function Verify-Checksum
{
    Param (
        [string]$File=$(throw("You must specify a filename to get the checksum of.")),
        [string]$Expected=$(throw("Checksum required"))
    )
    switch ($Expected.Length) {
        40 { $Algorithm = "SHA1" }
        64 { $Algorithm = "SHA256" }
        default { throw "Unknown hash length for: $Expected" }
    }
    Write-Host "Verifying checksum of $File"
    $fs = new-object System.IO.FileStream $File, "Open"
    $algo = [type]"System.Security.Cryptography.$Algorithm"
    $crypto = $algo::Create()
    $hash = [BitConverter]::ToString($crypto.ComputeHash($fs)).Replace("-", "")
    $fs.Close()
    if ($hash -ine $Expected) {
        throw "Checksum verification failed, got: '$hash' expected: '$Expected'"
    }
}

function Run-Executable
{
    Param (
        [string]$Executable=$(throw("You must specify a program to run.")),
        [string[]]$Arguments
    )

    $stdoutFile = [System.IO.Path]::GetTempFileName()
    $stderrFile = [System.IO.Path]::GetTempFileName()

    if ([string]::IsNullOrEmpty($Arguments)) {
        Write-Host "Running `"$Executable`""
        $p = Start-Process -FilePath "$Executable" -Wait -PassThru `
            -RedirectStandardOutput $stdoutFile -RedirectStandardError $stderrFile
    } else {
        Write-Host "Running `"$Executable`" with arguments `"$Arguments`""
        $p = Start-Process -FilePath "$Executable" -ArgumentList $Arguments -PassThru `
            -RedirectStandardOutput $stdoutFile -RedirectStandardError $stderrFile
        Wait-Process -InputObject $p
    }

    $stdoutContent = [System.IO.File]::ReadAllText($stdoutFile)
    $stderrContent = [System.IO.File]::ReadAllText($stderrFile)
    Remove-Item -Path $stdoutFile, $stderrFile -Force -ErrorAction Ignore

    $hasOutput = $false
    if ([string]::IsNullOrEmpty($stdoutContent) -eq $false -or [string]::IsNullOrEmpty($stderrContent) -eq $false) {
        $hasOutput = $true
        Write-Host
        Write-Host "======================================================================"
    }
    if ([string]::IsNullOrEmpty($stdoutContent) -eq $false) {
        Write-Host "stdout of `"$Executable`":"
        Write-Host "======================================================================"
        Write-Host $stdoutContent
        Write-Host "======================================================================"
    }
    if ([string]::IsNullOrEmpty($stderrContent) -eq $false) {
        Write-Host "stderr of `"$Executable`":"
        Write-Host "======================================================================"
        Write-Host $stderrContent
        Write-Host "======================================================================"
    }
    if ($hasOutput) {
        Write-Host
    }
    if ($p.ExitCode -ne 0) {
        throw "Process $($Executable) exited with exit code $($p.ExitCode)"
    }
}

function Extract-tar_gz
{
    Param (
        [string]$Source,
        [string]$Destination
    )
    Write-Host "Extracting '$Source' to '$Destination'..."

    if ((Get-Command "7z.exe" -ErrorAction SilentlyContinue) -eq $null) {
        $zipExe = join-path (${env:ProgramFiles(x86)}, ${env:ProgramFiles}, ${env:ProgramW6432} -ne $null)[0] '7-zip\7z.exe'
        if (-not (test-path $zipExe)) {
            $zipExe = "C:\Utils\sevenzip\7z.exe"
            if (-not (test-path $zipExe)) {
                throw "Could not find 7-zip."
            }
        }
    } else {
        $zipExe = "7z.exe"
    }
    Run-Executable "cmd.exe"  "/C $zipExe x -y `"$Source`" -so | $zipExe x -y -aoa -si -ttar `"-o$Destination`""
}

function Extract-7Zip
{
    Param (
        [string]$Source,
        [string]$Destination,
        [string]$Filter
    )
    Write-Host "Extracting '$Source' to '$Destination'..."

    if ((Get-Command "7z.exe" -ErrorAction SilentlyContinue) -eq $null) {
        $zipExe = join-path (${env:ProgramFiles(x86)}, ${env:ProgramFiles}, ${env:ProgramW6432} -ne $null)[0] '7-zip\7z.exe'
        if (-not (test-path $zipExe)) {
            $zipExe = "C:\Utils\sevenzip\7z.exe"
            if (-not (test-path $zipExe)) {
                throw "Could not find 7-zip."
            }
        }
    } else {
        $zipExe = "7z.exe"
    }

    if ([string]::IsNullOrEmpty($Filter)) {
        Run-Executable "$zipExe" "x -y `"-o$Destination`" `"$Source`""
    } else {
        Run-Executable "$zipExe" "x -y -aoa `"-o$Destination`" `"$Source`" $Filter"
    }
}

function BadParam
{
    Param ([string]$Description)
    throw("You must specify $Description")
}

