functions/Set-DbatoolsConfig.ps1

function Set-DbatoolsConfig {
    <#
        .SYNOPSIS
            Sets configuration entries.
 
        .DESCRIPTION
            This function creates or changes configuration values.
            These are used in dbatools to provide dynamic configuration information outside the PowerShell variable system.
 
        .PARAMETER FullName
            The full name of a configuration element. Must be namespaced <Module>.<Name>.
            The name can have any number of sub-segments, in order to better group configurations thematically.
 
        .PARAMETER Name
            Name of the configuration entry. If an entry of exactly this non-casesensitive name already exists, its value will be overwritten.
            Duplicate names across different modules are possible and will be treated separately.
            If a name contains namespace notation and no module is set, the first namespace element will be used as module instead of name. Example:
            -Name "Nordwind.Server"
            Is Equivalent to
            -Name "Server" -Module "Nordwind"
 
        .PARAMETER Module
            This allows grouping configuration elements into groups based on the module/component they server.
            If this parameter is not set, the configuration element is stored under its name only, which increases the likelyhood of name conflicts in large environments.
 
        .PARAMETER Value
            The value to assign to the named configuration element.
 
        .PARAMETER Description
            Using this, the configuration setting is given a description, making it easier for a user to comprehend, what a specific setting is for.
 
        .PARAMETER Validation
            The name of the validation script used for input validation.
            These can be used to validate make sure that input is of the proper data type.
            New validation scripts can be registered using Register-DbatoolsConfigValidation
 
        .PARAMETER Handler
            A scriptblock that is executed when a value is being set.
            Is only executed if the validation was successful (assuming there was a validation, of course)
 
        .PARAMETER Hidden
            Setting this parameter hides the configuration from casual discovery. Configurations with this set will only be returned by Get-Config, if the parameter "-Force" is used.
            This should be set for all system settings a user should have no business changing (e.g. for Infrastructure related settings such as mail server).
 
        .PARAMETER Default
            Setting this parameter causes the system to treat this configuration as a default setting. If the configuration already exists, no changes will be performed.
            Useful in scenarios where for some reason it is not practical to automatically set defaults before loading userprofiles.
 
        .PARAMETER Initialize
            Use this when setting configurations as part of module import.
            When initializing a configuration, it will only do a thing if the configuration hasn't already been initialized (So if you load the module multiple times or in multiple runspaces, it won't make a difference)
            Also, if there already was a non-initialized setting set for a given configuration, it will then try to set the old value again.
            This value will be processed by handlers, if any are set.
 
        .PARAMETER DisableValidation
            This parameters disables the input validation - if any - when processing a setting.
            Normally this shouldn't be circumvented, but just in case, it can be disabled.
 
        .PARAMETER DisableHandler
            Internal Use Only.
            This parameter disables the configuration handlers.
            Configuration handlers are designed to automatically validate and process input set to a config value, in addition to writing the value.
            In many cases, this is used to improve performance, by forking the value location also to a static C#-field, which is then used, rather than searching a Hashtable.
            Sometimes it may only be used to introduce input validation.
            During module import, some handlers are registered and many values written to configuration.
            However, some of those values actually are already set as default values within the library. Processing a handler will cost a few ms.
            Add up a couple dozen such events and the delay is very notable.
 
        .PARAMETER EnableException
            By default, when something goes wrong we try to catch it, interpret it and give you a friendly warning message.
            This avoids overwhelming you with "sea of red" exceptions, but is inconvenient because it basically disables advanced scripting.
            Using this switch turns this "nice by default" feature off and enables you to catch exceptions with your own try/catch.
 
        .NOTES
            Tags: Config, Module
            Author: Friedrich Weinmann
 
        .EXAMPLE
            PS C:\> Set-DbatoolsConfig -Name 'User' -Value "Friedrich" -Description "The user under which the show must go on."
 
            Creates a configuration entry named "User" with the value "Friedrich"
 
        .EXAMPLE
            PS C:\> Set-DbatoolsConfig -Name 'mymodule.User' -Value "Friedrich" -Description "The user under which the show must go on." -Handler $scriptBlock -Initialize -Validation String
 
            Creates a configuration entry ...
            - Named "mymodule.user"
            - With the value "Friedrich"
            - It adds a description as noted
            - It registers the scriptblock stored in $scriptBlock as handler
            - It initializes the script. This block only executes the first time a it is run like this. Subsequent calls will be ignored.
            - It registers the basic string input type validator
            This is the default example for modules using the configuration system.
            Note: While the -Handler parameter is optional, it is important to add it at the initial initialize call, if you are planning to add it.
            Only then will the system validate previous settings (such as what a user might have placed in his user profile)
 
        .EXAMPLE
            PS C:\> Set-DbatoolsConfig 'ConfigLink' 'https://www.example.com/config.xml' 'Company' -Hidden
 
            Creates a configuration entry named "ConfigLink" in the "Company" module with the value 'https://www.example.com/config.xml'.
            This entry is hidden from casual discovery using Get-Config.
 
