param(
    [uri]$ReleaseUri = 'https://xoderony.github.io/downloads/releases/expriverse-demo-latest.json',
    [string]$InstallRoot,
    [switch]$NoLaunch,
    [switch]$NoShortcut,
    [switch]$AllowLoopbackHttp
)

# Keep functions and state local even when this script is invoked through irm | iex.
& {
    param($ReleaseUri, $InstallRoot, $NoLaunch, $NoShortcut, $AllowLoopbackHttp)
    $ErrorActionPreference = 'Stop'
    Set-StrictMode -Version Latest

    function Read-Choice {
        param([string]$Prompt)
        do {
            $answer = (Read-Host ($Prompt + ' [Y/N，回车为 N]')).Trim()
        } while ($answer -notmatch '^(?i:y|yes|n|no|是|否)?$')
        return $answer -match '^(?i:y|yes|是)$'
    }

    function Assert-NoDirectoryLinks {
        param([string]$Path)
        $current = [IO.Path]::GetFullPath($Path)
        while (-not [string]::IsNullOrEmpty($current)) {
            if (Test-Path -LiteralPath $current) {
                $item = Get-Item -LiteralPath $current -Force
                if (-not $item.PSIsContainer -or ($item.Attributes -band [IO.FileAttributes]::ReparsePoint) -ne 0) {
                    throw ('安装路径包含文件、链接或目录联接，请选择普通本地文件夹：' + $current)
                }
            }
            $current = [IO.Path]::GetDirectoryName($current.TrimEnd('\'))
        }
    }

    function Get-InstallRoot {
        param([string]$Requested)
        $defaultRoot = Join-Path ([Environment]::GetFolderPath('LocalApplicationData')) 'Expriverse'
        $interactivePath = [string]::IsNullOrWhiteSpace($Requested)
        if ($interactivePath) {
            $Requested = Read-Host ('安装到哪个父目录？直接回车使用 ' + $defaultRoot)
            if ([string]::IsNullOrWhiteSpace($Requested)) { $Requested = $defaultRoot }
        }
        $Requested = $Requested.Trim().Trim('"')
        # Explicit paths (including the updater's environment value) are literal.
        if ($interactivePath) { $Requested = [Environment]::ExpandEnvironmentVariables($Requested) }
        if ($Requested.Contains('%')) { throw '安装路径不能包含 % 符号：Windows CMD 可能将其展开为环境变量。请选择其他目录。' }
        if ($Requested -notmatch '^[A-Za-z]:[\\/]') { throw '请输入完整的本地目录，例如 D:\游戏\Expriverse。' }
        $full = [IO.Path]::GetFullPath($Requested).TrimEnd('\')
        if ($full -match '^[A-Za-z]:$') { $full += '\' }
        Assert-NoDirectoryLinks $full
        return $full
    }

    function Assert-DownloadUri {
        param([uri]$Uri, [ValidateSet('Manifest', 'Archive')][string]$Kind, [bool]$AllowHttp, [bool]$IsRedirect = $false)
        if (-not $Uri.IsAbsoluteUri -or -not [string]::IsNullOrEmpty($Uri.UserInfo) -or
            -not [string]::IsNullOrEmpty($Uri.Fragment)) { throw '下载地址无效。' }
        if ($AllowHttp -and $Uri.Scheme -ceq 'http' -and $Uri.IsLoopback) {
            # This opt-in is for isolated local QA only, never an HTTP production fallback.
            if ($IsRedirect) { throw '本机测试下载不接受重定向。' }
            return
        }
        if ($Uri.Scheme -cne 'https' -or $Uri.Port -ne 443) { throw '下载只允许受信任的 HTTPS 地址。' }
        if ($Kind -ceq 'Manifest') {
            if ($Uri.DnsSafeHost -ine 'xoderony.github.io' -or
                $Uri.AbsolutePath -cnotmatch '^/downloads/releases/expriverse-demo-[a-z0-9-]{1,48}\.json$' -or
                -not [string]::IsNullOrEmpty($Uri.Query) -or $IsRedirect) {
                throw '版本信息必须直接来自 xoderony.github.io 的 downloads/releases 目录。'
            }
            return
        }
        $releasePath = '/Xoderony/Xoderony.github.io/releases/download/demo-v0.1.0/Expriverse-win-x64.zip'
        if ($Uri.DnsSafeHost -ieq 'github.com' -and $Uri.AbsolutePath -ceq $releasePath -and
            [string]::IsNullOrEmpty($Uri.Query)) { return }
        # Only a validated redirect from the pinned GitHub asset can reach this host.
        if ($IsRedirect -and $Uri.DnsSafeHost -ieq 'release-assets.githubusercontent.com' -and
            $Uri.AbsolutePath.StartsWith('/github-production-release-asset/', [StringComparison]::Ordinal)) { return }
        throw '安装包地址或重定向不在允许的 GitHub Release 范围内。'
    }

