using System;
using System.Collections.Generic;
using System.Text.Json;

namespace StellaOps.Provenance;

public static partial class ProvenanceJsonParser
{
    private static DsseProvenance ParseDsse(JsonElement root)
    {
        if (!root.TryGetProperty("dsse", out var dsseElement) || dsseElement.ValueKind != JsonValueKind.Object)
        {
            throw new InvalidOperationException("Provenance metadata missing dsse block.");
        }

        var keyElement = GetRequiredProperty(dsseElement, "key");
        var dsse = new DsseProvenance
        {
            EnvelopeDigest = GetRequiredString(dsseElement, "envelopeDigest"),
            PayloadType = GetRequiredString(dsseElement, "payloadType"),
            Key = new DsseKeyInfo
            {
                KeyId = GetRequiredString(keyElement, "keyId"),
                Issuer = GetOptionalString(keyElement, "issuer"),
                Algo = GetOptionalString(keyElement, "algo"),
            },
            Chain = ParseChain(dsseElement)
        };

        if (dsseElement.TryGetProperty("rekor", out var rekorElement) && rekorElement.ValueKind == JsonValueKind.Object)
        {
            dsse.Rekor = new DsseRekorInfo
            {
                LogIndex = GetInt64(rekorElement, "logIndex"),
                Uuid = GetRequiredString(rekorElement, "uuid"),
                IntegratedTime = GetOptionalInt64(rekorElement, "integratedTime"),
                MirrorSeq = GetOptionalInt64(rekorElement, "mirrorSeq")
            };
        }

        return dsse;
    }

    private static IReadOnlyCollection<DsseChainLink>? ParseChain(JsonElement dsseElement)
    {
        if (!dsseElement.TryGetProperty("chain", out var chainElement)
            || chainElement.ValueKind != JsonValueKind.Array
            || chainElement.GetArrayLength() == 0)
        {
            return null;
        }

        var links = new List<DsseChainLink>(chainElement.GetArrayLength());
        foreach (var entry in chainElement.EnumerateArray())
        {
            if (entry.ValueKind != JsonValueKind.Object)
            {
                continue;
            }

            var type = GetOptionalString(entry, "type");
            var id = GetOptionalString(entry, "id");
            var digest = GetOptionalString(entry, "digest");

            if (string.IsNullOrEmpty(type) || string.IsNullOrEmpty(id) || string.IsNullOrEmpty(digest))
            {
                continue;
            }

            links.Add(new DsseChainLink
            {
                Type = type,
                Id = id,
                Digest = digest
            });
        }

        return links.Count == 0 ? null : links;
    }
}