using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.EntityFrameworkCore;
using NpgsqlTypes;
using Pf2eModel;
using Pf2eModel.Model.Base;
using Pf2eModel.Model.Enum;

namespace Pf2eWeb.Pages
{
    public class EntityTypeModel : PageModel
    {
        private readonly Pf2eDbContext _context;

        public EntityTypeModel(Pf2eDbContext context)
        {
            _context = context;
        }

        [BindProperty(SupportsGet = true)]
        public int? PageNum { get; set; }

        public IList<Entity> Entity { get; set; } = default!;

        public EntityType CurrentType;

        public int LastPage;

        public int CurrentPage => PageNum ?? 1;

        public const int PerPage = 30;

        public void OnGet(string type)
        {
            CurrentType = Enum<EntityType>(type);

            int count = _context.Entities.Count(entity => entity.Type == CurrentType);

            LastPage = (int)Math.Ceiling(count / (double)PerPage);

            Entity = _context
                .Entities.Where(entity => entity.Type == CurrentType)
                .Skip((CurrentPage - 1) * PerPage)
                .Take(PerPage)
                .ToList();
        }

        /// <summary>
        /// Преобразование значения из JSON в перечисление.
        /// </summary>
        /// <param name="value">Значение, которое нужно преобразовать</param>
        /// <returns>Объект типа `T`, если преобразование успешно, иначе выбрасывает исключение</returns>
        public static T Enum<T>(string value)
            where T : Enum
        {
            foreach (System.Reflection.FieldInfo field in typeof(T).GetFields())
            {
                List<string> variants = [field.Name];

                if (
                    Attribute.GetCustomAttribute(field, typeof(PgNameAttribute))
                    is PgNameAttribute pgAttribute
                )
                {
                    variants.Add(pgAttribute.PgName);
                }

                if (variants.Contains(value))
                {
                    return (T)field.GetValue(null)!;
                }
            }

            throw new Exception($"Can't resolve enum value \"{value}\" for type {typeof(T)}");
        }

        public List<int> Pagination
        {
            get
            {
                List<int> pages = [1];

                int start = Math.Max(2, CurrentPage - 1);
                int end = Math.Min(LastPage - 1, CurrentPage + 1);

                if (start > 2)
                    pages.Add(-1);

                for (int i = start; i <= end; i++)
                    pages.Add(i);

                if (end < LastPage - 1)
                    pages.Add(-1);

                if (LastPage > 1)
                    pages.Add(LastPage);

                return pages;
            }
        }
    }
}