[CmdletBinding()]
param(
    [Parameter(Mandatory = $true)]
    [ValidatePattern('^v[0-9][0-9A-Za-z._-]*$')]
    [string]$Version,

    [string]$InstallDir = $(
        if ($env:GETH_INSTALL_DIR) { $env:GETH_INSTALL_DIR }
        else { Join-Path $env:LOCALAPPDATA 'Programs\geth\bin' }
    ),

    [string]$ReleaseBaseUrl = $(
        if ($env:GETH_RELEASE_BASE_URL) { $env:GETH_RELEASE_BASE_URL }
        else { 'https://forge.tionis.dev/eric/geth/releases/download' }
    ),

    [string]$ArchivePath,

    [string]$ChecksumPath,

    [switch]$NoModifyPath,

    [switch]$PrintAsset
)

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

if (-not [Environment]::Is64BitOperatingSystem) {
    throw 'No geth release artifact is available for 32-bit Windows.'
}

$asset = "geth-$Version-windows-x86_64.zip"
if ($PrintAsset) {
    Write-Output $asset
    return
}

$releaseBase = $ReleaseBaseUrl.TrimEnd('/')
$url = "$releaseBase/$Version/$asset"
$tempDir = Join-Path ([IO.Path]::GetTempPath()) ("geth-install-" + [Guid]::NewGuid())
$extractDir = Join-Path $tempDir 'extract'

try {
    New-Item -ItemType Directory -Force -Path $tempDir, $extractDir | Out-Null
    if ($ArchivePath) {
        $archive = (Resolve-Path -LiteralPath $ArchivePath).Path
        $checksumCandidate = if ($ChecksumPath) { $ChecksumPath } else { "$ArchivePath.sha256" }
        $checksum = (Resolve-Path -LiteralPath $checksumCandidate).Path
        Write-Host "using local archive $archive"
    } else {
        if ($ChecksumPath) { throw '-ChecksumPath requires -ArchivePath.' }
        if (([Uri]$url).Scheme -ne 'https') { throw 'Release downloads require an HTTPS base URL.' }
        $archive = Join-Path $tempDir $asset
        $checksum = "$archive.sha256"
        Write-Host "downloading $url"
        Invoke-WebRequest -Uri $url -OutFile $archive
        Invoke-WebRequest -Uri "$url.sha256" -OutFile $checksum
    }

    $expected = ((Get-Content -LiteralPath $checksum -Raw).Trim() -split '\s+')[0].ToLowerInvariant()
    if ($expected -notmatch '^[0-9a-f]{64}$') {
        throw "Invalid SHA-256 file for $asset."
    }
    $actual = (Get-FileHash -LiteralPath $archive -Algorithm SHA256).Hash.ToLowerInvariant()
    if ($actual -ne $expected) {
        throw "Checksum mismatch for $asset."
    }
    Write-Host "verified SHA-256: $actual"

    Expand-Archive -LiteralPath $archive -DestinationPath $extractDir -Force
    $sourceBinary = Join-Path $extractDir 'geth.exe'
    if (-not (Test-Path -LiteralPath $sourceBinary -PathType Leaf)) {
        throw 'Archive does not contain geth.exe.'
    }

    New-Item -ItemType Directory -Force -Path $InstallDir | Out-Null
    $destination = Join-Path $InstallDir 'geth.exe'
    $staged = Join-Path $InstallDir ('.geth.install.' + [Guid]::NewGuid() + '.exe')
    try {
        Copy-Item -LiteralPath $sourceBinary -Destination $staged
        Move-Item -LiteralPath $staged -Destination $destination -Force
    } catch {
        Remove-Item -LiteralPath $staged -Force -ErrorAction SilentlyContinue
        throw "Could not replace $destination. Stop the daemon with 'geth daemon stop' and retry. $($_.Exception.Message)"
    }

    if (-not $NoModifyPath) {
        $userPath = [Environment]::GetEnvironmentVariable('Path', 'User')
        $pathParts = @($userPath -split ';' | Where-Object { $_ })
        if ($pathParts -notcontains $InstallDir) {
            $newUserPath = (@($pathParts) + $InstallDir) -join ';'
            try {
                [Environment]::SetEnvironmentVariable('Path', $newUserPath, 'User')
                Write-Host "added $InstallDir to the current user's PATH; open a new terminal to use it"
            } catch {
                Write-Warning "Could not update the user PATH. Add this directory manually: $InstallDir"
            }
        } else {
            Write-Host "$InstallDir is already on the current user's PATH"
        }
    }

    Write-Host "installed geth to $destination"
    Write-Host "the daemon was not started; run 'geth daemon install' when ready"
} finally {
    if (Test-Path -LiteralPath $tempDir) {
        Remove-Item -LiteralPath $tempDir -Recurse -Force
    }
}