function Get-DefaultDownloadLocation
{
    return $env:USERPROFILE + "\downloads\"
}

function Get-DownloadLocation
{
    Param ([string]$TargetName = $(BadParam("a target filename")))
    return (Get-DefaultDownloadLocation) + $TargetName
}

function Download
{
    Param (
        [string] $OfficialUrl = $(BadParam("the official download URL")),
        [string] $CachedUrl   = $(BadParam("the locally cached URL")),
        [string] $Destination = $(BadParam("a download target location"))
    )
    $ProgressPreference = 'SilentlyContinue'
    [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
    try {
        Write-Host "Downloading from cached location ($CachedUrl) to $Destination"
        if ($CachedUrl.StartsWith("http")) {
            Invoke-WebRequest -UseBasicParsing $CachedUrl -OutFile $Destination
        } else {
            Copy-Item $CachedUrl $Destination -errorAction stop
        }
    } catch {
        Write-Host "Cached download failed: Downloading from official location: $OfficialUrl"
        Invoke-WebRequest -UseBasicParsing $OfficialUrl -OutFile $Destination
    }
}

function Add-Path
{
    Param (
        [string]$Path
    )
    Write-Host "Adding $Path to Path"

    $oldPath = [System.Environment]::GetEnvironmentVariable('Path', 'Machine')
    [Environment]::SetEnvironmentVariable("Path", $oldPath + ";$Path", [EnvironmentVariableTarget]::Machine)
    $Env:PATH = [System.Environment]::GetEnvironmentVariable('Path', 'Machine')
}

function Prepend-Path
{
    Param (
        [string]$Path
    )
    Write-Host "Adding $Path to Path"

    $oldPath = [System.Environment]::GetEnvironmentVariable('Path', 'Machine')
    [Environment]::SetEnvironmentVariable("Path", "$Path;" + $oldPath, [EnvironmentVariableTarget]::Machine)
    $Env:PATH = [System.Environment]::GetEnvironmentVariable('Path', 'Machine')
}

function Set-EnvironmentVariable
{
    Param (
        [string]$Key = $(BadParam("a key")),
        [string]$Value = $(BadParam("a value."))
    )
    Write-Host "Setting environment variable `"$($Key)`" to `"$($Value)`""

    [Environment]::SetEnvironmentVariable($Key, $Value, [EnvironmentVariableTarget]::Machine)
    # Make the envvar immediately available to subsequent scripts run in the same session.
    [Environment]::SetEnvironmentVariable($Key, $Value, [EnvironmentVariableTarget]::Process)
}

function Is64BitWinHost
{
    return [environment]::Is64BitOperatingSystem
}

enum CpuArch {
    x64
    x86
    arm64
    unknown
}

function Get-CpuArchitecture
{
    # Possible values are "AMD64", "IA64", "ARM64", and "x86"
    $arch = [System.Environment]::GetEnvironmentVariable('PROCESSOR_ARCHITECTURE', 'Machine')
    if ($arch -eq "AMD64") {
        return [CpuArch]::x64
    } elseif ($arch -eq "x86") {
        return [CpuArch]::x86
    } elseif ($arch -eq "ARM64") {
        return [CpuArch]::arm64
    }

    return [CpuArch]::unknown
}

function IsProxyEnabled {
    return (Get-ItemProperty -Path 'HKCU:\Software\Microsoft\Windows\CurrentVersion\Internet Settings').proxyEnable
}

function Get-Proxy {
    return (Get-ItemProperty -Path 'HKCU:\Software\Microsoft\Windows\CurrentVersion\Internet Settings').proxyServer
}

function Retry{
    <#
    usage:
    Retry{CODE}
    Retry{CODE} <num of retries> <delay_s>
    #delay is in seconds
    #>
    Param(
        [Parameter(mandatory=$true)]
        [scriptblock]$command,
        [int][ValidateRange(1, 20)]$retry = 5,
        [int][ValidateRange(1, 60)]$delay_s = 5
    )
    $success=$false
    $retry_count=0
    do{
        try {
            Invoke-Command -ScriptBlock $command
            $success=$true
        }
        catch {
            $retry_count++
            Write-Host "Error: $_, try: $retry_count, retrying in $delay_s seconds"
            Start-Sleep -Seconds $delay_s
        }
    } until ($success -or $retry+1 -le $retry_count)

    if (-not $success) {
        Throw("Failed to run command successfully in $retry_count tries")
    }
}

function Remove {

    Param (
        [string]$Path = $(BadParam("a path"))
    )
    Write-Host "Removing $Path"
    $i = 0
    While ( Test-Path($Path) ){
        Try{
            remove-item -Force -Recurse -Path $Path -ErrorAction Stop
        }catch{
            $i +=1
            if ($i -eq 5) {exit 1}
            Write-Verbose "$Path locked, trying again in 5"
            Start-Sleep -seconds 5
        }
    }
}

function DisableSchedulerTask {

    Param (
        [string]$Task = $(BadParam("a task"))
    )

