# 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 __future__ import absolute_import

import re

import struct

import zlib

from .i18n import _

from . import (

    error,

    policy,

    pycompat,

    util,

)

bdiff = policy.importmod(r'bdiff')

mpatch = policy.importmod(r'mpatch')

blocks = bdiff.blocks

fixws = bdiff.fixws

patches = mpatch.patches

patchedsize = mpatch.patchedsize

textdiff = bdiff.bdiff

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

    nobinary ignores binary files

    noprefix disables the 'a/' and 'b/' prefixes (ignored in plain mode)

    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,

        'nobinary': False,

        'noprefix': False,

        'index': 0,

        'ignorews': False,

        'ignorewsamount': False,

        'ignoreblanklines': False,

        'upgrade': False,

        'showsimilarity': False,

        }

    def __init__(self, **opts):

        opts = pycompat.byteskwargs(opts)

        for k in self.defaults.keys():

            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 error.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 = bdiff.fixws(text, 1)

    elif opts.ignorewsamount:

        text = bdiff.fixws(text, 0)

    if blank and opts.ignoreblanklines:

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

    return text

def splitblock(base1, lines1, base2, lines2, opts):

    # The input lines matches except for interwoven blank lines. We

    # transform it into a sequence of matching blocks and blank blocks.

    lines1 = [(wsclean(opts, l) and 1 or 0) for l in lines1]

    lines2 = [(wsclean(opts, l) and 1 or 0) for l in lines2]

    s1, e1 = 0, len(lines1)

    s2, e2 = 0, len(lines2)

    while s1 < e1 or s2 < e2:

        i1, i2, btype = s1, s2, '='

        if (i1 >= e1 or lines1[i1] == 0

            or i2 >= e2 or lines2[i2] == 0):

            # Consume the block of blank lines

            btype = '~'

            while i1 < e1 and lines1[i1] == 0:

                i1 += 1

            while i2 < e2 and lines2[i2] == 0:

                i2 += 1

        else:

            # Consume the matching lines

            while i1 < e1 and lines1[i1] == 1 and lines2[i2] == 1:

                i1 += 1

                i2 += 1

        yield [base1 + s1, base1 + i1, base2 + s2, base2 + i2], btype

        s1 = i1

        s2 = i2

def hunkinrange(hunk, linerange):

    """Return True if `hunk` defined as (start, length) is in `linerange`

    defined as (lowerbound, upperbound).

    >>> hunkinrange((5, 10), (2, 7))

    True

    >>> hunkinrange((5, 10), (6, 12))

    True

    >>> hunkinrange((5, 10), (13, 17))

    True

    >>> hunkinrange((5, 10), (3, 17))

    True

    >>> hunkinrange((5, 10), (1, 3))

    False

    >>> hunkinrange((5, 10), (18, 20))

    False

    >>> hunkinrange((5, 10), (1, 5))

    False

    >>> hunkinrange((5, 10), (15, 27))

    False

    """

    start, length = hunk

    lowerbound, upperbound = linerange

    return lowerbound < start + length and start < upperbound

def blocksinrange(blocks, rangeb):

    """filter `blocks` like (a1, a2, b1, b2) from items outside line range

    `rangeb` from ``(b1, b2)`` point of view.

    Return `filteredblocks, rangea` where:

    * `filteredblocks` is list of ``block = (a1, a2, b1, b2), stype`` items of

      `blocks` that are inside `rangeb` from ``(b1, b2)`` point of view; a

      block ``(b1, b2)`` being inside `rangeb` if

      ``rangeb[0] < b2 and b1 < rangeb[1]``;

    * `rangea` is the line range w.r.t. to ``(a1, a2)`` parts of `blocks`.

    """

    lbb, ubb = rangeb

    lba, uba = None, None

    filteredblocks = []

    for block in blocks:

        (a1, a2, b1, b2), stype = block

        if lbb >= b1 and ubb <= b2 and stype == '=':

            # rangeb is within a single "=" hunk, restrict back linerange1

            # by offsetting rangeb

            lba = lbb - b1 + a1

            uba = ubb - b1 + a1

        else:

            if b1 <= lbb < b2:

                if stype == '=':

                    lba = a2 - (b2 - lbb)

                else:

                    lba = a1

            if b1 < ubb <= b2:

                if stype == '=':

                    uba = a1 + (ubb - b1)

                else:

                    uba = a2

        if hunkinrange((b1, (b2 - b1)), rangeb):

            filteredblocks.append(block)

    if lba is None or uba is None or uba < lba:

        raise error.Abort(_('line range exceeds file size'))

    return filteredblocks, (lba, uba)

def allblocks(text1, text2, opts=None, lines1=None, lines2=None):

    """Return (block, type) tuples, where block is an mdiff.blocks

    line entry. type is '=' for blocks matching exactly one another

    (bdiff blocks), '!' for non-matching blocks and '~' for blocks

    matching only after having filtered blank lines.

    line1 and line2 are text1 and text2 split with splitnewlines() if

    they are already available.

