using FictionArchive.Service.Shared.Services.EventBus;
using FictionArchive.Service.UserService.Models.Database;
using FictionArchive.Service.UserService.Models.IntegrationEvents;
using FictionArchive.Service.UserService.Services.AuthenticationClient;
using Microsoft.EntityFrameworkCore;

namespace FictionArchive.Service.UserService.Services;

public class UserManagementService
{
    private readonly ILogger<UserManagementService> _logger;
    private readonly UserServiceDbContext _dbContext;
    private readonly IAuthenticationServiceClient _authClient;
    private readonly IEventBus _eventBus;

    public UserManagementService(
        UserServiceDbContext dbContext,
        ILogger<UserManagementService> logger,
        IAuthenticationServiceClient authClient,
        IEventBus eventBus)
    {
        _dbContext = dbContext;
        _logger = logger;
        _authClient = authClient;
        _eventBus = eventBus;
    }

    /// <summary>
    /// Invites a new user by creating them in Authentik, saving to the database, and sending a recovery email.
    /// </summary>
    /// <param name="inviter">The user sending the invite</param>
    /// <param name="email">Email address of the invitee</param>
    /// <param name="username">Username for the invitee</param>
    /// <returns>The created user, or null if the invite failed</returns>
    public async Task<User?> InviteUserAsync(User inviter, string email, string username)
    {
        // Check if inviter has available invites
        if (inviter.AvailableInvites <= 0)
        {
            _logger.LogWarning("User {InviterId} has no available invites", inviter.Id);
            return null;
        }

        // Check if email is already in use
        var existingUser = await _dbContext.Users
            .AsQueryable()
            .FirstOrDefaultAsync(u => u.Email == email);

        if (existingUser != null)
        {
            _logger.LogWarning("Email {Email} is already in use", email);
            return null;
        }

        // Check if username is already in use
        var existingUsername = await _dbContext.Users
            .AsQueryable()
            .FirstOrDefaultAsync(u => u.Username == username);

        if (existingUsername != null)
        {
            _logger.LogWarning("Username {Username} is already in use", username);
            return null;
        }

        // Create user in Authentik
        var authentikUser = await _authClient.CreateUserAsync(username, email, username);
        if (authentikUser == null)
        {
            _logger.LogError("Failed to create user {Username} in Authentik", username);
            return null;
        }

        // Send recovery email via Authentik
        var emailSent = await _authClient.SendRecoveryEmailAsync(authentikUser.Pk);
        if (!emailSent)
        {
            _logger.LogWarning(
                "User {Username} was created in Authentik but recovery email failed to send. Authentik pk: {Pk}",
                username, authentikUser.Pk);
            // Continue anyway - the user is created, admin can resend email manually
        }

        // Create user in local database
        var newUser = new User
        {
            Username = username,
            Email = email,
            OAuthProviderId = authentikUser.Pk.ToString(),
            Disabled = false,
            AvailableInvites = 0,
            InviterId = inviter.Id
        };

        _dbContext.Users.Add(newUser);

        // Decrement inviter's available invites
        inviter.AvailableInvites--;

        await _dbContext.SaveChangesAsync();

        await _eventBus.Publish(new UserInvitedEvent
        {
            InvitedUserId = newUser.Id,
            InvitedUsername = newUser.Username,
            InvitedEmail = newUser.Email,
            InvitedOAuthProviderId = newUser.OAuthProviderId,
            InviterId = inviter.Id,
            InviterUsername = inviter.Username,
            InviterOAuthProviderId = inviter.OAuthProviderId
        });

        _logger.LogInformation(
            "User {Username} was successfully invited by {InviterId}. New user id: {NewUserId}",
            username, inviter.Id, newUser.Id);

        return newUser;
    }

    /// <summary>
    /// Gets a user by their OAuth provider ID (Authentik UID).
    /// </summary>
    public async Task<User?> GetUserByOAuthProviderIdAsync(string oAuthProviderId)
    {
        return await _dbContext.Users
            .AsQueryable()
            .FirstOrDefaultAsync(u => u.OAuthProviderId == oAuthProviderId);
    }

    /// <summary>
    /// Gets all users as a queryable for GraphQL.
    /// </summary>
    public IQueryable<User> GetUsers()
    {
        return _dbContext.Users.AsQueryable();
    }

    /// <summary>
    /// Gets all users invited by a specific user.
    /// </summary>
    /// <param name="inviterId">The ID of the user who sent the invites</param>
    /// <returns>List of users invited by the specified user</returns>
    public async Task<List<User>> GetInvitedByUserAsync(Guid inviterId)
    {
        return await _dbContext.Users
            .AsQueryable()
            .Where(u => u.InviterId == inviterId)
            .OrderByDescending(u => u.CreatedTime)
            .ToListAsync();
    }
}