using MediatR;
using ColaFlow.Modules.ProjectManagement.Application.DTOs;
using ColaFlow.Modules.ProjectManagement.Application.Common.Interfaces;
using ColaFlow.Modules.ProjectManagement.Domain.Repositories;
using ColaFlow.Modules.ProjectManagement.Domain.ValueObjects;
using ColaFlow.Modules.ProjectManagement.Domain.Exceptions;
using ColaFlow.Modules.ProjectManagement.Domain.Aggregates.ProjectAggregate;

namespace ColaFlow.Modules.ProjectManagement.Application.Queries.GetTaskById;

/// <summary>
/// Handler for GetTaskByIdQuery
/// </summary>
public sealed class GetTaskByIdQueryHandler(
    IProjectRepository projectRepository,
    ITenantContext tenantContext)
    : IRequestHandler<GetTaskByIdQuery, TaskDto>
{
    private readonly IProjectRepository _projectRepository = projectRepository ?? throw new ArgumentNullException(nameof(projectRepository));
    private readonly ITenantContext _tenantContext = tenantContext ?? throw new ArgumentNullException(nameof(tenantContext));

    public async Task<TaskDto> Handle(GetTaskByIdQuery request, CancellationToken cancellationToken)
    {
        // Get current tenant ID (Defense in Depth - Layer 2)
        var currentTenantId = _tenantContext.GetCurrentTenantId();

        // Use read-only method for query (AsNoTracking for better performance)
        var taskId = TaskId.From(request.TaskId);
        var task = await _projectRepository.GetTaskByIdReadOnlyAsync(taskId, cancellationToken);

        if (task == null)
            throw new NotFoundException("Task", request.TaskId);

        // CRITICAL SECURITY: Explicit TenantId validation (Defense in Depth)
        if (task.TenantId.Value != currentTenantId)
            throw new NotFoundException("Task", request.TaskId);

        // Map to DTO
        return new TaskDto
        {
            Id = task.Id.Value,
            Title = task.Title,
            Description = task.Description,
            StoryId = task.StoryId.Value,
            Status = task.Status.Name,
            Priority = task.Priority.Name,
            AssigneeId = task.AssigneeId?.Value,
            EstimatedHours = task.EstimatedHours,
            ActualHours = task.ActualHours,
            CreatedBy = task.CreatedBy.Value,
            CreatedAt = task.CreatedAt,
            UpdatedAt = task.UpdatedAt
        };
    }
}