    """

    if opts is None:

        opts = defaultopts

    if opts.ignorews or opts.ignorewsamount:

        text1 = wsclean(opts, text1, False)

        text2 = wsclean(opts, text2, False)

    diff = bdiff.blocks(text1, text2)

    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]

        s = [s[1], s1[0], s[3], s1[2]]

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

        # and deals with the special first match case described above

        if s[0] != s[1] or s[2] != s[3]:

            type = '!'

            if opts.ignoreblanklines:

                if lines1 is None:

                    lines1 = splitnewlines(text1)

                if lines2 is None:

                    lines2 = splitnewlines(text2)

                old = wsclean(opts, "".join(lines1[s[0]:s[1]]))

                new = wsclean(opts, "".join(lines2[s[2]:s[3]]))

                if old == new:

                    type = '~'

            yield s, type

        yield s1, '='

def unidiff(a, ad, b, bd, fn1, fn2, opts=defaultopts):

    """Return a unified diff as a (headers, hunks) tuple.

    If the diff is not null, `headers` is a list with unified diff header

    lines "--- <original>" and "+++ <new>" and `hunks` is a generator yielding

    (hunkrange, hunklines) coming from _unidiff().

    Otherwise, `headers` and `hunks` are empty.

    """

    def datetag(date, fn=None):

        if not opts.git and not opts.nodates:

            return '\t%s' % date

        if fn and ' ' in fn:

            return '\t'

        return ''

    sentinel = [], ()

    if not a and not b:

        return sentinel

    if opts.noprefix:

        aprefix = bprefix = ''

    else:

        aprefix = 'a/'

        bprefix = 'b/'

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

    fn1 = util.pconvert(fn1)

    fn2 = util.pconvert(fn2)

    def checknonewline(lines):

        for text in lines:

            if text[-1:] != '\n':

                text += "\n\ No newline at end of file\n"

            yield text

    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 sentinel

        headerlines = []

        hunks = (None, ['Binary file %s has changed\n' % fn1]),

    elif not a:

        b = splitnewlines(b)

        if a is None:

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

        else:

            l1 = "--- %s%s%s" % (aprefix, fn1, datetag(ad, fn1))

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

        headerlines = [l1, l2]

        size = len(b)

        hunkrange = (0, 0, 1, size)

        hunklines = ["@@ -0,0 +1,%d @@\n" % size] + ["+" + e for e in b]

        hunks = (hunkrange, checknonewline(hunklines)),

    elif not b:

        a = splitnewlines(a)

        l1 = "--- %s%s%s" % (aprefix, fn1, datetag(ad, fn1))

        if b is None:

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

        else:

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

        headerlines = [l1, l2]

        size = len(a)

        hunkrange = (1, size, 0, 0)

        hunklines = ["@@ -1,%d +0,0 @@\n" % size] + ["-" + e for e in a]

        hunks = (hunkrange, checknonewline(hunklines)),

    else:

        diffhunks = _unidiff(a, b, opts=opts)

        try:

            hunkrange, hunklines = next(diffhunks)

        except StopIteration:

            return sentinel

        headerlines = [

            "--- %s%s%s" % (aprefix, fn1, datetag(ad, fn1)),

            "+++ %s%s%s" % (bprefix, fn2, datetag(bd, fn2)),

        ]

        def rewindhunks():

            yield hunkrange, checknonewline(hunklines)

            for hr, hl in diffhunks:

                yield hr, checknonewline(hl)

        hunks = rewindhunks()

    return headerlines, hunks

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

    """Yield hunks of a headerless unified diff from t1 and t2 texts.

    Each hunk consists of a (hunkrange, hunklines) tuple where `hunkrange` is a

    tuple (s1, l1, s2, l2) representing the range information of the hunk to

    form the '@@ -s1,l1 +s2,l2 @@' header and `hunklines` is a list of lines

    of the hunk combining said header followed by line additions and

    deletions.

    """

    l1 = splitnewlines(t1)

    l2 = splitnewlines(t2)

    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

        # zero-length hunk ranges report their start line as one less

        if alen:

            astart += 1

        if blen:

            bstart += 1

        hunkrange = astart, alen, bstart, blen

        hunklines = (

            ["@@ -%d,%d +%d,%d @@%s\n" % (hunkrange + (func,))]