#!/usr/bin/env python
#
# Make simple revision merges much easier
#
# Copyright (c) 2006 Philipp von Weitershausen
#
# Usage: ezmerge rev branch [path]
#    or: ezmerge beginrev:endrev branch [path]
#

import os
import popen2

def revs(rev):
    """
    Make sense out of convenient way of mentioning revisions

    For example, the revision 43 starts at r42 and ends at r43:

      >>> revs('43')
      (42, '43')

    Revision ranges are also supported:

      >>> revs('42:21252')
      (41, 21252)
      >>> revs('42:HEAD')
      (41, 'HEAD')

    Even reverse diffs that undo certain revisions are supported
    correctly:

      >>> revs('42:41') # undo r42
      (42, 41)
    """
    if ':' in rev:
        rev, endrev = rev.split(':')
        rev = int(rev)
        if not endrev == 'HEAD':
            endrev = int(endrev)
        if rev < endrev:
            rev -= 1
    else:
        endrev = rev
        rev = int(rev) - 1
    return rev, endrev

def svninfo(path):
    """
    Return svn information about ``path``.
    """
    stdout, stdin = popen2.popen2('svn info %s' % path)
    return stdout.read()

def determinebranch(branch, path, svninfo=svninfo):
    """
    Let's set up a dummy 'svn info' command handler:

      >>> def dummyinfo(path):
      ...     return '''\
      ... Path: .
      ... URL: http://dev.worldcookery.com/svn/bla/trunk/blergh
      ... Repository UUID: ab69c8a2-bfcb-0310-9bff-acb20127a769
      ... Revision: 1654
      ... Node Kind: directory
      ... '''

    ``determinebranch()`` takes the svn path of the current working
    directory path and mangles in either trunk or a branch repository
    path.  Here's an example for turning 'trunk' into 'branches':

      >>> determinebranch('foobar', '.', svninfo=dummyinfo)
      'http://dev.worldcookery.com/svn/bla/branches/foobar/blergh'

    Of course, if the current working copy is a trunk and we specify
    trunk, it keeps the trunk:

      >>> determinebranch('trunk', '.', svninfo=dummyinfo)
      'http://dev.worldcookery.com/svn/bla/trunk/blergh'

    Here's the whole thing the other way around:

      >>> def dummyinfo(path):
      ...     return '''\
      ... Path: .
      ... URL: http://dev.worldcookery.com/svn/bla/branches/foobar/blergh
      ... Repository UUID: ab69c8a2-bfcb-0310-9bff-acb20127a769
      ... Revision: 1654
      ... Node Kind: directory
      ... '''

      >>> determinebranch('trunk', '.', svninfo=dummyinfo)
      'http://dev.worldcookery.com/svn/bla/trunk/blergh'
 
    """
    lines = svninfo(path).splitlines()
    if lines[1].startswith('URL: '):
        url = lines[1][5:]
    else:
        url = lines[2][5:]

    chunks = url.split('/')
    chunks.reverse()
    new_chunks = []

    while chunks:
        ch = chunks.pop()
        if ch in ('branch', 'branches'):
            chunks.pop()
            if branch == 'trunk':
                new_chunks.append(branch)
            else:
                new_chunks.append(ch)
                new_chunks.append(branch)
        elif ch == 'trunk' and branch != 'trunk':
            new_chunks.append('branches')
            new_chunks.append(branch)
        else:
            new_chunks.append(ch)

    return '/'.join(new_chunks)

def main(argv):
    assert len(argv) in (3, 4)
    rev = argv[1]
    branch = argv[2]
    path = '.'
    if len(argv) == 4:
        path = sys.argv[3]

    beginrev, endrev = revs(rev)
    branch = determinebranch(branch, path)
    cmd = "svn merge -r %s:%s %s %s" % (beginrev, endrev, branch, path)
    print cmd
    os.system(cmd)

if __name__ == '__main__':
    import sys
    if sys.argv[1] == 'test':
        import doctest
        doctest.testmod()
    else:
        main(sys.argv)