[CmdletBinding()]
param(
    [ValidateRange(1, 16)][int]$MaxParallelActions = 16,
    [ValidateRange(60, 900)][int]$TimeoutSeconds = 900
)

# Stages only inside Saved/BuildHost, builds the isolated host, then audits the exact Core object
# files used by the UE module link. Le projet propriétaire et son éditeur ne sont jamais lancés.
Set-StrictMode -Version Latest
$ErrorActionPreference = 'Stop'

$PluginRoot = [IO.Path]::GetFullPath((Join-Path $PSScriptRoot '..'))
$HostRoot = Join-Path $PluginRoot 'Saved\BuildHost\HostProject'
$HostProject = Join-Path $HostRoot 'HostProject.uproject'
$StagePlugin = Join-Path $HostRoot 'Plugins\VoxelForge'
$StageStandalone = Join-Path $StagePlugin 'Standalone'
$LogRoot = Join-Path $PluginRoot 'Saved\BuildHost'
$EngineRoot = 'E:\Program Files\Epic Games\UE_5.7'
$UbtDll = Join-Path $EngineRoot 'Engine\Binaries\DotNET\UnrealBuildTool\UnrealBuildTool.dll'
$CoreManifest = Join-Path $PluginRoot 'Standalone\Core\core_sources.txt'
$BuildLog = Join-Path $LogRoot 'UBT-CoreIntegration.log'
$BuildStdout = Join-Path $LogRoot 'UBT-CoreIntegration.stdout.log'
$BuildStderr = Join-Path $LogRoot 'UBT-CoreIntegration.stderr.log'
$AuditLibrary = Join-Path $LogRoot 'VoxelForgeCore_ue_link_inputs.lib'
$AuditResult = Join-Path $LogRoot 'VoxelForgeCore_ue_link_safety.log'

function Assert-UnderPath([string]$Candidate, [string]$Root) {
    $candidateFull = [IO.Path]::GetFullPath($Candidate).TrimEnd('\', '/')
    $rootFull = [IO.Path]::GetFullPath($Root).TrimEnd('\', '/')
    if (-not ($candidateFull.Equals($rootFull, [StringComparison]::OrdinalIgnoreCase) -or
        $candidateFull.StartsWith($rootFull + '\', [StringComparison]::OrdinalIgnoreCase))) {
        throw "Refusing a BuildHost path outside its root: $candidateFull"
    }
}

function Copy-DirectoryContents([string]$Source, [string]$Destination) {
    if (-not (Test-Path -LiteralPath $Source -PathType Container)) {
        throw "Canonical Core source directory is missing: $Source"
    }
    [IO.Directory]::CreateDirectory($Destination) | Out-Null
    foreach ($item in @(Get-ChildItem -LiteralPath $Source -Force)) {
        $target = Join-Path $Destination $item.Name
        if ($item.PSIsContainer) {
            Copy-DirectoryContents $item.FullName $target
        } else {
            Copy-Item -LiteralPath $item.FullName -Destination $target -Force
        }
    }
}

function Find-VsTool([string]$ToolName) {
    $toolRoot = 'E:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC'
    foreach ($version in @(Get-ChildItem -LiteralPath $toolRoot -Directory | Sort-Object Name -Descending)) {
        $candidate = Join-Path $version.FullName "bin\Hostx64\x64\$ToolName"
        if (Test-Path -LiteralPath $candidate -PathType Leaf) { return $candidate }
    }
    throw "$ToolName was not found in the configured VS 2022 toolchain."
}

foreach ($required in @($HostProject, $UbtDll, $CoreManifest)) {
    if (-not (Test-Path -LiteralPath $required -PathType Leaf)) { throw "Required file is missing: $required" }
}
Assert-UnderPath $StagePlugin $HostRoot
Assert-UnderPath $StageStandalone $StagePlugin
Assert-UnderPath $LogRoot $PluginRoot

