[CmdletBinding()]
param(
    [ValidateNotNullOrEmpty()]
    [string]$InstallRoot = (Join-Path $env:LOCALAPPDATA 'MercuryToolbox'),
    [string]$CodexHome
)

$ErrorActionPreference = 'Stop'
Set-StrictMode -Version Latest

. (Join-Path $PSScriptRoot 'toolbox-commands.ps1')

function Normalize-PathValue {
    param(
        [AllowNull()]
        [string]$PathValue
    )

    if ([string]::IsNullOrWhiteSpace($PathValue)) {
        return ''
    }

    return $PathValue.Replace('/', '\').Trim().TrimEnd('\').ToLowerInvariant()
}

function Split-PathEntries {
    param(
        [AllowNull()]
        [string]$PathValue
    )

    if ([string]::IsNullOrWhiteSpace($PathValue)) {
        return @()
    }

    return $PathValue.Split(';', [System.StringSplitOptions]::RemoveEmptyEntries)
}

function Remove-PathEntry {
    param(
        [AllowNull()]
        [string]$ExistingPath,
        [Parameter(Mandatory = $true)]
        [string]$Entry
    )

    $normalizedEntry = Normalize-PathValue -PathValue $Entry
    $remaining = [System.Collections.Generic.List[string]]::new()
    $changed = $false

    foreach ($existing in (Split-PathEntries -PathValue $ExistingPath)) {
        if ((Normalize-PathValue -PathValue $existing) -eq $normalizedEntry) {
            $changed = $true
            continue
        }
        $remaining.Add($existing)
    }

    return @{
        Changed = $changed
        Value = ($remaining -join ';')
    }
}

function Resolve-CodexHomePath {
    param(
        [AllowNull()]
        [string]$ExplicitCodexHome
    )

    if (-not [string]::IsNullOrWhiteSpace($ExplicitCodexHome)) {
        return $ExplicitCodexHome
    }

    if (-not [string]::IsNullOrWhiteSpace($env:CODEX_HOME)) {
        return $env:CODEX_HOME
    }

    return (Join-Path $env:USERPROFILE '.codex')
}

function Test-CodexSkillOwnedByMercury {
    param(
        [Parameter(Mandatory = $true)]
        [string]$SkillRoot
    )

    $markerPath = Join-Path $SkillRoot '.mercury-toolbox-owner.json'
    if (-not (Test-Path -LiteralPath $markerPath)) {
        return $false
    }

    try {
        $marker = Get-Content -LiteralPath $markerPath -Raw | ConvertFrom-Json
        return [string]$marker.owner -eq 'mercury-toolbox'
    }
    catch {
        return $false
    }
}

function Assert-ExistingPathNotReparsePoint {
    param(
        [Parameter(Mandatory = $true)]
        [string]$Path,
        [Parameter(Mandatory = $true)]
        [string]$Description
    )

    $resolvedPath = [System.IO.Path]::GetFullPath($Path)
    if (-not (Test-Path -LiteralPath $resolvedPath)) {
        return
    }

    $item = Get-Item -LiteralPath $resolvedPath -Force
    if (($item.Attributes -band [System.IO.FileAttributes]::ReparsePoint) -ne 0) {
        throw "$Description must not be a reparse point: $resolvedPath"
    }
}

function Assert-ExistingTreeHasNoReparsePoints {
    param(
        [Parameter(Mandatory = $true)]
        [string]$Path,
        [Parameter(Mandatory = $true)]
        [string]$Description
    )

    $resolvedPath = [System.IO.Path]::GetFullPath($Path)
    if (-not (Test-Path -LiteralPath $resolvedPath)) {
        return
    }

    $reparsePoints = @(Get-ChildItem -LiteralPath $resolvedPath -Force -Recurse -Attributes ReparsePoint)
    if ($reparsePoints.Count -gt 0) {
        throw "$Description must not contain reparse points: $($reparsePoints[0].FullName)"
    }
}

