#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
#    visa_study.py - Alternative high-level VISA implementation
#
#    Copyright © 2005, 2006, 2007, 2008
#                Torsten Bronger <bronger@physik.rwth-aachen.de>,
#                Gregor Thalhammer <gth@users.sourceforge.net>.
#  
#    This file is part of PyVISA.
#  
#    PyVISA is free software; you can redistribute it and/or modify it under
#    the terms of the MIT licence:
#
#    Permission is hereby granted, free of charge, to any person obtaining a
#    copy of this software and associated documentation files (the "Software"),
#    to deal in the Software without restriction, including without limitation
#    the rights to use, copy, modify, merge, publish, distribute, sublicense,
#    and/or sell copies of the Software, and to permit persons to whom the
#    Software is furnished to do so, subject to the following conditions:
#
#    The above copyright notice and this permission notice shall be included in
#    all copies or substantial portions of the Software.
#
#    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
#    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
#    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
#    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
#    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
#    DEALINGS IN THE SOFTWARE.
#

"""visa_study.py defines an Python interface to the VISA library
"""

__version__ = "$Revision: 334 $"
# $Source$

from ctypes import *
from visa_messages import *
from vpp43_types import *
from vpp43_constants import *
from visa_attributes import attributes_s, attributes
import os
import types
import sys
import logging

log = logging.getLogger('visa')


#load Visa library
if os.name == 'nt':
    visa = windll.visa32
elif os.name == 'posix':
    visa = cdll.LoadLibrary('libvisa.so')
else:
    raise "No implementation for your platform available."
    

class VisaError(IOError):
    """Base class for VISA errors"""
    def __init__(self, value):
        self.value = value
        
    def __str__(self):
        if self.value:
            (shortdesc, longdesc) = completion_and_error_messages[self.value]
            hexvalue = self.value #convert errorcodes (negative) to long
            if hexvalue < 0:
                hexvalue = hexvalue + 0x100000000L
            return shortdesc + " (%X): "%hexvalue + longdesc
            
#Checks return values for errors
def CheckStatus(status):
    #status = ViStatus(status).value
    if status < 0:
        raise VisaError(status)
    else:
        return status
    
#implement low level VISA functions

#VISA Resource Management
visa.viOpenDefaultRM.restype = CheckStatus
visa.viOpen.restype = CheckStatus
visa.viFindRsrc.restype = CheckStatus
visa.viFindNext.restype = CheckStatus
visa.viParseRsrc.restype = CheckStatus
visa.viParseRsrcEx.restype = CheckStatus
visa.viClose.restype    = CheckStatus
visa.viGetAttribute.restype = CheckStatus
visa.viSetAttribute.restype = CheckStatus

def OpenDefaultRM():
    """Return a session to the Default Resource Manager resource."""
    sesn = ViSession()
    result = visa.viOpenDefaultRM(byref(sesn))
    return (result, sesn.value)

def Open(sesn, rsrcName, accessMode, openTimeout):
    """Open a session to the specified device."""
    sesn = ViSession(sesn)
    rsrcName = ViRsrc(rsrcName)
    accessMode = ViAccessMode(accessMode)
    openTimout = ViUInt32(openTimeout)
    vi = ViSession()
    result = visa.viOpen(sesn, rsrcName, accessMode, openTimeout, byref(vi))
    return (result, vi.value)

def FindRsrc(session, expr):
    """Query a VISA system to locate the resources associated with a
    specified interface.

    This operation matches the value specified in the expr parameter
    with the resources available for a particular interface.

