#!/usr/bin/env python
# ScalerFactory.py
#   Copyright (C) 2006 CCLRC, Graeme Winter
#
#   This code is distributed under the BSD license, a copy of which is
#   included in the root directory of this package.
#
# 21/SEP/06

import os
import sys
import copy

if not os.environ.has_key('XIA2_ROOT'):
    raise RuntimeError, 'XIA2_ROOT not defined'
if not os.environ.has_key('XIA2CORE_ROOT'):
    raise RuntimeError, 'XIA2CORE_ROOT not defined'

sys.path.append(os.path.join(os.environ['XIA2CORE_ROOT'], 'Python'))
sys.path.append(os.path.join(os.environ['XIA2_ROOT']))

# scaler implementations
from CCP4ScalerR import CCP4ScalerR
from CCP4ScalerA import CCP4ScalerA
from XDSScalerR import XDSScalerR
from XDSScalerA import XDSScalerA

# selection stuff
from Handlers.PipelineSelection import get_preferences

# other odds and ends
from DriverExceptions.NotAvailableError import NotAvailableError
from Handlers.Streams import Debug

def Scaler():
    '''Create a Scaler implementation.'''

    scaler = None
    preselection = get_preferences().get('scaler')

    if not scaler and \
       (not preselection or preselection == 'ccp4r'):
        try:
            scaler = CCP4ScalerR()
            Debug.write('Using CCP4R Scaler')
        except NotAvailableError, e:
            if preselection == 'ccp4r':
                raise RuntimeError, 'preselected scaler ccp4r not available'
            pass

    if not scaler and \
       (not preselection or preselection == 'ccp4a'):
        try:
            scaler = CCP4ScalerA()
            Debug.write('Using CCP4A Scaler')
        except NotAvailableError, e:
            if preselection == 'ccp4a':
                raise RuntimeError, 'preselected scaler ccp4a not available'
            pass

    if not scaler and \
       (not preselection or preselection == 'xdsr'):
        try:
            scaler = XDSScalerR()
            Debug.write('Using XDSR Scaler')
        except NotAvailableError, e:
            if preselection == 'xdsr':
                raise RuntimeError, 'preselected scaler xdsr not available'
        pass

    if not scaler and \
       (not preselection or preselection == 'xdsa'):
        try:
            scaler = XDSScalerA()
            Debug.write('Using XDSA Scaler')
        except NotAvailableError, e:
            if preselection == 'xdsa':
                raise RuntimeError, 'preselected scaler xdsa not available'
        pass

    return scaler