    function Open-Download {
        param([uri]$Uri, [ValidateSet('Manifest', 'Archive')][string]$Kind, [bool]$AllowHttp = $false)
        Add-Type -AssemblyName System.Net.Http
        $handler = [Net.Http.HttpClientHandler]::new()
        $client = $null
        $response = $null
        try {
            $handler.AllowAutoRedirect = $false
            $handler.UseCookies = $false
            $handler.UseDefaultCredentials = $false
            # Per-client TLS, no certificate bypass or process/machine security changes.
            if ($null -eq $handler.PSObject.Properties['SslProtocols']) {
                throw '请更新 Windows 的 .NET Framework 至 4.7.2 或更高版本，或使用 PowerShell 7。'
            }
            $handler.SslProtocols = [Security.Authentication.SslProtocols]::Tls12
            $client = [Net.Http.HttpClient]::new($handler)
            $client.Timeout = [TimeSpan]::FromSeconds(30)
            $client.DefaultRequestHeaders.UserAgent.ParseAdd('Expriverse-Installer/2')
            $current = $Uri
            $seen = [Collections.Generic.HashSet[string]]::new([StringComparer]::Ordinal)
            for ($hop = 0; $hop -le 5; $hop++) {
                Assert-DownloadUri $current $Kind $AllowHttp ($hop -gt 0)
                if (-not $seen.Add($current.AbsoluteUri)) { throw '下载地址出现循环重定向。' }
                $response = $client.GetAsync($current, [Net.Http.HttpCompletionOption]::ResponseHeadersRead).GetAwaiter().GetResult()
                $status = [int]$response.StatusCode
                if ($status -eq 200) {
                    $stream = $response.Content.ReadAsStreamAsync().GetAwaiter().GetResult()
                    return [pscustomobject]@{ Response = $response; Client = $client; Stream = $stream; ContentLength = $response.Content.Headers.ContentLength }
                }
                if ($status -in @(301, 302, 303, 307, 308) -and $Kind -ceq 'Archive' -and $hop -lt 5) {
                    $location = $response.Headers.Location
                    if ($null -eq $location) { throw '安装包重定向缺少目标地址。' }
                    $next = [uri]::new($current, $location.OriginalString)
                    Assert-DownloadUri $next $Kind $AllowHttp $true
                    $response.Dispose()
                    $response = $null
                    $current = $next
                    continue
                }
                throw ('下载失败：HTTP ' + $status + '，或重定向超过允许次数。')
            }
            throw '下载重定向超过允许次数。'
        } catch {
            if ($null -ne $response) { $response.Dispose() }
            if ($null -ne $client) { $client.Dispose() } else { $handler.Dispose() }
            throw
        }
    }

    function Read-ResponseChunk {
        param([IO.Stream]$Stream, [byte[]]$Buffer)
        $readTask = $Stream.ReadAsync($Buffer, 0, $Buffer.Length)
        if (-not $readTask.Wait(120000)) { throw '读取下载内容超时，请重试。' }
        return $readTask.GetAwaiter().GetResult()
    }

    function Close-Download {
        param($Download)
        try { $Download.Stream.Dispose(); $Download.Response.Dispose() }
        finally { $Download.Client.Dispose() }
    }

    function Read-Release {
        param([uri]$Uri, [bool]$AllowHttp)
        Assert-DownloadUri $Uri 'Manifest' $AllowHttp
        $download = Open-Download $Uri 'Manifest' $AllowHttp
        $memory = [IO.MemoryStream]::new()
        try {
            $buffer = New-Object byte[] 4096
            while (($read = Read-ResponseChunk $download.Stream $buffer) -gt 0) {
                if ($memory.Length + $read -gt 65536) { throw '版本信息文件过大。' }
                $memory.Write($buffer, 0, $read)
            }
            $text = [Text.UTF8Encoding]::new($false, $true).GetString($memory.ToArray()).TrimStart([char]0xfeff)
            $release = $text | ConvertFrom-Json
        } finally { $memory.Dispose(); Close-Download $download }
        if ($null -eq $release -or $release -is [array]) { throw '版本信息格式无效。' }
        foreach ($name in @('schemaVersion', 'id', 'title', 'file', 'bytes', 'expandedBytes', 'sha256', 'launcher', 'layout', 'executable')) {
            if ($null -eq $release.PSObject.Properties[$name]) { throw ('版本信息缺少字段：' + $name) }
        }
        if ($release.schemaVersion -ne 2 -or
            $release.id -isnot [string] -or $release.id -cnotmatch '^expriverse-demo-[a-z0-9-]{1,48}$' -or
            $release.title -isnot [string] -or [string]::IsNullOrWhiteSpace($release.title) -or
            $release.title.Length -gt 200 -or $release.title -match '[\x00-\x1f\x7f]' -or
            $release.sha256 -isnot [string] -or $release.sha256 -notmatch '^[a-fA-F0-9]{64}$' -or
            [string]$release.bytes -notmatch '^[1-9][0-9]*$' -or
            [string]$release.expandedBytes -notmatch '^[1-9][0-9]*$' -or
            $release.file -isnot [string] -or
            $release.launcher -cne 'Start-Expriverse.cmd' -or $release.layout -cne 'flat' -or
            $release.executable -cne 'Expriverse.Windows.exe') { throw '版本信息格式无效，未开始安装。' }
        if ([long]$release.bytes -gt 4GB -or [long]$release.expandedBytes -gt 20GB) { throw '版本信息中的安装包大小超出允许范围。' }
        $archiveUri = [uri]::new($Uri, $release.file)
        Assert-DownloadUri $archiveUri 'Archive' $AllowHttp
        if (($Uri.Scheme -eq 'http' -or $archiveUri.Scheme -eq 'http') -and
            ($Uri.Scheme -ne 'http' -or $archiveUri.Scheme -ne 'http' -or $archiveUri.Authority -ine $Uri.Authority)) {
            throw '本机测试安装包必须与测试版本信息同源。'
        }
        return @{ Metadata = $release; ArchiveUri = $archiveUri }
    }