    In comparison to the original VISA function, this returns the
    complete list of found resources."""

    sesn = ViSession(session)
    expr = ViString(expr)
    findList = ViFindList()
    retcnt = ViUInt32()
    instrDesc = c_buffer('\000', 256)

    resource_list = []
    result = visa.viFindRsrc(sesn, expr, byref(findList), byref(retcnt), instrDesc)
    if result>=0:
        resource_list.append(instrDesc.value)
        for i in range(1, retcnt.value):
            visa.viFindNext(findList, instrDesc)
            resource_list.append(instrDesc.value)
        visa.viClose(findList)
    return resource_list

def ParseRsrc(sesn, rsrcName):
    """Parse a resource string to get the interface information."""
    intfType = ViUInt16()
    intfNum = ViUInt16()
    result = visa.viParseRsrc(
        ViSession(sesn),
        ViRsrc(rsrcName),
        byref(intfType),
        byref(intfNum))
    return (result, intfType.value, intfNum.value)

def ParseRsrcEx(sesn, rsrcName):
    """Parse a resource string to get extended interface information."""
    intfType = ViUInt16()
    intfNum = ViUInt16()
    rsrcClass = c_buffer(256)
    unaliasedExpandedRsrcName = c_buffer(256)
    aliasIfExists = c_buffer(256)
    result = visa.viParseRsrcEx(sesn, rsrcName, byref(intfType), byref(intfNum),
                                rsrcClass, unaliasedExpandedRsrcName, aliasIfExists)
    return (result, intfType.value, intfNum.value, rsrcClass.value,
            unaliasedExpandedRsrcName.value, aliasIfExists.value)


    
#VISA Resource Template

def Close(object):
    """Close the specified session, event, or find list.

    This operation closes a session, event, or a find list. In this
    process all the data structures that had been allocated for the
    specified vi are freed."""
    result = visa.viClose(ViObject(object))
    return result

def GetAttribute(vi, attribute):
    """Retrieve the state of an attribute. Argument can be numeric or
    string argument"""
    #convert argument to numeric (attr_value)
    if isinstance(attribute, types.StringTypes):
        attr_name, attr_info = attribute, attributes_s[attribute]
        attr_value = attr_info.attribute_value
    else:
        attr_value,  attr_info = attribute, attributes[attribute]
        attr_name = attr_info.attribute_name

    #call viGetAttribute, convert output to proper data type
    attr_type = attr_info.datatype
    if attr_type is ViString:
        attr_val = c_buffer(256)
        result = visa.viGetAttribute(vi, attr_value, attr_val)
    elif attr_type is ViBuf:
        attr_val = c_void_p()
        result = visa.viGetAttribute(vi, attr_value, byref(attr_val))
    else:
        attr_val = attr_type(attr_value)
        result = visa.viGetAttribute(vi, attr_value, byref(attr_val))
    val = attr_val.value

    #convert result to string
    if attr_info.values:
        value_ext = attr_info.values.tostring(val)
    else:
        if isinstance(val, (types.IntType, types.LongType)):
            value_ext = str(val) + " (%s)"%hex(val)
        else:
            value_ext = str(val)
    
    return (attr_name, val, value_ext)

def SetAttribute(vi, attribute, value):
    """Set attribute"""
    #convert attribute to numeric ('attr_value')
    if isinstance(attribute, types.StringTypes):
        attr_name, attr_info = attribute, attributes_s[attribute]
        attr_value = attr_info.attribute_value
    else:
        attr_value,  attr_info = attribute, attributes[attribute]
        attr_name = attr_info.attribute_name

    #convert value to numeric ('val'), when appropriate
    if isinstance(value, types.StringTypes):
        if attr_info.values: 
            val = attr_info.values.fromstring(value)
        else: #fallback, FIXME
            val = str(value)
            print 'conversion from string argument not possible'
    else:
        val = value

    cval = attr_info.datatype(val)
    result = visa.viSetAttribute(vi, attr_value, cval)

    return result

#Basic I/O

visa.viWrite.restype = CheckStatus
def Write(vi, buf):
    vi = ViSession(vi)
    buf = c_buffer(buf, len(buf))
    count = ViUInt32(len(buf))
    retCount = ViUInt32()
    log.debug("Write: %s", buf)
    result = visa.viWrite(vi, buf, count, byref(retCount))
    return retCount.value