        .EXAMPLE
            PS C:\> Set-DbatoolsConfig 'Network.Firewall' '10.0.0.2' -Default
 
            Creates a configuration entry named "Firewall" in the "Network" module with the value '10.0.0.2'
            This is only set, if the setting does not exist yet. If it does, this command will apply no changes.
    #>

    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSUseShouldProcessForStateChangingFunctions", "")]
    [CmdletBinding(DefaultParameterSetName = "FullName")]
    Param (
        [Parameter(ParameterSetName = "FullName", Position = 0, Mandatory = $true)]
        [string]$FullName,
        [Parameter(ParameterSetName = "Module", Position = 1, Mandatory = $true)]
        [string]$Name,
        [Parameter(ParameterSetName = "Module", Position = 0)]
        [string]$Module,
        [Parameter(ParameterSetName = "FullName", Position = 1)]
        [Parameter(ParameterSetName = "Module", Position = 2)]
        [AllowNull()]
        [AllowEmptyCollection()]
        [AllowEmptyString()]
        $Value,
        [string]$Description,
        [string]$Validation,
        [System.Management.Automation.ScriptBlock]$Handler,
        [switch]$Hidden,
        [switch]$Default,
        [switch]$Initialize,
        [switch]$DisableValidation,
        [switch]$DisableHandler,
        [switch]$EnableException
    )

    #region Prepare Names
    if ($PSCmdlet.ParameterSetName -eq "FullName") {
        if (-not $FullName.Trim(".").Contains(".")) {
            Stop-Function -Message "Invalid Name: $FullName ! At least one '.' is required, to separate module from name" -EnableException $EnableException -Category InvalidArgument
            return
        }

        $Module = $FullName.Split(".")[0].ToLower().Trim(".")
        $Name = $FullName.Substring(($Module.Length + 1)).ToLower().Trim(".")
        $internalFullName = $FullName.ToLower().Trim(".")
    }
    else {
        $Name = $Name.ToLower().Trim(".")
        if ($Module) { $Module = $Module.ToLower().Trim(".") }

        if ((Test-Bound -ParameterName "Module" -Not) -and ($Name -match ".+\..+")) {
            $r = $Name | select-string "^(.+?)\..+" -AllMatches
            $Module = $r.Matches[0].Groups[1].Value
            $Name = $Name.Substring($Module.Length + 1)
        }
        elseif ((Test-Bound -ParameterName "Module" -Not) -and ($Name -notmatch ".+\..+")) {
            Stop-Function -Message "Invalid Name: $Name ! At least one '.' is required when not explicitly specifying a module name, to separate module from name" -EnableException $EnableException -Category InvalidArgument
            return
        }

        If ($Module) { $internalFullName = $Module, $Name -join "." }
        else { $internalFullName = $Name }
    }
    #endregion Prepare Names

    #region Prepare runtime and kill execution as needed
    if ([Sqlcollaborative.Dbatools.Configuration.ConfigurationHost]::Configurations.ContainsKey($internalFullName)) {
        $itExists = $true
        $itIsInitialized = [Sqlcollaborative.Dbatools.Configuration.ConfigurationHost]::Configurations[$internalFullName].Initialized
        $itIsEnforced = [Sqlcollaborative.Dbatools.Configuration.ConfigurationHost]::Configurations[$internalFullName].PolicyEnforced
    }
    else {
        $itExists = $false
        $itIsInitialized = $false
        $itIsEnforced = $false
    }

    if ($itExists -and $Default) { return }
    if ($itIsInitialized -and $Initialize) { return }
    if ($itIsEnforced -and (-not $Initialize)) {
        Stop-Function -Message "Could not update configuration due to policy settings: $internalFullName" -EnableException $EnableException -Category PermissionDenied
        return
    }

    if (Test-Bound -ParameterName "Validation") {
        if (-not ([Sqlcollaborative.Dbatools.Configuration.ConfigurationHost]::Validation.Keys -contains $Validation.ToLower())) {
            Stop-Function -Message "Invalid validation name: $Validation. Supported validations: $([Sqlcollaborative.Dbatools.Configuration.ConfigurationHost]::Validation.Keys -join ", ")" -Category InvalidArgument -Target $Name
            return
        }
    }
    #endregion Prepare runtime and kill execution as needed

