# 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")

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:

        b = b.splitlines(1)

        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:

        a = a.splitlines(1)

        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:

        al = a.splitlines(1)

        bl = b.splitlines(1)

        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

textdiff = bdiff.bdiff