#!@PYTHON@
""" Remote log reader for Pacemaker's Cluster Test Suite (CTS)

Reads a specified number of lines from the supplied offset
Returns the current offset
Contains logic for handling truncation
"""

# Pacemaker targets compatibility with Python 2.7 and 3.2+
from __future__ import print_function, unicode_literals, absolute_import, division

__copyright__ = "Copyright 2014-2018 the Pacemaker project contributors"
__license__ = "GNU General Public License version 2 or later (GPLv2+) WITHOUT ANY WARRANTY"

import sys
import os
import fcntl

if __name__ == '__main__':

    limit    = 0
    offset   = 0
    prefix   = ''
    filename = '/var/log/messages'

    skipthis=None
    args=sys.argv[1:]
    for i in range(0, len(args)):
        if skipthis:
            skipthis=None
            continue

        elif args[i] == '-l' or args[i] == '--limit':
            skipthis=1
            limit = int(args[i+1])

        elif args[i] == '-f' or args[i] == '--filename':
            skipthis=1
            filename = args[i+1]

        elif args[i] == '-o' or args[i] == '--offset':
            skipthis=1
            offset = args[i+1]

        elif args[i] == '-p' or args[i] == '--prefix':
            skipthis=1
            prefix = args[i+1]

        elif args[i] == '-t' or args[i] == '--tag':
            skipthis=1

    if not os.access(filename, os.R_OK):
        print(prefix + 'Last read: %d, limit=%d, count=%d - unreadable' % (0, limit, 0))
        sys.exit(1)

    logfile=open(filename, 'r')
    logfile.seek(0, os.SEEK_END)
    newsize=logfile.tell()

    if offset != 'EOF':
        offset = int(offset)
        if newsize >= offset:
            logfile.seek(offset)
        else:
            print(prefix + ('File truncated from %d to %d' % (offset, newsize)))
            if (newsize*1.05) < offset:
                logfile.seek(0)
            # else: we probably just lost a few logs after a fencing op
            #       continue from the new end
            # TODO: accept a timestamp and discard all messages older than it

    # Don't block when we reach EOF
    fcntl.fcntl(logfile.fileno(), fcntl.F_SETFL, os.O_NONBLOCK)

    count = 0
    while True:
        if logfile.tell() >= newsize:   break
        elif limit and count >= limit: break

        line = logfile.readline()
        if not line: break

        print(line.strip())
        count += 1

    print(prefix + 'Last read: %d, limit=%d, count=%d' % (logfile.tell(), limit, count))
    logfile.close()