#
# The Logging Module
#


import os,sys,time


#
# Module globals
# This are changed by the indicated accessor functions.
#
gUseLogFile = 1                 # Set by 'ToFile()' and ToScreen()'
gUseScreen = 0                  # Set by 'ToFile()' and ToScreen()'
gLogFileName = 'logging.txt'    # Set by 'ToFile()'.
gAutoNewLine = 0                # See 'AutoNewLine()'
gTimeStampNextWrite = 0
gTimeStampTime = time.time()


#
# The functions below are not for external consumption. They implement
#


def WriteRaw(msg):
    if gUseScreen:
        sys.stdout.write(msg)
    if gUseLogFile:
        
        # timestamp calculations need to be made for every write to allow server processes
        # which may run for months on end
        
        fn = gLogFileName
        # Append month to end of file name.
        t = time.localtime()
        fn = fn + ' ' + str(t[1]) + '-' + str(t[0])
        fn = fn + '.txt'
        
        # removing the text flag as it is not cross platform
        #f = os.open(fn, os.O_CREAT | os.O_APPEND | os.O_TEXT | os.O_WRONLY)
        
        f = os.open(fn, os.O_CREAT | os.O_APPEND | os.O_WRONLY)
        os.fdopen(f, 'w').write(msg)


#
# The following functions make up the interface to this module.
#

def ToFile(fn, alsoToScreen = 0):
    '''
    Start sending log messages to the text file indicated by 'fn'. 'fn' should not end with
    any extension. The month and ".txt" will be appended to whatever file name you pass.
    '''
    global gUseScreen, gUseLogFile, gLogFileName
    
    # Remove extension if present. Save the root file name in a global to be used by WriteRaw
    if fn[-4:] == '.txt' or fn[-4:] == '.TXT': fn = fn[:-4]

    gUseScreen = alsoToScreen
    gUseLogFile = 1
    gLogFileName = fn


def ToScreen():
    '''
    Start sending log messages to the screen.
    '''
    global gUseScreen, gUseLogFile
    gUseScreen = 1
    gUseLogFile = 0


def ToFileAndScreen(fn):
    ToFile(fn, 1)


def AutoNewLine(b):
    '''
    Set whether or not a new line character should automatically be
    appending to the end of all calls to 'Write()'. Pass '1' to append the
    new line, '0' to not.
    '''
    global gAutoNewLine
    gAutoNewLine = b


def TimeStamp():
    '''
    Write a time stamp to the current logging device.
    '''
    WriteRaw('--------------------------------------------------------------------\n')
    if gTimeStampNextWrite:
        WriteRaw(time.ctime(gTimeStampTime) + '\n')
    else:
        WriteRaw(time.ctime() + '\n')
    WriteRaw('\n')


def TimeStampNextWrite():
    global gTimeStampNextWrite, gTimeStampTime
    gTimeStampNextWrite = 1
    gTimeStampTime = time.time()


def CancelTimeStamp():
    global gTimeStampNextWrite
    gTimeStampNextWrite = 0


def Write(msg):
    '''
    Write a log message to the output device.
    '''
    global gTimeStampNextWrite
    if gTimeStampNextWrite:
        TimeStamp()
        gTimeStampNextWrite = 0
    if gAutoNewLine:
        WriteRaw(msg + '\n')
    else:
        WriteRaw(msg)