using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;
using FluentAssertions;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;
using StellaOps.Signals.Models;
using StellaOps.Signals.Options;
using StellaOps.Signals.Parsing;
using StellaOps.Signals.Persistence;
using StellaOps.Signals.Services;
using StellaOps.Signals.Storage;
using StellaOps.Signals.Storage.Models;
using Xunit;

namespace StellaOps.Signals.Tests;

public class CallgraphIngestionServiceTests
{
    private readonly InMemoryCallgraphRepository _repository = new();
    private readonly InMemoryArtifactStore _artifactStore = new();
    private readonly CallgraphNormalizationService _normalizer = new();
    private readonly TimeProvider _timeProvider = TimeProvider.System;

    [Fact]
    public async Task IngestAsync_normalizes_graph_and_persists_manifest_hash()
    {
        var parser = new StubParser("java");
        var resolver = new StubParserResolver(parser);
        var options = Microsoft.Extensions.Options.Options.Create(new SignalsOptions());
        var reachabilityStore = new InMemoryReachabilityStoreRepository(_timeProvider);
        var callGraphSyncService = new StubCallGraphSyncService();
        var service = new CallgraphIngestionService(
            resolver,
            _artifactStore,
            _repository,
            reachabilityStore,
            _normalizer,
            callGraphSyncService,
            options,
            _timeProvider,
            NullLogger<CallgraphIngestionService>.Instance);

        var artifactJson = @"{""nodes"":[{""id"":""com/example/Foo.bar:(I)V"",""kind"":""fn""}],
""edges"":[{""source"":""com/example/Foo.bar:(I)V"",""target"":""com/example/Foo.bar:(I)V""}]}";

        var request = new CallgraphIngestRequest(
            Language: "java",
            Component: "demo",
            Version: "1.0.0",
            ArtifactFileName: "graph.json",
            ArtifactContentType: "application/json",
            ArtifactContentBase64: Convert.ToBase64String(Encoding.UTF8.GetBytes(artifactJson)),
            SchemaVersion: null,
            Metadata: new Dictionary<string, string?> { ["source"] = "test" },
            Analyzer: new Dictionary<string, string?> { ["name"] = "stub" });

        var response = await service.IngestAsync(request, CancellationToken.None);

        response.CallgraphId.Should().NotBeNullOrWhiteSpace();
        response.GraphHash.Should().NotBeNullOrWhiteSpace();
        response.NodeCount.Should().Be(1);
        response.EdgeCount.Should().Be(1);
        response.ManifestCasUri.Should().Be("cas://signals/manifests/graph.json");

        var stored = _repository.LastUpserted!;
        stored.Artifact.Hash.Should().Be(response.ArtifactHash);
        stored.Nodes[0].Namespace.Should().Be("com.example.Foo");
        stored.Nodes[0].Language.Should().Be("java");
        stored.Metadata!["schemaVersion"].Should().Be("1.0");
        stored.Metadata!["analyzer.name"].Should().Be("stub");
        stored.Artifact.GraphHash.Should().Be(response.GraphHash);

        var storedNodes = await reachabilityStore.GetFuncNodesByGraphAsync(response.GraphHash, CancellationToken.None);
        storedNodes.Should().HaveCount(1);
        storedNodes[0].SymbolId.Should().Be("com/example/Foo.bar:(I)V");

        var storedEdges = await reachabilityStore.GetCallEdgesByGraphAsync(response.GraphHash, CancellationToken.None);
        storedEdges.Should().HaveCount(1);
        storedEdges[0].SourceId.Should().Be("com/example/Foo.bar:(I)V");
        storedEdges[0].TargetId.Should().Be("com/example/Foo.bar:(I)V");
    }

    private sealed class StubParser : ICallgraphParser
    {
        public StubParser(string language) => Language = language;
        public string Language { get; }
        public Task<CallgraphParseResult> ParseAsync(Stream artifactStream, CancellationToken cancellationToken)
        {
            artifactStream.Position = 0;
            using var doc = JsonDocument.Parse(artifactStream);
            var nodes = new List<CallgraphNode>();
            foreach (var node in doc.RootElement.GetProperty("nodes").EnumerateArray())
            {
                nodes.Add(new CallgraphNode(node.GetProperty("id").GetString()!, "", "function", null, null, null));
            }