    Write-Host "Disabling $Task from Task Scheduler"
    SCHTASKS /Change /TN "Microsoft\Windows\$Task" /DISABLE
}

function DeleteSchedulerTask {

   Param (
        [string]$Task = $(BadParam("a task"))
    )

    Write-Host "Disabling $Task from Task Scheduler"
    SCHTASKS /DELETE /TN "Microsoft\Windows\$Task" /F
}

function GetVsProperty {
    Param (
        [string]$Component = 'Microsoft.VisualStudio.Component.VC.CoreIde',
        [string]$Property,
        [switch]$Latest
    )

    $vsWhereProcessInfo = New-Object System.Diagnostics.ProcessStartInfo
    $vsWhereProcessInfo.FileName = "${Env:ProgramFiles(x86)}\Microsoft Visual Studio\Installer\vswhere.exe"
    $vsWhereProcessInfo.RedirectStandardError = $true
    $vsWhereProcessInfo.RedirectStandardOutput = $true
    $vsWhereProcessInfo.UseShellExecute = $false

    # -sort: sorts the instances from newest version and last installed to oldest
    $vsWhereProcessInfo.Arguments = " -nologo -sort -products * -requires $Component -property $Property"
    if ($Latest) {
        # -latest: return only the newest version and last installed
        $vsWhereProcessInfo.Arguments += ' -latest'
    }

    $vsWhereProcess = New-Object System.Diagnostics.Process
    $vsWhereProcess.StartInfo = $vsWhereProcessInfo

    $vsWhereProcess.Start() | Out-Null
    $vsWhereProcess.WaitForExit()

    $standardOutput = $vsWhereProcess.StandardOutput.ReadToEnd()
    if ([string]::IsNullOrEmpty($standardOutput)) {
        throw "vswhere could not find property '$Property'"
    }

    $exitCode = $vsWhereProcess.ExitCode
    if ($exitCode -ne 0) {
        $standardError = $vsWhereProcess.StandardError.ReadToEnd()
        throw "vswhere failed with exit code $exitCode ($standardError)"
    }

    return $standardOutput.Split([Environment]::NewLine, [StringSplitOptions]::RemoveEmptyEntries) | Select-Object -Last 1
}

function GetVsInstallationPath {
    Param (
        [switch]$Latest
    )

    return GetVsProperty -Property 'installationPath' @PSBoundParameters
}

function EnterVSDevShell {
    Param (
        [string]$HostArch = "amd64",
        [string]$Arch = "amd64"
    )

    # We pick the oldest build tools we can find and use that to be compatible with it and any newer version:
    # If MSVC has an ABI break this will stop working, and yet another build must be added.
    $VSPath = GetVsInstallationPath

    Write-Host "Enter VisualStudio developer shell (-host_arch=$HostArch -arch=$Arch -VsInstallPath='$VSPath')"
    try {
        Import-Module "$VSPath\Common7\Tools\Microsoft.VisualStudio.DevShell.dll"
        Enter-VsDevShell -SkipAutomaticLocation -VsInstallPath $VSPath -DevCmdArguments "-host_arch=$HostArch -arch=$Arch -no_logo"
    } catch {
        Write-Host "Failed to enter VisualStudio DevShell"
        return $false
    }
    return $true
}

function Invoke-MtCommand {
  param(
    [String] $vcVarsScript,
    [String] $arch,
    [String] $manifest,
    [String] $executable
  )
  $tempFile = [IO.Path]::GetTempFileName()
  Add-Content -Path $tempFile -Value $manifest
  $cmdLine = """$vcVarsScript"" $arch &  mt.exe -manifest ""$tempFile"" -outputresource:""$executable"";1"
  Write-Output Executing $cmdLine
  & $Env:SystemRoot\system32\cmd.exe /c $cmdLine | Write-Output
  Remove-Item $tempFile
}

function Invoke-NMake {
    param([string[]]$NmakeArgs)
    # Temporarily remove MAKE flags for NMAKE process
    $old = @{
        MAKEFLAGS  = (Get-Item Env:MAKEFLAGS  -ErrorAction Ignore).Value
        MFLAGS     = (Get-Item Env:MFLAGS     -ErrorAction Ignore).Value
        MAKE       = (Get-Item Env:MAKE       -ErrorAction Ignore).Value
        NMAKEFLAGS = (Get-Item Env:NMAKEFLAGS -ErrorAction Ignore).Value
    }
    foreach ($n in $old.Keys) {Remove-Item "Env:$n" -ErrorAction SilentlyContinue}
    try   {& nmake @NmakeArgs}
    finally {
        foreach ($n in $old.Keys) {
            if ($old[$n]) {Set-EnvironmentVariable -Key "$n" -Value $old[$n]}
            else {Remove-Item "Env:$n" -ErrorAction SilentlyContinue}
        }
    }
}
