param
(
    [Parameter(Mandatory, HelpMessage="Start commit reference")]$From,
    [Parameter(HelpMessage="End commit reference")]$To = "HEAD^"
)

function Test-Version ([System.Version]$version) {
    $revision = $version.Revision
    if ($revision -eq 0) {
        throw "Version must not have revision 0, PowerShell Gallery will not accept it.";
    }
    Write-Host "Version revision ($revision) is valid in $version.";
}

function Test-InstallerVersion([string]$from, [string]$to) {
    $response = git diff --name-only $from $to

    # check if there are any changes in the installer
    $isInstallerUpdated = $false
    foreach ($file in $response) {
        if ($file -like "modules/Installer/*") {
            $isInstallerUpdated = $true
        }
    }

    # if there are no changes in the installer, return success
    if ($isInstallerUpdated -eq $false) {
        Write-Host "AWS.Tools.Installer is not updated"
        exit 0
    }

    # get the publicly available version of the installer
    $publicInstallerModule = Find-Module -Name AWS.Tools.Installer
    $publicVersion = $publicInstallerModule.Version
    Write-Host "Public AWS.Tools.Installer version: $publicVersion"

    # get the local version of the installer

    # Unload the module if it is already loaded
    if(Get-Module -Name AWS.Tools.Installer)
    {
        Remove-Module -Name AWS.Tools.Installer
    }
    $installerModulePath = Join-Path  "." "modules" "Installer" "AWS.Tools.Installer.psd1"
    Import-Module $installerModulePath
    $localInstallerModule = Get-Module -Name AWS.Tools.Installer
    $localVersion = $localInstallerModule.Version
    Write-Host "Local AWS.Tools.Installer version: $localVersion"

    # check if the new version has 0 revision
    Test-Version -Version $localVersion

    if ($localVersion -le $publicVersion) {
        throw "Local AWS.Tools.Installer version is less than or equal to public version.
Bump the version in modules/Installer/AWS.Tools.Installer.psd1 else the installer will not be updated in the PowerShell Gallery."
    }

    Write-Host "Local AWS.Tools.Installer version ($localVersion) is greater than public version ($publicVersion)."
}

Test-InstallerVersion -From $From -To $To