# Licensed to the .NET Foundation under one or more agreements.
# The .NET Foundation licenses this file to you under the Apache 2.0 License.
# See the LICENSE file in the project root for more information.

<#
.SYNOPSIS

 Activates an IronPython environment, placing its commands at the head of $Env:PATH.

.DESCRIPTION

 This script modifies the current PowerShell environment such that a given IronPython installation becomes the active one. By default, the installation containing this script is being activated, or, if the script is not part of an installation, the latest MSI-installed version of IronPython (Windows only).

 IronPython environments do not nest. Entering a new environment from within an active environment automatically exits the current one.

 The following modifications are made:

 * The Env:PATH variable is modified by adding the path to the environment commands at the beginning of the existing list of paths.
 * The PowerShell prompt is modified to display the name of the environment.
 * A new function Exit-IronPythonEnvironment is defined, with an alias "exipy". Use this function to undo all modifications done on entering.

 When switch -Isolated is used, additional modifications are performed:

 * Variable Env:IRONPYTHONPATH is cleared.
 * Alias:ipy, if exists, is deleted.
 * Function:ipy, if exists, is deleted.
#>
[CmdletBinding()]
param(
# Path to an IronPython environment to enter.
[Parameter(Position=0)]
[SupportsWildcards()]
[string]$Path,

# On enter, unset Env:IRONPYTHONPATH, Alias:ipy, and Function:ipy. Restore on exit.
[switch]$Isolated,

# Color of the environment name printed on the prompt.
[ConsoleColor]$PromptColor=[ConsoleColor]::DarkGray
)

if(-not$Path){
# Locate default environment to activate
if(Test-Path(Join-Path$PSScriptRoot"IronPython.dll")){
$Path=$PSScriptRoot
}elseif($IsWindows-and(Test-PathHKLM:\SOFTWARE\IronPython\*\InstallPath)){
$installKey=(Resolve-PathHKLM:\SOFTWARE\IronPython\*\InstallPath)[-1]# grab the latest
$Path=Get-ItemPropertyValue-Path$installKey-Name'(default)'
}else{
Write-Error"Cannot locate default environment."
exit1
}
}

if(-not(Test-Path$Path-PathTypeContainer)){
Write-Error"Environment not found: $Path"
exit1
}

if((Resolve-Path$Path).Count-gt1){
Write-Error"Environment path resolved to multiple locations:"
Resolve-Path$Path|Write-Error
exit1
}

functionglobal:Exit-IronPythonEnvironment([switch]$NonDestructive){
<#
.SYNOPSIS
 Undo all environment modifications done by Enter-IronPythonEnvironment

.PARAMETER NonDestructive
 Keep function Exit-IronPythonEnvironment and its alias. Subsequent invocations of this function while not within an IronPython environment will result in no-op.
 #>

if(Test-PathFunction:IronPythonParentPrompt){
Copy-ItemFunction:IronPythonParentPromptFunction:prompt
Remove-ItemFunction:IronPythonParentPrompt
}

if(Test-PathVariable:IronPythonParentEnvironment){
$Env:IRONPYTHONPATH=$IronPythonParentEnvironment["libpath"]
$Env:PATH=$IronPythonParentEnvironment["binpath"]

$oldAlias=$IronPythonParentEnvironment["alias"]
if($null-ne$oldAlias){
Set-Alias-Nameipy`
-Value$oldAlias.Definition`
-Description$oldAlias.Description`
-Option$oldAlias.Options`
-Scopeglobal
}
if($null-ne$IronPythonParentEnvironment["function"]){
Copy-Item$IronPythonParentEnvironment["function"]Function:ipy
}
Remove-ItemVariable:IronPythonParentEnvironment
}

Remove-Variable-NameIronPythonEnvironment*-Scopeglobal

if(-not$NonDestructive){
Remove-ItemFunction:Exit-IronPythonEnvironment
Remove-ItemAlias:exipy-ErrorActionIgnore
}
}

Exit-IronPythonEnvironment-NonDestructive

$global:IronPythonEnvironmentPath=Resolve-Path$Path
$global:IronPythonEnvironmentName=Split-Path$IronPythonEnvironmentPath-Leaf
$global:IronPythonEnvironmentColor="$PromptColor"

# Save stuff that already exists

$global:IronPythonParentEnvironment=@{"binpath"=$Env:PATH}

if($Isolated){
if(Test-PathAlias:ipy){
$IronPythonParentEnvironment["alias"]=Get-ItemAlias:ipy
Remove-ItemAlias:ipy
}

if(Test-PathFunction:ipy){
$IronPythonParentEnvironment["function"]=Get-Itemfunction:ipy
Remove-ItemFunction:ipy
}

if(Test-PathEnv:IRONPYTHONPATH){
$IronPythonParentEnvironment["libpath"]=$Env:IRONPYTHONPATH
Remove-ItemEnv:IRONPYTHONPATH
}
}

functionglobal:IronPythonParentPrompt{""}
Copy-ItemFunction:promptFunction:IronPythonParentPrompt

# Set new stuff for the environment to be operational

functionglobal:prompt{
Write-Host-NoNewline-ForegroundColor$IronPythonEnvironmentColor"«$IronPythonEnvironmentName» "
IronPythonParentPrompt
}

[string[]]$newEnvPaths=@($IronPythonEnvironmentPath)
if($IsWindows){
$newEnvPaths+=Join-Path$IronPythonEnvironmentPath"Scripts"
}else{
$newEnvPaths+=Join-Path$IronPythonEnvironmentPath"bin"
}
$newEnvPaths+=$env:PATH
$env:PATH=$newEnvPaths-join[IO.Path]::PathSeparator

Set-AliasexipyExit-IronPythonEnvironment-Scopeglobal