Write-Host 'Staging plugin source and canonical Core inputs into BuildHost.'
$stageSource = Join-Path $StagePlugin 'Source'
Assert-UnderPath $stageSource $StagePlugin
if (Test-Path -LiteralPath $stageSource -PathType Container) {
    $sourceItem = Get-Item -LiteralPath $stageSource -Force
    if (($sourceItem.Attributes -band [IO.FileAttributes]::ReparsePoint) -ne 0) {
        throw "Refusing to replace a linked BuildHost source path: $stageSource"
    }
    $nestedLinks = @(Get-ChildItem -LiteralPath $stageSource -Force -Recurse |
        Where-Object { ($_.Attributes -band [IO.FileAttributes]::ReparsePoint) -ne 0 })
    if ($nestedLinks.Count -gt 0) {
        throw "Refusing to replace BuildHost source containing a link: $($nestedLinks[0].FullName)"
    }
    Remove-Item -LiteralPath $stageSource -Recurse -Force
}
Copy-DirectoryContents (Join-Path $PluginRoot 'Source') $stageSource
Copy-DirectoryContents (Join-Path $PluginRoot 'Standalone\Core\include') (Join-Path $StageStandalone 'Core\include')
Copy-DirectoryContents (Join-Path $PluginRoot 'Standalone\Core\src') (Join-Path $StageStandalone 'Core\src')
Copy-DirectoryContents (Join-Path $PluginRoot 'Standalone\Compat') (Join-Path $StageStandalone 'Compat')
Copy-DirectoryContents (Join-Path $PluginRoot 'Standalone\Source') (Join-Path $StageStandalone 'Source')
Copy-Item -LiteralPath $CoreManifest -Destination (Join-Path $StageStandalone 'Core\core_sources.txt') -Force
Copy-Item -LiteralPath (Join-Path $PluginRoot 'VoxelForge.uplugin') `
    -Destination (Join-Path $StagePlugin 'VoxelForge.uplugin') -Force

# The verified owner-asset copies are already staged under BuildHost. Read only those copies here;
# never resolve, open, copy, or compare against the owner's project Content directory.
$hostAssetRoot = Join-Path $HostRoot 'Content\VoxelForge'
$expectedAssetHashes = @{
    'DA_Settings' = '5D2977F57E75A63B6B73499CD6E0AA7FBBF3718CE7F70318107BF922F0819AB7'
    'DA_Strate1' = 'CDA1F985E589F28CA6E93A068FECC3CA92487E4AD5700F2C301C4B563E40E5F9'
    'DA_Strate2' = '02F56A18CED991BAF93DFB2F69438152275E8353B5E279C1CB7DD6E079E352E2'
    'DA_Strate3' = 'F47437F8D156C608AA06E40C5B76716ED4A19FA0F057688E7FECC04DC976428C'
    'DA_Strate4' = '279570AE3CBA7B3507269C8209A7C931EEB7A15CC3241CE07B50120996B1C656'
}
foreach ($assetName in $expectedAssetHashes.Keys) {
    $stagedAsset = Join-Path $hostAssetRoot "$assetName.uasset"
    if (-not (Test-Path -LiteralPath $stagedAsset -PathType Leaf)) {
        throw "Verified BuildHost asset copy is missing: $stagedAsset"
    }
    $stagedHash = (Get-FileHash -LiteralPath $stagedAsset -Algorithm SHA256).Hash
    if ($stagedHash -ne $expectedAssetHashes[$assetName]) {
        throw "BuildHost asset copy differs from the recorded round-2 hash: $assetName"
    }
}

$dotnet = (Get-Command dotnet.exe -ErrorAction Stop).Source
$argumentList = @(
    ('"{0}"' -f $UbtDll), 'UnrealEditor', 'Win64', 'Development',
    ('-Project="{0}"' -f $HostProject), '-WaitMutex', '-NoHotReloadFromIDE',
    '-NoUBA', '-NoXGE', '-NoFASTBuild', '-NoSNDBS',
    "-MaxParallelActions=$MaxParallelActions", ('-Log="{0}"' -f $BuildLog)
)
$crashRoots = @((Join-Path $HostRoot 'Saved\Crashes'), (Join-Path $StagePlugin 'Saved\Crashes'))
$crashBefore = @{}
foreach ($crashRoot in $crashRoots) {
    if (Test-Path -LiteralPath $crashRoot -PathType Container) {
        foreach ($crash in @(Get-ChildItem -LiteralPath $crashRoot -Directory -Filter 'UECC-*' -Recurse -Force)) {
            $crashBefore[$crash.FullName.ToLowerInvariant()] = $crash.LastWriteTimeUtc.Ticks
        }
    }
}