            var edges = new List<CallgraphEdge>();
            foreach (var edge in doc.RootElement.GetProperty("edges").EnumerateArray())
            {
                edges.Add(new CallgraphEdge(
                    edge.GetProperty("source").GetString()!,
                    edge.GetProperty("target").GetString()!,
                    "call"));
            }

            return Task.FromResult(new CallgraphParseResult(nodes, edges, Array.Empty<CallgraphRoot>(), "1.0", "1.0", null));
        }
    }

    private sealed class StubParserResolver : ICallgraphParserResolver
    {
        private readonly ICallgraphParser _parser;
        public StubParserResolver(ICallgraphParser parser) => _parser = parser;
        public ICallgraphParser Resolve(string language) => _parser;
    }

    private sealed class InMemoryArtifactStore : ICallgraphArtifactStore
    {
        private readonly Dictionary<string, byte[]> artifacts = new(StringComparer.Ordinal);
        private readonly Dictionary<string, byte[]> manifests = new(StringComparer.Ordinal);

        public Task<StoredCallgraphArtifact> SaveAsync(CallgraphArtifactSaveRequest request, Stream content, CancellationToken cancellationToken)
        {
            using var ms = new MemoryStream();
            content.CopyTo(ms);
            artifacts[request.Hash] = ms.ToArray();

            if (request.ManifestContent is not null)
            {
                using var manifestMs = new MemoryStream();
                request.ManifestContent.CopyTo(manifestMs);
                manifests[request.Hash] = manifestMs.ToArray();
            }

            var path = $"cas://signals/artifacts/{request.FileName}";
            var manifestPath = "cas://signals/manifests/graph.json";

            return Task.FromResult(new StoredCallgraphArtifact(
                Path: path,
                Length: ms.Length,
                Hash: request.Hash,
                ContentType: request.ContentType,
                CasUri: path,
                ManifestPath: manifestPath,
                ManifestCasUri: manifestPath));
        }

        public Task<Stream?> GetAsync(string hash, string? fileName = null, CancellationToken cancellationToken = default)
        {
            if (artifacts.TryGetValue(hash, out var bytes))
            {
                return Task.FromResult<Stream?>(new MemoryStream(bytes, writable: false));
            }

            return Task.FromResult<Stream?>(null);
        }

        public Task<Stream?> GetManifestAsync(string hash, CancellationToken cancellationToken = default)
        {
            if (manifests.TryGetValue(hash, out var bytes))
            {
                return Task.FromResult<Stream?>(new MemoryStream(bytes, writable: false));
            }

            return Task.FromResult<Stream?>(null);
        }

        public Task<bool> ExistsAsync(string hash, CancellationToken cancellationToken = default)
        {
            return Task.FromResult(artifacts.ContainsKey(hash));
        }
    }

    private sealed class InMemoryCallgraphRepository : ICallgraphRepository
    {
        public CallgraphDocument? LastUpserted { get; private set; }

        public Task<CallgraphDocument?> GetByIdAsync(string id, CancellationToken cancellationToken)
        {
            return Task.FromResult(LastUpserted?.Id == id ? LastUpserted : null);
        }

        public Task<CallgraphDocument> UpsertAsync(CallgraphDocument document, CancellationToken cancellationToken)
        {
            LastUpserted = document;
            return Task.FromResult(document);
        }
    }

    private sealed class StubCallGraphSyncService : ICallGraphSyncService
    {
        public CallGraphSyncResult? LastSyncResult { get; private set; }
        public CallgraphDocument? LastSyncedDocument { get; private set; }

        public Task<CallGraphSyncResult> SyncAsync(
            Guid scanId,
            string artifactDigest,
            CallgraphDocument document,
            CancellationToken cancellationToken = default)
        {
            LastSyncedDocument = document;
            var result = new CallGraphSyncResult(
                ScanId: scanId,
                NodesProjected: document.Nodes.Count,
                EdgesProjected: document.Edges.Count,
                EntrypointsProjected: document.Entrypoints.Count,
                WasUpdated: true,
                DurationMs: 1);
            LastSyncResult = result;
            return Task.FromResult(result);
        }

        public Task DeleteByScanAsync(Guid scanId, CancellationToken cancellationToken = default)
        {
            return Task.CompletedTask;
        }
    }
}