    function Save-Archive {
        param([uri]$Uri, [string]$Destination, [long]$ExpectedBytes, [bool]$AllowHttp = $false)
        $download = Open-Download $Uri 'Archive' $AllowHttp
        $outputStream = $null
        try {
            if ($null -ne $download.ContentLength -and $download.ContentLength -ne $ExpectedBytes) { throw '服务器返回的安装包大小与版本信息不符。' }
            $outputStream = [IO.File]::Open($Destination, [IO.FileMode]::CreateNew, [IO.FileAccess]::Write, [IO.FileShare]::None)
            $buffer = New-Object byte[] 131072
            [long]$received = 0
            $lastProgress = [DateTime]::MinValue
            while (($read = Read-ResponseChunk $download.Stream $buffer) -gt 0) {
                if ($read -gt ($ExpectedBytes - $received)) { throw '下载内容超过预期大小，已停止。' }
                $received += $read
                $outputStream.Write($buffer, 0, $read)
                if (([DateTime]::UtcNow - $lastProgress).TotalMilliseconds -ge 250) {
                    Write-Progress -Activity '正在下载 Expriverse' -Status ('{0:N1} / {1:N1} MiB' -f ($received / 1MB), ($ExpectedBytes / 1MB)) -PercentComplete ([int](100 * $received / $ExpectedBytes))
                    $lastProgress = [DateTime]::UtcNow
                }
            }
            if ($received -ne $ExpectedBytes) { throw '安装包下载不完整，请重试。' }
        } finally {
            if ($null -ne $outputStream) { $outputStream.Dispose() }
            Close-Download $download
            Write-Progress -Activity '正在下载 Expriverse' -Completed
        }
    }