visa.viRead.restype = CheckStatus
def Read(vi, count):
    vi = ViSession(vi)
    buf = create_string_buffer(count)
    count = ViUInt32(count)
    retCount = ViUInt32()
    result = visa.viRead(vi, buf, count, byref(retCount))
    log.debug("Read: buffer length %d at %s", sizeof(buf), hex(addressof(buf)))
    return (result, buf.raw[0:retCount.value])

visa.viWriteAsync.restype = CheckStatus
def WriteAsync(vi, buf):
    vi = ViSession(vi)
    buf = c_buffer(buf, len(buf))
    count = ViUInt32(len(buf))
    jobId = ViJobId()
    result = visa.viWriteAsync(vi, buf, count, byref(jobId))
    return jobId.value

visa.viReadAsync.restype = CheckStatus
def ReadAsync(vi, count):
    buf = create_string_buffer(count) #FIXME: buffer needs to survive garbage collection!
    jobId = ViJobId()
    log.debug("ReadAsync: buffer length %d at %s", sizeof(buf), hex(addressof(buf)))
    visa.viReadAsync(ViSession(vi),
                     buf,
                     ViUInt32(count),
                     byref(jobId))
    return jobId.value
    

#

visa.viGpibControlREN.restype = CheckStatus
def GpibControlREN(vi, mode):
    vi = ViSession(vi)
    mode = ViUInt16(mode)
    result = visa.viGpibControlREN(vi, mode)


#Event management

visa.viEnableEvent.restype = CheckStatus
def EnableEvent(vi, eventType, mechanism):
    visa.viEnableEvent(vi, eventType, mechanism, 0)

visa.viInstallHandler.restype = CheckStatus
visa.viInstallHandler.argtypes = [ViSession, ViEventType, ViHndlr, ViAddr]
#FIXME: dangerous ViAddr
def InstallHandler(vi, eventType, handler, userHandle):
    userHandle = ViAddr(userHandle)
    visa.viInstallHandler(vi, eventType, handler, userHandle)


#higher level classes and metho)ds

class ResourceManager:
    def __init__(self):
        result, self.session = OpenDefaultRM()

    def __del__(self):
        Close(self.session)

    def find_resource(self, expression):
        resource_list = FindRsrc(self.session, expression)
        return resource_list

    def parse_resource(self, resource_name):
        """give information about resource"""
        result, interface_type, interface_number, \
                rsrcClass, unaliasedExpandedRsrcName, \
                aliasIfExists = ParseRsrcEx(self.session, resource_name)
        return interface_type, interface_number, \
               rsrcClass, unaliasedExpandedRsrcName, \
               aliasIfExists

    def open(self, resourceName, exclusiveLock = None, loadConfig = None, openTimeout = 1000):
        accessMode = 0
        if exclusiveLock:
            accessMode = accessMode | VI_EXCLUSIVE_LOCK
        if loadConfig:
            accessMode = accessMode | VI_LOAD_CONFIG
        result, vi = Open(self.session, resourceName, accessMode, openTimeout)
        return Resource(vi)


class Resource:
    def __init__(self, vi):
        self.session = vi

    #def __del__(self): #shit happens
    #    self.close()

    def write(self, buf):
        return Write(self.session, buf)

    def read(self, maxcount = None):
        if maxcount:
            result, buf = Read(self.session, maxcount)
            return buf
        else:
            accumbuf = ''
            while 1:
                result, buf = Read(self.session, 1024)
                accumbuf = accumbuf + buf
                if result in (VI_SUCCESS, VI_SUCCESS_TERM_CHAR):
                    return accumbuf

    def getattr(self, attribute):
        attrvalue = GetAttribute(self.session, attribute)
        return attrvalue

    def setattr(self, attribute, value):
        SetAttribute(self.session, attribute, value)

