using MongoDB.Bson;

namespace StellaOps.Provenance.Mongo;

public static class ProvenanceMongoExtensions
{
    private const string ProvenanceFieldName = "provenance";
    private const string DsseFieldName = "dsse";
    private const string TrustFieldName = "trust";
    private const string ChainFieldName = "chain";
    private static BsonValue StringOrNull(string? value) =>
        value is null ? BsonNull.Value : new BsonString(value);

    /// <summary>
    /// Attach DSSE provenance + trust info to an event document in-place.
    /// Designed for generic BsonDocument-based event envelopes.
    /// </summary>
    public static BsonDocument AttachDsseProvenance(
        this BsonDocument eventDoc,
        DsseProvenance dsse,
        TrustInfo trust)
    {
        if (eventDoc is null) throw new ArgumentNullException(nameof(eventDoc));
        if (dsse is null) throw new ArgumentNullException(nameof(dsse));
        if (trust is null) throw new ArgumentNullException(nameof(trust));

        var dsseDoc = new BsonDocument
        {
            { "envelopeDigest", dsse.EnvelopeDigest },
            { "payloadType", dsse.PayloadType },
                    { "key", new BsonDocument
                        {
                            { "keyId", dsse.Key.KeyId },
                            { "issuer", StringOrNull(dsse.Key.Issuer) },
                            { "algo", StringOrNull(dsse.Key.Algo) }
                        }
                    }
        };

        if (dsse.Rekor is not null)
        {
            var rekorDoc = new BsonDocument
            {
                { "logIndex", dsse.Rekor.LogIndex },
                { "uuid", dsse.Rekor.Uuid }
            };

            if (dsse.Rekor.IntegratedTime is not null)
                rekorDoc.Add("integratedTime", dsse.Rekor.IntegratedTime);

            if (dsse.Rekor.MirrorSeq is not null)
                rekorDoc.Add("mirrorSeq", dsse.Rekor.MirrorSeq);

            dsseDoc.Add("rekor", rekorDoc);
        }

        if (dsse.Chain is not null && dsse.Chain.Count > 0)
        {
            var chainArray = new BsonArray();
            foreach (var link in dsse.Chain)
            {
                chainArray.Add(new BsonDocument
                {
                    { "type", link.Type },
                    { "id", link.Id },
                    { "digest", link.Digest }
                });
            }

            dsseDoc.Add(ChainFieldName, chainArray);
        }

        var trustDoc = new BsonDocument
        {
            { "verified", trust.Verified },
            { "verifier", StringOrNull(trust.Verifier) }
        };

        if (trust.Witnesses is not null)
            trustDoc.Add("witnesses", trust.Witnesses);

        if (trust.PolicyScore is not null)
            trustDoc.Add("policyScore", trust.PolicyScore);

        var provenanceDoc = new BsonDocument
        {
            { DsseFieldName, dsseDoc }
        };

        eventDoc[ProvenanceFieldName] = provenanceDoc;
        eventDoc[TrustFieldName] = trustDoc;

        return eventDoc;
    }

    /// <summary>
    /// Helper to query for "cryptographically proven" events:
    /// kind + subject.digest.sha256 + presence of Rekor logIndex + trust.verified = true.
    /// </summary>
    public static BsonDocument BuildProvenVexFilter(
        string kind,
        string subjectDigestSha256)
    {
        return new BsonDocument
        {
            { "kind", kind },
            { "subject.digest.sha256", subjectDigestSha256 },
            { $"{ProvenanceFieldName}.{DsseFieldName}.rekor.logIndex", new BsonDocument("$exists", true) },
            { $"{TrustFieldName}.verified", true }
        };
    }

    /// <summary>
    /// Helper to query for events influencing policy without solid provenance.
    /// </summary>
    public static BsonDocument BuildUnprovenEvidenceFilter(
        IEnumerable<string> kinds)
    {
        var kindsArray = new BsonArray(kinds);

        return new BsonDocument
        {
            {
                "kind", new BsonDocument("$in", kindsArray)
            },
            {
                "$or", new BsonArray
                {
                    new BsonDocument
                    {
                        { $"{TrustFieldName}.verified", new BsonDocument("$ne", true) }
                    },
                    new BsonDocument
                    {
                        { $"{ProvenanceFieldName}.{DsseFieldName}.rekor.logIndex",
                          new BsonDocument("$exists", false) }
                    }
                }
            }
        };
    }
}