[CmdletBinding()]
param(
    [string]$Root = ""
)

$ErrorActionPreference = "Stop"

if ([string]::IsNullOrWhiteSpace($Root)) {
    $basePath = if ($PSScriptRoot) {
        $PSScriptRoot
    }
    elseif ($PSCommandPath) {
        Split-Path -Parent $PSCommandPath
    }
    else {
        (Get-Location).Path
    }

    $Root = (Resolve-Path (Join-Path $basePath "..")).Path
}

$extensions = @(".cs", ".xaml", ".csproj", ".props", ".targets", ".sln", ".json", ".md", ".txt", ".xml", ".yml", ".yaml", ".ps1")
$utf8Bom = New-Object byte[] 3
$utf8Bom[0] = 0xEF
$utf8Bom[1] = 0xBB
$utf8Bom[2] = 0xBF

$scanRoots = @(
    (Join-Path $Root "src"),
    (Join-Path $Root "scripts")
) | Where-Object { Test-Path $_ }

$files = New-Object System.Collections.Generic.List[System.IO.FileInfo]
foreach ($scanRoot in $scanRoots) {
    Get-ChildItem -Path $scanRoot -Recurse -File |
        Where-Object { $extensions -contains $_.Extension.ToLowerInvariant() } |
        Where-Object { $_.FullName -notmatch '\\(bin|obj|\.git|\.decompiled|\.decompiledproj|src2|dist|\.tools)\\' } |
        Where-Object { $_.Name -notlike '*.bak-*' } |
        Where-Object { $_.Name -notlike '*.broken' } |
        ForEach-Object { $files.Add($_) }
}

$rootFiles = @(".editorconfig", ".gitattributes", "README.md", "AxCopilot.sln", "CLAUDE.md")
foreach ($relativePath in $rootFiles) {
    $fullPath = Join-Path $Root $relativePath
    if (Test-Path $fullPath) {
        $files.Add((Get-Item $fullPath))
    }
}

$problems = New-Object System.Collections.Generic.List[object]

foreach ($file in $files) {
    $bytes = [System.IO.File]::ReadAllBytes($file.FullName)
    if ($bytes.Length -lt 3) {
        $problems.Add([pscustomobject]@{
            File = $file.FullName
            Issue = "too-short-to-confirm-bom"
        })
        continue
    }

    $hasBom = $bytes[0] -eq $utf8Bom[0] -and $bytes[1] -eq $utf8Bom[1] -and $bytes[2] -eq $utf8Bom[2]
    if (-not $hasBom) {
        $problems.Add([pscustomobject]@{
            File = $file.FullName
            Issue = "missing-utf8-bom"
        })
        continue
    }

    try {
        $null = [System.Text.Encoding]::UTF8.GetString($bytes, 3, $bytes.Length - 3)
    }
    catch {
        $problems.Add([pscustomobject]@{
            File = $file.FullName
            Issue = "invalid-utf8-content"
        })
    }
}

if ($problems.Count -eq 0) {
    Write-Host "Encoding check passed. All scanned files use UTF-8 BOM."
    exit 0
}

Write-Host "Encoding check found issues:" -ForegroundColor Yellow
$problems | Sort-Object File | Format-Table -AutoSize
exit 1