<#
    MyTechie RustDesk Auto-Installer
    Version: 2.4.0
    RustDesk: 1.4.9
    Purpose: Install and configure RustDesk for MyTechie remote support.
#>

[CmdletBinding()]
param(
    [switch]$Elevated,
    [switch]$VerifyOnly,
    [switch]$SelfTest
)

Set-StrictMode -Version 2.0
$ErrorActionPreference = "Stop"
$ProgressPreference = "SilentlyContinue"

$InstallerVersion = "2.4.0"
$RustDeskVersion = "1.4.9"
$ScriptUrl = "https://mytechie.com.au/remote/windows.ps1"
$SupportUrl = "https://mytechie.com.au/remote/"
$RustDeskConfig = "0nI9MnVR9Uc2I1dGVWNQRUZn1UU3Q0cQ1UV6NVUoljQkdUTWV0YZVWdhlnYShjI6ISeltmIsIyNxETMyoTdh5SbvNmLllGajVGd51mLlR3btVmciojI5FGblJnIsIiNxETMyoTdh5SbvNmLllGajVGd51mLlR3btVmciojI0N3boJye"

$Assets = @{
    AMD64 = @{
        File = "rustdesk-1.4.9-x86_64.exe"
        Sha256 = "eaedeb0088e687bf46f7c46a9c6ea5493ce51f3134dfd6acbedb47b5b9136274"
    }
    ARM64 = @{
        File = "rustdesk-1.4.9-aarch64.exe"
        Sha256 = "c717bf52fdd601c58419e46c503176dd87187d174ebf8b3b5854ca381e8e9145"
    }
}

function Write-Step {
    param([int]$Number, [string]$Message)
    Write-Host ("[{0}/5] {1}" -f $Number, $Message) -ForegroundColor Cyan
}

function Stop-Setup {
    param([string]$Code, [string]$Message)
    Write-Host ""
    Write-Host "Setup failed ($Code)." -ForegroundColor Red
    Write-Host $Message -ForegroundColor Red
    Write-Host "Leave this window open and contact your MyTechie technician: $SupportUrl" -ForegroundColor Yellow
    exit 1
}

function Test-Administrator {
    $identity = [Security.Principal.WindowsIdentity]::GetCurrent()
    $principal = New-Object Security.Principal.WindowsPrincipal($identity)
    return $principal.IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator)
}

function Get-NativeArchitecture {
    try {
        $architecture = [Runtime.InteropServices.RuntimeInformation]::OSArchitecture.ToString()
    } catch {
        $architecture = if ($env:PROCESSOR_ARCHITEW6432) {
            $env:PROCESSOR_ARCHITEW6432
        } else {
            $env:PROCESSOR_ARCHITECTURE
        }
    }

    switch -Regex ($architecture.ToUpperInvariant()) {
        "^(AMD64|X64)$" { return "AMD64" }
        "^(ARM64)$" { return "ARM64" }
        default { Stop-Setup "WIN-ARCH" "Unsupported Windows architecture: $architecture" }
    }
}

function New-SupportPassword {
    $alphabet = "abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ23456789"
    $bytes = New-Object byte[] 16
    $rng = [Security.Cryptography.RandomNumberGenerator]::Create()
    try {
        $rng.GetBytes($bytes)
    } finally {
        $rng.Dispose()
    }

    return -join ($bytes | ForEach-Object {
        $alphabet[[int]$_ % $alphabet.Length]
    })
}

function Get-FileSha256 {
    param([string]$Path)

    $getFileHash = Get-Command Get-FileHash -ErrorAction SilentlyContinue
    if ($getFileHash) {
        return (Get-FileHash -LiteralPath $Path -Algorithm SHA256).Hash.ToLowerInvariant()
    }

    $stream = [IO.File]::OpenRead($Path)
    $sha256 = [Security.Cryptography.SHA256]::Create()
    try {
        $digest = $sha256.ComputeHash($stream)
        return -join ($digest | ForEach-Object { $_.ToString("x2") })
    } finally {
        $sha256.Dispose()
        $stream.Dispose()
    }
}

function Test-RustDeskRegistryEntry {
    param([object]$Entry)

    $displayName = $Entry.PSObject.Properties["DisplayName"]
    $installLocation = $Entry.PSObject.Properties["InstallLocation"]

    return (
        $null -ne $displayName -and
        $null -ne $installLocation -and
        [string]$displayName.Value -like "RustDesk*" -and
        -not [string]::IsNullOrWhiteSpace([string]$installLocation.Value)
    )
}

function Find-RustDeskExecutable {
    $candidates = @(
        (Join-Path $env:ProgramFiles "RustDesk\rustdesk.exe"),
        $(if (${env:ProgramFiles(x86)}) {
            Join-Path ${env:ProgramFiles(x86)} "RustDesk\rustdesk.exe"
        })
    )

