# mdiff.py - diff and patch routines for mercurial

#

# Copyright 2005, 2006 Matt Mackall <mpm@selenic.com>

#

# This software may be used and distributed according to the terms of the

# GNU General Public License version 2 or any later version.

from i18n import _

import bdiff, mpatch, util

import re, struct

def splitnewlines(text):

    '''like str.splitlines, but only split on newlines.'''

    lines = [l + '\n' for l in text.split('\n')]

    if lines:

        if lines[-1] == '\n':

            lines.pop()

        else:

            lines[-1] = lines[-1][:-1]

    return lines

class diffopts(object):

    '''context is the number of context lines

    text treats all files as text

    showfunc enables diff -p output

    git enables the git extended patch format

    nodates removes dates from diff headers

    ignorews ignores all whitespace changes in the diff

    ignorewsamount ignores changes in the amount of whitespace

    ignoreblanklines ignores changes whose lines are all blank

    upgrade generates git diffs to avoid data loss

    '''

    defaults = {

        'context': 3,

        'text': False,

        'showfunc': False,

        'git': False,

        'nodates': False,

        'ignorews': False,

        'ignorewsamount': False,

        'ignoreblanklines': False,

        'upgrade': False,

        }

    __slots__ = defaults.keys()

    def __init__(self, **opts):

        for k in self.__slots__:

            v = opts.get(k)

            if v is None:

                v = self.defaults[k]

            setattr(self, k, v)

        try:

            self.context = int(self.context)

        except ValueError:

            raise util.Abort(_('diff context lines count must be '

                               'an integer, not %r') % self.context)

    def copy(self, **kwargs):

        opts = dict((k, getattr(self, k)) for k in self.defaults)

        opts.update(kwargs)

        return diffopts(**opts)

defaultopts = diffopts()

def wsclean(opts, text, blank=True):

    if opts.ignorews:

        text = re.sub('[ \t\r]+', '', text)

    elif opts.ignorewsamount:

        text = re.sub('[ \t\r]+', ' ', text)

        text = text.replace(' \n', '\n')

    if blank and opts.ignoreblanklines:

        text = re.sub('\n+', '', text)

    return text

def diffline(revs, a, b, opts):

    parts = ['diff']

    if opts.git:

        parts.append('--git')

    if revs and not opts.git:

        parts.append(' '.join(["-r %s" % rev for rev in revs]))

    if opts.git:

        parts.append('a/%s' % a)

        parts.append('b/%s' % b)

    else:

        parts.append(a)

    return ' '.join(parts) + '\n'

def unidiff(a, ad, b, bd, fn1, fn2, r=None, opts=defaultopts):

    def datetag(date, addtab=True):

        if not opts.git and not opts.nodates:

            return '\t%s\n' % date

        if addtab and ' ' in fn1:

            return '\t\n'

        return '\n'

    if not a and not b:

        return ""

    epoch = util.datestr((0, 0))

    if not opts.text and (util.binary(a) or util.binary(b)):

        if a and b and len(a) == len(b) and a == b:

            return ""

        l = ['Binary file %s has changed\n' % fn1]

    elif not a:

        b = splitnewlines(b)

        if a is None:

            l1 = '--- /dev/null%s' % datetag(epoch, False)

        else:

            l1 = "--- %s%s" % ("a/" + fn1, datetag(ad))

        l2 = "+++ %s%s" % ("b/" + fn2, datetag(bd))

        l3 = "@@ -0,0 +1,%d @@\n" % len(b)

        l = [l1, l2, l3] + ["+" + e for e in b]

    elif not b:

        a = splitnewlines(a)

        l1 = "--- %s%s" % ("a/" + fn1, datetag(ad))

        if b is None:

            l2 = '+++ /dev/null%s' % datetag(epoch, False)

        else:

            l2 = "+++ %s%s" % ("b/" + fn2, datetag(bd))

        l3 = "@@ -1,%d +0,0 @@\n" % len(a)

        l = [l1, l2, l3] + ["-" + e for e in a]

    else:

        al = splitnewlines(a)

        bl = splitnewlines(b)

        l = list(_unidiff(a, b, al, bl, opts=opts))

        if not l:

            return ""

        l.insert(0, "--- a/%s%s" % (fn1, datetag(ad)))

        l.insert(1, "+++ b/%s%s" % (fn2, datetag(bd)))

    for ln in xrange(len(l)):

        if l[ln][-1] != '\n':

            l[ln] += "\n\ No newline at end of file\n"

    if r:

        l.insert(0, diffline(r, fn1, fn2, opts))

    return "".join(l)

