# mdiff.py - diff and patch routines for mercurial

#

# Copyright 2005 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.

from demandload import demandload

import struct, bdiff, util, mpatch

demandload(globals(), "re")

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

def unidiff(a, ad, b, bd, fn, r=None, text=False,

            showfunc=False, ignorews=False):

    if not a and not b: return ""

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

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

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

    elif not a:

        if a is None:

            l1 = "--- %s\t%s\n" % ("/dev/null", epoch)

        else:

            l1 = "--- %s\t%s\n" % ("a/" + fn, ad)

        l2 = "+++ %s\t%s\n" % ("b/" + fn, bd)

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

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

    elif not b:

        l1 = "--- %s\t%s\n" % ("a/" + fn, ad)

        if b is None:

            l2 = "+++ %s\t%s\n" % ("/dev/null", epoch)

        else:

            l2 = "+++ %s\t%s\n" % ("b/" + fn, bd)

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

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

    else:

        l = list(bunidiff(a, b, al, bl, "a/" + fn, "b/" + fn,

                          showfunc=showfunc, ignorews=ignorews))

        if not l: return ""

        # difflib uses a space, rather than a tab

        l[0] = "%s\t%s\n" % (l[0][:-2], ad)

        l[1] = "%s\t%s\n" % (l[1][:-2], 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]), fn))

    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

# context is the number of context lines

# showfunc enables diff -p output

# ignorews ignores all whitespace changes in the diff

def bunidiff(t1, t2, l1, l2, header1, header2, context=3, showfunc=False,

             ignorews=False):

    def contextend(l, len):

        ret = l + context

        if ret > len:

            ret = len

        return ret

    def contextstart(l):

        ret = l - 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 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 showfunc:

        funcre = re.compile('\w')

    if ignorews:

        wsre = re.compile('[ \t]')

    # 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 ignorews:

            wsold = wsre.sub('', "".join(old))

            wsnew = wsre.sub('', "".join(new))

            if wsold == wsnew:

                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] + 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])

patches = mpatch.patches

patchedsize = mpatch.patchedsize

textdiff = bdiff.bdiff