using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using HeuristicLab.BackgroundProcessing;
using System.Data;
using HeuristicLab.OKB.Client;
using HeuristicLab.OKB.Cockpit.Admin.OKBTables;

namespace HeuristicLab.OKB.Cockpit.Admin {

  public class TableLoadWorker : ObservableBackgroundWorker {

    public string TableName { get; private set; }
    public DataTable Table { get; private set; }
    public Dictionary<string, DataTable> ForeignKeys { get; private set; }
    private bool loadForeignKeys;

    public TableLoadWorker(string tableName, bool loadForeignKeys)
      : base("loading " + tableName) {
      WorkerReportsProgress = true;
      WorkerSupportsCancellation = true;
      TableName = tableName;
      this.loadForeignKeys = loadForeignKeys;
      DoWork += (s, a) => {
        Table = loadTable(TableName);
        if (loadForeignKeys)
          ForeignKeys = LoadForeignKeys();
      };
    }

    private DataTable loadTable(string tableName) {
      ReportProgress(0);
      TableServiceClient client = ClientFactory.Create<TableServiceClient, ITableService>();
      int nRows = 0;
      DataTable table = client.PrepareDataTable(out nRows, tableName);
      int stepSize = Math.Max(1, Math.Min(nRows / 100, 200));
      if (nRows > 0) {
        DataTable newRows = new DataTable();
        do {
          newRows = client.GetNextRows(stepSize);
          table.Merge(newRows);
          ReportProgress(100 * table.Rows.Count / nRows);
        } while (!CancellationPending && newRows.Rows.Count > 0);
      }
      client.FinishFetchingRows();
      client.Close();
      return table;
    }

    private Dictionary<string, DataTable> LoadForeignKeys() {
      var fk = new Dictionary<string, DataTable>();
      Name = "loading referenced tables";
      var foreignKeyColumns = Table.Columns.Cast<DataColumn>()
        .Where(c => c.ColumnName.EndsWith("Id") && c.ColumnName.Length > 2);
      foreach (var column in foreignKeyColumns) {
        string tableName = column.ColumnName.Substring(0, column.ColumnName.Length - 2);
        DataTable referencedTable = loadTable(tableName);
        fk[column.ColumnName] = referencedTable;
      }
      return fk;
    }
  }
}