using MongoDB.Bson;
using MongoDB.Bson.Serialization.Attributes;
using MongoDB.Driver;
using StellaOps.TaskRunner.Core.Configuration;
using StellaOps.TaskRunner.Core.Execution;

namespace StellaOps.TaskRunner.Infrastructure.Execution;

public sealed class MongoPackRunApprovalStore : IPackRunApprovalStore
{
    private readonly IMongoCollection<PackRunApprovalDocument> collection;

    public MongoPackRunApprovalStore(IMongoDatabase database, TaskRunnerMongoOptions options)
    {
        ArgumentNullException.ThrowIfNull(database);
        ArgumentNullException.ThrowIfNull(options);

        collection = database.GetCollection<PackRunApprovalDocument>(options.ApprovalsCollection);
        EnsureIndexes(collection);
    }

    public async Task SaveAsync(string runId, IReadOnlyList<PackRunApprovalState> approvals, CancellationToken cancellationToken)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(runId);
        ArgumentNullException.ThrowIfNull(approvals);

        var filter = Builders<PackRunApprovalDocument>.Filter.Eq(document => document.RunId, runId);

        await collection.DeleteManyAsync(filter, cancellationToken).ConfigureAwait(false);

        if (approvals.Count == 0)
        {
            return;
        }

        var documents = approvals
            .Select(approval => PackRunApprovalDocument.FromDomain(runId, approval))
            .ToList();

        await collection.InsertManyAsync(documents, cancellationToken: cancellationToken).ConfigureAwait(false);
    }

    public async Task<IReadOnlyList<PackRunApprovalState>> GetAsync(string runId, CancellationToken cancellationToken)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(runId);

        var filter = Builders<PackRunApprovalDocument>.Filter.Eq(document => document.RunId, runId);

        var documents = await collection
            .Find(filter)
            .SortBy(document => document.ApprovalId)
            .ToListAsync(cancellationToken)
            .ConfigureAwait(false);

        return documents
            .Select(document => document.ToDomain())
            .ToList();
    }

    public async Task UpdateAsync(string runId, PackRunApprovalState approval, CancellationToken cancellationToken)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(runId);
        ArgumentNullException.ThrowIfNull(approval);

        var filter = Builders<PackRunApprovalDocument>.Filter.And(
            Builders<PackRunApprovalDocument>.Filter.Eq(document => document.RunId, runId),
            Builders<PackRunApprovalDocument>.Filter.Eq(document => document.ApprovalId, approval.ApprovalId));

        var existingDocument = await collection
            .Find(filter)
            .FirstOrDefaultAsync(cancellationToken)
            .ConfigureAwait(false);

        if (existingDocument is null)
        {
            throw new InvalidOperationException($"Approval '{approval.ApprovalId}' not found for run '{runId}'.");
        }

        var document = PackRunApprovalDocument.FromDomain(runId, approval, existingDocument.Id);
        await collection
            .ReplaceOneAsync(filter, document, cancellationToken: cancellationToken)
            .ConfigureAwait(false);
    }

    public static IEnumerable<CreateIndexModel<PackRunApprovalDocument>> GetIndexModels()
    {
        yield return new CreateIndexModel<PackRunApprovalDocument>(
            Builders<PackRunApprovalDocument>.IndexKeys
                .Ascending(document => document.RunId)
                .Ascending(document => document.ApprovalId),
            new CreateIndexOptions { Unique = true, Name = "pack_run_approvals_run_approval" });

        yield return new CreateIndexModel<PackRunApprovalDocument>(
            Builders<PackRunApprovalDocument>.IndexKeys
                .Ascending(document => document.RunId)
                .Ascending(document => document.Status),
            new CreateIndexOptions { Name = "pack_run_approvals_run_status" });
    }

    private static void EnsureIndexes(IMongoCollection<PackRunApprovalDocument> target)
        => target.Indexes.CreateMany(GetIndexModels());

    public sealed class PackRunApprovalDocument
    {
        [BsonId]
        public ObjectId Id { get; init; }

        public string RunId { get; init; } = default!;

        public string ApprovalId { get; init; } = default!;

        public IReadOnlyList<string> RequiredGrants { get; init; } = Array.Empty<string>();

        public IReadOnlyList<string> StepIds { get; init; } = Array.Empty<string>();

        public IReadOnlyList<string> Messages { get; init; } = Array.Empty<string>();

        public string? ReasonTemplate { get; init; }

        public DateTime RequestedAt { get; init; }

        public string Status { get; init; } = default!;

        public string? ActorId { get; init; }

        public DateTime? CompletedAt { get; init; }

        public string? Summary { get; init; }

        public static PackRunApprovalDocument FromDomain(string runId, PackRunApprovalState approval, ObjectId? id = null)
            => new()
            {
                Id = id ?? ObjectId.GenerateNewId(),
                RunId = runId,
                ApprovalId = approval.ApprovalId,
                RequiredGrants = approval.RequiredGrants ?? Array.Empty<string>(),
                StepIds = approval.StepIds ?? Array.Empty<string>(),
                Messages = approval.Messages ?? Array.Empty<string>(),
                ReasonTemplate = approval.ReasonTemplate,
                RequestedAt = approval.RequestedAt.UtcDateTime,
                Status = approval.Status.ToString(),
                ActorId = approval.ActorId,
                CompletedAt = approval.CompletedAt?.UtcDateTime,
                Summary = approval.Summary
            };

        public PackRunApprovalState ToDomain()
        {
            var status = Enum.Parse<PackRunApprovalStatus>(Status, ignoreCase: true);

            return new PackRunApprovalState(
                ApprovalId,
                RequiredGrants?.ToList() ?? new List<string>(),
                StepIds?.ToList() ?? new List<string>(),
                Messages?.ToList() ?? new List<string>(),
                ReasonTemplate,
                new DateTimeOffset(RequestedAt, TimeSpan.Zero),
                status,
                ActorId,
                CompletedAt is null ? null : new DateTimeOffset(CompletedAt.Value, TimeSpan.Zero),
                Summary);
        }
    }
}