using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Routing;
using StellaOps.Replay.Core;
using StellaOps.Scanner.ProofSpine;
using StellaOps.Scanner.WebService.Contracts;
using StellaOps.Scanner.WebService.Security;
using StellaOps.Scanner.WebService.Serialization;

namespace StellaOps.Scanner.WebService.Endpoints;

internal static class ProofSpineEndpoints
{
    public static void MapProofSpineEndpoints(this RouteGroupBuilder apiGroup, string spinesSegment, string scansSegment)
    {
        ArgumentNullException.ThrowIfNull(apiGroup);

        var spines = apiGroup.MapGroup(NormalizeSegment(spinesSegment));
        spines.MapGet("/{spineId}", HandleGetSpineAsync)
            .WithName("scanner.spines.get")
            .Produces<ProofSpineResponseDto>(StatusCodes.Status200OK)
            .Produces(StatusCodes.Status200OK, contentType: CborNegotiation.ContentType)
            .Produces(StatusCodes.Status404NotFound)
            .RequireAuthorization(ScannerPolicies.ScansRead);

        var scans = apiGroup.MapGroup(NormalizeSegment(scansSegment));
        scans.MapGet("/{scanId}/spines", HandleListSpinesAsync)
            .WithName("scanner.spines.list-by-scan")
            .Produces<ProofSpineListResponseDto>(StatusCodes.Status200OK)
            .Produces(StatusCodes.Status200OK, contentType: CborNegotiation.ContentType)
            .RequireAuthorization(ScannerPolicies.ScansRead);
    }

    private static async Task<IResult> HandleGetSpineAsync(
        HttpRequest request,
        string spineId,
        IProofSpineRepository repository,
        ProofSpineVerifier verifier,
        CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(request);
        ArgumentNullException.ThrowIfNull(repository);
        ArgumentNullException.ThrowIfNull(verifier);

        if (string.IsNullOrWhiteSpace(spineId))
        {
            return Results.NotFound();
        }

        var spine = await repository.GetByIdAsync(spineId, cancellationToken).ConfigureAwait(false);
        if (spine is null)
        {
            return Results.NotFound();
        }

        var segments = await repository.GetSegmentsAsync(spineId, cancellationToken).ConfigureAwait(false);
        var full = spine with { Segments = segments };

        var verification = await verifier.VerifyAsync(full, cancellationToken).ConfigureAwait(false);
        var verificationBySegment = verification.Segments.ToDictionary(s => s.SegmentId, s => s, StringComparer.Ordinal);

        var dto = new ProofSpineResponseDto
        {
            SpineId = full.SpineId,
            ArtifactId = full.ArtifactId,
            VulnerabilityId = full.VulnerabilityId,
            PolicyProfileId = full.PolicyProfileId,
            Verdict = full.Verdict,
            VerdictReason = full.VerdictReason,
            RootHash = full.RootHash,
            ScanRunId = full.ScanRunId,
            CreatedAt = full.CreatedAt,
            SupersededBySpineId = full.SupersededBySpineId,
            Segments = full.Segments.Select(segment =>
            {
                verificationBySegment.TryGetValue(segment.SegmentId, out var segmentVerification);
                var status = segmentVerification?.Status ?? segment.Status;

                return new ProofSegmentDto
                {
                    SegmentId = segment.SegmentId,
                    SegmentType = ToWireSegmentType(segment.SegmentType),
                    Index = segment.Index,
                    InputHash = segment.InputHash,
                    ResultHash = segment.ResultHash,
                    PrevSegmentHash = segment.PrevSegmentHash,
                    Envelope = MapEnvelope(segment.Envelope),
                    ToolId = segment.ToolId,
                    ToolVersion = segment.ToolVersion,
                    Status = ToWireStatus(status),
                    CreatedAt = segment.CreatedAt,
                    VerificationErrors = segmentVerification?.Errors.Count > 0 ? segmentVerification.Errors : null
                };
            }).ToArray(),
            Verification = new ProofSpineVerificationDto
            {
                IsValid = verification.IsValid,
                Errors = verification.Errors.ToArray()
            }
        };

        if (CborNegotiation.AcceptsCbor(request))
        {
            return Results.Bytes(
                DeterministicCborSerializer.Serialize(dto),
                contentType: CborNegotiation.ContentType);
        }

        return Results.Ok(dto);
    }

    private static async Task<IResult> HandleListSpinesAsync(
        HttpRequest request,
        string scanId,
        IProofSpineRepository repository,
        CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(request);
        ArgumentNullException.ThrowIfNull(repository);

        if (string.IsNullOrWhiteSpace(scanId))
        {
            var empty = new ProofSpineListResponseDto { Items = Array.Empty<ProofSpineSummaryDto>(), Total = 0 };
            if (CborNegotiation.AcceptsCbor(request))
            {
                return Results.Bytes(
                    DeterministicCborSerializer.Serialize(empty),
                    contentType: CborNegotiation.ContentType);
            }

            return Results.Ok(empty);
        }

        var summaries = await repository.GetSummariesByScanRunAsync(scanId, cancellationToken).ConfigureAwait(false);
        var items = summaries.Select(summary => new ProofSpineSummaryDto
        {
            SpineId = summary.SpineId,
            ArtifactId = summary.ArtifactId,
            VulnerabilityId = summary.VulnerabilityId,
            Verdict = summary.Verdict,
            SegmentCount = summary.SegmentCount,
            CreatedAt = summary.CreatedAt
        }).ToArray();

        var response = new ProofSpineListResponseDto
        {
            Items = items,
            Total = items.Length
        };

        if (CborNegotiation.AcceptsCbor(request))
        {
            return Results.Bytes(
                DeterministicCborSerializer.Serialize(response),
                contentType: CborNegotiation.ContentType);
        }

        return Results.Ok(response);
    }

    private static DsseEnvelopeDto MapEnvelope(DsseEnvelope envelope)
        => new()
        {
            PayloadType = envelope.PayloadType,
            Payload = envelope.Payload,
            Signatures = envelope.Signatures.Select(signature => new DsseSignatureDto
            {
                KeyId = signature.KeyId,
                Sig = signature.Sig
            }).ToArray()
        };

    private static string ToWireSegmentType(ProofSegmentType type) => type switch
    {
        ProofSegmentType.SbomSlice => "SBOM_SLICE",
        ProofSegmentType.Match => "MATCH",
        ProofSegmentType.Reachability => "REACHABILITY",
        ProofSegmentType.GuardAnalysis => "GUARD_ANALYSIS",
        ProofSegmentType.RuntimeObservation => "RUNTIME_OBSERVATION",
        ProofSegmentType.PolicyEval => "POLICY_EVAL",
        _ => type.ToString()
    };

    private static string ToWireStatus(ProofSegmentStatus status)
        => status.ToString().ToLowerInvariant();

    private static string NormalizeSegment(string segment)
    {
        if (string.IsNullOrWhiteSpace(segment))
        {
            return "/";
        }

        var trimmed = segment.Trim('/');
        return "/" + trimmed;
    }
}