# -*- coding: utf-8 -*-
"""
    rhodecode.lib.diffs
    ~~~~~~~~~~~~~~~~~~~

    Set of diffing helpers, previously part of vcs


    :created_on: Dec 4, 2011
    :author: marcink
    :copyright: (C) 2010-2012 Marcin Kuzminski <marcin@python-works.com>
    :original copyright: 2007-2008 by Armin Ronacher
    :license: GPLv3, see COPYING for more details.
"""
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import re
import io
import difflib
import markupsafe

from itertools import tee, imap

from mercurial import patch
from mercurial.mdiff import diffopts
from mercurial.bundlerepo import bundlerepository
from mercurial import localrepo

from pylons.i18n.translation import _

from rhodecode.lib.vcs.exceptions import VCSError
from rhodecode.lib.vcs.nodes import FileNode, SubModuleNode
from rhodecode.lib.helpers import escape
from rhodecode.lib.utils import EmptyChangeset, make_ui


def wrap_to_table(str_):
    return '''<table class="code-difftable">
                <tr class="line no-comment">
                <td class="lineno new"></td>
                <td class="code no-comment"><pre>%s</pre></td>
                </tr>
              </table>''' % str_


def wrapped_diff(filenode_old, filenode_new, cut_off_limit=None,
                ignore_whitespace=True, line_context=3,
                enable_comments=False):
    """
    returns a wrapped diff into a table, checks for cut_off_limit and presents
    proper message
    """

    if filenode_old is None:
        filenode_old = FileNode(filenode_new.path, '', EmptyChangeset())

    if filenode_old.is_binary or filenode_new.is_binary:
        diff = wrap_to_table(_('binary file'))
        stats = (0, 0)
        size = 0

    elif cut_off_limit != -1 and (cut_off_limit is None or
    (filenode_old.size < cut_off_limit and filenode_new.size < cut_off_limit)):

        f_gitdiff = get_gitdiff(filenode_old, filenode_new,
                                ignore_whitespace=ignore_whitespace,
                                context=line_context)
        diff_processor = DiffProcessor(f_gitdiff, format='gitdiff')

        diff = diff_processor.as_html(enable_comments=enable_comments)
        stats = diff_processor.stat()
        size = len(diff or '')
    else:
        diff = wrap_to_table(_('Changeset was too big and was cut off, use '
                               'diff menu to display this diff'))
        stats = (0, 0)
        size = 0
    if not diff:
        submodules = filter(lambda o: isinstance(o, SubModuleNode),
                            [filenode_new, filenode_old])
        if submodules:
            diff = wrap_to_table(escape('Submodule %r' % submodules[0]))
        else:
            diff = wrap_to_table(_('No changes detected'))

    cs1 = filenode_old.changeset.raw_id
    cs2 = filenode_new.changeset.raw_id

    return size, cs1, cs2, diff, stats


def get_gitdiff(filenode_old, filenode_new, ignore_whitespace=True, context=3):
    """
    Returns git style diff between given ``filenode_old`` and ``filenode_new``.

    :param ignore_whitespace: ignore whitespaces in diff
    """
    # make sure we pass in default context
    context = context or 3
    submodules = filter(lambda o: isinstance(o, SubModuleNode),
                        [filenode_new, filenode_old])
    if submodules:
        return ''

    for filenode in (filenode_old, filenode_new):
        if not isinstance(filenode, FileNode):
            raise VCSError("Given object should be FileNode object, not %s"
                % filenode.__class__)

    repo = filenode_new.changeset.repository
    old_raw_id = getattr(filenode_old.changeset, 'raw_id', repo.EMPTY_CHANGESET)
    new_raw_id = getattr(filenode_new.changeset, 'raw_id', repo.EMPTY_CHANGESET)

    vcs_gitdiff = repo.get_diff(old_raw_id, new_raw_id, filenode_new.path,
                                 ignore_whitespace, context)
    return vcs_gitdiff


class DiffProcessor(object):
    """
    Give it a unified diff and it returns a list of the files that were
    mentioned in the diff together with a dict of meta information that
    can be used to render it in a HTML template.
    """
    _chunk_re = re.compile(r'@@ -(\d+)(?:,(\d+))? \+(\d+)(?:,(\d+))? @@(.*)')

    def __init__(self, diff, differ='diff', format='gitdiff'):
        """
        :param diff:   a text in diff format or generator
        :param format: format of diff passed, `udiff` or `gitdiff`
        """
        if isinstance(diff, basestring):
            diff = [diff]

        self.__udiff = diff
        self.__format = format
        self.adds = 0
        self.removes = 0

        if isinstance(self.__udiff, basestring):
            self.lines = iter(self.__udiff.splitlines(1))

        elif self.__format == 'gitdiff':
            udiff_copy = self.copy_iterator()
            self.lines = imap(self.escaper, self._parse_gitdiff(udiff_copy))
        else:
            udiff_copy = self.copy_iterator()
            self.lines = imap(self.escaper, udiff_copy)

