<#
.SYNOPSIS
    Automates the setup of uutils/coreutils on Windows by creating batch file shims.
#>
[CmdletBinding(SupportsShouldProcess = $true)]
param(
    [string]$ShimsDirectory = (Join-Path $env:LOCALAPPDATA "uutils-shims"),
    [switch]$ForceInstall,
    [switch]$ForcePathAddition,
    [switch]$SkipPathCheck
)

$ErrorActionPreference = "Stop"

function Show-Menu ([string]$Title, [string]$PromptMessage)
{
    Write-Host "`n--- $Title ---"
    $options = @(
        [System.Management.Automation.Host.ChoiceDescription]::new("&Yes", "Proceed.")
        [System.Management.Automation.Host.ChoiceDescription]::new("&No", "Skip.")
    )
    return (0 -eq $host.UI.PromptForChoice($Title, $PromptMessage, $options, 0))
}

function Find-CoreutilsExecutable
{
    Write-Verbose "Searching for coreutils.exe..."

    $coreutilsCmd = Get-Command coreutils -ErrorAction SilentlyContinue
    if ($coreutilsCmd -and (Test-Path $coreutilsCmd.Source))
    {
        return $coreutilsCmd.Source
    }

    $wingetBase = Join-Path $env:LOCALAPPDATA "Microsoft\WinGet\Packages"
    $pkgId = "uutils.coreutils_Microsoft.Winget.Source_8wekyb3d8bbwe"

    if (Test-Path $wingetBase)
    {
        $path = Get-ChildItem (Join-Path $wingetBase $pkgId) -Recurse -Filter "coreutils.exe" |
            Sort-Object LastWriteTime -Descending | Select-Object -ExpandProperty FullName -First 1
        if ($path)
        { return $path
        }
    }

    if ($ForceInstall -or (Show-Menu "Install Coreutils" "coreutils.exe not found. Install via winget?"))
    {
        Write-Host "Installing uutils via winget..." -ForegroundColor Cyan
        Start-Process winget -ArgumentList "install uutils.coreutils --source winget -e --accept-package-agreements" -Wait
        return Get-ChildItem (Join-Path $wingetBase $pkgId) -Recurse -Filter "coreutils.exe" | Select-Object -ExpandProperty FullName -First 1
    }
    return $null
}

function Get-CoreutilsCommands ([string]$CoreutilsExePath)
{
    Write-Verbose "Parsing commands from $CoreutilsExePath"
    $raw = (& $CoreutilsExePath --list | Out-String)

    if ($raw -match "Currently defined functions:")
    {
        $clean = $raw -split "Currently defined functions:" | Select-Object -Last 1
        $commands = $clean.Replace("[", "").Replace("]", "").Replace("`n", " ").Replace("`r", " ") -split '[, ]+' |
            Where-Object { $_.Trim() -ne "" }
        return $commands
    }

    return $raw -split '\s+' | Where-Object { $_ -ne "" }
}

function New-UtilityShim
{
    [CmdletBinding(SupportsShouldProcess = $true)]
    param([string]$CoreutilsExePath, [array]$Commands, [string]$TargetDir)

    if (-not (Test-Path $TargetDir))
    {
        if ($PSCmdlet.ShouldProcess($TargetDir, "Create Directory"))
        {
            New-Item -Path $TargetDir -ItemType Directory -Force | Out-Null
        }
    }

    $created = 0
    foreach ($cmd in $Commands)
    {
        $fileName = if ($cmd -eq "[")
        { "bracket.bat"
        } else
        { "$cmd.bat"
        }
        $path = Join-Path $TargetDir $fileName

        $content = "@echo off`n`"$CoreutilsExePath`" $cmd %*"

        if ($PSCmdlet.ShouldProcess("Shim for $cmd", "Create batch file at $path"))
        {
            Set-Content -Path $path -Value $content -Encoding Ascii
            $created++
        }
    }
    Write-Host "Created $created shims in $TargetDir" -ForegroundColor Cyan
}

function Update-UserPath
{
    [CmdletBinding(SupportsShouldProcess = $true)]
    param([string]$Dir, [switch]$ForcePathAddition)

    $currentPath = [System.Environment]::GetEnvironmentVariable("Path", "User")
    if ($currentPath -split ';' -contains $Dir)
    {
        Write-Host "Directory already in User PATH." -ForegroundColor Green
        return
    }

    if ($ForcePathAddition -or (Show-Menu "Update PATH" "Add $Dir to User PATH?"))
    {
        $newPath = "$currentPath;$Dir".Trim(';')

        if ($PSCmdlet.ShouldProcess("User PATH Environment Variable", "Append $Dir"))
        {
            [System.Environment]::SetEnvironmentVariable("Path", $newPath, "User")
            Write-Host "PATH updated. Restart your terminal to apply changes." -ForegroundColor Yellow
        }
    }
}

Write-Host "--- uutils setup ---" -ForegroundColor Magenta
$exe = Find-CoreutilsExecutable
if ($exe)
{
    $cmds = Get-CoreutilsCommands -CoreutilsExePath $exe
    New-UtilityShim -CoreutilsExePath $exe -Commands $cmds -TargetDir $ShimsDirectory

    if (-not $SkipPathCheck)
    {
        Update-UserPath -Dir $ShimsDirectory -ForcePathAddition:$ForcePathAddition
    }
} else
{
    Write-Error "Coreutils not found."
}