    function Expand-SafeArchive {
        param([string]$ArchivePath, [string]$Destination, [long]$ExpectedExpandedBytes)
        Add-Type -AssemblyName System.IO.Compression.FileSystem
        if ($ExpectedExpandedBytes -le 0 -or (Test-Path -LiteralPath $Destination)) { throw '解压目标必须是新目录，且解压大小必须有效。' }
        Assert-NoDirectoryLinks ([IO.Path]::GetDirectoryName([IO.Path]::GetFullPath($Destination)))
        $root = [IO.Path]::GetFullPath($Destination).TrimEnd('\') + '\'
        $archive = [IO.Compression.ZipFile]::OpenRead($ArchivePath)
        try {
            if ($archive.Entries.Count -gt 100000) { throw '安装包文件数量过多。' }
            $names = [Collections.Generic.HashSet[string]]::new([StringComparer]::OrdinalIgnoreCase)
            $files = [Collections.Generic.HashSet[string]]::new([StringComparer]::OrdinalIgnoreCase)
            $directories = [Collections.Generic.HashSet[string]]::new([StringComparer]::OrdinalIgnoreCase)
            $validated = [Collections.Generic.List[object]]::new()
            [long]$total = 0
            foreach ($entry in $archive.Entries) {
                $name = $entry.FullName.Replace('/', '\')
                if ([string]::IsNullOrEmpty($name) -or [IO.Path]::IsPathRooted($name) -or $name.Contains(':')) { throw '安装包包含无效或绝对路径。' }
                $isDirectory = $name.EndsWith('\')
                foreach ($part in $name.TrimEnd('\').Split('\')) {
                    if ([string]::IsNullOrEmpty($part) -or $part -in @('.', '..') -or
                        $part.EndsWith('.') -or $part.EndsWith(' ') -or $part.IndexOfAny([IO.Path]::GetInvalidFileNameChars()) -ge 0 -or
                        $part -match '^(?i:con|prn|aux|nul|com[1-9¹²³]|lpt[1-9¹²³])(?:\.|$)') { throw '安装包包含不安全的文件路径。' }
                }
                $target = [IO.Path]::GetFullPath([IO.Path]::Combine($root, $name)).TrimEnd('\')
                if (-not $target.StartsWith($root, [StringComparison]::OrdinalIgnoreCase) -or -not $names.Add($target)) { throw '安装包包含越界或重复路径。' }
                $unixType = ($entry.ExternalAttributes -shr 16) -band 0xf000
                if (($entry.ExternalAttributes -band 0x400) -ne 0 -or
                    ($isDirectory -and $unixType -notin @(0, 0x4000)) -or
                    (-not $isDirectory -and $unixType -notin @(0, 0x8000))) { throw '安装包不得包含链接、目录联接或特殊文件。' }
                if ($isDirectory -and $entry.Length -ne 0) { throw '安装包目录条目不能包含数据。' }
                if ($isDirectory) {
                    if ($files.Contains($target)) { throw '安装包包含文件与目录冲突。' }
                    [void]$directories.Add($target)
                } else {
                    if ($directories.Contains($target)) { throw '安装包包含文件与目录冲突。' }
                    [void]$files.Add($target)
                }
                $ancestor = [IO.Path]::GetDirectoryName($target)
                while ($ancestor.StartsWith($root, [StringComparison]::OrdinalIgnoreCase)) {
                    if ($files.Contains($ancestor)) { throw '安装包包含文件与子目录冲突。' }
                    [void]$directories.Add($ancestor)
                    $ancestor = [IO.Path]::GetDirectoryName($ancestor)
                }
                if ($entry.Length -gt ($ExpectedExpandedBytes - $total)) { throw '解压后大小超过版本信息，已停止。' }
                $total += $entry.Length
                $validated.Add([pscustomobject]@{ Entry = $entry; Target = $target; IsDirectory = $isDirectory })
            }
            if ($total -ne $ExpectedExpandedBytes) { throw '解压后大小与版本信息不符。' }
            # Preflight every path before creating files, then bound the actual decoded bytes too.
            [IO.Directory]::CreateDirectory($Destination) | Out-Null
            $buffer = New-Object byte[] 131072
            [long]$actualTotal = 0
            foreach ($item in $validated) {
                if ($item.IsDirectory) { [IO.Directory]::CreateDirectory($item.Target) | Out-Null; continue }
                [IO.Directory]::CreateDirectory([IO.Path]::GetDirectoryName($item.Target)) | Out-Null
                $inputStream = $item.Entry.Open()
                $outputStream = $null
                try {
                    $outputStream = [IO.File]::Open($item.Target, [IO.FileMode]::CreateNew, [IO.FileAccess]::Write, [IO.FileShare]::None)
                    [long]$actualEntry = 0
                    while (($read = $inputStream.Read($buffer, 0, $buffer.Length)) -gt 0) {
                        if ($read -gt ($item.Entry.Length - $actualEntry) -or $read -gt ($ExpectedExpandedBytes - $actualTotal)) { throw '安装包实际解压数据超过声明大小，已停止。' }
                        $actualEntry += $read
                        $actualTotal += $read
                        $outputStream.Write($buffer, 0, $read)
                    }
                    if ($actualEntry -ne $item.Entry.Length) { throw '安装包文件解压不完整。' }
                } finally {
                    if ($null -ne $outputStream) { $outputStream.Dispose() }
                    $inputStream.Dispose()
                }
            }
            if ($actualTotal -ne $ExpectedExpandedBytes) { throw '安装包实际解压大小不符。' }
        } finally { $archive.Dispose() }
    }

    function Remove-OwnedWorkDirectory {
        param([string]$Path, [string]$Parent, [string]$Token)
        $expected = [IO.Path]::GetFullPath((Join-Path $Parent ('.expriverse-install-' + $Token)))
        if ($Token -notmatch '^[a-f0-9]{32}$' -or -not [string]::Equals([IO.Path]::GetFullPath($Path), $expected, [StringComparison]::OrdinalIgnoreCase)) { throw '临时目录所有权不匹配，拒绝清理。' }
        if (-not (Test-Path -LiteralPath $Path)) { return }
        Assert-NoDirectoryLinks $Path
        $marker = Join-Path $Path '.expriverse-owner'
        if (-not (Test-Path -LiteralPath $marker -PathType Leaf) -or
            ((Get-Item -LiteralPath $marker -Force).Attributes -band [IO.FileAttributes]::ReparsePoint) -ne 0 -or
            [IO.File]::ReadAllText($marker) -cne $Token) { throw '临时目录所有权标记不匹配，拒绝清理。' }
        $pending = [Collections.Generic.Stack[string]]::new()
        $pending.Push($Path)
        while ($pending.Count -gt 0) {
            foreach ($item in Get-ChildItem -LiteralPath $pending.Pop() -Force) {
                if (($item.Attributes -band [IO.FileAttributes]::ReparsePoint) -ne 0) { throw '临时目录包含链接，拒绝清理。' }
                if ($item.PSIsContainer) { $pending.Push($item.FullName) }
            }
        }
        Remove-Item -LiteralPath $expected -Recurse -Force
    }

