using System.Collections.Concurrent;
using System.Security;

namespace StellaOps.Scanner.Analyzers.Lang.Rust.Internal;

internal static class RustFileHashCache
{
    private static readonly ConcurrentDictionary<RustFileCacheKey, string> Sha256Cache = new();

    public static bool TryGetSha256(string path, out string? sha256)
    {
        sha256 = null;

        if (!RustFileCacheKey.TryCreate(path, out var key))
        {
            return false;
        }

        try
        {
            sha256 = Sha256Cache.GetOrAdd(key, static (_, state) => ComputeSha256(state), path);
            return !string.IsNullOrEmpty(sha256);
        }
        catch (IOException)
        {
            return false;
        }
        catch (UnauthorizedAccessException)
        {
            return false;
        }
        catch (SecurityException)
        {
            return false;
        }
    }

    private static string ComputeSha256(string path)
    {
        using var stream = File.Open(path, FileMode.Open, FileAccess.Read, FileShare.Read);
        using var sha = System.Security.Cryptography.SHA256.Create();
        var hash = sha.ComputeHash(stream);
        return Convert.ToHexString(hash).ToLowerInvariant();
    }
}