        # Select a differ.
        if differ == 'difflib':
            self.differ = self._highlight_line_difflib
        else:
            self.differ = self._highlight_line_udiff

    def escaper(self, string):
        return markupsafe.escape(string)

    def copy_iterator(self):
        """
        make a fresh copy of generator, we should not iterate thru
        an original as it's needed for repeating operations on
        this instance of DiffProcessor
        """
        self.__udiff, iterator_copy = tee(self.__udiff)
        return iterator_copy

    def _extract_rev(self, line1, line2):
        """
        Extract the operation (A/M/D), filename and revision hint from a line.
        """

        try:
            if line1.startswith('--- ') and line2.startswith('+++ '):
                l1 = line1[4:].split(None, 1)
                old_filename = (l1[0].replace('a/', '', 1)
                                if len(l1) >= 1 else None)
                old_rev = l1[1] if len(l1) == 2 else 'old'

                l2 = line2[4:].split(None, 1)
                new_filename = (l2[0].replace('b/', '', 1)
                                if len(l1) >= 1 else None)
                new_rev = l2[1] if len(l2) == 2 else 'new'

                filename = (old_filename
                            if old_filename != '/dev/null' else new_filename)

                operation = 'D' if new_filename == '/dev/null' else None
                if not operation:
                    operation = 'M' if old_filename != '/dev/null' else 'A'

                return operation, filename, new_rev, old_rev
        except (ValueError, IndexError):
            pass

        return None, None, None, None

    def _parse_gitdiff(self, diffiterator):
        def line_decoder(l):
            if l.startswith('+') and not l.startswith('+++'):
                self.adds += 1
            elif l.startswith('-') and not l.startswith('---'):
                self.removes += 1
            return l.decode('utf8', 'replace')

        output = list(diffiterator)
        size = len(output)

        if size == 2:
            l = []
            l.extend([output[0]])
            l.extend(output[1].splitlines(1))
            return map(line_decoder, l)
        elif size == 1:
            return  map(line_decoder, output[0].splitlines(1))
        elif size == 0:
            return []

        raise Exception('wrong size of diff %s' % size)

    def _highlight_line_difflib(self, line, next_):
        """
        Highlight inline changes in both lines.
        """

        if line['action'] == 'del':
            old, new = line, next_
        else:
            old, new = next_, line

        oldwords = re.split(r'(\W)', old['line'])
        newwords = re.split(r'(\W)', new['line'])

        sequence = difflib.SequenceMatcher(None, oldwords, newwords)

        oldfragments, newfragments = [], []
        for tag, i1, i2, j1, j2 in sequence.get_opcodes():
            oldfrag = ''.join(oldwords[i1:i2])
            newfrag = ''.join(newwords[j1:j2])
            if tag != 'equal':
                if oldfrag:
                    oldfrag = '<del>%s</del>' % oldfrag
                if newfrag:
                    newfrag = '<ins>%s</ins>' % newfrag
            oldfragments.append(oldfrag)
            newfragments.append(newfrag)

        old['line'] = "".join(oldfragments)
        new['line'] = "".join(newfragments)

    def _highlight_line_udiff(self, line, next_):
        """
        Highlight inline changes in both lines.
        """
        start = 0
        limit = min(len(line['line']), len(next_['line']))
        while start < limit and line['line'][start] == next_['line'][start]:
            start += 1
        end = -1
        limit -= start
        while -end <= limit and line['line'][end] == next_['line'][end]:
            end -= 1
        end += 1
        if start or end:
            def do(l):
                last = end + len(l['line'])
                if l['action'] == 'add':
                    tag = 'ins'
                else:
                    tag = 'del'
                l['line'] = '%s<%s>%s</%s>%s' % (
                    l['line'][:start],
                    tag,
                    l['line'][start:last],
                    tag,
                    l['line'][last:]
                )
            do(line)
            do(next_)

    def _parse_udiff(self, inline_diff=True):
        """
        Parse the diff an return data for the template.
        """
        lineiter = self.lines
        files = []
        try:
            line = lineiter.next()
            while 1:
                # continue until we found the old file
                if not line.startswith('--- '):
                    line = lineiter.next()
                    continue

                chunks = []
                stats = [0, 0]
                operation, filename, old_rev, new_rev = \
                    self._extract_rev(line, lineiter.next())
                files.append({
                    'filename':         filename,
                    'old_revision':     old_rev,
                    'new_revision':     new_rev,
                    'chunks':           chunks,
                    'operation':        operation,
                    'stats':            stats,
                })