    function Get-GameWrappers {
        # These audited ASCII wrappers are generated locally; no bundled script is executed.
        $launcher = @'
@echo off
setlocal DisableDelayedExpansion
cd /d "%~dp0"
if not exist "%~dp0Expriverse.Windows.exe" (
    echo Expriverse.Windows.exe is missing. Run the installer again.
    pause
    exit /b 1
)
start "" /d "%~dp0" "%~dp0Expriverse.Windows.exe"
if errorlevel 1 (
    echo Could not start Expriverse. Check that Steam is running.
    pause
    exit /b 1
)
exit /b 0
'@
        $updater = @'
@echo off
setlocal DisableDelayedExpansion
set "EXPRIVERSE_INSTALL_ROOT=%~dp0.."
"%SystemRoot%\System32\WindowsPowerShell\v1.0\powershell.exe" -NoLogo -NoProfile -Command "$ErrorActionPreference='Stop'; try { Add-Type -AssemblyName System.Net.Http; $h=[Net.Http.HttpClientHandler]::new(); $h.AllowAutoRedirect=$false; $h.UseCookies=$false; $h.UseDefaultCredentials=$false; $h.SslProtocols=[Security.Authentication.SslProtocols]::Tls12; $c=[Net.Http.HttpClient]::new($h); $c.Timeout=[TimeSpan]::FromSeconds(120); try { $r=$c.GetAsync('https://xoderony.github.io/downloads/install-expriverse.txt',[Net.Http.HttpCompletionOption]::ResponseHeadersRead).GetAwaiter().GetResult(); try { if ([int]$r.StatusCode -ne 200) { throw 'Bootstrap download failed or redirected.' }; $s=$r.Content.ReadAsStreamAsync().GetAwaiter().GetResult(); $m=[IO.MemoryStream]::new(); try { $b=New-Object byte[] 4096; while ($true) { $t=$s.ReadAsync($b,0,$b.Length); if (-not $t.Wait(120000)) { throw 'Download timed out.' }; $n=$t.GetAwaiter().GetResult(); if ($n -eq 0) { break }; if ($m.Length+$n -gt 262144) { throw 'Bootstrap is too large.' }; $m.Write($b,0,$n) }; $src=[Text.UTF8Encoding]::new($false,$true).GetString($m.ToArray()).TrimStart([char]0xfeff) } finally { $m.Dispose(); $s.Dispose() } } finally { $r.Dispose() } } finally { $c.Dispose() }; & ([scriptblock]::Create($src)) -InstallRoot $env:EXPRIVERSE_INSTALL_ROOT; if (-not $?) { exit 1 } } catch { Write-Host $_.Exception.Message -ForegroundColor Red; exit 1 }"
if errorlevel 1 (
    echo Update did not complete. See the message above.
    pause
    exit /b 1
)
pause
exit /b 0
'@
        return @{
            'Start-Expriverse.cmd' = ($launcher.Replace("`r`n", "`n").Replace("`n", "`r`n") + "`r`n")
            'Update-Expriverse.cmd' = ($updater.Replace("`r`n", "`n").Replace("`n", "`r`n") + "`r`n")
        }
    }

    function New-GameWrappers {
        param([string]$Directory)
        $wrappers = Get-GameWrappers
        foreach ($name in $wrappers.Keys) {
            $target = Join-Path $Directory $name
            if (Test-Path -LiteralPath $target) { throw ('安装包不应包含由安装器生成的文件：' + $name) }
            [IO.File]::WriteAllText($target, $wrappers[$name], [Text.Encoding]::ASCII)
        }
    }

    function Assert-InstalledFiles {
        param([string]$Directory)
        if (-not (Test-Path -LiteralPath (Join-Path $Directory 'Expriverse.Windows.exe') -PathType Leaf)) { throw '已有游戏缺少主程序，请检查安装目录。' }
        $wrappers = Get-GameWrappers
        foreach ($name in $wrappers.Keys) {
            $path = Join-Path $Directory $name
            if (-not (Test-Path -LiteralPath $path -PathType Leaf) -or [IO.File]::ReadAllText($path) -cne $wrappers[$name]) {
                throw ('已有游戏的启动或更新入口缺失或已修改，未执行：' + $name)
            }
        }
    }

