using System.Globalization;
using System.Text.Json.Nodes;
using Microsoft.Extensions.Logging;
using StellaOps.Findings.Ledger.Domain;
using StellaOps.Findings.Ledger.Infrastructure;
using StellaOps.Findings.Ledger.Infrastructure.AirGap;
using StellaOps.Findings.Ledger.Observability;

namespace StellaOps.Findings.Ledger.Services;

public sealed record AirgapImportInput(
    string TenantId,
    string BundleId,
    string? MirrorGeneration,
    string MerkleRoot,
    DateTimeOffset TimeAnchor,
    string? Publisher,
    string? HashAlgorithm,
    IReadOnlyList<string> Contents,
    string? ImportOperator);

public sealed record AirgapImportResult(
    bool Success,
    Guid ChainId,
    long? SequenceNumber,
    Guid? LedgerEventId,
    string? Error);

public sealed class AirgapImportService
{
    private readonly ILedgerEventRepository _ledgerEventRepository;
    private readonly ILedgerEventWriteService _writeService;
    private readonly IAirgapImportRepository _repository;
    private readonly TimeProvider _timeProvider;
    private readonly ILogger<AirgapImportService> _logger;

    public AirgapImportService(
        ILedgerEventRepository ledgerEventRepository,
        ILedgerEventWriteService writeService,
        IAirgapImportRepository repository,
        TimeProvider timeProvider,
        ILogger<AirgapImportService> logger)
    {
        _ledgerEventRepository = ledgerEventRepository ?? throw new ArgumentNullException(nameof(ledgerEventRepository));
        _writeService = writeService ?? throw new ArgumentNullException(nameof(writeService));
        _repository = repository ?? throw new ArgumentNullException(nameof(repository));
        _timeProvider = timeProvider ?? throw new ArgumentNullException(nameof(timeProvider));
        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
    }

    public async Task<AirgapImportResult> RecordAsync(AirgapImportInput input, CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(input);

        var chainId = LedgerChainIdGenerator.FromTenantSubject(input.TenantId, $"airgap::{input.BundleId}");
        var chainHead = await _ledgerEventRepository.GetChainHeadAsync(input.TenantId, chainId, cancellationToken).ConfigureAwait(false);
        var sequence = (chainHead?.SequenceNumber ?? 0) + 1;
        var previousHash = chainHead?.EventHash ?? LedgerEventConstants.EmptyHash;

        var eventId = Guid.NewGuid();
        var recordedAt = _timeProvider.GetUtcNow();

        var payload = new JsonObject
        {
            ["airgap"] = new JsonObject
            {
                ["bundleId"] = input.BundleId,
                ["mirrorGeneration"] = input.MirrorGeneration,
                ["merkleRoot"] = input.MerkleRoot,
                ["timeAnchor"] = input.TimeAnchor.ToUniversalTime().ToString("O", CultureInfo.InvariantCulture),
                ["publisher"] = input.Publisher,
                ["hashAlgorithm"] = input.HashAlgorithm,
                ["contents"] = new JsonArray(input.Contents.Select(c => (JsonNode)c).ToArray())
            }
        };

        var envelope = new JsonObject
        {
            ["event"] = new JsonObject
            {
                ["id"] = eventId.ToString(),
                ["type"] = LedgerEventConstants.EventAirgapBundleImported,
                ["tenant"] = input.TenantId,
                ["chainId"] = chainId.ToString(),
                ["sequence"] = sequence,
                ["policyVersion"] = input.MirrorGeneration ?? "airgap-bundle",
                ["artifactId"] = input.BundleId,
                ["finding"] = new JsonObject
                {
                    ["id"] = input.BundleId,
                    ["artifactId"] = input.BundleId,
                    ["vulnId"] = "airgap-import"
                },
                ["actor"] = new JsonObject
                {
                    ["id"] = input.ImportOperator ?? "airgap-operator",
                    ["type"] = "operator"
                },
                ["occurredAt"] = FormatTimestamp(input.TimeAnchor),
                ["recordedAt"] = FormatTimestamp(recordedAt),
                ["payload"] = payload.DeepClone()
            }
        };

        var draft = new LedgerEventDraft(
            input.TenantId,
            chainId,
            sequence,
            eventId,
            LedgerEventConstants.EventAirgapBundleImported,
            input.MirrorGeneration ?? "airgap-bundle",
            input.BundleId,
            input.BundleId,
            SourceRunId: null,
            ActorId: input.ImportOperator ?? "airgap-operator",
            ActorType: "operator",
            OccurredAt: input.TimeAnchor.ToUniversalTime(),
            RecordedAt: recordedAt,
            Payload: payload,
            CanonicalEnvelope: envelope,
            ProvidedPreviousHash: previousHash);

        var writeResult = await _writeService.AppendAsync(draft, cancellationToken).ConfigureAwait(false);
        if (writeResult.Status is not (LedgerWriteStatus.Success or LedgerWriteStatus.Idempotent))
        {
            var error = string.Join(";", writeResult.Errors);
            return new AirgapImportResult(false, chainId, sequence, writeResult.Record?.EventId, error);
        }

        var ledgerEventId = writeResult.Record?.EventId;

        var record = new AirgapImportRecord(
            input.TenantId,
            input.BundleId,
            input.MirrorGeneration,
            input.MerkleRoot,
            input.TimeAnchor.ToUniversalTime(),
            input.Publisher,
            input.HashAlgorithm,
            new JsonArray(input.Contents.Select(c => (JsonNode)c).ToArray()),
            recordedAt,
            input.ImportOperator,
            ledgerEventId);

        await _repository.InsertAsync(record, cancellationToken).ConfigureAwait(false);
        LedgerTimeline.EmitAirgapImport(_logger, input.TenantId, input.BundleId, input.MerkleRoot, ledgerEventId);

        return new AirgapImportResult(true, chainId, sequence, ledgerEventId, null);
    }

    private static string FormatTimestamp(DateTimeOffset value)
        => value.ToUniversalTime().ToString("yyyy-MM-dd'T'HH:mm:ss.fff'Z'");
}