﻿// Copyright © 2008, 2014, Oracle and/or its affiliates. All rights reserved.
//
// MySQL Connector/NET is licensed under the terms of the GPLv2
// <http://www.gnu.org/licenses/old-licenses/gpl-2.0.html>, like most 
// MySQL Connectors. There are special exceptions to the terms and 
// conditions of the GPLv2 as it is applied to this software, see the 
// FLOSS License Exception
// <http://www.mysql.com/about/legal/licensing/foss-exception.html>.
//
// This program is free software; you can redistribute it and/or modify 
// it under the terms of the GNU General Public License as published 
// by the Free Software Foundation; version 2 of the License.
//
// This program is distributed in the hope that it will be useful, but 
// WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
// or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 
// for more details.
//
// You should have received a copy of the GNU General Public License along 
// with this program; if not, write to the Free Software Foundation, Inc., 
// 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA

using System.Collections.Generic;
using System.Text;
using System;
using System.Collections;
using System.Diagnostics;
#if EF6
using System.Data.Entity.Core.Common.CommandTrees;
using System.Data.Entity.Core.Metadata.Edm;
#else
using System.Data.Metadata.Edm;
using System.Data.Common.CommandTrees;
#endif


namespace MySql.Data.Entity
{
  class SelectStatement : InputFragment
  {
    private Dictionary<string, ColumnFragment> columnHash;
    private bool hasRenamedColumns;
    private SqlGenerator generator;

    public SelectStatement(SqlGenerator generator)
      : base(null)
    {
      Columns = new List<ColumnFragment>();
      this.generator = generator;
    }

    public InputFragment From;
    public List<ColumnFragment> Columns { get; private set; }
    public SqlFragment Where;
    public SqlFragment Limit;
    public SqlFragment Skip;
    public List<SqlFragment> GroupBy { get; internal set; }
    public List<SortFragment> OrderBy { get; internal set; }
    public bool IsDistinct;

    public void AddGroupBy(SqlFragment f)
    {
      if (GroupBy == null)
        GroupBy = new List<SqlFragment>();
      GroupBy.Add(f);
    }

    public void AddOrderBy(SortFragment f)
    {
      if (OrderBy == null)
        OrderBy = new List<SortFragment>();
      OrderBy.Add(f);
    }

    public override void WriteSql(StringBuilder sql)
    {
      if (IsWrapped)
        sql.Append("(");
      sql.Append("SELECT");
      if (IsDistinct)
        sql.Append(" DISTINCT ");

      WriteList(Columns, sql);

      if (From != null)
      {
        sql.Append("\r\nFROM ");
        From.WriteSql(sql);
      }
      if (Where != null)
      {
        sql.Append("\r\n WHERE ");
        Where.WriteSql(sql);
      }
      if (GroupBy != null)
      {
        sql.Append("\r\n GROUP BY ");
        WriteList(GroupBy, sql);
      }
      WriteOrderBy(sql);
      if (Limit != null || Skip != null)
      {
        sql.Append(" LIMIT ");
        if (Skip != null)
          sql.AppendFormat("{0},", Skip);
        if (Limit == null)
          sql.Append("18446744073709551615");
        else
          sql.AppendFormat("{0}", Limit);
      }
      if (IsWrapped)
      {
        sql.Append(")");
        if (Name != null)
          sql.AppendFormat(" AS {0}", QuoteIdentifier(Name));
      }
    }

    private void WriteOrderBy(StringBuilder sql)
    {
      if (OrderBy == null) return;
      sql.Append("\r\n ORDER BY ");
      WriteList(OrderBy, sql);
    }

    public override void Wrap(Scope scope)
    {
      base.Wrap(scope);

      // now we need to add default columns if necessary
      if (Columns.Count == 0)
        AddDefaultColumns(scope);

      // next we need to remove child extents of the select from scope
      if (Name != null)
      {
        scope.Remove(this);
        scope.Add(Name, this);
      }
    }

    void AddDefaultColumns(Scope scope)
    {
      if (columnHash == null)
        columnHash = new Dictionary<string, ColumnFragment>();

      List<ColumnFragment> columns = GetDefaultColumnsForFragment(From);
      bool Exists = false;
      if (From is TableFragment && scope.GetFragment((From as TableFragment).Table) == null)
      {
        scope.Add((From as TableFragment).Table, From);
        Exists = true;
      }

      foreach (ColumnFragment column in columns)
      {
        // first we need to set the input for this column
        InputFragment input = scope.FindInputFromProperties(column.PropertyFragment);
        column.TableName = input.Name;

        // then we rename the column if necessary
        if (columnHash.ContainsKey(column.ColumnName.ToUpper()))
        {
          column.ColumnAlias = MakeColumnNameUnique(column.ColumnName);
          columnHash.Add(column.ColumnAlias, column);
        }
        else
          columnHash.Add(column.ColumnName.ToUpper(), column);
        Columns.Add(column);
      }
      if (Exists)
      {
        scope.Remove((From as TableFragment).Table, From);
      }
    }

    internal void AddColumn(ColumnFragment column, Scope scope)
    {
      InputFragment input = scope.FindInputFromProperties(column.PropertyFragment);
      column.TableName = input.Name;

