namespace StellaOps.AuditPack.Services;

public sealed partial class AuditBundleReader
{
    private static async Task<ReplayInputs> LoadReplayInputsAsync(
        string bundleDir,
        CancellationToken ct)
    {
        var sbom = await ReadRequiredFileAsync(bundleDir, "sbom.json", "SBOM", ct).ConfigureAwait(false);
        var feeds = await ReadRequiredFileAsync(bundleDir, "feeds/feeds-snapshot.ndjson", "feeds", ct).ConfigureAwait(false);
        var policy = await ReadRequiredFileAsync(bundleDir, "policy/policy-bundle.tar.gz", "policy", ct).ConfigureAwait(false);
        var verdict = await ReadRequiredFileAsync(bundleDir, "verdict.json", "verdict", ct).ConfigureAwait(false);

        var vex = await ReadOptionalFileAsync(bundleDir, "vex/vex-statements.json", ct).ConfigureAwait(false);
        var proof = await ReadOptionalFileAsync(bundleDir, "proof/proof-bundle.json", ct).ConfigureAwait(false);
        var trustRoots = await ReadOptionalFileAsync(bundleDir, "trust/trust-roots.json", ct).ConfigureAwait(false);
        var scoring = await ReadOptionalFileAsync(bundleDir, "scoring-rules.json", ct).ConfigureAwait(false);
        var timeAnchor = await ReadOptionalFileAsync(bundleDir, "time-anchor.json", ct).ConfigureAwait(false);

        return new ReplayInputs
        {
            Sbom = sbom,
            FeedsSnapshot = feeds,
            PolicyBundle = policy,
            VexStatements = vex,
            Verdict = verdict,
            ProofBundle = proof,
            TrustRoots = trustRoots,
            ScoringRules = scoring,
            TimeAnchor = timeAnchor
        };
    }

    private static async Task<byte[]> ReadRequiredFileAsync(
        string bundleDir,
        string relativePath,
        string label,
        CancellationToken ct)
    {
        var filePath = GetBundlePath(bundleDir, relativePath);
        if (!File.Exists(filePath))
        {
            throw new FileNotFoundException($"{label} file not found", filePath);
        }

        return await File.ReadAllBytesAsync(filePath, ct).ConfigureAwait(false);
    }

    private static async Task<byte[]?> ReadOptionalFileAsync(
        string bundleDir,
        string relativePath,
        CancellationToken ct)
    {
        var filePath = GetBundlePath(bundleDir, relativePath);
        if (!File.Exists(filePath))
        {
            return null;
        }

        return await File.ReadAllBytesAsync(filePath, ct).ConfigureAwait(false);
    }
}