                
    def setlocal(self):
        #VI_GPIB_REN_DEASSERT        = 0 
        #VI_GPIB_REN_ASSERT          = 1
        #VI_GPIB_REN_DEASSERT_GTL    = 2
        #VI_GPIB_REN_ASSERT_ADDRESS  = 3
        #VI_GPIB_REN_ASSERT_LLO      = 4
        #VI_GPIB_REN_ASSERT_ADDRESS_LLO = 5
        #VI_GPIB_REN_ADDRESS_GTL     = 6

        mode = 6
        #Test Marconi 2019: 0 local, 1 remote, 2 local, 4 local lockout, 5 local, 6 local
        GpibControlREN(self.session, mode)
        
    def close(self):
        Close(self.session)

    def install_handler(self, eventType, handler, user_handle):
        return InstallHandler(self.session,
                              eventType,
                              handler,
                              user_handle)

    def enable_event(self, eventType, mechanism):
        return EnableEvent(self.session, eventType, mechanism)
    
#_RM = ResourceManager() #liefert Exception in __del__ beim Beenden
#open = _RM.Open
#find_resource = _RM.FindResource

#for faster testing
def testvisa():

    logging.basicConfig(level = logging.DEBUG)
    #log.setLevel(logging.DEBUG) #FIXME
    
    #open ResourceManager
    RM = ResourceManager()

    #find resources
    resourcelist = RM.find_resource('ASRL?::INSTR')
    print resourcelist

    #get some information without opening
    result = RM.parse_resource('ASRL1::INSTR')
    print result

    #open
    device = RM.open('ASRL1::INSTR')

    #high level write
    device.write('*IDN?')

    #high level read
    #print device.read() #don't wan't to wait for timeout...

    #try getting all attributes
    for key in attributes_s.keys():
        try:
            print device.getattr(key)
        except IOError, value:
            print "Error retrieving Attribute ", key

    #set some attributes, try different combinations of numeric/string arguments
    device.setattr('VI_ATTR_ASRL_DATA_BITS', 7)
    print device.getattr(VI_ATTR_ASRL_DATA_BITS)

    #attribute value, string argument
    device.setattr(VI_ATTR_ASRL_STOP_BITS, 'VI_ASRL_STOP_TWO')
    print device.getattr('VI_ATTR_ASRL_STOP_BITS')
    print

    #bitfields
    device.setattr('VI_ATTR_ASRL_FLOW_CNTRL', VI_ASRL_FLOW_XON_XOFF | VI_ASRL_FLOW_RTS_CTS)
    print device.getattr('VI_ATTR_ASRL_FLOW_CNTRL')

    #bitfield with string argument
    device.setattr(VI_ATTR_ASRL_FLOW_CNTRL, 'VI_ASRL_FLOW_NONE')
    print device.getattr('VI_ATTR_ASRL_FLOW_CNTRL')
    
    #callback functions
    
    def event_handler(vi, event_type, context, userhandle):
    #def event_handler(vi, event_type, context): #FIX: should accept four arguments
        sys.stdout.flush()
        print 'in event handler'
        print 'vi: ', vi
        print 'event_type: ', event_type
        print 'context: ', context

        print GetAttribute(context, VI_ATTR_EVENT_TYPE)
        print GetAttribute(context, VI_ATTR_STATUS)
        print GetAttribute(context, VI_ATTR_JOB_ID)
        print GetAttribute(context, VI_ATTR_BUFFER)
        print GetAttribute(context, VI_ATTR_RET_COUNT)
        print GetAttribute(context, VI_ATTR_OPER_NAME)
        print 'userhandle: ', userhandle
        print 'leaving event handler'

        return VI_SUCCESS

    device.install_handler(VI_EVENT_IO_COMPLETION, ViHndlr(event_handler), 13)

    device.enable_event(VI_EVENT_IO_COMPLETION, VI_HNDLR)

    print 'session', device.session
    jobId = WriteAsync(device.session, 'going to nowhere city')
    print "jobId: ", jobId

    jobId = ReadAsync(device.session, 10)
    print "jobId: ", jobId
        
    device.close()

if __name__ == '__main__':
    testvisa()