using System;
using System.Data;
using System.IO;
using System.Collections.Generic;
using System.ComponentModel;
using System.Reflection;

namespace Sog
{
    public static class CsvHelper
    {
        /// <summary>
        /// 写入CSV文件
        /// </summary>
        /// <param name="dt">DataTable</param>
        /// <param name="fileName">文件全名</param>
        /// <returns>是否写入成功</returns>
        public static bool SaveCSV(DataTable dt, string fullFileName)
        {
            var r = false;
            FileStream fs = new FileStream(fullFileName, System.IO.FileMode.Create, System.IO.FileAccess.Write);
            StreamWriter sw = new StreamWriter(fs, System.Text.Encoding.Default);
            string data = "";

            //写出列名称
            for (int i = 0; i < dt.Columns.Count; i++)
            {
                data += dt.Columns[i].ColumnName.ToString();
                if (i < dt.Columns.Count - 1)
                {
                    data += ",";
                }
            }
            sw.WriteLine(data);

            //写出各行数据
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                data = "";
                for (int j = 0; j < dt.Columns.Count; j++)
                {
                    data += dt.Rows[i][j].ToString();
                    if (j < dt.Columns.Count - 1)
                    {
                        data += ",";
                    }
                }
                sw.WriteLine(data);
            }

            sw.Close();
            fs.Close();

            r = true;
            return r;
        }

        
        public static List<T> GetByFullPath<T>(string fullFileName) where T : class, new()
        {
            DataTable dt = OpenCSV(fullFileName);
            return TableToEntity<T>(dt);
        }

        /// <summary>
        /// 打开CSV 文件
        /// </summary>
        /// <param name="fileName">文件全名</param>
        /// <returns>DataTable</returns>
        public static DataTable OpenCSV(string fullFileName)
        {
            return OpenCSV(fullFileName, 0, 0, 0, 0, true);
        }

        /// <summary>
        /// 打开CSV 文件
        /// </summary>
        /// <param name="fileName">文件全名</param>
        /// <param name="firstRow">开始行</param>
        /// <param name="firstColumn">开始列</param>
        /// <param name="getRows">获取多少行</param>
        /// <param name="getColumns">获取多少列</param>
        /// <param name="haveTitleRow">是有标题行</param>
        /// <returns>DataTable</returns>
        public static DataTable OpenCSV(string fullFileName, Int16 firstRow = 0, Int16 firstColumn = 0, Int16 getRows = 0, Int16 getColumns = 0, bool haveTitleRow = true)
        {
            DataTable dt = new DataTable();
            FileStream fs = new FileStream(fullFileName, System.IO.FileMode.Open, System.IO.FileAccess.Read);
            StreamReader sr = new StreamReader(fs, System.Text.Encoding.Default);
            //记录每次读取的一行记录
            string strLine = "";
            //记录每行记录中的各字段内容
            string[] aryLine;
            //标示列数
            int columnCount = 0;
            //是否已建立了表的字段
            bool bCreateTableColumns = false;
            //第几行
            int iRow = 1;

            //去除无用行
            if (firstRow > 0)
            {
                for (int i = 1; i < firstRow; i++)
                {
                    sr.ReadLine();
                }
            }

            // { ",", ".", "!", "?", ";", ":", " " };
            string[] separators = { "," };
            //逐行读取CSV中的数据
            while ((strLine = sr.ReadLine()) != null)
            {
                strLine = strLine.Trim();
                aryLine = strLine.Split(separators, System.StringSplitOptions.RemoveEmptyEntries);

                if (bCreateTableColumns == false)
                {
                    bCreateTableColumns = true;
                    columnCount = aryLine.Length;
                    //创建列
                    for (int i = firstColumn; i < (getColumns == 0 ? columnCount : firstColumn + getColumns); i++)
                    {
                        DataColumn dc
                            = new DataColumn(haveTitleRow == true ? aryLine[i] : "COL" + i.ToString());
                        dt.Columns.Add(dc);
                    }

                    bCreateTableColumns = true;

                    if (haveTitleRow == true)
                    {
                        continue;
                    }
                }


                DataRow dr = dt.NewRow();
                for (int j = firstColumn; j < (getColumns == 0 ? columnCount : firstColumn + getColumns); j++)
                {
                    dr[j - firstColumn] = aryLine[j];
                }
                dt.Rows.Add(dr);

                iRow = iRow + 1;
                if (getRows > 0)
                {
                    if (iRow > getRows)
                    {
                        break;
                    }
                }

            }

            sr.Close();
            fs.Close();
            return dt;
        }

        /// <summary>
        /// DataTable转换成实体类
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="dt"></param>
        /// <returns></returns>
        public static List<T> TableToEntity<T>(DataTable dt) where T : class, new()
        {
            List<T> list = new List<T>();
            try
            {
                foreach (DataRow row in dt.Rows)
                {
                    T entity = new T();
                    PropertyInfo[] pArray = entity.GetType().GetProperties();

                    foreach (PropertyInfo p in pArray)
                    {
                        if (dt.Columns.Contains(p.Name))
                        {
                            if (!p.CanWrite) continue;
                            var value = row[p.Name];
                            if (value != DBNull.Value)
                            {
                                Type targetType = p.PropertyType;
                                Type convertType = targetType;
                                if (targetType.IsGenericType && targetType.GetGenericTypeDefinition().Equals(typeof(Nullable<>)))
                                {
                                    //可空类型
                                    NullableConverter nullableConverter = new NullableConverter(targetType);
                                    convertType = nullableConverter.UnderlyingType;
                                }
                                if (!string.IsNullOrEmpty(convertType.FullName) && !string.IsNullOrEmpty(value.ToString()))
                                {
                                    value = Convert.ChangeType(value, convertType);
                                }
                                switch (convertType.FullName)
                                {
                                    case "System.Decimal":
                                        p.SetValue(entity, Convert.ToDecimal(value), null);
                                        break;
                                    case "System.String":
                                        p.SetValue(entity, Convert.ToString(value), null);
                                        break;
                                    case "System.Int32":
                                        p.SetValue(entity, Convert.ToInt32(value), null);
                                        break;
                                    case "System.Int64":
                                        p.SetValue(entity, Convert.ToInt64(value), null);
                                        break;
                                    case "System.Int16":
                                        p.SetValue(entity, Convert.ToInt16(value), null);
                                        break;
                                    case "System.Double":
                                        p.SetValue(entity, Convert.ToDouble(value), null);
                                        break;
                                    case "System.DateTime":
                                        p.SetValue(entity, Convert.ToDateTime(value), null);
                                        break;
                                    default:
                                        p.SetValue(entity, value, null);
                                        break;
                                }
                            }
                        }
                    }
                    list.Add(entity);
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }

            if (list.Count > 0)
                return list;
            else
                return null;
        }
    }
}