using Diligent.WebAPI.Contracts.DTOs.Categories;
namespace Diligent.WebAPI.Business.Services
{
    public class CategoryService : ICategoryService
    {
        private readonly DatabaseContext _context;
        private readonly IMapper _mapper;
        private readonly UserManager<User> _userManager;
        private readonly IUserService _userService;

        public CategoryService(DatabaseContext context, IMapper mapper, UserManager<User> userManager, IUserService userService)
        {
            _context = context;
            _mapper = mapper;
            _userManager = userManager;
            _userService = userService;
        }

        public async Task<CategoriesParentChild> GetRootCategories(int userId,int parentCategoryId)
        {
            var user = await _userManager.FindByIdAsync(userId.ToString());
            var role = (await _userManager.GetRolesAsync(user))[0];

            if(parentCategoryId != -1 && role != "SuperAdmin")
            {
                var categories = await _context.UserCategories.Where(x => x.UserId == userId && x.CategoryId == parentCategoryId).ToListAsync();
                if (categories.Count == 0) return null;
            }

            if (role == "SuperAdmin")
                if (parentCategoryId == -1)
                {
                    return new CategoriesParentChild
                    {
                        Categories = _mapper.Map<List<CategoriesNamesResponse>>
                        (await _context.Categories.Where(k => k.ParentCategory == null).ToListAsync()),
                        ChildParentRelations = await GetByParentChild(parentCategoryId)
                    };
                }
                else
                {
                    return new CategoriesParentChild
                    {
                        Categories = await GetChildCategories(parentCategoryId, userId, role),
                        ChildParentRelations = await GetByParentChild(parentCategoryId)
                    };
                }

            var userCategories = new List<UserCategories>();

            if(parentCategoryId == -1)
                userCategories = await _context.UserCategories
               .Where(k => k.UserId == userId && k.Category.ParentCategory == null)
               .Include(t => t.Category)
               .ToListAsync();
            else
                return new CategoriesParentChild
                {
                    Categories = await GetChildCategories(parentCategoryId, userId, role),
                    ChildParentRelations = await GetByParentChild(parentCategoryId)
                };

            return new CategoriesParentChild
            {
                Categories = GetCategoriesFromUserCategories(userCategories),
                ChildParentRelations = await GetByParentChild(parentCategoryId)
            };
        }
        public async Task<Category> GetCategoryEntityById(int? id) =>
            await _context.Categories.Where(x => x.Id == id).FirstOrDefaultAsync();

        public async Task<List<IsGrantedCategory>> GetCategories(int userId)
        {
            var grantedCategories = await _context.UserCategories.Where(k => k.UserId == userId).ToListAsync();
            var allCategories = await _context.Categories.ToListAsync();
            var result = new List<IsGrantedCategory>();
            for (int i = 0; i < allCategories.Count; i++)
            {
                var newCategory = new IsGrantedCategory
                {
                    Id = allCategories[i].Id,
                    Name = allCategories[i].Name,
                };
                bool isGranted = false;
                for (int j = 0; j < grantedCategories.Count; j++)
                {
                    if(grantedCategories[j].CategoryId == allCategories[i].Id && userId == grantedCategories[j].UserId)
                    {
                        isGranted = true;
                        break;
                    }
                }
                newCategory.IsChecked = isGranted;
                result.Add(newCategory);
                isGranted = false;
            }

            return result;
        }
        public async Task<List<TreeViewCategoryResponse>> GetAllCategories(int userId)
        {
            var user = await _userManager.FindByIdAsync(userId.ToString());
            var role = (await _userManager.GetRolesAsync(user))[0];
            List<Category> categories = new();
            if(role == "SuperAdmin")
            {
                categories = await _context.Categories.Include(k => k.ParentCategory).ToListAsync(); 
            }
            else
            {
                categories = await getCategoriesUserCanSee(user.Id);
            }

            List<TreeViewCategoryResponse> response = new();

            foreach (var category in categories)
            {
                TreeViewCategoryResponse treeViewCategory = new();
                if(category.ParentCategory == null)
                {
                    treeViewCategory.Id = category.Id;
                    treeViewCategory.Name = category.Name;
                    treeViewCategory.TreeViewCategories = GetTreeCategoryItem(categories, category.Id);
                    response.Add(treeViewCategory);
                }

