# Installs Larva, the toolchain of the Antril language, on Windows (PowerShell 5 or later):
#
#   irm https://antril.org/install.ps1 | iex
#
# It reads the latest release from https://antril.org/download/latest.json, downloads LarvaSetup-<version>-win-x64.exe
# into a temporary folder, checks its SHA-256 and runs it with --silent: Larva for your user, no administrator rights,
# into %LOCALAPPDATA%\Programs\Larva, with `larva` on your PATH.
#
# Settings (environment variables, set before running it):
#   $env:LARVA_INSTALL_DIR = "D:\Tools\Larva"     install there (the setup's --dir)
#   $env:LARVA_INSTALL_ARGS = "--no-path --no-hive"  more options for the setup: --no-path, --no-registry, --no-hive, --no-types
#   $env:LARVA_INSTALL_DRYRUN = "1"               download and check, then stop before installing
#
# With options as arguments:
#   & ([scriptblock]::Create((irm https://antril.org/install.ps1))) --no-path

function Install-Larva {
    param([string[]] $Options)

    $ErrorActionPreference = 'Stop'
    $base = 'https://antril.org'
    if ($env:LARVA_INSTALL_BASE) { $base = $env:LARVA_INSTALL_BASE.TrimEnd('/') }

    function Say([string] $text) { Write-Host $text }
    function Step([string] $text) { Write-Host "==> " -ForegroundColor Green -NoNewline; Write-Host $text }
    function Fail([string] $text) { Write-Host "error: " -ForegroundColor Red -NoNewline; Write-Host $text; return $false }

    if ($PSVersionTable.PSVersion.Major -lt 5) {
        return (Fail "PowerShell 5 or later is needed (this is $($PSVersionTable.PSVersion)).")
    }
    if (-not [Environment]::Is64BitOperatingSystem) {
        return (Fail "Larva needs 64-bit Windows.")
    }
    # Windows PowerShell 5 may still default to old TLS versions.
    try { [Net.ServicePointManager]::SecurityProtocol = [Net.ServicePointManager]::SecurityProtocol -bor [Net.SecurityProtocolType]::Tls12 } catch { }

    # The setup's options: the folder, $env:LARVA_INSTALL_ARGS, then the arguments.
    $setup = New-Object System.Collections.Generic.List[string]
    $setup.Add('--silent')
    if ($env:LARVA_INSTALL_DIR) {
        $setup.Add('--dir')
        $setup.Add([IO.Path]::GetFullPath($env:LARVA_INSTALL_DIR))
    }
    if ($env:LARVA_INSTALL_ARGS) {
        foreach ($word in ($env:LARVA_INSTALL_ARGS -split '\s+')) { if ($word) { $setup.Add($word) } }
    }
    $dryRun = $env:LARVA_INSTALL_DRYRUN -and $env:LARVA_INSTALL_DRYRUN -ne '0'
    foreach ($option in $Options) {
        if ($option -eq '--dry-run') { $dryRun = $true } elseif ($option) { $setup.Add($option) }
    }

    Step "Looking for the latest Larva at $base"
    try {
        $latest = Invoke-RestMethod -UseBasicParsing -Uri "$base/download/latest.json" -Headers @{ 'Cache-Control' = 'no-cache' }
    } catch {
        return (Fail "could not read $base/download/latest.json: $($_.Exception.Message)")
    }
    $version = [string] $latest.version
    if (-not $version) { return (Fail "$base/download/latest.json names no version.") }

    $arch = 'x64'
    if ($env:PROCESSOR_ARCHITECTURE -eq 'ARM64' -or $env:PROCESSOR_ARCHITEW6432 -eq 'ARM64') { $arch = 'arm64' }
    $asset = $latest.assets | Where-Object { $_.name -eq "LarvaSetup-$version-win-$arch.exe" } | Select-Object -First 1
    if (-not $asset -and $arch -ne 'x64') {
        # Windows on Arm runs the x64 build.
        $asset = $latest.assets | Where-Object { $_.name -eq "LarvaSetup-$version-win-x64.exe" } | Select-Object -First 1
    }
    if (-not $asset) { return (Fail "Larva $version has no Windows installer. See $base/download") }
    if (-not $asset.sha256) { return (Fail "$($asset.name) has no SHA-256 to check it against. See $base/download") }

    $folder = Join-Path ([IO.Path]::GetTempPath()) ("larva-install-" + [Guid]::NewGuid().ToString('N').Substring(0, 8))
    New-Item -ItemType Directory -Force -Path $folder | Out-Null
    $file = Join-Path $folder $asset.name
    try {
        $megabytes = [Math]::Round($asset.size / 1MB, 1)
        Step "Downloading $($asset.name) ($megabytes MB)"
        $progress = $ProgressPreference
        $ProgressPreference = 'SilentlyContinue'   # the progress bar of Windows PowerShell 5 makes downloads crawl
        try {
            Invoke-WebRequest -UseBasicParsing -Uri $asset.url -OutFile $file
        } catch {
            return (Fail "could not download $($asset.url): $($_.Exception.Message)")
        } finally {
            $ProgressPreference = $progress
        }

        Step "Checking its SHA-256"
        $hash = (Get-FileHash -Algorithm SHA256 -LiteralPath $file).Hash.ToLowerInvariant()
        if ($hash -ne ([string] $asset.sha256).ToLowerInvariant()) {
            return (Fail "the SHA-256 of $($asset.name) is $hash, not $($asset.sha256): the download is damaged or not Larva's. Nothing was installed.")
        }
        Say "    $hash  ok"

        # Start-Process joins its arguments with spaces: quote the ones that have some.
        $quoted = $setup | ForEach-Object { if ($_ -match '\s') { '"' + $_ + '"' } else { $_ } }
        if ($dryRun) {
            Step "Dry run: would run $($asset.name) $($quoted -join ' ')"
            Say "Nothing was installed (LARVA_INSTALL_DRYRUN)."
            return $true
        }

        Step "Installing Larva $version"
        $process = Start-Process -FilePath $file -ArgumentList $quoted -Wait -PassThru -NoNewWindow
        if ($process.ExitCode -ne 0) {
            return (Fail "the setup ended with exit code $($process.ExitCode). Run $($asset.name) from $base/download to see the wizard.")
        }

        $installed = if ($env:LARVA_INSTALL_DIR) { [IO.Path]::GetFullPath($env:LARVA_INSTALL_DIR) } else { Join-Path $env:LOCALAPPDATA 'Programs\Larva' }
        $larva = Join-Path $installed 'larva.exe'
        if (-not ($setup -contains '--no-path') -and (Test-Path $larva)) {
            # This window too (new ones read the PATH the setup changed).
            if (-not (($env:Path -split ';') -contains $installed)) { $env:Path = "$installed;$env:Path" }
        }
        if (Test-Path $larva) {
            $answer = & $larva --version 2>$null
            Step "Installed $answer into $installed"
        } else {
            Step "Installed Larva $version"
        }
        Say ""
        Say "Next: larva new Console-App Hello --lang antril; cd Hello; larva run"
        Say "Documentation: $base/docs"
        return $true
    } finally {
        Remove-Item -Recurse -Force -LiteralPath $folder -ErrorAction SilentlyContinue
    }
}

# Not `exit`: piped to iex, this runs in the caller's own session.
$null = Install-Larva -Options $args