    #region Initializing a configuration
    if ($Initialize) {
        if ($itExists) {
            $oldValue = [Sqlcollaborative.Dbatools.Configuration.ConfigurationHost]::Configurations[$internalFullName].Value
            $cfg = [Sqlcollaborative.Dbatools.Configuration.ConfigurationHost]::Configurations[$internalFullName]
        }
        else { $cfg = New-Object Sqlcollaborative.Dbatools.Configuration.Config }
        $cfg.Name = $Name
        $cfg.Module = $Module
        $cfg.Description = $Description
        $cfg.Value = $Value
        $cfg.Handler = $Handler
        if ($Validation) { $cfg.Validation = [Sqlcollaborative.Dbatools.Configuration.ConfigurationHost]::Validation[$Validation.ToLower()] }
        $cfg.Hidden = $Hidden
        $cfg.Initialized = $true
        [Sqlcollaborative.Dbatools.Configuration.ConfigurationHost]::Configurations[$internalFullName] = $cfg

        if ($itExists) { Set-DbatoolsConfig -Name $internalFullName -Value $oldValue }
    }
    #endregion Initializing a configuration

    #region Regular configuration update
    else {
        if (-not $itExists) {
            $cfg = New-Object Sqlcollaborative.Dbatools.Configuration.Config
            $cfg.Name = $Name
            $cfg.Module = $Module
            $cfg.Description = $Description
            $cfg.Handler = $Handler
            if ($Validation) { $cfg.Validation = [Sqlcollaborative.Dbatools.Configuration.ConfigurationHost]::Validation[$Validation.ToLower()] }
            $cfg.Hidden = $Hidden
            [Sqlcollaborative.Dbatools.Configuration.ConfigurationHost]::Configurations[$internalFullName] = $cfg

            Set-DbatoolsConfig -Name $internalFullName -Value $Value
            return
        }

        else {
            [Sqlcollaborative.Dbatools.Configuration.Config]$cfg = [Sqlcollaborative.Dbatools.Configuration.ConfigurationHost]::Configurations[$internalFullName]
            if ((-not $DisableValidation) -and ($cfg.Validation) -and (Test-Bound -ParameterName "Value")) {
                $testResult = [scriptblock]::Create($cfg.Validation.ToString()).Invoke($Value)
                if (-not $TestResult.Success) {
                    Stop-Function -Message "Could not update configuration $internalFullName | Failed validation: $($testResult.Message)" -EnableException $EnableException -Category InvalidResult -Target $internalFullName
                    return
                }
                $Value = $testResult.Value
            }

            if (Test-Bound -ParameterName "Hidden") { [Sqlcollaborative.Dbatools.Configuration.ConfigurationHost]::Configurations[$internalFullName].Hidden = $Hidden }
            if (Test-Bound -ParameterName "Value") { [Sqlcollaborative.Dbatools.Configuration.ConfigurationHost]::Configurations[$internalFullName].Value = $Value }
            if (Test-Bound -ParameterName "Description") { [Sqlcollaborative.Dbatools.Configuration.ConfigurationHost]::Configurations[$internalFullName].Description = $Description }
            if (Test-Bound -ParameterName "Handler") { [Sqlcollaborative.Dbatools.Configuration.ConfigurationHost]::Configurations[$internalFullName].Handler = $Handler }
            if (Test-Bound -ParameterName "Validation") { [Sqlcollaborative.Dbatools.Configuration.ConfigurationHost]::Configurations[$internalFullName].Validation = [Sqlcollaborative.Dbatools.Configuration.ConfigurationHost]::Validation[$Validation.ToLower()] }

            if ((-not $DisableHandler) -and ($cfg.Handler) -and (Test-Bound -ParameterName "Value")) {
                try { [scriptblock]::Create($cfg.Handler.ToString()).Invoke($Value) }
                catch {
                    Stop-Function -Message "Could not update configuration $internalFullName | Failed handling $_" -EnableException $EnableException -Category InvalidResult -Target $internalFullName
                    return
                }
            }
        }
    }
    Test-DbaDeprecation -DeprecatedOn "1.0.0" -EnableException:$false -Alias Set-DbaConfig
    #endregion Regular configuration update
}