#!/usr/bin/env python

import logging
import os
import re
import sre_constants
import subprocess
import sys
import tempfile

LOG_FORMAT = '%(asctime)-15s %(message)s'
LOG_LEVEL = logging.DEBUG
LOGGER = None

def setupLogging():
    global LOGGER
    if not LOGGER:
        logging.basicConfig(format=LOG_FORMAT, level=LOG_LEVEL)
        LOGGER = logging.getLogger('gcooper-pr-editor')

def info(fmt, *args, **kwargs):
    global LOGGER
    setupLogging()
    LOGGER.info(fmt, *args, **kwargs)

def warning(fmt, *args, **kwargs):
    global LOGGER
    setupLogging()
    LOGGER.warning(fmt, *args, **kwargs)

def error(fmt, *args, **kwargs):
    global LOGGER
    setupLogging()
    LOGGER.error(fmt, *args, **kwargs)
    sys.exit(1)

def SetUserEmail(file_path, user_name, user_mail):
    '''Change the email address of a user in file 'file_path'.

    Edit a file at 'file_path' in place, and replace the email address in
    lines that match the pattern:

        User Name <User Mail>


    with the new email address specified as 'user_mail'.

    Args:
        file_path       (str) The path of the file to edit.
        user_name       (str) The name of the user to search for.  Only lines
                        that contain both this user name *and* an email
                        address, enclosed in <> characters, are affected.
        user_mail       (str) The new email address to use for lines that
                        match the user's name.
    '''
    info('Preparing match/replace patterns')
    match_pattern = ''
    matcher = None
    try:
        match_pattern = r'^.*\b(%s)\s*<(\S+)>.*$' % (user_name)
        replace_pattern = r'%s\s*<\S+>' % (user_name)
        replace_text = '%s <%s>' % (user_name, user_mail)
        matcher = re.compile(match_pattern)
    except sre_constants.error, e:
        error('Cannot compile match/replace patterns', match_pattern)
        return None
    info('Match pattern    = "%s"', match_pattern)
    info('Replace pattern  = "%s"', replace_pattern)
    info('Replacement text = "%s"', replace_text)

    try:
        (fd, ftemp_path) = tempfile.mkstemp()
        ftemp = os.fdopen(fd, 'w+')
        with file(file_path) as finput:
            for line in finput.readlines():
                text = line
                m = matcher.match(line)
                if m:
                    text = re.sub(replace_pattern, replace_text, line)
                ftemp.write(text)
            ftemp.flush()
            info('Input file copied at %s', ftemp_path)

            cmd = [ 'diff', '-u', file_path, ftemp_path ]
            proc = subprocess.Popen(cmd, stdout=subprocess.PIPE)
            info('Changes applied:')
            for line in proc.stdout:
                info('  %s', line.rstrip())
        ftemp.close()
        info('Replacing file %s with %s', file_path, ftemp_path)
        os.rename(ftemp_path, file_path)
    except IOError, e:
        error('Cannot edit input file at %s -- %s', file_path, str(e))
    return None

if __name__ == '__main__':
    setupLogging()

    user_name = 'Garrett Cooper'
    user_mail = 'yaneurabeya@gmail.com'
    for filename in sys.argv[1:]:
        SetUserEmail(filename, user_name, user_mail)