            }

            return response;
        }
        private List<CategoriesNamesResponse> GetCategoriesFromUserCategories(List<UserCategories> userCategories)
        {
            var res = new List<CategoriesNamesResponse>();

            for (int i = 0; i < userCategories.Count; i++)
            {
                res.Add(_mapper.Map<CategoriesNamesResponse>(userCategories[i].Category));
            }

            return res;
        }
        private async Task<List<CategoriesNamesResponse>> GetByParentChild(int categoryId)
        {
            var categories = await _context.Categories.Include(x => x.ParentCategory).ToListAsync();
            var categoryById = categories.Where(x => x.Id == categoryId).FirstOrDefault();

            List<CategoriesNamesResponse> dto = new();
            while (true)
            {
                if (categoryById == null) break;
                dto.Add(new CategoriesNamesResponse
                {
                    Id = categoryById.Id,
                    Name = categoryById.Name
                });
                categoryById = categoryById.ParentCategory;
            }

            dto.Reverse();

            return dto;
        }
        private async Task<List<CategoriesNamesResponse>> GetChildCategories(int parentCategoryId, int userId, string role)
        {
            if (role == "SuperAdmin")
                return _mapper.Map<List<CategoriesNamesResponse>>(
                    await _context.Categories
                    .Where(k => k.ParentCategory != null && k.ParentCategory.Id == parentCategoryId)
                    .ToListAsync());

            var userCategories = await _context.UserCategories
                .Where(k => k.UserId == userId && k.Category != null && k.Category.ParentCategory != null && k.Category.ParentCategory.Id == parentCategoryId)
                .Include(t => t.Category)
                .ToListAsync();

            return GetCategoriesFromUserCategories(userCategories);
        }

        private async Task<List<Category>> getCategoriesUserCanSee(int userId)
        {
            var k = await _context.UserCategories.Include(c => c.Category).ThenInclude(p => p.ParentCategory).Where(t => t.UserId == userId).ToListAsync();
            List<Category> t = new();
            foreach (var m in k)
            {
                Category category = m.Category;
                while (true)
                {
                    bool s = false;
                    for (int i = 0; i < k.Count; i++)
                    {
                        if (category.Id == k[i].CategoryId)
                        {
                            s = true;
                            break;
                        }
                    }
                    if (s && category.ParentCategory is null)
                    {
                        t.Add(m.Category);
                        break;
                    }
                    else if (!s && category.ParentCategory is null)
                    {
                        break;
                    }
                    else if (s == true)
                    {
                        category = category.ParentCategory;
                        continue;
                    }
                    else
                    {
                        break;
                    }
                }

            }

            return t;
        }
        private List<TreeViewCategoryResponse> GetTreeCategoryItem(List<Category> items, int id)
        {
            List<TreeViewCategoryResponse> response = new();

            foreach (var item in items)
            {
                if(item.ParentCategory != null && item.ParentCategory.Id == id) 
                {
                    TreeViewCategoryResponse treeViewCategory = new();
                    treeViewCategory.Id = item.Id;
                    treeViewCategory.Name = item.Name;
                    treeViewCategory.TreeViewCategories = GetTreeCategoryItem(items, item.Id);
                    response.Add(treeViewCategory);
                }
            }

            return response;
        }

        public async Task CreateAsync(CreateCategoryDto createCategoryDto, int userId)
        {
            Category category = null;
            if(createCategoryDto.ParentId != null)
            {
                category = await _context.Categories.Where(x => x.Id == createCategoryDto.ParentId).FirstOrDefaultAsync();
            }
            var newCategory = new Category { Name = createCategoryDto.Name, ParentCategory = category };

            await _context.Categories.AddAsync(newCategory);

            await _context.SaveChangesAsync();

            await _userService.GrantCategoryToUserAsync(new GrantUserCategoryRequestDto { 
                UserId = userId, Categories = new List<GrantCategoryToUserRequestDto> { 
                    new GrantCategoryToUserRequestDto { Id = newCategory.Id, IsChecked = true }
                }
            });
        }
    }
}