using DigitalData.Core.Abstraction.Application.Repository;
using EnvelopeGenerator.Domain.Entities;
using MediatR;
using Microsoft.EntityFrameworkCore;
using System.Linq.Expressions;

namespace EnvelopeGenerator.Application.DocStatus.Commands;

/// <summary>
/// Represents a command to save the status of a document, either by creating a new status or updating an existing one based on the provided envelope and receiver identifiers.
/// It returns the identifier of the saved document status.
/// </summary>
public record SaveDocStatusCommand : ModifyDocStatusCommandBase, IRequest<int?>;

/// <summary>
/// 
/// </summary>
public class SaveDocStatusCommandHandler : IRequestHandler<SaveDocStatusCommand, int?>
{
    private readonly IRepository<DocumentStatus> _repo;

    /// <summary>
    /// 
    /// </summary>
    /// <param name="repo"></param>
    public SaveDocStatusCommandHandler(IRepository<DocumentStatus> repo)
    {
        _repo = repo;
    }

    /// <summary>
    /// 
    /// </summary>
    /// <param name="request"></param>
    /// <param name="cancel"></param>
    /// <returns></returns>
    public async Task<int?> Handle(SaveDocStatusCommand request, CancellationToken cancel)
    {
        Expression<Func<DocumentStatus, bool>> filter = ds => ds.EnvelopeId == request.EnvelopeId && ds.ReceiverId == request.ReceiverId;

        // ceck if exists
        bool isExists = await _repo.ReadOnly().Where(filter).AnyAsync(cancel);

        if (isExists)
        {
            var uReq = request.To<UpdateDocStatusCommand>();
            await _repo.UpdateAsync(uReq, filter, cancel);
        }
        else
        {
            var cReq = request.To<CreateDocStatusCommand>();
            await _repo.CreateAsync(cReq, cancel);
        }

        var docStatus = await _repo.ReadOnly().Where(filter).FirstOrDefaultAsync(cancel);
        return docStatus?.Id;
    }
}