# creates a headerless unified diff

# t1 and t2 are the text to be diffed

# l1 and l2 are the text broken up into lines

def _unidiff(t1, t2, l1, l2, opts=defaultopts):

    def contextend(l, len):

        ret = l + opts.context

        if ret > len:

            ret = len

        return ret

    def contextstart(l):

        ret = l - opts.context

        if ret < 0:

            return 0

        return ret

    lastfunc = [0, '']

    def yieldhunk(hunk):

        (astart, a2, bstart, b2, delta) = hunk

        aend = contextend(a2, len(l1))

        alen = aend - astart

        blen = b2 - bstart + aend - a2

        func = ""

        if opts.showfunc:

            lastpos, func = lastfunc

            # walk backwards from the start of the context up to the start of

            # the previous hunk context until we find a line starting with an

            # alphanumeric char.

            for i in xrange(astart - 1, lastpos - 1, -1):

                if l1[i][0].isalnum():

                    func = ' ' + l1[i].rstrip()[:40]

                    lastfunc[1] = func

                    break

            # by recording this hunk's starting point as the next place to

            # start looking for function lines, we avoid reading any line in

            # the file more than once.

            lastfunc[0] = astart

        for x in delta:

            yield x

        for x in xrange(a2, aend):

            yield ' ' + l1[x]

    # bdiff.blocks gives us the matching sequences in the files.  The loop

    # below finds the spaces between those matching sequences and translates

    # them into diff output.

    #

    if opts.ignorews or opts.ignorewsamount:

        t1 = wsclean(opts, t1, False)

        t2 = wsclean(opts, t2, False)

    diff = bdiff.blocks(t1, t2)

    hunk = None

    for i, s1 in enumerate(diff):

        # The first match is special.

        # we've either found a match starting at line 0 or a match later

        # in the file.  If it starts later, old and new below will both be

        # empty and we'll continue to the next match.

        if i > 0:

            s = diff[i - 1]

        else:

            s = [0, 0, 0, 0]

        delta = []

        a1 = s[1]

        a2 = s1[0]

        b1 = s[3]

        b2 = s1[2]

        old = l1[a1:a2]

        new = l2[b1:b2]

        # bdiff sometimes gives huge matches past eof, this check eats them,

        # and deals with the special first match case described above

        if not old and not new:

            continue

        if opts.ignoreblanklines:

            if wsclean(opts, "".join(old)) == wsclean(opts, "".join(new)):

                continue

        astart = contextstart(a1)

        bstart = contextstart(b1)

        prev = None

        if hunk:

            # join with the previous hunk if it falls inside the context

            if astart < hunk[1] + opts.context + 1:

                prev = hunk

                astart = hunk[1]

                bstart = hunk[3]

            else:

                for x in yieldhunk(hunk):

                    yield x

        if prev:

            # we've joined the previous hunk, record the new ending points.

            hunk[1] = a2

            hunk[3] = b2

            delta = hunk[4]

        else:

            # create a new hunk

            hunk = [astart, a2, bstart, b2, delta]

        delta[len(delta):] = [' ' + x for x in l1[astart:a1]]

        delta[len(delta):] = ['-' + x for x in old]

        delta[len(delta):] = ['+' + x for x in new]

    if hunk:

        for x in yieldhunk(hunk):

            yield x

def patchtext(bin):

    pos = 0

    t = []

    while pos < len(bin):

        p1, p2, l = struct.unpack(">lll", bin[pos:pos + 12])

        pos += 12

        t.append(bin[pos:pos + l])

        pos += l

    return "".join(t)

def patch(a, bin):

    if len(a) == 0:

        # skip over trivial delta header

        return buffer(bin, 12)

    return mpatch.patches(a, [bin])

# similar to difflib.SequenceMatcher.get_matching_blocks

def get_matching_blocks(a, b):

    return [(d[0], d[2], d[1] - d[0]) for d in bdiff.blocks(a, b)]

def trivialdiffheader(length):

    return struct.pack(">lll", 0, 0, length)

patches = mpatch.patches

patchedsize = mpatch.patchedsize

textdiff = bdiff.bdiff