$legacyBinDir = Join-Path $InstallRoot 'bin'
$currentRoot = Join-Path $InstallRoot 'current'
$activeBinDir = Join-Path $currentRoot 'bin'
$versionsRoot = Join-Path $InstallRoot 'versions'
$shareRoot = Join-Path $InstallRoot 'share\mercury-toolbox'
$codexSkillRoot = Join-Path (Resolve-CodexHomePath -ExplicitCodexHome $CodexHome) 'skills\mercury-toolbox'
$legacyCommandNames = @('context', 'waitfor')

Assert-ExistingPathNotReparsePoint -Path $InstallRoot -Description 'InstallRoot'
Assert-ExistingPathNotReparsePoint -Path $versionsRoot -Description 'versions root'
Assert-ExistingPathNotReparsePoint -Path $shareRoot -Description 'share root'
Assert-ExistingPathNotReparsePoint -Path $codexSkillRoot -Description 'Codex skill root'
Assert-ExistingTreeHasNoReparsePoints -Path $shareRoot -Description 'share root'
Assert-ExistingTreeHasNoReparsePoints -Path $codexSkillRoot -Description 'Codex skill root'

if (Test-Path -LiteralPath $legacyBinDir) {
    foreach ($commandName in Get-ToolboxCommandNames) {
        $commandPath = Join-Path $legacyBinDir "$commandName.exe"
        if (Test-Path -LiteralPath $commandPath) {
            Remove-Item -LiteralPath $commandPath -Force
        }
    }

    foreach ($legacyName in $legacyCommandNames) {
        $legacyPath = Join-Path $legacyBinDir "$legacyName.exe"
        if (Test-Path -LiteralPath $legacyPath) {
            Remove-Item -LiteralPath $legacyPath -Force
        }
    }

    $remainingBinItems = @(Get-ChildItem -LiteralPath $legacyBinDir -Force)
    if ($remainingBinItems.Count -eq 0) {
        Remove-Item -LiteralPath $legacyBinDir -Force
    }
}

if (Test-Path -LiteralPath $currentRoot) {
    Remove-Item -LiteralPath $currentRoot -Force
}

if (Test-Path -LiteralPath $versionsRoot) {
    Remove-Item -LiteralPath $versionsRoot -Recurse -Force
}

if (Test-Path -LiteralPath $shareRoot) {
    Remove-Item -LiteralPath $shareRoot -Recurse -Force
}

if (Test-Path -LiteralPath $codexSkillRoot) {
    if (Test-CodexSkillOwnedByMercury -SkillRoot $codexSkillRoot) {
        Remove-Item -LiteralPath $codexSkillRoot -Recurse -Force
    }
    else {
        Write-Warning "Skipping Codex skill removal because Mercury Toolbox does not own this skill copy: $codexSkillRoot"
    }
}

if (Test-Path -LiteralPath $InstallRoot) {
    $remainingItems = @(Get-ChildItem -LiteralPath $InstallRoot -Force)
    if ($remainingItems.Count -eq 0) {
        Remove-Item -LiteralPath $InstallRoot -Force
    }
}

$userPath = [Environment]::GetEnvironmentVariable('Path', 'User')
foreach ($entry in @($legacyBinDir, $activeBinDir)) {
    $pathUpdate = Remove-PathEntry -ExistingPath $userPath -Entry $entry
    if ($pathUpdate.Changed) {
        $userPath = $pathUpdate.Value
    }
}
[Environment]::SetEnvironmentVariable('Path', $userPath, 'User')

foreach ($entry in @($legacyBinDir, $activeBinDir)) {
    $sessionUpdate = Remove-PathEntry -ExistingPath $env:Path -Entry $entry
    if ($sessionUpdate.Changed) {
        $env:Path = $sessionUpdate.Value
    }
}

Write-Host "Mercury Toolbox package removed from $InstallRoot"
Write-Host "Removed Codex skill root: $codexSkillRoot"