    $registryRoots = @(
        "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\*",
        "HKLM:\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\*"
    )

    foreach ($root in $registryRoots) {
        $entry = Get-ItemProperty $root -ErrorAction SilentlyContinue |
            Where-Object { Test-RustDeskRegistryEntry -Entry $_ } |
            Select-Object -First 1
        if ($entry) {
            $installLocation = $entry.PSObject.Properties["InstallLocation"].Value
            $candidates += Join-Path $installLocation "rustdesk.exe"
        }
    }

    foreach ($candidate in $candidates) {
        if ($candidate -and (Test-Path -LiteralPath $candidate)) {
            return (Resolve-Path -LiteralPath $candidate).Path
        }
    }

    return $null
}

function Download-VerifiedInstaller {
    param(
        [hashtable]$Asset,
        [string]$Destination
    )

    $url = "https://github.com/rustdesk/rustdesk/releases/download/$RustDeskVersion/$($Asset.File)"
    for ($attempt = 1; $attempt -le 3; $attempt++) {
        try {
            Invoke-WebRequest -Uri $url -OutFile $Destination -UseBasicParsing -Headers @{
                "User-Agent" = "MyTechie-RustDesk-Installer/$InstallerVersion"
            }
            break
        } catch {
            if ($attempt -eq 3) {
                Stop-Setup "WIN-DOWNLOAD" "RustDesk could not be downloaded after three attempts."
            }
            Write-Host "Download attempt $attempt failed. Retrying..." -ForegroundColor Yellow
            Start-Sleep -Seconds 3
        }
    }

    $actualHash = Get-FileSha256 -Path $Destination
    if ($actualHash -ne $Asset.Sha256) {
        Remove-Item -LiteralPath $Destination -Force -ErrorAction SilentlyContinue
        Stop-Setup "WIN-INTEGRITY" "The RustDesk download did not match the approved SHA-256 digest."
    }

    Write-Host "Verified RustDesk $RustDeskVersion ($($Asset.File))." -ForegroundColor Green
}

if ($SelfTest) {
    $missingProperties = [pscustomobject]@{ Publisher = "Example" }
    $validEntry = [pscustomobject]@{
        DisplayName = "RustDesk"
        InstallLocation = "C:\Program Files\RustDesk"
    }
    $emptyLocation = [pscustomobject]@{
        DisplayName = "RustDesk"
        InstallLocation = " "
    }
    $unrelatedEntry = [pscustomobject]@{
        DisplayName = "Example Application"
        InstallLocation = "C:\Program Files\Example"
    }

    if (Test-RustDeskRegistryEntry -Entry $missingProperties) {
        Write-Error "Registry self-test accepted an entry without DisplayName."
        exit 1
    }
    if (-not (Test-RustDeskRegistryEntry -Entry $validEntry)) {
        Write-Error "Registry self-test rejected a valid RustDesk entry."
        exit 1
    }
    if (Test-RustDeskRegistryEntry -Entry $emptyLocation) {
        Write-Error "Registry self-test accepted an empty install location."
        exit 1
    }
    if (Test-RustDeskRegistryEntry -Entry $unrelatedEntry) {
        Write-Error "Registry self-test accepted an unrelated application."
        exit 1
    }

    Write-Host "Windows registry compatibility self-test passed."
    exit 0
}

Write-Host ""
Write-Host "=== MyTechie Remote Support Installer v$InstallerVersion ===" -ForegroundColor Cyan
Write-Host ""

if (-not $VerifyOnly -and -not (Test-Administrator)) {
    if ($Elevated) {
        Stop-Setup "WIN-ELEVATION" "Administrator access was not granted."
    }

    Write-Host "Windows will ask for administrator permission." -ForegroundColor Yellow
    $bootstrap = Join-Path ([IO.Path]::GetTempPath()) ("mytechie-rustdesk-{0}.ps1" -f [Guid]::NewGuid())
    try {
        Invoke-WebRequest -Uri $ScriptUrl -OutFile $bootstrap -UseBasicParsing -Headers @{
            "User-Agent" = "MyTechie-RustDesk-Bootstrap/$InstallerVersion"
        }
        $arguments = "-NoProfile -ExecutionPolicy Bypass -File `"$bootstrap`" -Elevated"
        $process = Start-Process powershell.exe -Verb RunAs -ArgumentList $arguments -Wait -PassThru
        exit $process.ExitCode
    } catch {
        Stop-Setup "WIN-ELEVATION" "The administrator setup window could not be opened."
    } finally {
        Remove-Item -LiteralPath $bootstrap -Force -ErrorAction SilentlyContinue
    }
}

$architecture = Get-NativeArchitecture
$asset = $Assets[$architecture]
$tempDirectory = Join-Path ([IO.Path]::GetTempPath()) ("mytechie-rustdesk-{0}" -f [Guid]::NewGuid())
$installerPath = Join-Path $tempDirectory $asset.File

try {
    if ($VerifyOnly) {
        Write-Step 1 "Checking the approved RustDesk package"
        New-Item -ItemType Directory -Path $tempDirectory -Force | Out-Null
        Download-VerifiedInstaller -Asset $asset -Destination $installerPath
        Write-Host "Verification complete. No software was installed." -ForegroundColor Green
        exit 0
    }

