// <copyright file="UserGroupService.cs" company="alveus.dev">
// Copyright (c) alveus.dev. All rights reserved. Licensed under the MIT License.
// </copyright>

using Astral.Core.Entities;
using Astral.Core.Exceptions;
using Astral.Core.RepositoryInterfaces;
using Astral.Services.Dtos;
using Astral.Services.Exceptions;
using Astral.Services.Interfaces;
using AutoMapper;
using Injectio.Attributes;
using Microsoft.Extensions.Logging;

namespace Astral.Services.Services;

/// <inheritdoc />
[RegisterScoped]
public class UserGroupService : IUserGroupService
{
    private readonly ILogger<UserGroupService> _logger;
    private readonly IMapper _mapper;
    private readonly IUserGroupRepository _userGroupRepository;
    private readonly IUserRepository _userRepository;

    /// <summary>
    /// Initializes a new instance of the <see cref="UserGroupService" /> class.
    /// </summary>
    /// <param name="userGroupRepository">Instance of <see cref="IUserGroupRepository" />.</param>
    /// <param name="userRepository">Instance of <see cref="IUserRepository" />.</param>
    /// <param name="mapper">Instance of <see cref="IMapper" />.</param>
    /// <param name="logger">Instance of <see cref="ILogger" />.</param>
    public UserGroupService(
        IUserGroupRepository userGroupRepository,
        IUserRepository userRepository,
        IMapper mapper,
        ILogger<UserGroupService> logger)
    {
        _userGroupRepository = userGroupRepository;
        _userRepository = userRepository;
        _mapper = mapper;
        _logger = logger;
    }

    /// <inheritdoc />
    public async Task<UserGroupDto> CreateUserGroup(Guid ownerUserId, string title, string description)
    {
        var user = await _userRepository.FindByIdAsync(ownerUserId);
        if (user is null)
        {
            _logger.LogError("Attempted to create a user group for a user that does not exist: {userId}", ownerUserId);
            throw new UserNotFoundException();
        }

        var uniqueId = await GetUniqueId();

        var userGroup = new UserGroup
        {
            Id = uniqueId,
            CreatedAt = DateTime.UtcNow,
            OwnerUserId = ownerUserId,
            Title = title,
            Description = description ?? string.Empty,
            Internal = false
        };

        _logger.LogInformation(
            "Creating new user group {groupTitle} [{groupId}] for user {user} [{userId}]",
            userGroup.Title,
            userGroup.Id,
            user.Username,
            user.Id);

        await _userGroupRepository.AddAsync(userGroup);

        return _mapper.Map<UserGroupDto>(userGroup);
    }

    /// <inheritdoc />
    public async Task<UserGroupDto> CreateInternalGroup(Guid ownerUserId, string title, string description)
    {
        var user = await _userRepository.FindByIdAsync(ownerUserId);
        if (user is null)
        {
            _logger.LogError("Attempted to create a user group for a user that does not exist: {userId}", ownerUserId);
            throw new UserNotFoundException();
        }

        var uniqueId = await GetUniqueId();

        var userGroup = new UserGroup
        {
            Id = uniqueId,
            CreatedAt = DateTime.UtcNow,
            OwnerUserId = ownerUserId,
            Title = title,
            Description = description ?? string.Empty,
            Internal = true
        };

        _logger.LogInformation(
            "Creating new internal user group {groupTitle} [{groupId}] for user {user} [{userId}]",
            userGroup.Title,
            userGroup.Id,
            user.Username,
            user.Id);

        await _userGroupRepository.AddAsync(userGroup);

        return _mapper.Map<UserGroupDto>(userGroup);
    }

    /// <summary>
    /// Create a unique guid.
    /// </summary>
    /// <returns>The new guid.</returns>
    private async Task<Guid> GetUniqueId()
    {
        var attempt = 0;
        const int maxAttempts = 10;

        var newId = Guid.NewGuid();
        while (await _userGroupRepository.FindByIdAsync(newId) is not null)
        {
            attempt++;
            if (attempt >= maxAttempts)
            {
                _logger.LogCritical("Unable to generate a unique guid for user group");
                throw new UnexpectedErrorException();
            }

            newId = Guid.NewGuid();
        }

        return newId;
    }
}