using SqlSugar;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Threading.Tasks;
using Wood.Entity;

namespace Wood.Data.Repository
{
	/// <summary>
	/// 分页拓展类
	/// </summary>
	public static class SqlSugarPagedExtensions
	{
		/// <summary>
		/// 分页拓展
		/// </summary>
		/// <param name="query"><see cref="ISugarQueryable{TEntity}"/>对象</param>
		/// <param name="pageIndex">当前页码，从1开始</param>
		/// <param name="pageSize">页码容量</param>
		/// <param name="expression">查询结果 Select 表达式</param>
		/// <returns></returns>
		public static TDataPaged<TResult> ToPagedList<TEntity, TResult>(this ISugarQueryable<TEntity> query, int pageIndex, int pageSize,
			Expression<Func<TEntity, TResult>> expression)
		{
			var total = 0;
			var items = query.ToPageList(pageIndex, pageSize, ref total, expression);
			return CreateSqlSugarPagedList(items, total, pageIndex, pageSize);
		}

		/// <summary>
		/// 分页拓展
		/// </summary>
		/// <param name="query"><see cref="ISugarQueryable{TEntity}"/>对象</param>
		/// <param name="pageIndex">当前页码，从1开始</param>
		/// <param name="pageSize">页码容量</param>
		/// <returns></returns>
		public static TDataPaged<TEntity> ToPagedList<TEntity>(this ISugarQueryable<TEntity> query, int pageIndex, int pageSize)
		{
			var total = 0;
			var items = query.ToPageList(pageIndex, pageSize, ref total);
			return CreateSqlSugarPagedList(items, total, pageIndex, pageSize);
		}

		/// <summary>
		/// 分页拓展
		/// </summary>
		/// <param name="query"><see cref="ISugarQueryable{TEntity}"/>对象</param>
		/// <param name="pageIndex">当前页码，从1开始</param>
		/// <param name="pageSize">页码容量</param>
		/// <param name="expression">查询结果 Select 表达式</param>
		/// <returns></returns>
		public static async Task<TDataPaged<TResult>> ToPagedListAsync<TEntity, TResult>(this ISugarQueryable<TEntity> query, int pageIndex, int pageSize,
			Expression<Func<TEntity, TResult>> expression)
		{
			RefAsync<int> total = 0;
			var items = await query.ToPageListAsync(pageIndex, pageSize, total, expression);
			return CreateSqlSugarPagedList(items, total, pageIndex, pageSize);
		}

		/// <summary>
		/// 分页拓展
		/// </summary>
		/// <param name="query"><see cref="ISugarQueryable{TEntity}"/>对象</param>
		/// <param name="pageIndex">当前页码，从1开始</param>
		/// <param name="pageSize">页码容量</param>
		/// <returns></returns>
		public static async Task<TDataPaged<TEntity>> ToPagedListAsync<TEntity>(this ISugarQueryable<TEntity> query, int pageIndex, int pageSize)
		{
			RefAsync<int> total = 0;
			var items = await query.ToPageListAsync(pageIndex, pageSize, total);
			return CreateSqlSugarPagedList(items, total, pageIndex, pageSize);
		}

		/// <summary>
		/// 分页拓展
		/// </summary>
		/// <param name="query"><see cref="ISugarQueryable{TEntity}"/>对象</param>
		/// <param name="pageIndex">当前页码，从1开始</param>
		/// <param name="pageSize">页码容量</param>
		/// <param name="expression">查询结果 Select 表达式</param>
		/// <returns></returns>
		public static async Task<TDataPaged<TResult>> ToPagedListAsync<TEntity, TResult>(this ISugarQueryable<TEntity> query, Pagination pagination,
			Expression<Func<TEntity, TResult>> expression)
		{
			RefAsync<int> total = 0;
			var items = await query.OrderBy(pagination.Sort).ToPageListAsync(pagination.PageIndex, pagination.PageSize, total, expression);
			return CreateSqlSugarPagedList(items, total, pagination.PageIndex, pagination.PageSize);
		}

		/// <summary>
		/// 分页拓展
		/// </summary>
		/// <param name="query"><see cref="ISugarQueryable{TEntity}"/>对象</param>
		/// <param name="pageIndex">当前页码，从1开始</param>
		/// <param name="pageSize">页码容量</param>
		/// <returns></returns>
		public static async Task<TDataPaged<TEntity>> ToPagedListAsync<TEntity>(this ISugarQueryable<TEntity> query, Pagination pagination)
		{
			RefAsync<int> total = 0;
			
			var items = await query.OrderBy(pagination.Sort).ToPageListAsync(pagination.PageIndex, pagination.PageSize, total);
			return CreateSqlSugarPagedList(items, total, pagination.PageIndex, pagination.PageSize);
		}

		/// <summary>
		/// 分页拓展
		/// </summary>
		/// <param name="list">集合对象</param>
		/// <param name="pageIndex">当前页码，从1开始</param>
		/// <param name="pageSize">页码容量</param>
		/// <returns></returns>
		public static TDataPaged<TEntity> ToPagedList<TEntity>(this IEnumerable<TEntity> list, int pageIndex, int pageSize)
		{
			var total = list.Count();
			var items = list.Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList();
			return CreateSqlSugarPagedList(items, total, pageIndex, pageSize);
		}

		/// <summary>
		/// 创建 <see cref="SqlSugarPagedList{TEntity}"/> 对象
		/// </summary>
		/// <typeparam name="TEntity"></typeparam>
		/// <param name="items">分页内容的对象集合</param>
		/// <param name="total">总条数</param>
		/// <param name="pageIndex">当前页码，从1开始</param>
		/// <param name="pageSize">页码容量</param>
		/// <returns></returns>
		public static TDataPaged<TEntity> CreateSqlSugarPagedList<TEntity>(IEnumerable<TEntity> items, int total, int pageIndex, int pageSize)
		{
			var totalPages = pageSize > 0 ? (int)Math.Ceiling(total / (double)pageSize) : 0;
			return new TDataPaged<TEntity>
			{
				Page = pageIndex,
				PageSize = pageSize,
				Data = items,
				Total = total,
				TotalPages = totalPages,
				HasNextPage = pageIndex < totalPages,
				HasPrevPage = pageIndex - 1 > 0
			};
		}
	}
}