$buildSucceeded = $false
for ($attempt = 1; $attempt -le 2 -and -not $buildSucceeded; ++$attempt) {
    $attemptStdout = if ($attempt -eq 1) { $BuildStdout } else { Join-Path $LogRoot 'UBT-CoreIntegration.retry.stdout.log' }
    $attemptStderr = if ($attempt -eq 1) { $BuildStderr } else { Join-Path $LogRoot 'UBT-CoreIntegration.retry.stderr.log' }
    Write-Host "BuildHost UBT attempt $attempt of 2; max parallel actions=$MaxParallelActions; normal priority."
    $process = Start-Process -FilePath $dotnet -ArgumentList $argumentList -WorkingDirectory $PluginRoot `
        -RedirectStandardOutput $attemptStdout -RedirectStandardError $attemptStderr `
        -WindowStyle Hidden -PassThru
    $process.PriorityClass = [Diagnostics.ProcessPriorityClass]::Normal
    $started = [datetime]::UtcNow
    while (-not $process.HasExited) {
        Start-Sleep -Seconds 5
        $process.Refresh()
        if (([datetime]::UtcNow - $started).TotalSeconds -gt $TimeoutSeconds) {
            Stop-Process -Id $process.Id -Force -ErrorAction SilentlyContinue
            throw "BuildHost UBT exceeded the $TimeoutSeconds-second time box; stopped PID $($process.Id)."
        }
        if (-not $process.HasExited -and $process.PrivateMemorySize64 -gt 8GB) {
            Stop-Process -Id $process.Id -Force -ErrorAction SilentlyContinue
            throw "BuildHost UBT exceeded the 8 GiB private-memory limit; stopped PID $($process.Id)."
        }
    }
    $process.WaitForExit()
    $process.Refresh()
    $buildExitCode = $process.ExitCode
    if ([string]::IsNullOrEmpty([string]$buildExitCode) -and (Test-Path -LiteralPath $BuildLog -PathType Leaf) -and
        ((Get-Content -LiteralPath $BuildLog -Raw) -match '(?m)^Result: Succeeded\s*$')) {
        # Some Windows Start-Process handles lose the exit-code field after UBT's child exits;
        # accept only UBT's explicit successful target result in that case.
        $buildExitCode = 0
    }
    if ($buildExitCode -eq 0) {
        $buildSucceeded = $true
        Write-Host "BuildHost UBT attempt $attempt passed."
    } elseif ($buildExitCode -eq -1073741502 -and $attempt -eq 1) {
        Write-Warning 'BuildHost UBT exited with 0xC0000142; retrying once as requested.'
    } else {
        throw "BuildHost UBT attempt $attempt failed with exit code '$buildExitCode'. See $BuildLog."
    }
}

if (-not $buildSucceeded) { throw 'BuildHost UBT did not complete successfully.' }

$manifestRows = @(Get-Content -LiteralPath $CoreManifest | ForEach-Object { $_.Trim().Replace('\', '/') } |
    Where-Object { $_ -and -not $_.StartsWith('#') })
$expectedObjects = @($manifestRows | ForEach-Object {
    'VFCore_' + ($_ -replace '[^A-Za-z0-9]+', '_') + '.cpp.obj'
})
$objectRoot = Join-Path $StagePlugin 'Intermediate\Build'
$coreObjects = @(Get-ChildItem -LiteralPath $objectRoot -Recurse -File -Filter 'VFCore_*.cpp.obj' |
    Where-Object { $_.FullName -match '\\VoxelForgeCore\\' })
$actualObjects = @($coreObjects | ForEach-Object { $_.Name } | Sort-Object -Unique)
$missingObjects = @($expectedObjects | Where-Object { $actualObjects -notcontains $_ })
$unexpectedObjects = @($actualObjects | Where-Object { $expectedObjects -notcontains $_ })
if ($missingObjects.Count -gt 0 -or $unexpectedObjects.Count -gt 0 -or $coreObjects.Count -ne $manifestRows.Count) {
    throw "Core link input inventory mismatch: expected $($manifestRows.Count) shims, found $($coreObjects.Count); missing=[$($missingObjects -join ',')], extra=[$($unexpectedObjects -join ',')]."
}

$libTool = Find-VsTool 'lib.exe'
if (Test-Path -LiteralPath $AuditLibrary -PathType Leaf) { Remove-Item -LiteralPath $AuditLibrary -Force }
& $libTool '/nologo' ("/OUT:{0}" -f $AuditLibrary) @($coreObjects.FullName)
if ($LASTEXITCODE -ne 0 -or -not (Test-Path -LiteralPath $AuditLibrary -PathType Leaf)) {
    throw "Could not archive the exact UBT Core link inputs for symbol inspection (exit $LASTEXITCODE)."
}
& (Join-Path $PluginRoot 'Standalone\Core\CheckCoreSymbols.ps1') `
    -LibraryPath $AuditLibrary -ResultPath $AuditResult

$newCrashes = [Collections.Generic.List[string]]::new()
foreach ($crashRoot in $crashRoots) {
    if (Test-Path -LiteralPath $crashRoot -PathType Container) {
        foreach ($crash in @(Get-ChildItem -LiteralPath $crashRoot -Directory -Filter 'UECC-*' -Recurse -Force)) {
            if (-not $crashBefore.ContainsKey($crash.FullName.ToLowerInvariant())) {
                [void]$newCrashes.Add($crash.FullName)
            }
        }
    }
}
if ($newCrashes.Count -gt 0) {
    throw "New UECC crash folders appeared during the BuildHost run: $($newCrashes -join '; ')"
}

Write-Host "Verified the five recorded asset hashes in the existing BuildHost Content copies."
Write-Host "Core manifest shims linked and audited: $($coreObjects.Count)"
Write-Host "Link-safety result: $AuditResult"
Write-Host "Build log: $BuildLog"