      // then we rename the column if necessary
      if (columnHash.ContainsKey(column.ColumnName.ToUpper()))
      {
        column.ColumnAlias = MakeColumnNameUnique(column.ColumnName);
        columnHash.Add(column.ColumnAlias, column);
      }
      else
      {
        if( !string.IsNullOrEmpty(column.ColumnAlias) )
          columnHash.Add(column.ColumnAlias.ToUpper(), column);
        else
          columnHash.Add(column.ColumnName.ToUpper(), column);
      }
      Columns.Add(column);
    }

    List<ColumnFragment> GetDefaultColumnsForFragment(InputFragment input)
    {
      List<ColumnFragment> columns = new List<ColumnFragment>();

      if (input is TableFragment)
      {
        return GetDefaultColumnsForTable(input as TableFragment);
      }
      else if (input is JoinFragment || input is UnionFragment)
      {
        Debug.Assert(input.Left != null);
        if (input is UnionFragment)
        {
          generator.Ops.Push(OpType.Union);
        }
        columns = GetDefaultColumnsForFragment(input.Left);
        if (input is JoinFragment && input.Right != null)
        {
          List<ColumnFragment> right = GetDefaultColumnsForFragment(input.Right);
          columns.AddRange(right);
        }
        if (input is UnionFragment)
        {
          generator.Ops.Pop();
        }
      }
      else if (input is SelectStatement)
      {
        SelectStatement select = input as SelectStatement;
        foreach (ColumnFragment cf in select.Columns)
        {
          ColumnFragment newColumn = new ColumnFragment(cf.TableName,
              string.IsNullOrEmpty(cf.ColumnAlias) ? cf.ActualColumnName : cf.ColumnAlias
              );
          if ( generator.GetTopOp() == OpType.Join )
          {
            newColumn.ColumnAlias = cf.ColumnAlias;
            newColumn.PushInput(cf.ColumnName);
            if (cf.TableName != null)
              newColumn.PushInput(cf.TableName);
          }
          else
          {
            newColumn.PushInput(cf.ActualColumnName);
            if (cf.TableName != null && cf.ColumnAlias == null)
              newColumn.PushInput(cf.TableName);
          }
          if (select.Name != null)
          {
            newColumn.PushInput(select.Name);      // add the scope 
          }
          columns.Add(newColumn);
        }
        return columns;
      }
      else
        throw new NotImplementedException();
      if (!String.IsNullOrEmpty(input.Name) && input.Name != From.Name)
        foreach (ColumnFragment c in columns)
        {
            c.PushInput(input.Name);
        }
      return columns;
    }

    List<ColumnFragment> GetDefaultColumnsForTable(TableFragment table)
    {
      List<ColumnFragment> columns = new List<ColumnFragment>();

      foreach (EdmProperty property in Metadata.GetProperties(table.Type.EdmType))
      {
        ColumnFragment col = new ColumnFragment(table.Name, property.Name);
        col.PushInput(property.Name);
        col.PushInput((table.Name != null) ? table.Name : table.Table);
        columns.Add(col);
      }
      return columns;
    }

    private string MakeColumnNameUnique(string baseName)
    {
      int i = 1;
      baseName = baseName.ToUpper();
      hasRenamedColumns = true;
      while (true)
      {
        string name = String.Format("{0}{1}", baseName, i);
        if (!columnHash.ContainsKey(name)) return name;
        i++;
      }
    }

    public bool HasDifferentNameForColumn(ColumnFragment column)
    {
      if (!hasRenamedColumns) return false;      
      foreach (ColumnFragment c in Columns)
      {
        if (!c.Equals(column)) continue;
        if (String.IsNullOrEmpty(c.ColumnAlias)) return false;
        column.ColumnName = c.ColumnAlias;
        return true;
      }
      return false;
    }

    public bool IsCompatible(DbExpressionKind expressionKind)
    {
      switch (expressionKind)
      {
        case DbExpressionKind.Filter:
          return Where == null && Columns.Count == 0;
        case DbExpressionKind.Project:
          return Columns.Count == 0;
        case DbExpressionKind.Limit:
          return Limit == null;
        case DbExpressionKind.Skip:
          return Skip == null;
        case DbExpressionKind.Sort:
          return Columns.Count == 0 &&
              GroupBy == null &&
              OrderBy == null;
        case DbExpressionKind.GroupBy:
          return Columns.Count == 0 &&
              GroupBy == null &&
              OrderBy == null &&
              Limit == null;
      }
      throw new InvalidOperationException();
    }

    internal override void Accept(SqlFragmentVisitor visitor)
    {
      if (From != null) From.Accept(visitor);
      if (Columns != null)
      {
        foreach (ColumnFragment cf in Columns)
        {
          cf.Accept(visitor);
        }
      }
      if (Where != null) Where.Accept(visitor);
      if (Limit != null) Limit.Accept(visitor);
      if (Skip != null) Skip.Accept(visitor);
      if (GroupBy != null)
      {
        foreach (SqlFragment grp in GroupBy)
        {
          grp.Accept(visitor);
        }
      }
      if (OrderBy != null)
      {
        foreach (SortFragment sort in OrderBy)
        {
          sort.Accept(visitor);
        }
      }

      visitor.Visit(this);

    }
  }
}
