param(
    [switch]$NoRun
)

# Ensure script runs from repo root (where this script lives)
$root = Split-Path -Parent $MyInvocation.MyCommand.Path
Set-Location $root

Write-Host "Working directory: $PWD"

# Require Visual Studio 18 (2026)
function Find-VisualStudio {
    $vswherePaths = @()
    if ($env:ProgramFiles -ne $null) { $vswherePaths += Join-Path $env:ProgramFiles 'Microsoft Visual Studio\Installer\vswhere.exe' }
    if (${env:ProgramFiles(x86)} -ne $null) { $vswherePaths += Join-Path ${env:ProgramFiles(x86)} 'Microsoft Visual Studio\Installer\vswhere.exe' }

    foreach ($p in $vswherePaths) {
        if (Test-Path $p) { return @{Tool=$p} }
    }

    return $null
}

function Get-VS18 {
    $fv = Find-VisualStudio
    $vswhere = $null
    if ($fv -and $fv.Tool) { $vswhere = $fv.Tool }
    if ($vswhere) {
        try {
            $inst18 = & $vswhere -version "[18.0,19.0)" -products * -requires Microsoft.Component.MSBuild -property installationPath 2>$null
            if ($inst18) {
                $candidate = 'Visual Studio 18 2026'
                $has = & cmake --help | Select-String -Pattern $candidate -SimpleMatch -Quiet
                if ($has) {
                    $inst18Path = $inst18.Trim()
                    $vcvars = Join-Path $inst18Path 'VC\\Auxiliary\\Build\\vcvarsall.bat'
                    if (Test-Path $vcvars) { return @{Generator=$candidate; InstallPath=$inst18Path} }
                    Write-Error "Visual Studio 18 detected at $inst18Path but C++ toolchain (vcvarsall.bat) is missing. Install the Desktop development with C++ workload."
                }
            }
        } catch {
            # fall through to path checks below
        }
    }

    # fallback: check common install locations (allow for non-standard drive)
    $commonPaths = @(
        'D:\Program Files\Microsoft Visual Studio\2026\Community',
        'D:\Program Files\Microsoft Visual Studio\2026\Professional',
        'D:\Program Files\Microsoft Visual Studio\2026\Enterprise',
        'C:\Program Files\Microsoft Visual Studio\2026\Community',
        'C:\Program Files\Microsoft Visual Studio\2026\Professional',
        'C:\Program Files\Microsoft Visual Studio\2026\Enterprise'
    )
    foreach ($p in $commonPaths) {
        if (Test-Path $p) {
            $vcvars = Join-Path $p 'VC\\Auxiliary\\Build\\vcvarsall.bat'
            if (Test-Path $vcvars) { return @{Generator='Visual Studio 18 2026'; InstallPath=$p} }
        }
    }

    return $null
}

# Resolve vcpkg root/toolchain (prefer env, then C:\vcpkg, then repo-local)
$vcpkgRoot = $env:VCPKG_ROOT
if (-not $vcpkgRoot -or -not (Test-Path $vcpkgRoot)) {
    if (Test-Path 'C:\vcpkg') {
        $vcpkgRoot = 'C:\vcpkg'
        $env:VCPKG_ROOT = $vcpkgRoot
    } elseif (Test-Path (Join-Path $root 'vcpkg')) {
        $vcpkgRoot = Join-Path $root 'vcpkg'
        $env:VCPKG_ROOT = $vcpkgRoot
    }
}

$toolchainFile = $null
if ($vcpkgRoot) {
    $candidateToolchain = Join-Path $vcpkgRoot 'scripts\buildsystems\vcpkg.cmake'
    if (Test-Path $candidateToolchain) { $toolchainFile = $candidateToolchain }
}

# Determine VS18 generator and reconfigure build-msvc if needed
$preferred = Get-VS18
if ($preferred) {
    Write-Host "Detected Visual Studio: $($preferred.Generator) at $($preferred.InstallPath)"
} else {
    Write-Error "Visual Studio 18 (2026) with Desktop development with C++ workload not found. Install VS 2026 and retry."
    exit 1
}

if (-not $toolchainFile) {
    Write-Error "vcpkg toolchain not found. Set VCPKG_ROOT or install vcpkg (expected scripts/buildsystems/vcpkg.cmake)."
    exit 1
}

