using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations.Schema;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;

namespace FastDBF
{
    public class DbfHelper
    {

        private static readonly string basePath = Directory.GetCurrentDirectory();


        
 
public static (bool, string) WriteDdf<T>(T model, string dbfName) where T : class
        {
            List<T> ts = new List<T>();
            ts.Add(model);
            return WriteDdf<T>(model, dbfName);
        }

        /// <summary>
        /// 寫入dbf
        /// </summary>
 

        /// <typeparam name="T"></typeparam>
        /// <param name="list">列表資料</param>
        /// <param name="dbfPath">dbf儲存路徑</param>
        /// <returns></returns>
        public static (bool, string) WriteDdf<T>(List<T> list, string dbfName) where
 
 T : class
        {
            if (list == null) return (false, "傳入資料為空");
            DbfFile dbfFile = new DbfFile(Encoding.UTF8);

            try
            {
                //建立dbf檔案
                string writeDirectory = Path.Combine(basePath, "DbfFile");
                string writePath = Path.Combine(writeDirectory, dbfName);

                if (!Directory.Exists(writeDirectory)) Directory.CreateDirectory(writeDirectory);
                bool fileIsExists = File.Exists(writePath);
                dbfFile.Open(writePath, FileMode.Append, FileAccess.Write);
                dbfFile._headerWritten = fileIsExists;

                var dicProperty = Mapping<T>();

                //create a header
                foreach (var it in dicProperty)
                {
                    dbfFile.Header.AddColumn(new DbfColumn(it.Key, DbfColumn.DbfColumnType.Character, 255, 0));
                }

                foreach (var it in list)
                {
                    var orec = new DbfRecord(dbfFile.Header) { AllowDecimalTruncate = true };
                    foreach (var col in dicProperty)
                    {
                        var pro = col.Value;
                        object value = pro.GetValue(it);
                        if (value == null || value == DBNull.Value)
                        {
                            value = "";
                        }
                        orec[col.Key] = value.ToString();
                    }
                    dbfFile.Write(orec, true);
                }
                dbfFile.Dispose();
                return (true, "寫入成功");

            }
            catch (Exception ex)
            {
                dbfFile.Dispose();
                return (false, $"寫入失敗：{ex.ToString()}");
            }

        }


        /// <summary>
        /// 讀取dbf檔案
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="dbfPath">dbf檔案路徑</param>
        /// <returns></returns>
        public static (bool, List<T>, string) ReadDdf<T>(string dbfName) where T : class
        {
            List<T> list = new List<T>();
            DbfFile dbfFile = new DbfFile(Encoding.UTF8);

            try
            {
                //獲取一個DBF檔案物件
                string readPath = Path.Combine(basePath, "DbfFile", dbfName);
                if (!File.Exists(readPath)) return (false, null, "檔案不存在");
                dbfFile.Open(readPath, FileMode.Open, FileAccess.Read);

                var dicProperty = Mapping<T>();

                //讀取dbf的欄位名
                DbfHeader dh = dbfFile.Header;
                List<string> dbfColumns = new List<string>();
                for (int index = 0; index < dh.ColumnCount; index++)
                {
                    dbfColumns.Add(dh[index].Name);
                }
                //讀取資料
                int i = 0;
                while (dbfFile.Read(i) != null)
                {
                    //讀取一行
                    DbfRecord record = dbfFile.Read(i);
                    if (record == null)
                    {
                        continue;
                    }
                    T t = Activator.CreateInstance<T>();
                    foreach (var col in dbfColumns)
                    {
                        var data = dicProperty.FirstOrDefault(r => r.Key == col);
                        if (data.Key == null)
                        {
                            continue;
                        }
                        var pro = data.Value;
                        if (pro == null || !pro.CanWrite)
                        {
                            continue;
                        }
                        string value = record[col];
                        if (value == null)
                        {
                            continue;
                        }
                        pro.SetValue(t, Convert.ChangeType(value.Trim(), pro.PropertyType));
                    }
                    list.Add(t);
                    i++;
                }
                dbfFile.Close();
                return (true, list, "");
            }
            catch (Exception ex)
            {
                dbfFile.Dispose();
                return (false, null, $"讀取失敗：{ex.ToString()}");
            }

        }

        /// <summary>
        /// 對映
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <returns></returns>
        private static List<KeyValuePair<string, PropertyInfo>> Mapping<T>() where T : class
        {
            Type type = typeof(T);
            var properties = type.GetProperties();

            List<KeyValuePair<string, PropertyInfo>> result = new List<KeyValuePair<string, PropertyInfo>>();

            //儲存dbf欄位和實體的對映關係
            //實體沒有ColumnAttribute,則認為dbf欄位名稱和實體名稱一致
            foreach (var pro in properties)
            {
                var attrs = pro.GetCustomAttributes(true).SingleOrDefault(attr => attr.GetType().Name == typeof(ColumnAttribute).Name) as dynamic;
                if (attrs == null)
                    result.Add(new KeyValuePair<string, PropertyInfo>(pro.Name, pro));
                else
                    result.Add(new KeyValuePair<string, PropertyInfo>(attrs.Name, pro));
            }
            return result;
        }

    }
}