using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using System.Web;
using API.Constants;
using API.Data;
using API.DTOs.Account;
using API.Entities;
using API.Errors;
using Kavita.Common;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Identity;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace API.Services;

#nullable enable

public interface IAccountService
{
    Task<IEnumerable<ApiException>> ChangeUserPassword(AppUser user, string newPassword);
    Task<IEnumerable<ApiException>> ValidatePassword(AppUser user, string password);
    Task<IEnumerable<ApiException>> ValidateUsername(string username);
    Task<IEnumerable<ApiException>> ValidateEmail(string email);
    Task<bool> HasBookmarkPermission(AppUser? user);
    Task<bool> HasDownloadPermission(AppUser? user);
    Task<bool> CanChangeAgeRestriction(AppUser? user);
}

public class AccountService : IAccountService
{
    private readonly UserManager<AppUser> _userManager;
    private readonly ILogger<AccountService> _logger;
    private readonly IUnitOfWork _unitOfWork;
    public const string DefaultPassword = "[k.2@RZ!mxCQkJzE";

    public AccountService(UserManager<AppUser> userManager, ILogger<AccountService> logger, IUnitOfWork unitOfWork)
    {
        _userManager = userManager;
        _logger = logger;
        _unitOfWork = unitOfWork;
    }

    public async Task<IEnumerable<ApiException>> ChangeUserPassword(AppUser user, string newPassword)
    {
        var passwordValidationIssues = (await ValidatePassword(user, newPassword)).ToList();
        if (passwordValidationIssues.Count != 0) return passwordValidationIssues;

        var result = await _userManager.RemovePasswordAsync(user);
        if (!result.Succeeded)
        {
            _logger.LogError("Could not update password");
            return result.Errors.Select(e => new ApiException(400, e.Code, e.Description));
        }

        result = await _userManager.AddPasswordAsync(user, newPassword);
        if (result.Succeeded) return [];

        _logger.LogError("Could not update password");
        return result.Errors.Select(e => new ApiException(400, e.Code, e.Description));
    }

    public async Task<IEnumerable<ApiException>> ValidatePassword(AppUser user, string password)
    {
        foreach (var validator in _userManager.PasswordValidators)
        {
            var validationResult = await validator.ValidateAsync(_userManager, user, password);
            if (!validationResult.Succeeded)
            {
                return validationResult.Errors.Select(e => new ApiException(400, e.Code, e.Description));
            }
        }

        return Array.Empty<ApiException>();
    }
    public async Task<IEnumerable<ApiException>> ValidateUsername(string username)
    {
        if (await _userManager.Users.AnyAsync(x => x.NormalizedUserName != null
                                                   && x.NormalizedUserName.Equals(username, StringComparison.CurrentCultureIgnoreCase)))
        {
            return
            [
                new(400, "Username is already taken")
            ];
        }

        return [];
    }

    public async Task<IEnumerable<ApiException>> ValidateEmail(string email)
    {
        var user = await _unitOfWork.UserRepository.GetUserByEmailAsync(email);
        if (user == null) return [];

        return
        [
            new ApiException(400, "Email is already registered")
        ];
    }

    /// <summary>
    /// Does the user have the Bookmark permission or admin rights
    /// </summary>
    /// <param name="user"></param>
    /// <returns></returns>
    public async Task<bool> HasBookmarkPermission(AppUser? user)
    {
        if (user == null) return false;
        var roles = await _userManager.GetRolesAsync(user);

        return roles.Contains(PolicyConstants.BookmarkRole) || roles.Contains(PolicyConstants.AdminRole);
    }

    /// <summary>
    /// Does the user have the Download permission or admin rights
    /// </summary>
    /// <param name="user"></param>
    /// <returns></returns>
    public async Task<bool> HasDownloadPermission(AppUser? user)
    {
        if (user == null) return false;
        var roles = await _userManager.GetRolesAsync(user);

        return roles.Contains(PolicyConstants.DownloadRole) || roles.Contains(PolicyConstants.AdminRole);
    }

    /// <summary>
    /// Does the user have Change Restriction permission or admin rights and not Read Only
    /// </summary>
    /// <param name="user"></param>
    /// <returns></returns>
    public async Task<bool> CanChangeAgeRestriction(AppUser? user)
    {
        if (user == null) return false;

        var roles = await _userManager.GetRolesAsync(user);
        if (roles.Contains(PolicyConstants.ReadOnlyRole)) return false;

        return roles.Contains(PolicyConstants.ChangePasswordRole) || roles.Contains(PolicyConstants.AdminRole);
    }
}