using ErrorOr;
using Mediator;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;
using Musify.Application.Albums.Responses;
using Musify.Application.Configuration;
using Musify.Application.Contracts;
using Musify.Application.Events;
using Musify.Application.Services;
using Musify.Domain.Entities;
using Musify.Domain.ValueObjects;

namespace Musify.Application.Albums;

public record CreateAlbumCommand(
    long UserId,
    string Title,
    string? Description,
    int? ReleaseYear,
    Guid PictureIntentId)
    : ICommand<ErrorOr<AlbumApplicationResponse>>;

public class CreateAlbumCommandHandler(
    IEventBus eventBus,
    IDatabase database,
    UploadIntentValidator uploadIntentValidator,
    ILogger<CreateAlbumCommandHandler> logger,
    ApplicationStorageConfiguration storageConfiguration,
    AlbumConfiguration albumConfiguration,
    UploadIntentConfiguration uploadIntentConfiguration)
    : ICommandHandler<CreateAlbumCommand, ErrorOr<AlbumApplicationResponse>>
{
    public async ValueTask<ErrorOr<AlbumApplicationResponse>> Handle(CreateAlbumCommand request, CancellationToken cancellationToken)
    {
        var userExists = await database.Users
            .AsNoTracking()
            .AnyAsync(user => user.Id == request.UserId, cancellationToken);
        if (!userExists)
        {
            logger.LogWarning("User {UserId} not found", request.UserId);
            return Error.NotFound(description: $"User {request.UserId} not found");
        }

        var pictureIntent = await uploadIntentValidator.ValidateAndLoadAsync(
            uploadIntentConfiguration, request.PictureIntentId, request.UserId, UploadIntentPurpose.AlbumPicture, cancellationToken);
        if (pictureIntent.IsError)
            return pictureIntent.Errors;

        var intent = pictureIntent.Value;
        var title = request.Title.Trim();

        var album = new Album
        {
            OwnerUserId = request.UserId,
            Title = title,
            NormalizedTitle = title.ToUpperInvariant(),
            Description = request.Description,
            ReleaseYear = request.ReleaseYear,
            Pictures = EntityPictures.Pending(intent.ObjectName)
        };

        await database.Albums.AddAsync(album, cancellationToken);

        var finalPictureKey = albumConfiguration.Routes.BuildOriginalPicturePath(request.UserId, intent.ObjectName);
        var publishResult = await PublishCreateAlbumEventAsync(album.Id, intent, finalPictureKey, cancellationToken);
        if (publishResult.IsError)
            return publishResult.Errors;

        try
        {
            await database.SaveChangesAsync(cancellationToken);
        }
        catch (Exception exception)
        {
            logger.LogError(exception, "Failed to save album for user {UserId}", request.UserId);
            return Error.Failure(description: $"Failed to create album for user {request.UserId}");
        }

        logger.LogInformation("Created album {AlbumId} for user {UserId}", album.Id, request.UserId);

        return AlbumApplicationResponse.FromEntity(album, trackCount: 0);
    }

    private async Task<ErrorOr<Success>> PublishCreateAlbumEventAsync(
        Guid albumId,
        UploadIntent pictureIntent,
        string finalPictureKey,
        CancellationToken cancellationToken)
    {
        try
        {
            var sizes = albumConfiguration.PicturesSizes.ToImageSizes(albumConfiguration.Routes);
            await eventBus.PublishAsync(
                new CreateAlbumResourcesEvent(
                    albumId,
                    pictureIntent.Id,
                    storageConfiguration.Bucket,
                    pictureIntent.Key,
                    finalPictureKey,
                    sizes.Small,
                    sizes.Medium,
                    sizes.Large),
                cancellationToken);
            return new Success();
        }
        catch (Exception exception)
        {
            logger.LogError(exception, "Failed to publish create album event for album {AlbumId}", albumId);
            return Error.Failure(description: $"Failed to publish create album event for album {albumId}");
        }
    }
}