# -*- coding: utf-8 -*-
#
# Copyright (C) 2006-2009 Edgewall Software
# Copyright (C) 2006 Matthew Good <matt@matt-good.net>
# All rights reserved.
#
# This software is licensed as described in the file COPYING, which
# you should have received as part of this distribution. The terms
# are also available at http://trac.edgewall.org/wiki/TracLicense.
#
# Author: Matthew Good <matt@matt-good.net>

"""Syntax highlighting based on Pygments."""

from datetime import datetime
import os
from pkg_resources import resource_filename
import re

from trac.core import *
from trac.config import ListOption, Option
from trac.mimeview.api import IHTMLPreviewRenderer, Mimeview
from trac.prefs import IPreferencePanelProvider
from trac.util import get_module_path, get_pkginfo
from trac.util.datefmt import http_date, localtz
from trac.util.translation import _
from trac.web import IRequestHandler
from trac.web.chrome import add_stylesheet

from genshi import QName, Stream
from genshi.core import Attrs, START, END, TEXT

# Kludge to workaround the lack of absolute imports in Python version prior to
# 2.5
pygments = __import__('pygments', {}, {}, ['lexers', 'styles', 'formatters'])
get_all_lexers = pygments.lexers.get_all_lexers
get_lexer_by_name = pygments.lexers.get_lexer_by_name
HtmlFormatter = pygments.formatters.html.HtmlFormatter
get_all_styles = pygments.styles.get_all_styles
get_style_by_name = pygments.styles.get_style_by_name

__all__ = ['PygmentsRenderer']


class PygmentsRenderer(Component):
    """Syntax highlighting based on Pygments."""

    implements(IHTMLPreviewRenderer, IPreferencePanelProvider, IRequestHandler)

    default_style = Option('mimeviewer', 'pygments_default_style', 'trac',
        """Pygments でのシンタックスハイライトでデフォルトで使われるスタイルを設定します。""")

    pygments_modes = ListOption('mimeviewer', 'pygments_modes',
        '', doc=
        """Pygments が処理できるMIME タイプを追加します。
        
        それぞれのエントリは `mimetype:mode:quality` というタプルで
        設定しなければなりません。 `mimetype` には MIME タイプを、
        `mode` には変換に使用する Pygments のモードを、
        `quality` には変換に関連する quality ratio を
        設定します。 `quality` で設定した値で、
        Pygments のデフォルトの quality ratio
        を上書きします。""")

    expand_tabs = True
    returns_source = True

    QUALITY_RATIO = 7

    EXAMPLE = """<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Hello, world!</title>
    <script>
      jQuery(document).ready(function($) {
        $("h1").fadeIn("slow");
      });
    </script>
  </head>
  <body>
    <h1>Hello, world!</h1>
  </body>
</html>"""

    def __init__(self):
        version = get_pkginfo(pygments).get('version')
        # if installed from source, fallback to the hardcoded version info
        if not version and hasattr(pygments, '__version__'):
            version = pygments.__version__
        self.env.systeminfo.append(('Pygments',version))
                                        
        self._types = None

    # IHTMLPreviewRenderer implementation

    def get_quality_ratio(self, mimetype):
        # Extend default MIME type to mode mappings with configured ones
        if self._types is None:
            self._init_types()
        try:
            return self._types[mimetype][1]
        except KeyError:
            return 0

    def render(self, context, mimetype, content, filename=None, rev=None):
        req = context.req
        if self._types is None:
            self._init_types()
        add_stylesheet(req, '/pygments/%s.css' %
                       req.session.get('pygments_style', self.default_style))
        try:
            if len(content) > 0:
                mimetype = mimetype.split(';', 1)[0]
                language = self._types[mimetype][0]
                return self._generate(language, content)
        except (KeyError, ValueError):
            raise Exception("No Pygments lexer found for mime-type '%s'."
                            % mimetype)

    # IPreferencePanelProvider implementation

    def get_preference_panels(self, req):
        yield ('pygments', _('Pygments Theme'))

    def render_preference_panel(self, req, panel):
        styles = list(get_all_styles())

        if req.method == 'POST':
            style = req.args.get('style')
            if style and style in styles:
                req.session['pygments_style'] = style
            req.redirect(req.href.prefs(panel or None))

        output = self._generate('html', self.EXAMPLE)
        return 'prefs_pygments.html', {
            'output': output,
            'selection': req.session.get('pygments_style', self.default_style),
            'styles': styles
        }

    # IRequestHandler implementation

    def match_request(self, req):
        match = re.match(r'/pygments/(\w+)\.css', req.path_info)
        if match:
            req.args['style'] = match.group(1)
            return True

    def process_request(self, req):
        style = req.args['style']
        try:
            style_cls = get_style_by_name(style)
        except ValueError, e:
            raise HTTPNotFound(e)

        parts = style_cls.__module__.split('.')
        filename = resource_filename('.'.join(parts[:-1]), parts[-1] + '.py')
        mtime = datetime.fromtimestamp(os.path.getmtime(filename), localtz)
        last_modified = http_date(mtime)
        if last_modified == req.get_header('If-Modified-Since'):
            req.send_response(304)
            req.end_headers()
            return

        formatter = HtmlFormatter(style=style_cls)
        content = u'\n\n'.join([
            formatter.get_style_defs('div.code pre'),
            formatter.get_style_defs('table.code td')
        ]).encode('utf-8')

        req.send_response(200)
        req.send_header('Content-Type', 'text/css; charset=utf-8')
        req.send_header('Last-Modified', last_modified)
        req.send_header('Content-Length', len(content))
        req.write(content)

    # Internal methods

    def _init_types(self):
        self._types = {}
        for lexname, aliases, _, mimetypes in get_all_lexers():
            name = aliases and aliases[0] or lexname
            for mimetype in mimetypes:
                self._types[mimetype] = (name, self.QUALITY_RATIO)
        self._types.update(
            Mimeview(self.env).configured_modes_mapping('pygments')
        )

    def _generate(self, language, content):
        lexer = get_lexer_by_name(language, stripnl=False)
        return GenshiHtmlFormatter().generate(lexer.get_tokens(content))


class GenshiHtmlFormatter(HtmlFormatter):
    """A Pygments formatter subclass that generates a Python stream instead
    of writing markup as strings to an output file.
    """

    def generate(self, tokens):
        pos = (None, -1, -1)
        span = QName('span')
        class_ = QName('class')

        def _generate():
            attrs = lc = None
            text = []

            for ttype, value in tokens:
                c = self._get_css_class(ttype)
                if c == 'n':
                    c = ''
                if c == lc:
                    text.append(value)
                elif value: # if no value, leave old span open
                    if text:
                        yield TEXT, u''.join(text), pos
                    if attrs:
                        yield END, span, pos
                        attrs = None
                    text = [value]
                    lc = c
                    if c:
                        attrs = Attrs([(class_, c)])
                        yield START, (span, attrs), pos
            if text:
                yield TEXT, u''.join(text), pos
            if attrs:
                yield END, span, pos
        return Stream(_generate())
