#! /usr/bin/python

# Copyright (C) 2005 Canonical Ltd

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

# Author: Martin Pool <mbp@canonical.com>




"""Store and retrieve weaves in files.

There is one format marker followed by a blank line, followed by a
series of version headers, followed by the weave itself.

Each version marker has 'i' and the included previous versions, then
'1' and the SHA-1 of the text, if known.  The inclusions do not need
to list versions included by a parent.

The weave is bracketed by 'w' and 'W' lines, and includes the '{}[]'
processing instructions.  Lines of text are prefixed by '.' if the
line contains a newline, or ',' if not.
"""

# TODO: When extracting a single version it'd be enough to just pass
# an iterator returning the weave lines...

FORMAT_1 = '# bzr weave file v3\n'


def write_weave(weave, f, format=None):
    if format == None or format == 1:
        return write_weave_v1(weave, f)
    else:
        raise ValueError("unknown weave format %r" % format)


def write_weave_v1(weave, f):
    """Write weave to file f."""
    print >>f, FORMAT_1,

    for version, included in enumerate(weave._v):
        if included:
            # mininc = weave.minimal_parents(version)
            mininc = included
            print >>f, 'i',
            for i in mininc:
                print >>f, i,
            print >>f
        else:
            print >>f, 'i'
        print >>f, '1', weave._sha1s[version]
        print >>f

    print >>f, 'w'

    for l in weave._l:
        if isinstance(l, tuple):
            assert l[0] in '{}[]'
            print >>f, '%s %d' % l
        else: # text line
            if not l:
                print >>f, ', '
            elif l[-1] == '\n':
                assert l.find('\n', 0, -1) == -1
                print >>f, '.', l,
            else:
                assert l.find('\n') == -1
                print >>f, ',', l

    print >>f, 'W'



def read_weave(f):
    return read_weave_v1(f)


def read_weave_v1(f):
    from weave import Weave, WeaveFormatError
    w = Weave()

    wfe = WeaveFormatError
    l = f.readline()
    if l != FORMAT_1:
        raise WeaveFormatError('invalid weave file header: %r' % l)

    ver = 0
    while True:
        l = f.readline()
        if l[0] == 'i':
            ver += 1

            if len(l) > 2:
                included = map(int, l[2:].split(' '))
                w._addversion(included)
            else:
                w._addversion(None)

            l = f.readline()[:-1]
            assert l.startswith('1 ')
            w._sha1s.append(l[2:])
                
            l = f.readline()
            assert l == '\n'
        elif l == 'w\n':
            break
        else:
            raise WeaveFormatError('unexpected line %r' % l)

    while True:
        l = f.readline()
        if l == 'W\n':
            break
        elif l.startswith('. '):
            w._l.append(intern(l[2:]))  # include newline
        elif l.startswith(', '):
            w._l.append(l[2:-1])        # exclude newline
        else:
            assert l[0] in '{}[]', l
            assert l[1] == ' ', l
            w._l.append((intern(l[0]), int(l[2:])))

    return w