    function Test-GamePrerequisites {
        $systemDirectory = [Environment]::GetFolderPath('System')
        foreach ($library in @('VCRUNTIME140.dll', 'MSVCP140.dll', 'VCRUNTIME140_1.dll')) {
            if (-not (Test-Path -LiteralPath (Join-Path $systemDirectory $library) -PathType Leaf)) {
                Write-Host '游戏已安装，但还缺少 Microsoft Visual C++ x64 运行库。' -ForegroundColor Yellow
                Write-Host '请先下载并安装微软运行库，然后使用游戏启动器；本次跳过自动启动。'
                Write-Host 'https://aka.ms/vc14/vc_redist.x64.exe'
                return $false
            }
        }
        return $true
    }

    function New-GameShortcut {
        param([string]$Directory, [string]$Version, [string]$DesktopDirectory)
        $shortcutPath = Join-Path $DesktopDirectory 'Expriverse.lnk'
        if (Test-Path -LiteralPath $shortcutPath) { Write-Host ('快捷方式已存在，未覆盖：' + $shortcutPath); return }
        $shell = New-Object -ComObject WScript.Shell
        try {
            $shortcut = $shell.CreateShortcut($shortcutPath)
            try {
                $shortcut.TargetPath = Join-Path $Directory 'Start-Expriverse.cmd'
                $shortcut.WorkingDirectory = $Directory
                $shortcut.Description = 'Expriverse 多人 Demo'
                $shortcut.Save()
            }
            finally { [void][Runtime.InteropServices.Marshal]::FinalReleaseComObject($shortcut) }
        }
        finally { [void][Runtime.InteropServices.Marshal]::FinalReleaseComObject($shell) }
        Write-Host '已创建桌面快捷方式。'
    }
    function Show-InstalledGame {
        param([string]$Directory, [string]$Version, [bool]$SkipLaunch, [bool]$SkipShortcut)
        $launcher = Join-Path $Directory 'Start-Expriverse.cmd'
        if (-not (Test-Path -LiteralPath $launcher -PathType Leaf)) { throw '已有目录缺少 Start-Expriverse.cmd，请换一个安装父目录。' }
        Write-Host ''
        Write-Host ('游戏目录：' + $Directory) -ForegroundColor Green
        Write-Host '文件会保留；以后双击 Start-Expriverse.cmd 即可运行，不需要保持安装终端打开。'
        $prerequisitesReady = Test-GamePrerequisites
        if (-not $SkipShortcut -and (Read-Choice '创建桌面快捷方式？')) {
            try {
                New-GameShortcut $Directory $Version ([Environment]::GetFolderPath('DesktopDirectory'))
            }
            catch { Write-Warning ('游戏已保留，但快捷方式未创建：' + $_.Exception.Message) }
        }
        if ($prerequisitesReady -and -not $SkipLaunch -and (Read-Choice '请先打开 Steam 并登录。现在启动游戏？')) {
            try { Start-Process -FilePath $launcher -WorkingDirectory $Directory | Out-Null }
            catch { Write-Warning ('自动启动失败，请在游戏目录双击启动器：' + $_.Exception.Message) }
        }
    }

    function Assert-SafeTree {
        param([string]$Path)
        Assert-NoDirectoryLinks $Path
        $pending = [Collections.Generic.Stack[string]]::new()
        $pending.Push($Path)
        while ($pending.Count -gt 0) {
            foreach ($item in Get-ChildItem -LiteralPath $pending.Pop() -Force) {
                if (($item.Attributes -band [IO.FileAttributes]::ReparsePoint) -ne 0) { throw '游戏目录包含链接，不能更新。' }
                if ($item.PSIsContainer) { $pending.Push($item.FullName) }
            }
        }
    }

