#
# DBD::ADO
#
# Copyright (c) 2001, 2002 Michael Neumann <neumann@s-direktnet.de>
# 
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without 
# modification, are permitted provided that the following conditions 
# are met:
# 1. Redistributions of source code must retain the above copyright 
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright 
#    notice, this list of conditions and the following disclaimer in the 
#    documentation and/or other materials provided with the distribution.
# 3. The name of the author may not be used to endorse or promote products
#    derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
# INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
# AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
# THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
# OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
# WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
# OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
# ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
# $Id$
#

require "win32ole"

module DBI
module DBD
module ADO

VERSION          = "0.1"
USED_DBD_VERSION = "0.1"

class Driver < DBI::BaseDriver

  def initialize
    super(USED_DBD_VERSION)
  end

  def connect(dbname, user, auth, attr)
    # connect to database

    handle = WIN32OLE.new('ADODB.Connection')
    handle.Open(dbname)
    handle.BeginTrans()  # start new Transaction

    return Database.new(handle, attr)
  rescue RuntimeError => err
    raise DBI::DatabaseError.new(err.message)
  end

end

class Database < DBI::BaseDatabase
 
  def disconnect
    @handle.RollbackTrans()
    @handle.Close()
  rescue RuntimeError => err
    raise DBI::DatabaseError.new(err.message)
  end

  def prepare(statement)
    # TODO: create Command instead?
    Statement.new(@handle, statement, self)
  end

  def commit
    # TODO: raise error if AutoCommit on => better in DBI?
    @handle.CommitTrans()
    @handle.BeginTrans()
  rescue RuntimeError => err
    raise DBI::DatabaseError.new(err.message)
  end

  def rollback
    # TODO: raise error if AutoCommit on => better in DBI?
    @handle.RollbackTrans()
    @handle.BeginTrans()
  rescue RuntimeError => err
    raise DBI::DatabaseError.new(err.message)
  end

  def []=(attr, value)
    if attr == 'AutoCommit' then
      # TODO: commit current transaction?
      @attr[attr] = value
    else
      super
    end
  end


end # class Database


class Statement < DBI::BaseStatement
  include SQL::BasicBind
  include SQL::BasicQuote

  def initialize(handle, statement, db)
    @handle = handle
    @statement = statement
    @params = []
    @db = db
  end

  def bind_param(param, value, attribs)
    raise InterfaceError, "only ? parameters supported" unless param.is_a? Fixnum

    @params[param-1] = value 
  end

  def execute
    # TODO: use Command and Parameter
    # TODO: substitute all ? by the parametes
    sql = bind(self, @statement, @params)
    @res_handle = @handle.Execute(sql) 

    # TODO: SELECT and AutoCommit finishes the result-set
    #       what to do?
    if @db['AutoCommit'] == true and not SQL.query?(@statement) then
      @db.commit
    end

  rescue RuntimeError => err
    raise DBI::DatabaseError.new(err.message)
  end

  def finish
    # if DCL, DDL or INSERT UPDATE and DELETE, this gives an Error
    # because no Result-Set is available
    if @res_handle.Fields.Count() != 0 then
      @res_handle.Close()
    end
  rescue RuntimeError => err
    raise DBI::DatabaseError.new(err.message)
  end

  def fetch        
    retval = fetch_currentrow
    @res_handle.MoveNext() unless retval.nil?
    retval
  rescue RuntimeError => err
    raise DBI::DatabaseError.new(err.message)
  end



  def fetch_scroll(direction, offset)
    case direction
    when DBI::SQL_FETCH_NEXT
      return fetch
    when DBI::SQL_FETCH_PRIOR
      # TODO: check if already the first?
      #return nil if @res_handle.AbsolutePosition()
      @res_handle.MovePrevious()
      return fetch_currentrow
    when DBI::SQL_FETCH_FIRST
      @res_handle.MoveFirst()
      return fetch_currentrow
    when DBI::SQL_FETCH_LAST
      @res_handle.MoveLast()
      return fetch_currentrow
    when DBI::SQL_FETCH_RELATIVE
      @res_handle.Move(offset)
      return fetch_currentrow
    when DBI::SQL_FETCH_ABSOLUTE
      ap = @res_handle.AbsolutePositon()      
      @res_handle.Move(offset-ap)
      return fetch_currentrow      
    else
      raise DBI::InterfaceError
    end    
  rescue RuntimeError => err
    raise DBI::DatabaseError.new(err.message)
  end

  def column_info
    num_cols = @res_handle.Fields().Count()
    retval = Array.new(num_cols)

    for i in 0...num_cols do
      retval[i] = {'name' => @res_handle.Fields(i).Name()}
    end

    retval
  rescue RuntimeError => err
    raise DBI::DatabaseError.new(err.message)
  end

  def rows
    # TODO: how to get the RPC in ADO? 
    nil
  end

  
  private

  def fetch_currentrow    
    return nil if @res_handle.EOF() or @res_handle.BOF()
      
    # TODO: don't create new Array each time
    num_cols = @res_handle.Fields().Count()
    retval = Array.new(num_cols)

    for i in 0...num_cols do
      retval[i] = @res_handle.Fields(i).Value()
    end
  
    retval
  end
  

end


end # module ADO
end # module DBD
end # module DBI