# -*- coding: iso-8859-1 -*-
"""
    MoinMoin - Side by side diffs

    @copyright: 2002 by Jürgen Hermann <jh@web.de>
    @copyright: 2002 by Scott Moonen <smoonen@andstuff.org>
    @license: GNU GPL, see COPYING for details.
"""

from MoinMoin.support import difflib
from MoinMoin.wikiutil import escape

def indent(line):
    eol = ''
    while line and line[0] == '\n':
        eol += '\n'
        line = line[1:]
    stripped = line.lstrip()
    if len(line) - len(stripped):
        line = "&nbsp;" * (len(line) - len(stripped)) + stripped
    #return "%d / %d / %s" % (len(line), len(stripped), line)
    return eol + line


# This code originally by Scott Moonen, used with permission.
def diff(request, old, new):
    """ Find changes between old and new and return
        HTML markup visualising them.
    """
    _ = request.getText
    t_line = _("Line") + " %d"

    seq1 = old.splitlines()
    seq2 = new.splitlines()

    seqobj = difflib.SequenceMatcher(None, seq1, seq2)
    linematch = seqobj.get_matching_blocks()

    if len(seq1) == len(seq2) and linematch[0] == (0, 0, len(seq1)):
        # No differences.
        return _("No differences found!")

    lastmatch = (0, 0)

    result = """
<table class="diff">
<tr>
<td class="diff-removed">
<span>
%s
</span>
</td>
<td class="diff-added">
<span>
%s
</span>
</td>
</tr>
""" % (_('Deletions are marked like this.'), _('Additions are marked like this.'),)

    # Print all differences
    for match in linematch:
        # Starts of pages identical?
        if lastmatch == match[0:2]:
            lastmatch = (match[0] + match[2], match[1] + match[2])
            continue
        llineno, rlineno = lastmatch[0]+1, lastmatch[1]+1
        result += """
<tr class="diff-title">
<td>
%s:
</td>
<td>
%s:
</td>
</tr>
""" % ( request.formatter.line_anchorlink(1, llineno) + request.formatter.text(t_line % llineno) + request.formatter.line_anchorlink(0),
        request.formatter.line_anchorlink(1, rlineno) + request.formatter.text(t_line % rlineno) + request.formatter.line_anchorlink(0))

        leftpane  = ''
        rightpane = ''
        linecount = max(match[0] - lastmatch[0], match[1] - lastmatch[1])
        for line in range(linecount):
            if line < match[0] - lastmatch[0]:
                if line > 0:
                    leftpane += '\n'
                leftpane += seq1[lastmatch[0] + line]
            if line < match[1] - lastmatch[1]:
                if line > 0:
                    rightpane += '\n'
                rightpane += seq2[lastmatch[1] + line]

        charobj   = difflib.SequenceMatcher(None, leftpane, rightpane)
        charmatch = charobj.get_matching_blocks()

        if charobj.ratio() < 0.5:
            # Insufficient similarity.
            if leftpane:
                leftresult = """<span>%s</span>""" % indent(escape(leftpane))
            else:
                leftresult = ''

            if rightpane:
                rightresult = """<span>%s</span>""" % indent(escape(rightpane))
            else:
                rightresult = ''
        else:
            # Some similarities; markup changes.
            charlast = (0, 0)

            leftresult  = ''
            rightresult = ''
            for thismatch in charmatch:
                if thismatch[0] - charlast[0] != 0:
                    leftresult += """<span>%s</span>""" % indent(
                        escape(leftpane[charlast[0]:thismatch[0]]))
                if thismatch[1] - charlast[1] != 0:
                    rightresult += """<span>%s</span>""" % indent(
                        escape(rightpane[charlast[1]:thismatch[1]]))
                leftresult += escape(leftpane[thismatch[0]:thismatch[0] + thismatch[2]])
                rightresult += escape(rightpane[thismatch[1]:thismatch[1] + thismatch[2]])
                charlast = (thismatch[0] + thismatch[2], thismatch[1] + thismatch[2])

        leftpane  = '<br>\n'.join(map(indent, leftresult.splitlines()))
        rightpane = '<br>\n'.join(map(indent, rightresult.splitlines()))

        # removed width="50%%"
        result += """
<tr>
<td class="diff-removed">
%s
</td>
<td class="diff-added">
%s
</td>
</tr>
""" % (leftpane, rightpane)

        lastmatch = (match[0] + match[2], match[1] + match[2])

    result += '</table>\n'
    return result