    function Read-InstalledRelease {
        param([string]$Directory)
        if (-not (Test-Path -LiteralPath $Directory)) { return $null }
        Assert-SafeTree $Directory
        $marker = Join-Path $Directory '.expriverse-release.json'
        if (-not (Test-Path -LiteralPath $marker -PathType Leaf)) { throw '目标目录不是新版安装器管理的游戏，拒绝替换。请选择空的安装位置。' }
        if ((Get-Item -LiteralPath $marker -Force).Length -gt 65536) { throw '已有安装的所有权标记过大。' }
        $installed = [IO.File]::ReadAllText($marker) | ConvertFrom-Json
        if ($null -eq $installed -or $installed -is [array]) { throw '已有安装的所有权标记无效。' }
        foreach ($name in @('installFormat', 'id', 'sha256', 'bytes', 'expandedBytes', 'launcher')) {
            if ($null -eq $installed.PSObject.Properties[$name]) { throw '目标目录不是新版安装器管理的游戏，拒绝替换。' }
        }
        if ($installed.installFormat -ne 2 -or $installed.id -isnot [string] -or
            $installed.id -cnotmatch '^expriverse-demo-[a-z0-9-]{1,48}$' -or
            $installed.sha256 -isnot [string] -or $installed.sha256 -notmatch '^[a-fA-F0-9]{64}$' -or
            [string]$installed.bytes -notmatch '^[1-9][0-9]*$' -or
            [string]$installed.expandedBytes -notmatch '^[1-9][0-9]*$' -or
            $installed.launcher -cne 'Start-Expriverse.cmd') { throw '目标目录不是新版安装器管理的游戏，拒绝替换。' }
        foreach ($name in @('local', 'roaming', 'Logs', 'cache')) {
            $path = Join-Path $Directory $name
            if ((Test-Path -LiteralPath $path) -and -not (Test-Path -LiteralPath $path -PathType Container)) {
                throw ('已有状态路径不是普通目录，拒绝替换：' + $name)
            }
        }
        return $installed
    }

    function Assert-GameStopped {
        param([string]$Directory)
        $executable = Join-Path $Directory 'Expriverse.Windows.exe'
        foreach ($process in Get-Process -Name 'Expriverse.Windows' -ErrorAction SilentlyContinue) {
            if ([string]::IsNullOrEmpty($process.Path)) { throw '无法核实正在运行的游戏位置，请退出游戏后重试。' }
            if ([string]::Equals($process.Path, $executable, [StringComparison]::OrdinalIgnoreCase)) { throw '请先退出此目录中的游戏，再运行更新。' }
        }
        if (Test-Path -LiteralPath $executable -PathType Leaf) {
            try {
                $handle = [IO.File]::Open($executable, [IO.FileMode]::Open, [IO.FileAccess]::ReadWrite, [IO.FileShare]::None)
                $handle.Dispose()
            } catch { throw '游戏文件正在使用，请退出游戏后重试。' }
        }
    }

    function Move-GameDirectory {
        param([string]$Source, [string]$Destination)
        [IO.Directory]::Move($Source, $Destination)
    }

    function Install-Expriverse {
        param([uri]$Uri, [string]$RequestedRoot, [bool]$SkipLaunch, [bool]$SkipShortcut, [bool]$AllowHttp)
        if ([Environment]::OSVersion.Platform -ne [PlatformID]::Win32NT -or -not [Environment]::Is64BitOperatingSystem -or -not [Environment]::Is64BitProcess) { throw '请在 64 位 Windows 的 Windows PowerShell 或 PowerShell 中运行。' }
        Write-Host 'Expriverse 安装 / 更新' -ForegroundColor Cyan
        $download = Read-Release $Uri $AllowHttp
        $release = $download.Metadata
        $parent = Get-InstallRoot $RequestedRoot
        $directory = Join-Path $parent 'game'
        $installed = Read-InstalledRelease $directory
        $sameVersion = $null -ne $installed -and $installed.id -ceq $release.id
        if ($sameVersion -and ($installed.sha256 -ine $release.sha256 -or
            [string]$installed.bytes -cne [string]$release.bytes -or
            [string]$installed.expandedBytes -cne [string]$release.expandedBytes)) {
            throw '同一版本编号的安装包信息发生变化，拒绝跳过或替换。请联系发布者使用新的版本编号。'
        }
        if (-not $sameVersion) {
            if ($null -ne $installed) { Assert-GameStopped $directory }
            Write-Host ('目标版本：' + $release.id + '；游戏目录：' + $directory)
            Write-Host ('下载 {0:N1} MiB，解压 {1:N1} MiB；更新时还需保留旧版和设置的空间。' -f ([long]$release.bytes / 1MB), ([long]$release.expandedBytes / 1MB))
            Write-Host '更新只保留 local、roaming 和 Logs；其他程序目录文件会被替换，cache 缓存重新生成。请保持游戏关闭。'
            if (-not (Read-Choice '确认下载并安装？')) { Write-Host '已取消，未修改安装文件。'; return }
        }

