using System;
using System.Collections.Generic;
using System.IO;

namespace BCG
{
   public class TextReaderStream : ViewStream
   {
      #region constructors
      public TextReaderStream(string file)
      {
         myFile = file;
      }
      #endregion

      #region ViewStream
      protected override void myOnFirstSubscriber()
      {
         StreamReader reader = new StreamReader(myFile);

         #region get schema
         IBlueTableSchema? schema;
         string? schemaStr;
         if ((schemaStr = reader.ReadLine()) == null)
         {
            reader.Close();
            return;
         }

         schema = myGetSchema(schemaStr);
         #endregion

         #region read rows and fire update
         BlueTable adds = new BlueTable(schema);
         BlueTable dels = new BlueTable(schema);

         string? rowStr;
         while ((rowStr = reader.ReadLine()) != null)
         {
            adds.addRow(myGetRow(schema, rowStr));
         }

         myFireEvent(new DataPacket(adds, adds, dels));
         #endregion

         reader.Close();
      }
      #endregion

      #region helpers
      private IBlueTableSchema myGetSchema(string schemaStr)
      {
         List<ColumnInfo> columnInfos = new List<ColumnInfo>();

         List<string> columnInfoStrs = new List<string>(schemaStr.Split(new string[] { TextWriterStream.DELIM }, StringSplitOptions.None));
         for(int i = 0; i < columnInfoStrs.Count; ++i)
         {
            string columnInfoStr = columnInfoStrs[i];

            List<string> columnInfoStrParts = new List<string>(columnInfoStr.Split(new char[] { ':' }, StringSplitOptions.None));
            if (columnInfoStrParts.Count != 2)
            {
               throw (new Exception(String.Format("Unable to decode schema string '{0}'", schemaStr)));
            }

            columnInfos.Add(new ColumnInfo(columnInfoStrParts[0], i, Type.GetType(columnInfoStrParts[1])));
         }

         return (new BlueTableSchema(columnInfos.ToArray(), ""));
      }

      private IBlueRow myGetRow(IBlueTableSchema schema, string rowStr)
      {
         List<string> valueStrs = new List<string>(rowStr.Split(new string[] { TextWriterStream.DELIM }, StringSplitOptions.None));

         if (schema.columnInfo.Length != valueStrs.Count)
         {
            throw (new Exception(String.Format("Unable to decode row string '{0}'", rowStr)));
         }

         List<object> values = new List<object>();
         for(int i = 0; i < schema.columnInfo.Length; ++i)
         {
            values.Add(Convert.ChangeType(valueStrs[i], schema.columnInfo[i].colType));
         }

         return (new BlueRow(schema, values.ToArray()));
      }
      #endregion

      #region state
      private string myFile;
      #endregion
   }
}