                line = lineiter.next()
                while line:
                    match = self._chunk_re.match(line)
                    if not match:
                        break

                    lines = []
                    chunks.append(lines)

                    old_line, old_end, new_line, new_end = \
                        [int(x or 1) for x in match.groups()[:-1]]
                    old_line -= 1
                    new_line -= 1
                    gr = match.groups()
                    context = len(gr) == 5
                    old_end += old_line
                    new_end += new_line

                    if context:
                        # skip context only if it's first line
                        if int(gr[0]) > 1:
                            lines.append({
                                'old_lineno': '...',
                                'new_lineno': '...',
                                'action':     'context',
                                'line':       line,
                            })

                    line = lineiter.next()
                    while old_line < old_end or new_line < new_end:
                        if line:
                            command, line = line[0], line[1:]
                        else:
                            command = ' '
                        affects_old = affects_new = False

                        # ignore those if we don't expect them
                        if command in '#@':
                            continue
                        elif command == '+':
                            affects_new = True
                            action = 'add'
                            stats[0] += 1
                        elif command == '-':
                            affects_old = True
                            action = 'del'
                            stats[1] += 1
                        else:
                            affects_old = affects_new = True
                            action = 'unmod'

                        if line.find('No newline at end of file') != -1:
                            lines.append({
                                'old_lineno':   '...',
                                'new_lineno':   '...',
                                'action':       'context',
                                'line':         line
                            })

                        else:
                            old_line += affects_old
                            new_line += affects_new
                            lines.append({
                                'old_lineno':   affects_old and old_line or '',
                                'new_lineno':   affects_new and new_line or '',
                                'action':       action,
                                'line':         line
                            })

                        line = lineiter.next()

        except StopIteration:
            pass

        sorter = lambda info: {'A': 0, 'M': 1, 'D': 2}.get(info['operation'])
        if inline_diff is False:
            return sorted(files, key=sorter)

        # highlight inline changes
        for diff_data in files:
            for chunk in diff_data['chunks']:
                lineiter = iter(chunk)
                try:
                    while 1:
                        line = lineiter.next()
                        if line['action'] != 'unmod':
                            nextline = lineiter.next()
                            if nextline['action'] in ['unmod', 'context'] or \
                               nextline['action'] == line['action']:
                                continue
                            self.differ(line, nextline)
                except StopIteration:
                    pass

        return sorted(files, key=sorter)

    def prepare(self, inline_diff=True):
        """
        Prepare the passed udiff for HTML rendering. It'l return a list
        of dicts
        """
        return self._parse_udiff(inline_diff=inline_diff)

    def _safe_id(self, idstring):
        """Make a string safe for including in an id attribute.

        The HTML spec says that id attributes 'must begin with
        a letter ([A-Za-z]) and may be followed by any number
        of letters, digits ([0-9]), hyphens ("-"), underscores
        ("_"), colons (":"), and periods (".")'. These regexps
        are slightly over-zealous, in that they remove colons
        and periods unnecessarily.

        Whitespace is transformed into underscores, and then
        anything which is not a hyphen or a character that
        matches \w (alphanumerics and underscore) is removed.

        """
        # Transform all whitespace to underscore
        idstring = re.sub(r'\s', "_", '%s' % idstring)
        # Remove everything that is not a hyphen or a member of \w
        idstring = re.sub(r'(?!-)\W', "", idstring).lower()
        return idstring

    def raw_diff(self):
        """
        Returns raw string as udiff
        """
        udiff_copy = self.copy_iterator()
        if self.__format == 'gitdiff':
            udiff_copy = self._parse_gitdiff(udiff_copy)
        return u''.join(udiff_copy)

    def as_html(self, table_class='code-difftable', line_class='line',
                new_lineno_class='lineno old', old_lineno_class='lineno new',
                code_class='code', enable_comments=False, diff_lines=None):
        """
        Return given diff as html table with customized css classes
        """
        def _link_to_if(condition, label, url):
            """
            Generates a link if condition is meet or just the label if not.
            """

