilePath = $PROFILE }

    if (!$Force) {

        # Search the user's profiles to see if any are using posh-git already, there is an extra search

        # ($profilePath) taking place to accomodate the Pester tests.

        $importedInProfile = Test-PoshGitImportedInScript $profilePath

        if (!$importedInProfile -and !$underTest) {

            $importedInProfile = Test-PoshGitImportedInScript $PROFILE

        }

        if (!$importedInProfile -and !$underTest) {

            $importedInProfile = Test-PoshGitImportedInScript $PROFILE.CurrentUserCurrentHost

        }

        if (!$importedInProfile -and !$underTest) {

            $importedInProfile = Test-PoshGitImportedInScript $PROFILE.CurrentUserAllHosts

        }

        if (!$importedInProfile -and !$underTest) {

            $importedInProfile = Test-PoshGitImportedInScript $PROFILE.AllUsersCurrentHost

        }

        if (!$importedInProfile -and !$underTest) {

            $importedInProfile = Test-PoshGitImportedInScript $PROFILE.AllUsersAllHosts

        }

        if ($importedInProfile) {

            Write-Warning "Skipping add of posh-git import to file '$profilePath'."

            Write-Warning "posh-git appears to already be imported in one of your profile scripts."

            Write-Warning "If you want to force the add, use the -Force parameter."

            return

        }

    }

    if (!$profilePath) {

        Write-Warning "Skipping add of posh-git import to profile; no profile found."

        Write-Verbose "`$PROFILE              = '$PROFILE'"

        Write-Verbose "CurrentUserCurrentHost = '$($PROFILE.CurrentUserCurrentHost)'"

        Write-Verbose "CurrentUserAllHosts    = '$($PROFILE.CurrentUserAllHosts)'"

        Write-Verbose "AllUsersCurrentHost    = '$($PROFILE.AllUsersCurrentHost)'"

        Write-Verbose "AllUsersAllHosts       = '$($PROFILE.AllUsersAllHosts)'"

        return

    }

    # If the profile script exists and is signed, then we should not modify it

    if (Test-Path -LiteralPath $profilePath) {

        if (!(Get-Command Get-AuthenticodeSignature -ErrorAction SilentlyContinue))

        {

            Write-Verbose "Platform doesn't support script signing, skipping test for signed profile."

        }

        else {

            $sig = Get-AuthenticodeSignature $profilePath

            if ($null -ne $sig.SignerCertificate) {

                Write-Warning "Skipping add of posh-git import to profile; '$profilePath' appears to be signed."

                Write-Warning "Add the command 'Import-Module posh-git' to your profile and resign it."

                return

            }

        }

    }

    # Check if the location of this module file is in the PSModulePath

    if (Test-InPSModulePath $ModuleBasePath) {

        $profileContent = "`nImport-Module posh-git"

    }

    else {

        $modulePath = Join-Path $ModuleBasePath posh-git.psd1

        $profileContent = "`nImport-Module '$modulePath'"

    }

    # Make sure the PowerShell profile directory exists

    $profileDir = Split-Path $profilePath -Parent

    if (!(Test-Path -LiteralPath $profileDir)) {

        if ($PSCmdlet.ShouldProcess($profileDir, "Create current user PowerShell profile directory")) {

            New-Item $profileDir -ItemType Directory -Force -Verbose:$VerbosePreference > $null

        }

    }

    if ($PSCmdlet.ShouldProcess($profilePath, "Add 'Import-Module posh-git' to profile")) {

        Add-Content -LiteralPath $profilePath -Value $profileContent -Encoding UTF8

    }

}