# bdiff.py - CFFI implementation of bdiff.c
#
# Copyright 2016 Maciej Fijalkowski <fijall@gmail.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 struct

from ..pure.bdiff import *
from . import _bdiff

ffi = _bdiff.ffi
lib = _bdiff.lib

if True:
    if True:
        def blocks(sa, sb):
            a = ffi.new("struct bdiff_line**")
            b = ffi.new("struct bdiff_line**")
            ac = ffi.new("char[]", str(sa))
            bc = ffi.new("char[]", str(sb))
            l = ffi.new("struct bdiff_hunk*")
            try:
                an = lib.bdiff_splitlines(ac, len(sa), a)
                bn = lib.bdiff_splitlines(bc, len(sb), b)
                if not a[0] or not b[0]:
                    raise MemoryError
                count = lib.bdiff_diff(a[0], an, b[0], bn, l)
                if count < 0:
                    raise MemoryError
                rl = [None] * count
                h = l.next
                i = 0
                while h:
                    rl[i] = (h.a1, h.a2, h.b1, h.b2)
                    h = h.next
                    i += 1
            finally:
                lib.free(a[0])
                lib.free(b[0])
                lib.bdiff_freehunks(l.next)
            return rl

        def bdiff(sa, sb):
            a = ffi.new("struct bdiff_line**")
            b = ffi.new("struct bdiff_line**")
            ac = ffi.new("char[]", str(sa))
            bc = ffi.new("char[]", str(sb))
            l = ffi.new("struct bdiff_hunk*")
            try:
                an = lib.bdiff_splitlines(ac, len(sa), a)
                bn = lib.bdiff_splitlines(bc, len(sb), b)
                if not a[0] or not b[0]:
                    raise MemoryError
                count = lib.bdiff_diff(a[0], an, b[0], bn, l)
                if count < 0:
                    raise MemoryError
                rl = []
                h = l.next
                la = lb = 0
                while h:
                    if h.a1 != la or h.b1 != lb:
                        lgt = (b[0] + h.b1).l - (b[0] + lb).l
                        rl.append(struct.pack(">lll", (a[0] + la).l - a[0].l,
                            (a[0] + h.a1).l - a[0].l, lgt))
                        rl.append(str(ffi.buffer((b[0] + lb).l, lgt)))
                    la = h.a2
                    lb = h.b2
                    h = h.next

            finally:
                lib.free(a[0])
                lib.free(b[0])
                lib.bdiff_freehunks(l.next)
            return "".join(rl)