param(
    [string[]]$ScanPaths = @(
        "Unity/Assets/BundleResources/DataAssets",
        "Unity/Assets/BundleResources/Export"
    )
)

$ErrorActionPreference = "Stop"

$repoRoot = git rev-parse --show-toplevel 2>$null
if (-not $repoRoot) {
    throw "Not inside a git repository."
}
$repoRoot = [System.IO.Path]::GetFullPath($repoRoot.Trim())

function Resolve-RepoPath([string]$Path) {
    if ([System.IO.Path]::IsPathRooted($Path)) {
        return [System.IO.Path]::GetFullPath($Path)
    }
    return [System.IO.Path]::GetFullPath((Join-Path $repoRoot $Path))
}

$metaGuids = @{}
$assetsPath = Resolve-RepoPath "Unity/Assets"
Get-ChildItem -LiteralPath $assetsPath -Filter "*.meta" -Recurse -File | ForEach-Object {
    $metaText = [System.IO.File]::ReadAllText($_.FullName, [System.Text.Encoding]::UTF8)
    if ($metaText -match '(?m)^guid: ([0-9a-f]{32})') {
        $metaGuids[$Matches[1]] = $_.FullName
    }
}

$issues = New-Object System.Collections.Generic.List[string]
$assetRegex = [regex]'\{fileID: ([^,}]+), guid: ([0-9a-f]{32}), type: ([0-9]+)\}'

foreach ($scanPath in $ScanPaths) {
    $fullScanPath = Resolve-RepoPath $scanPath
    if (-not (Test-Path -LiteralPath $fullScanPath)) {
        throw "Scan path not found: $fullScanPath"
    }

    Get-ChildItem -LiteralPath $fullScanPath -Filter "*.asset" -Recurse -File | ForEach-Object {
        $relativePath = $_.FullName
        if ($relativePath.StartsWith($repoRoot, [System.StringComparison]::OrdinalIgnoreCase)) {
            $relativePath = $relativePath.Substring($repoRoot.Length).TrimStart('\', '/')
        }
        $lines = [System.IO.File]::ReadAllLines($_.FullName, [System.Text.Encoding]::UTF8)
        for ($i = 0; $i -lt $lines.Count; $i++) {
            foreach ($match in $assetRegex.Matches($lines[$i])) {
                $fileId = $match.Groups[1].Value
                $guid = $match.Groups[2].Value
                if ($fileId -eq "0") {
                    continue
                }

                if (-not $metaGuids.ContainsKey($guid)) {
                    $issues.Add("${relativePath}:$($i + 1) references missing Unity guid $guid")
                }
            }
        }
    }
}

if ($issues.Count -gt 0) {
    throw "Missing Unity asset references:`n$($issues -join "`n")"
}

Write-Host "Unity asset references OK: scanned $($ScanPaths -join ', ')."