# 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, incorporated herein by reference.

import bdiff, mpatch, re, struct, util, md5

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'''

    defaults = {

        'context': 3,

        'text': False,

        'showfunc': False,

        'git': False,

        'nodates': False,

        'ignorews': False,

        'ignorewsamount': False,

        'ignoreblanklines': 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)

defaultopts = diffopts()

def wsclean(opts, text):

    if opts.ignorews:

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

    elif opts.ignorewsamount:

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

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

    if opts.ignoreblanklines:

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

    return text

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)):

        def h(v):

            # md5 is used instead of sha1 because md5 is supposedly faster

            return md5.new(v).digest()

        if a and b and len(a) == len(b) and h(a) == h(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(bunidiff(a, b, al, bl, "a/" + fn1, "b/" + fn2, opts=opts))

        if not l: return ""

        # difflib uses a space, rather than a tab

        l[0] = "%s%s" % (l[0][:-2], datetag(ad))

        l[1] = "%s%s" % (l[1][:-2], 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, "diff %s %s\n" %

                    (' '.join(["-r %s" % rev for rev in r]), fn1))

    return "".join(l)

# somewhat self contained replacement for difflib.unified_diff

# t1 and t2 are the text to be diffed

# l1 and l2 are the text broken up into lines

# header1 and header2 are the filenames for the diff output

def bunidiff(t1, t2, l1, l2, header1, header2, 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

    def yieldhunk(hunk, header):

        if header:

            for x in header:

                yield x

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

        aend = contextend(a2, len(l1))

        alen = aend - astart

        blen = b2 - bstart + aend - a2

        func = ""

        if opts.showfunc:

            # walk backwards from the start of the context

            # to find a line starting with an alphanumeric char.

            for x in xrange(astart, -1, -1):

                t = l1[x].rstrip()

                if funcre.match(t):

                    func = ' ' + t[:40]

                    break

        yield "@@ -%d,%d +%d,%d @@%s\n" % (astart + 1, alen,

                                           bstart + 1, blen, func)

        for x in delta:

            yield x

        for x in xrange(a2, aend):

            yield ' ' + l1[x]

    header = [ "--- %s\t\n" % header1, "+++ %s\t\n" % header2 ]

    if opts.showfunc:

        funcre = re.compile('\w')

    # 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.

    #

    diff = bdiff.blocks(t1, t2)

    hunk = None

    for i in xrange(len(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 = []

        s1 = diff[i]

        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.ignorews or opts.ignorewsamount or 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, header):

                    yield x

                # we only want to yield the header if the files differ, and

                # we only want to yield it once.

                header = None

        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, header):

            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):

    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