    Write-Step 1 "Checking this Windows device"
    Write-Host "Architecture: $architecture"

    $rustDeskExe = Find-RustDeskExecutable
    if ($rustDeskExe) {
        Write-Host "RustDesk is already installed. The existing app will be configured."
    } else {
        Write-Step 2 "Downloading and verifying RustDesk $RustDeskVersion"
        New-Item -ItemType Directory -Path $tempDirectory -Force | Out-Null
        Download-VerifiedInstaller -Asset $asset -Destination $installerPath

        Write-Host "Installing RustDesk..."
        $installProcess = Start-Process -FilePath $installerPath -ArgumentList "--silent-install" -Wait -PassThru
        if ($installProcess.ExitCode -ne 0) {
            Stop-Setup "WIN-INSTALL" "RustDesk returned installer exit code $($installProcess.ExitCode)."
        }

        for ($attempt = 1; $attempt -le 20; $attempt++) {
            $rustDeskExe = Find-RustDeskExecutable
            if ($rustDeskExe) { break }
            Start-Sleep -Seconds 2
        }
        if (-not $rustDeskExe) {
            Stop-Setup "WIN-INSTALL" "RustDesk finished installing, but rustdesk.exe could not be found."
        }
    }

    Write-Step 3 "Configuring the MyTechie relay and support password"
    $supportPassword = New-SupportPassword

    $configOutput = (& $rustDeskExe --config $RustDeskConfig 2>&1 | Out-String).Trim()
    if ($LASTEXITCODE -ne 0 -or $configOutput -match "required|failed|disabled") {
        Stop-Setup "WIN-CONFIG" "RustDesk rejected the MyTechie server configuration."
    }

    $passwordOutput = (& $rustDeskExe --password $supportPassword 2>&1 | Out-String).Trim()
    if ($LASTEXITCODE -ne 0 -or $passwordOutput -match "required|failed|disabled") {
        Stop-Setup "WIN-PASSWORD" "RustDesk could not set the support access password."
    }

    Write-Step 4 "Starting the RustDesk service"
    $service = Get-Service -Name "rustdesk" -ErrorAction SilentlyContinue
    if (-not $service) {
        $serviceOutput = (& $rustDeskExe --install-service 2>&1 | Out-String).Trim()
        if ($LASTEXITCODE -ne 0 -or $serviceOutput -match "failed") {
            Stop-Setup "WIN-SERVICE" "The RustDesk Windows service could not be installed."
        }
        Start-Sleep -Seconds 2
        $service = Get-Service -Name "rustdesk" -ErrorAction SilentlyContinue
    }

    if (-not $service) {
        Stop-Setup "WIN-SERVICE" "The RustDesk Windows service is missing after installation."
    }

    if ($service.Status -eq "Running") {
        Restart-Service -Name "rustdesk" -Force -ErrorAction Stop
    } else {
        Start-Service -Name "rustdesk" -ErrorAction Stop
    }

    Write-Step 5 "Waiting for this device's RustDesk ID"
    $rustDeskId = ""
    for ($attempt = 1; $attempt -le 15; $attempt++) {
        $idOutput = (& $rustDeskExe --get-id 2>$null | Out-String).Trim()
        $match = [regex]::Match($idOutput, "\b\d{6,}\b")
        if ($match.Success) {
            $rustDeskId = $match.Value
            break
        }
        Write-Host "Waiting for registration... ($attempt/15)"
        Start-Sleep -Seconds 2
    }

    Start-Process -FilePath $rustDeskExe

    if (-not $rustDeskId) {
        Stop-Setup "WIN-ID" "RustDesk is installed, but its ID is not ready. Open RustDesk from the Start menu and tell your technician the ID shown there."
    }

    Write-Host ""
    Write-Host "=========================================" -ForegroundColor Green
    Write-Host " MyTechie Remote Support Setup Complete" -ForegroundColor Green
    Write-Host "=========================================" -ForegroundColor Green
    Write-Host ""
    Write-Host "RustDesk ID:      $rustDeskId" -ForegroundColor White
    Write-Host "Access password:  $supportPassword" -ForegroundColor White
    Write-Host ""
    Write-Host "Share these details only with your MyTechie technician." -ForegroundColor Cyan
    Write-Host "This password remains active until it is changed, the installer is rerun, or RustDesk is removed." -ForegroundColor Yellow
    Write-Host ""

    if ([Environment]::UserInteractive) {
        [void](Read-Host "Press Enter after you have shared the ID and password")
    }
} finally {
    if (Test-Path -LiteralPath $tempDirectory) {
        Remove-Item -LiteralPath $tempDirectory -Recurse -Force -ErrorAction SilentlyContinue
    }
}