            if condition:
                return '''<a href="%(url)s">%(label)s</a>''' % {
                    'url': url,
                    'label': label
                }
            else:
                return label
        if diff_lines is None:
            diff_lines = self.prepare()
        _html_empty = True
        _html = []
        _html.append('''<table class="%(table_class)s">\n''' % {
            'table_class': table_class
        })
        for diff in diff_lines:
            for line in diff['chunks']:
                _html_empty = False
                for change in line:
                    _html.append('''<tr class="%(lc)s %(action)s">\n''' % {
                        'lc': line_class,
                        'action': change['action']
                    })
                    anchor_old_id = ''
                    anchor_new_id = ''
                    anchor_old = "%(filename)s_o%(oldline_no)s" % {
                        'filename': self._safe_id(diff['filename']),
                        'oldline_no': change['old_lineno']
                    }
                    anchor_new = "%(filename)s_n%(oldline_no)s" % {
                        'filename': self._safe_id(diff['filename']),
                        'oldline_no': change['new_lineno']
                    }
                    cond_old = (change['old_lineno'] != '...' and
                                change['old_lineno'])
                    cond_new = (change['new_lineno'] != '...' and
                                change['new_lineno'])
                    if cond_old:
                        anchor_old_id = 'id="%s"' % anchor_old
                    if cond_new:
                        anchor_new_id = 'id="%s"' % anchor_new
                    ###########################################################
                    # OLD LINE NUMBER
                    ###########################################################
                    _html.append('''\t<td %(a_id)s class="%(olc)s">''' % {
                        'a_id': anchor_old_id,
                        'olc': old_lineno_class
                    })

                    _html.append('''%(link)s''' % {
                        'link': _link_to_if(True, change['old_lineno'],
                                            '#%s' % anchor_old)
                    })
                    _html.append('''</td>\n''')
                    ###########################################################
                    # NEW LINE NUMBER
                    ###########################################################

                    _html.append('''\t<td %(a_id)s class="%(nlc)s">''' % {
                        'a_id': anchor_new_id,
                        'nlc': new_lineno_class
                    })

                    _html.append('''%(link)s''' % {
                        'link': _link_to_if(True, change['new_lineno'],
                                            '#%s' % anchor_new)
                    })
                    _html.append('''</td>\n''')
                    ###########################################################
                    # CODE
                    ###########################################################
                    comments = '' if enable_comments else 'no-comment'
                    _html.append('''\t<td class="%(cc)s %(inc)s">''' % {
                        'cc': code_class,
                        'inc': comments
                    })
                    _html.append('''\n\t\t<pre>%(code)s</pre>\n''' % {
                        'code': change['line']
                    })
                    _html.append('''\t</td>''')
                    _html.append('''\n</tr>\n''')
        _html.append('''</table>''')
        if _html_empty:
            return None
        return ''.join(_html)

    def stat(self):
        """
        Returns tuple of added, and removed lines for this instance
        """
        return self.adds, self.removes


class InMemoryBundleRepo(bundlerepository):
    def __init__(self, ui, path, bundlestream):
        self._tempparent = None
        localrepo.localrepository.__init__(self, ui, path)
        self.ui.setconfig('phases', 'publish', False)

        self.bundle = bundlestream

        # dict with the mapping 'filename' -> position in the bundle
        self.bundlefilespos = {}


def differ(org_repo, org_ref, other_repo, other_ref, discovery_data=None):
    """
    General differ between branches, bookmarks or separate but releated 
    repositories

    :param org_repo:
    :type org_repo:
    :param org_ref:
    :type org_ref:
    :param other_repo:
    :type other_repo:
    :param other_ref:
    :type other_ref:
    """

    bundlerepo = None
    ignore_whitespace = False
    context = 3
    org_repo = org_repo.scm_instance._repo
    other_repo = other_repo.scm_instance._repo
    opts = diffopts(git=True, ignorews=ignore_whitespace, context=context)
    org_ref = org_ref[1]
    other_ref = other_ref[1]

    if org_repo != other_repo:

        common, incoming, rheads = discovery_data

        # create a bundle (uncompressed if other repo is not local)
        if other_repo.capable('getbundle') and incoming:
            # disable repo hooks here since it's just bundle !
            # patch and reset hooks section of UI config to not run any
            # hooks on fetching archives with subrepos
            for k, _ in other_repo.ui.configitems('hooks'):
                other_repo.ui.setconfig('hooks', k, None)

            unbundle = other_repo.getbundle('incoming', common=common,
                                            heads=rheads)

            buf = io.BytesIO()
            while True:
                chunk = unbundle._stream.read(1024 * 4)
                if not chunk:
                    break
                buf.write(chunk)

            buf.seek(0)
            # replace chunked _stream with data that can do tell() and seek()
            unbundle._stream = buf

            ui = make_ui('db')
            bundlerepo = InMemoryBundleRepo(ui, path=org_repo.root,
                                            bundlestream=unbundle)
        return ''.join(patch.diff(bundlerepo or org_repo, node2=other_ref,
                                  opts=opts))
    else:
        return ''.join(patch.diff(org_repo, node1=org_ref, node2=other_ref,
                                  opts=opts))