# If build-msvc exists, check CMakeCache generator
$cacheFile = Join-Path $root 'build-msvc\CMakeCache.txt'
$reconfigured = $false
if (-not (Test-Path $cacheFile)) {
    Write-Host "Configuring build-msvc with generator $($preferred.Generator) and vcpkg toolchain $toolchainFile"
    & cmake -S . -B build-msvc -G "$($preferred.Generator)" -A x64 -DCMAKE_TOOLCHAIN_FILE="$toolchainFile" -DVCPKG_TARGET_TRIPLET=x64-windows
    $cfgExit = $LASTEXITCODE
    if ($cfgExit -ne 0) { Write-Error "CMake configure failed with exit code $cfgExit"; exit $cfgExit }
    $reconfigured = $true
} else {
    $genLine = Get-Content $cacheFile | Select-String -Pattern 'CMAKE_GENERATOR:INTERNAL=' -SimpleMatch
    $toolLine = Get-Content $cacheFile | Select-String -Pattern 'CMAKE_TOOLCHAIN_FILE:FILEPATH=' -SimpleMatch
    $currentGen = $null
    $currentTool = $null
    if ($genLine) { $currentGen = $genLine -replace '.*CMAKE_GENERATOR:INTERNAL=(.*)','$1' }
    if ($toolLine) { $currentTool = $toolLine -replace '.*CMAKE_TOOLCHAIN_FILE:FILEPATH=(.*)','$1' }
    $needsReconfigure = $false
    if ($currentGen -ne $preferred.Generator) { $needsReconfigure = $true }
    if (-not $currentTool -or ($currentTool -ne $toolchainFile)) { $needsReconfigure = $true }

    if ($needsReconfigure) {
        Write-Host "Generator or toolchain changed; cleaning build-msvc directory for fresh configure."
        Remove-Item -Path (Join-Path $root 'build-msvc') -Recurse -Force -ErrorAction SilentlyContinue
        Write-Host "Configuring build-msvc with generator $($preferred.Generator) and toolchain $toolchainFile"
        & cmake -S . -B build-msvc -G "$($preferred.Generator)" -A x64 -DCMAKE_TOOLCHAIN_FILE="$toolchainFile" -DVCPKG_TARGET_TRIPLET=x64-windows
        $cfgExit = $LASTEXITCODE
        if ($cfgExit -ne 0) { Write-Error "CMake configure failed with exit code $cfgExit"; exit $cfgExit }
        $reconfigured = $true
    } else {
        Write-Host "CMake cache matches required generator and toolchain."
    }
}

# Build Debug configuration
Write-Host "Running: cmake --build build-msvc --config Debug"
& cmake --build build-msvc --config Debug
$buildExit = $LASTEXITCODE
if ($buildExit -ne 0) {
    Write-Error "Build failed with exit code $buildExit"
    $vcpkgLog = Join-Path $root 'build-msvc\vcpkg-manifest-install.log'
    if (Test-Path $vcpkgLog) {
        $log = Get-Content $vcpkgLog -Raw
        if ($log -match 'Unable to find a valid Visual Studio instance') {
            Write-Error "vcpkg could not locate a valid Visual Studio 18 toolchain. Install VS 2026 with Desktop development with C++ workload and retry."
        }
    }

    exit $buildExit
}

if ($NoRun) {
    Write-Host "Build succeeded; skipping run because -NoRun was specified."
    exit 0
}

$exePath = Join-Path $root "build-msvc\Debug\tetris.exe"
if (-not (Test-Path $exePath)) {
    Write-Error "Executable not found: $exePath"
    exit 1
}

Write-Host "Launching: $exePath"
# Launch the executable and wait for it to exit so the caller sees its output.
& $exePath

exit $LASTEXITCODE