from __future__ import absolute_import, print_function

import collections

import struct

import unittest

import silenttestrunner

from mercurial import (

    bdiff,

    mpatch,

)

class diffreplace(

    collections.namedtuple('diffreplace', 'start end from_ to')):

    def __repr__(self):

        return 'diffreplace(%r, %r, %r, %r)' % self

class BdiffTests(unittest.TestCase):

    def assert_bdiff_applies(self, a, b):

        d = bdiff.bdiff(a, b)

        c = a

        if d:

            c = mpatch.patches(a, [d])

        self.assertEqual(

            c, b, ("bad diff+patch result from\n  %r to\n  "

                   "%r: \nbdiff: %r\npatched: %r" % (a, b, d, c[:200])))

    def assert_bdiff(self, a, b):

        self.assert_bdiff_applies(a, b)

        self.assert_bdiff_applies(b, a)

    def test_bdiff_basic(self):

        cases = [

            ("a\nc\n\n\n\n", "a\nb\n\n\n"),

            ("a\nb\nc\n", "a\nc\n"),

            ("", ""),

            ("a\nb\nc", "a\nb\nc"),

            ("a\nb\nc\nd\n", "a\nd\n"),

            ("a\nb\nc\nd\n", "a\nc\ne\n"),

            ("a\nb\nc\n", "a\nc\n"),

            ("a\n", "c\na\nb\n"),

            ("a\n", ""),

            ("a\n", "b\nc\n"),

            ("a\n", "c\na\n"),

            ("", "adjfkjdjksdhfksj"),

            ("", "ab"),

            ("", "abc"),

            ("a", "a"),

            ("ab", "ab"),

            ("abc", "abc"),

            ("a\n", "a\n"),

            ("a\nb", "a\nb"),

        ]

        for a, b in cases:

            self.assert_bdiff(a, b)

    def showdiff(self, a, b):

        bin = bdiff.bdiff(a, b)

        pos = 0

        q = 0

        actions = []

        while pos < len(bin):

            p1, p2, l = struct.unpack(">lll", bin[pos:pos + 12])

            pos += 12

            if p1:

                actions.append(a[q:p1])

            actions.append(diffreplace(p1, p2, a[p1:p2], bin[pos:pos + l]))

            pos += l

            q = p2

        if q < len(a):

            actions.append(a[q:])

        return actions

    def test_issue1295(self):

        cases = [

            ("x\n\nx\n\nx\n\nx\n\nz\n", "x\n\nx\n\ny\n\nx\n\nx\n\nz\n",

             ['x\n\nx\n\n', diffreplace(6, 6, '', 'y\n\n'), 'x\n\nx\n\nz\n']),

            ("x\n\nx\n\nx\n\nx\n\nz\n", "x\n\nx\n\ny\n\nx\n\ny\n\nx\n\nz\n",

             ['x\n\nx\n\n',

              diffreplace(6, 6, '', 'y\n\n'),

              'x\n\n',

              diffreplace(9, 9, '', 'y\n\n'),

              'x\n\nz\n']),

            # we should pick up abbbc. rather than bc.de as the longest match

            ("a\nb\nb\nb\nc\n.\nd\ne\n.\nf\n",

             "a\nb\nb\na\nb\nb\nb\nc\n.\nb\nc\n.\nd\ne\nf\n",

             ['a\nb\nb\n',

              diffreplace(6, 6, '', 'a\nb\nb\nb\nc\n.\n'),

              'b\nc\n.\nd\ne\n',

              diffreplace(16, 18, '.\n', ''),

              'f\n']),

        ]

        for old, new, want in cases:

            self.assertEqual(self.showdiff(old, new), want)

def showdiff(a, b):

    print('showdiff(\n  %r,\n  %r):' % (a, b))

    bin = bdiff.bdiff(a, b)

    pos = 0

    q = 0

    while pos < len(bin):

        p1, p2, l = struct.unpack(">lll", bin[pos:pos + 12])

        pos += 12

        if p1:

            print('', repr(a[q:p1]))

        print('', p1, p2, repr(a[p1:p2]), '->', repr(bin[pos:pos + l]))

        pos += l

        q = p2

    if q < len(a):

        print('', repr(a[q:]))

print("Nice diff for a trivial change:")

showdiff(

    ''.join('<%s\n-\n' % i for i in range(5)),

    ''.join('>%s\n-\n' % i for i in range(5)))

print("Diff 1 to 3 lines - preference for appending:")

showdiff('a\n', 'a\n' * 3)

print("Diff 1 to 5 lines - preference for appending:")

showdiff('a\n', 'a\n' * 5)

print("Diff 3 to 1 lines - preference for removing trailing lines:")

showdiff('a\n' * 3, 'a\n')

print("Diff 5 to 1 lines - preference for removing trailing lines:")

showdiff('a\n' * 5, 'a\n')

if __name__ == '__main__':

    silenttestrunner.main(__name__)