using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using BitzOrcas.Application.Authorization;
using BitzOrcas.Domain.Abstractions;
using BitzOrcas.Domain.Results;
using BitzOrcas.Endpoint.Attributes;
using BitzOrcas.Platform.Gdpr.Contracts;
using Mediator;

namespace BitzOrcas.Platform.Gdpr.Application.Commands;

/// <summary>
/// Command executing physical erasure of personal identifiable information
/// </summary>
[GenerateEndpoint(HttpRoute.Post, "/api/privacy/erasure/{id}/execute", Tag = "Privacy")]
public sealed record ExecuteRightToBeForgottenCommand(
    string RequestId,
    string DpoApprovalTicketNumber
) : ICommand<Result>, IAuthorizedRequest
{
    /// <summary>
    /// Protected resource: privacy module erasure resource
    /// </summary>
    public ResourceDescriptor Resource { get; } = new(GdprPermissions.Module, GdprPermissions.ErasureResource);

    /// <summary>
    /// Required authorization action
    /// </summary>
    public AuthorizationAction Action { get; } = AuthorizationAction.Manage;
}

/// <summary>
/// Erasure command handler
/// </summary>
public sealed class ExecuteRightToBeForgottenCommandHandler(
    IGdprStore store,
    IEnumerable<ISubjectDataErasureContributor> erasureContributors,
    IAppClock clock) : ICommandHandler<ExecuteRightToBeForgottenCommand, Result>
{
    public async ValueTask<Result> Handle(
        ExecuteRightToBeForgottenCommand command,
        CancellationToken cancellationToken)
    {
        // 1. Retrieve the approved data subject erasure request
        var request = await store.GetDsrByIdAsync(command.RequestId, cancellationToken);
        if (request is null)
        {
            return Result.Failure(GdprErrors.ErasureNotFound);
        }

        // 2. Cascade physical overwriting and pseudonymization across registered domain contributors
        foreach (var contributor in erasureContributors)
        {
            var contributorResult = await contributor.ExecuteErasureAsync(request.SubjectId, cancellationToken);
            if (contributorResult.IsFailure)
            {
                return contributorResult;
            }
        }

        // 3. Mark the erasure request completed to preserve compliance audit chain
        request.StatusCode = GdprErasureStatus.Completed.Value;
        request.CompletedAt = clock.UtcNow;
        var updateSuccess = await store.TryUpdateDsrAsync(request, GdprErasureStatus.Executing.Value, cancellationToken);

        return updateSuccess ? Result.Success() : Result.Failure(GdprErrors.ErasureAlreadyClosed);
    }
}