using System;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Reflection;

namespace Falcon.SugarApi
{
    /// <summary>
    /// 枚举扩展
    /// </summary>
    public static class IEnumerableExtend
    {
        /// <summary>
        /// 枚举转换为DataTable
        /// </summary>
        /// <param name="source">数据枚举</param>
        /// <returns>转换后Datatable</returns>
        /// <exception cref="ArgumentNullException">参数为Null</exception>
        public static DataTable ToDataTable(this IEnumerable<object> source) {
            _=source??throw new ArgumentNullException(nameof(source));
            var dt = new DataTable();
            if(source.Count()==0) {
                return dt;
            }
            for(int i = 0;i<source.Count();i++) {
                var item = source.ToArray()[i];
                foreach(PropertyInfo pro in item.GetType().GetProperties()) {
                    if(!dt.Columns.Contains(pro.Name)) {
                        dt.Columns.Add(new DataColumn {
                            ColumnName=pro.Name,
                            DataType=pro.PropertyType,
                        });
                    }
                }
            }
            foreach(var i in source) {
                var row = dt.NewRow();
                foreach(var p in i.GetType().GetProperties()) {
                    if(p.CanRead) {
                        var val = p.GetValue(i);
                        try {
                            row[p.Name]=val;
                        }
                        catch(Exception ex) {
                            throw new Exception($"值设置失败！{p.Name}:{val}",ex);
                        }
                    }
                }
                dt.Rows.Add(row);
            }
            return dt;
        }

        /// <summary>
        /// 枚举转换为DataTable
        /// </summary>
        /// <typeparam name="T">枚举的元素类型</typeparam>
        /// <param name="source">原数据</param>
        /// <returns>转换后Datatable</returns>
        /// <exception cref="ArgumentNullException">参数为Null</exception>
        public static DataTable ToDataTable<T>(this IEnumerable<T> source) {
            _=source??throw new ArgumentNullException(nameof(source));
            var type = typeof(T);
            var dt = new DataTable();
            var pros = typeof(T).GetProperties();
            foreach(PropertyInfo p in pros) {
                if(p.CanRead) {
                    dt.Columns.Add(new DataColumn {
                        ColumnName=p.Name,
                        DataType=p.PropertyType,
                    });
                }
            }
            foreach(var i in source) {
                var row = dt.NewRow();
                foreach(var p in pros) {
                    if(p.CanRead) {
                        var val = p.GetValue(i);
                        row[p.Name]=val;
                    }
                }
                dt.Rows.Add(row);
            }
            return dt;
        }

        /// <summary>
        /// 对枚举进行缩减，并返回缩减后的结果。
        /// </summary>
        /// <typeparam name="T">枚举的类型</typeparam>
        /// <typeparam name="TR">缩减结果类型</typeparam>
        /// <param name="source">原枚举</param>
        /// <param name="reduceFunc">缩减方法</param>
        /// <param name="initialValue">缩减初始值</param>
        /// <returns>缩减结果</returns>
        public static TR Reduce<T, TR>(this IEnumerable<T> source,Func<TR,T,TR> reduceFunc,TR initialValue) {
            if(reduceFunc==null) {
                throw new ArgumentNullException(nameof(reduceFunc));
            }
            var result = initialValue;
            foreach(var i in source) {
                result=reduceFunc(result,i);
            }
            return result;
        }

        /// <summary>
        /// 对枚举进行缩减，并返回缩减后的结果。
        /// </summary>
        /// <typeparam name="T">枚举的类型</typeparam>
        /// <typeparam name="TR">缩减结果类型</typeparam>
        /// <param name="source">原枚举</param>
        /// <param name="reduceFunc">缩减方法</param>
        /// <param name="initialValue">缩减初始值</param>
        /// <returns>缩减结果</returns>
        public static TR Reduce<T, TR>(this IEnumerable<T> source,TR initialValue,Func<TR,T,TR> reduceFunc) {
            if(reduceFunc==null) {
                throw new ArgumentNullException(nameof(reduceFunc));
            }
            var result = initialValue;
            if(source.IsNull()) {

            }
            foreach(var i in source) {
                result=reduceFunc(result,i);
            }
            return result;
        }

        /// <summary>
        /// 返回枚举是否为null或者集合无元素
        /// </summary>
        /// <typeparam name="T">枚举的元素类型</typeparam>
        /// <param name="values">枚举对象</param>
        /// <returns>为null或者无元素返回True，否则False</returns>
        public static bool IsNullOrEmpty<T>([AllowNull] this IEnumerable<T> values) => values==null||values.Count()==0;

        /// <summary>
        /// 返回枚举是否不为null或者集合无元素，结果是对IsNullOrEmpty去反。
        /// </summary>
        /// <typeparam name="T">枚举的元素类型</typeparam>
        /// <param name="values">枚举对象</param>
        /// <returns>枚举不为null或者无元素返回True，否则False</returns>
        public static bool IsNotNullOrEmpty<T>([AllowNull] this IEnumerable<T> values) => !values.IsNullOrEmpty();
    }
}