        $token = [guid]::NewGuid().ToString('N')
        $work = Join-Path $parent ('.expriverse-install-' + $token)
        $backup = Join-Path $work 'previous'
        $created = $false
        $preserveWork = $false
        $committed = $false
        $lock = $null
        try {
            Assert-NoDirectoryLinks $parent
            [IO.Directory]::CreateDirectory($parent) | Out-Null
            $lockPath = Join-Path $parent '.expriverse-update.lock'
            if ((Test-Path -LiteralPath $lockPath) -and ((Get-Item -LiteralPath $lockPath -Force).Attributes -band [IO.FileAttributes]::ReparsePoint) -ne 0) { throw '更新锁不能是链接。' }
            try { $lock = [IO.File]::Open($lockPath, [IO.FileMode]::OpenOrCreate, [IO.FileAccess]::ReadWrite, [IO.FileShare]::None) }
            catch { throw '另一个安装或更新正在使用此目录，请等待它结束。' }
            foreach ($pending in Get-ChildItem -LiteralPath $parent -Directory -Filter '.expriverse-install-*' -Force) {
                if (Test-Path -LiteralPath (Join-Path $pending.FullName 'previous')) { throw ('发现上次中断保留的旧版，请先检查并恢复：' + $pending.FullName) }
            }
            $current = Read-InstalledRelease $directory
            if (($null -eq $installed) -ne ($null -eq $current) -or
                ($null -ne $current -and ($current.id -cne $installed.id -or $current.sha256 -ine $installed.sha256))) { throw '安装状态已改变，请重新运行。' }
            if ($sameVersion) {
                Assert-InstalledFiles $directory
                Write-Host ('已是最新版本：' + $release.id) -ForegroundColor Green
                Show-InstalledGame $directory $release.id $SkipLaunch $SkipShortcut
                return
            }
            if (Test-Path -LiteralPath $work) { throw '临时目录已存在，请重新运行。' }
            [IO.Directory]::CreateDirectory($work) | Out-Null
            $created = $true
            [IO.File]::WriteAllText((Join-Path $work '.expriverse-owner'), $token, [Text.Encoding]::ASCII)
            $archivePath = Join-Path $work 'package.zip'
            Save-Archive $download.ArchiveUri $archivePath ([long]$release.bytes) $AllowHttp
            if ((Get-FileHash -LiteralPath $archivePath -Algorithm SHA256).Hash -ine $release.sha256) { throw 'SHA-256 校验失败，未替换游戏。' }
            $payload = Join-Path $work 'game'
            Expand-SafeArchive $archivePath $payload ([long]$release.expandedBytes)
            if (-not (Test-Path -LiteralPath (Join-Path $payload 'Expriverse.Windows.exe') -PathType Leaf)) { throw '安装包缺少根目录主程序：Expriverse.Windows.exe' }
            foreach ($name in @('local', 'roaming', 'Logs', 'cache', '.expriverse-release.json', '.expriverse-owner')) {
                if (Test-Path -LiteralPath (Join-Path $payload $name)) { throw ('安装包不应包含用户状态、缓存或所有权标记：' + $name) }
            }
            New-GameWrappers $payload
            $release | Add-Member -NotePropertyName installFormat -NotePropertyValue 2 -Force
            [IO.File]::WriteAllText((Join-Path $payload '.expriverse-release.json'), ($release | ConvertTo-Json), [Text.UTF8Encoding]::new($true))
            Assert-NoDirectoryLinks $parent
            try {
                if ($null -ne $installed) {
                    Assert-SafeTree $directory
                    Assert-GameStopped $directory
                    Move-GameDirectory $directory $backup
                    foreach ($name in @('local', 'roaming', 'Logs')) {
                        $state = Join-Path $backup $name
                        if (Test-Path -LiteralPath $state) { Copy-Item -LiteralPath $state -Destination (Join-Path $payload $name) -Recurse -Force }
                    }
                }
                foreach ($name in @('local', 'roaming', 'Logs', 'cache')) { [IO.Directory]::CreateDirectory((Join-Path $payload $name)) | Out-Null }
                Move-GameDirectory $payload $directory
                $committed = $true
            } catch {
                if (Test-Path -LiteralPath $backup) {
                    try { Move-GameDirectory $backup $directory }
                    catch { $preserveWork = $true; throw ('恢复旧版失败，完整旧版保留在 ' + $backup + '。请勿删除此目录。原因：' + $_.Exception.Message) }
                }
                throw
            }
            Write-Host ('安装 / 更新完成：' + $release.id) -ForegroundColor Green
        } finally {
            if (-not $committed -and (Test-Path -LiteralPath $backup)) {
                $preserveWork = $true
                Write-Warning ('更新中断，完整旧版保留在：' + $backup)
            }
            if ($created -and -not $preserveWork) {
                try { Remove-OwnedWorkDirectory $work $parent $token }
                catch { Write-Warning ('临时目录未完全清理：' + $work + '；' + $_.Exception.Message) }
            }
            if ($null -ne $lock) { $lock.Dispose() }
        }
        Show-InstalledGame $directory $release.id $SkipLaunch $SkipShortcut
    }


    try {
        Install-Expriverse $ReleaseUri $InstallRoot ([bool]$NoLaunch) ([bool]$NoShortcut) ([bool]$AllowLoopbackHttp)
    }
    catch { Write-Host ('安装未完成：' + $_.Exception.Message) -ForegroundColor Red; throw }
} $ReleaseUri $InstallRoot $NoLaunch $NoShortcut $AllowLoopbackHttp