"""
Helper script to rebuild virtualenv.py from virtualenv_support
"""

import re
import os

here = os.path.dirname(__file__)
script = os.path.join(here, '..', 'virtualenv.py')

file_regex = re.compile(
    r'##file (.*?)\n([a-zA-Z][a-zA-Z0-9_]+)\s*=\s*"""\n(.*?)"""\.decode\("base64"\)\.decode\("zlib"\)\n',
    re.S)

file_template = '##file %(filename)s\n%(varname)s = """\n%(data)s""".decode("base64").decode("zlib")\n'

def rebuild():
    f = open(script, 'rb')
    content = f.read()
    f.close()
    parts = []
    last_pos = 0
    match = None
    for match in file_regex.finditer(content):
        parts.append(content[last_pos:match.start()])
        last_pos = match.end()
        filename = match.group(1)
        varname = match.group(2)
        data = match.group(3)
        print 'Found reference to file %s' % filename
        f = open(os.path.join(here, '..', 'virtualenv_support', filename), 'rb')
        c = f.read()
        f.close()
        new_data = c.encode('zlib').encode('base64')
        if new_data == data:
            print '  Reference up to date (%s bytes)' % len(c)
            parts.append(match.group(0))
            continue
        print '  Content changed (%s bytes -> %s bytes)' % (
            zipped_len(data), len(c))
        new_match = file_template % dict(
            filename=filename,
            varname=varname,
            data=new_data)
        parts.append(new_match)
    parts.append(content[last_pos:])
    new_content = ''.join(parts)
    if new_content != content:
        print 'Content updated; overwriting...',
        f = open(script, 'wb')
        f.write(new_content)
        f.close()
        print 'done.'
    else:
        print 'No changes in content'
    if match is None:
        print 'No variables were matched/found'

def zipped_len(data):
    if not data:
        return 'no data'
    try:
        return len(data.decode('base64').decode('zlib'))
    except:
        return 'unknown'

if __name__ == '__main__':
    rebuild()