#!/usr/bin/env python

import os, sys, struct, stat

import difflib

import re

from optparse import OptionParser

from mercurial.bdiff import bdiff, blocks

VERSION="0.2"

usage = "usage: %prog [options] file1 file2"

parser = OptionParser(usage=usage)

parser.add_option("-d", "--difflib", action="store_true", default=False)

parser.add_option('-x', '--count', default=1)

parser.add_option('-c', '--context', type="int", default=3)

parser.add_option('-p', '--show-c-function', action="store_true", default=False)

parser.add_option('-w', '--ignore-all-space', action="store_true", 

                  default=False)

(options, args) = parser.parse_args()

if not args:

    parser.print_help()

    sys.exit(1)

# 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]

                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 = 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

# simple utility function to put all the

# files from a directory tree into a dict

def buildlist(names, top):

    tlen = len(top)

    for root, dirs, files in os.walk(top):

        l = root[tlen + 1:]

        for x in files:

            p = os.path.join(root, x)

            st = os.lstat(p)

            if stat.S_ISREG(st.st_mode):

                names[os.path.join(l, x)] = (st.st_dev, st.st_ino)

def diff_files(file1, file2):

    if file1 == None:

        b = file(file2).read().splitlines(1)

        l1 = "--- %s\n" % (file2)

        l2 = "+++ %s\n" % (file2)

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

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

    elif file2 == None:

        a = file(file1).read().splitlines(1)

        l1 = "--- %s\n" % (file1)

        l2 = "+++ %s\n" % (file1)

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

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

    else:

        t1 = file(file1).read()

        t2 = file(file2).read()

        l1 = t1.splitlines(1)

        l2 = t2.splitlines(1)

        if options.difflib:

            l = difflib.unified_diff(l1, l2, file1, file2)

        else:

            l = bunidiff(t1, t2, l1, l2, file1, file2, context=options.context,

                     showfunc=options.show_c_function,

                     ignorews=options.ignore_all_space)

    for x in l:

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

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

        print x,

file1 = args[0]

file2 = args[1]

if os.path.isfile(file1) and os.path.isfile(file2):

    diff_files(file1, file2)

elif os.path.isdir(file1):

    if not os.path.isdir(file2):

        sys.stderr.write("file types don't match\n")

        sys.exit(1)

    d1 = {}

    d2 = {}

    buildlist(d1, file1)

    buildlist(d2, file2)

    keys = d1.keys()

    keys.sort()

    for x in keys:

        if x not in d2:

            f2 = None

        else:

            f2 = os.path.join(file2, x)

            st1 = d1[x]

            st2 = d2[x]

            del d2[x]

            if st1[0] == st2[0] and st1[1] == st2[1]:

                sys.stderr.write("%s is a hard link\n" % x)

                continue

        x = os.path.join(file1, x)

        diff_files(x, f2)

    keys = d2.keys()

    keys.sort()

    for x in keys:

        f1 = None

        x = os.path.join(file2, x)

        diff_files(f1, x)