using eprintServer.Entities;
using eprintServer.Enums;
using eprintServer.Models;
using eprintServer.Services;

public abstract class BaseOAuthService
{
    protected readonly UserService _userService;
    protected readonly TokenService _tokenService;

    protected BaseOAuthService(UserService userService, TokenService tokenService)
    {
        _userService = userService;
        _tokenService = tokenService;
    }

    protected async Task<(User? user, string? token, string? error)> SignInUserAsync(ExternalUserData externalUser, Provider provider)
    {
        var user = await _userService.FindByLoginIdentifierAsync(externalUser.Email);

        if (user == null)
        {
            var userCount = await _userService.GetUserCountAsync();
            var username = _userService.GenerateUsername(externalUser.Name, userCount);
            var newUser = new User
            {
                Email = externalUser.Email,
                Name = externalUser.Name,
                Username = username,
                Role = RoleEnum.ROLE_USER,
                Provider = provider,
                Active = true,
                // Best practice: Set a random password for OAuth users so they can't login via password form
                Password = Guid.NewGuid().ToString() 
            };
            user = await _userService.SaveUserAsync(newUser);
        }
        else if (user.Provider != provider)
        {
            return (null, null, $"Email already registered via {user.Provider}.");
        }

        var token = _tokenService.CreateToken(user!);
        return (user, token, null);
    }
}