"""rest publishing functions

contains some functions and setup of docutils for cubicweb. Provides the
following ReST directives:

* `eid`, create link to entity in the repository by their eid

* `card`, create link to card entity in the repository by their wikiid
  (proposing to create it when the refered card doesn't exist yet)

* `winclude`, reference to a web documentation file (in wdoc/ directories)

* `sourcecode` (if pygments is installed), source code colorization

:organization: Logilab
:copyright: 2001-2010 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.
:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses
"""
__docformat__ = "restructuredtext en"

from cStringIO import StringIO
from itertools import chain
from logging import getLogger
from os.path import join

from docutils import statemachine, nodes, utils, io
from docutils.core import publish_string
from docutils.parsers.rst import Parser, states, directives
from docutils.parsers.rst.roles import register_canonical_role, set_classes

from logilab.mtconverter import ESC_UCAR_TABLE, ESC_CAR_TABLE, xml_escape

from cubicweb import UnknownEid
from cubicweb.ext.html4zope import Writer

# We provide our own parser as an attempt to get rid of
# state machine reinstanciation

import re
# compile states.Body patterns
for k, v in states.Body.patterns.items():
    if isinstance(v, str):
        states.Body.patterns[k] = re.compile(v)

# register ReStructured Text mimetype / extensions
import mimetypes
mimetypes.add_type('text/rest', '.rest')
mimetypes.add_type('text/rest', '.rst')


LOGGER = getLogger('cubicweb.rest')

def eid_reference_role(role, rawtext, text, lineno, inliner,
                       options={}, content=[]):
    try:
        try:
            eid_num, rest = text.split(u':', 1)
        except:
            eid_num, rest = text, '#'+text
        eid_num = int(eid_num)
        if eid_num < 0:
            raise ValueError
    except ValueError:
        msg = inliner.reporter.error(
            'EID number must be a positive number; "%s" is invalid.'
            % text, line=lineno)
        prb = inliner.problematic(rawtext, rawtext, msg)
        return [prb], [msg]
    # Base URL mainly used by inliner.pep_reference; so this is correct:
    context = inliner.document.settings.context
    try:
        refedentity = context._cw.entity_from_eid(eid_num)
    except UnknownEid:
        ref = '#'
        rest += u' ' + context._cw._('(UNEXISTANT EID)')
    else:
        ref = refedentity.absolute_url()
    set_classes(options)
    return [nodes.reference(rawtext, utils.unescape(rest), refuri=ref,
                            **options)], []


def winclude_directive(name, arguments, options, content, lineno,
                       content_offset, block_text, state, state_machine):
    """Include a reST file as part of the content of this reST file.

    same as standard include directive but using config.locate_doc_resource to
    get actual file to include.

    Most part of this implementation is copied from `include` directive defined
    in `docutils.parsers.rst.directives.misc`
    """
    context = state.document.settings.context
    source = state_machine.input_lines.source(
        lineno - state_machine.input_offset - 1)
    #source_dir = os.path.dirname(os.path.abspath(source))
    fid = arguments[0]
    for lang in chain((context._cw.lang, context.vreg.property_value('ui.language')),
                      context.config.available_languages()):
        rid = '%s_%s.rst' % (fid, lang)
        resourcedir = context.config.locate_doc_file(rid)
        if resourcedir:
            break
    else:
        severe = state_machine.reporter.severe(
              'Problems with "%s" directive path:\nno resource matching %s.'
              % (name, fid),
              nodes.literal_block(block_text, block_text), line=lineno)
        return [severe]
    path = join(resourcedir, rid)
    encoding = options.get('encoding', state.document.settings.input_encoding)
    try:
        state.document.settings.record_dependencies.add(path)
        include_file = io.FileInput(
            source_path=path, encoding=encoding,
            error_handler=state.document.settings.input_encoding_error_handler,
            handle_io_errors=None)
    except IOError, error:
        severe = state_machine.reporter.severe(
              'Problems with "%s" directive path:\n%s: %s.'
              % (name, error.__class__.__name__, error),
              nodes.literal_block(block_text, block_text), line=lineno)
        return [severe]
    try:
        include_text = include_file.read()
    except UnicodeError, error:
        severe = state_machine.reporter.severe(
              'Problem with "%s" directive:\n%s: %s'
              % (name, error.__class__.__name__, error),
              nodes.literal_block(block_text, block_text), line=lineno)
        return [severe]
    if options.has_key('literal'):
        literal_block = nodes.literal_block(include_text, include_text,
                                            source=path)
        literal_block.line = 1
        return literal_block
    else:
        include_lines = statemachine.string2lines(include_text,
                                                  convert_whitespace=1)
        state_machine.insert_input(include_lines, path)
        return []

winclude_directive.arguments = (1, 0, 1)
winclude_directive.options = {'literal': directives.flag,
                              'encoding': directives.encoding}

try:
    from pygments import highlight
    from pygments.lexers import get_lexer_by_name
    from pygments.formatters import HtmlFormatter
except ImportError:
    pygments_directive = None
else:
    _PYGMENTS_FORMATTER = HtmlFormatter()

    def pygments_directive(name, arguments, options, content, lineno,
                           content_offset, block_text, state, state_machine):
        try:
            lexer = get_lexer_by_name(arguments[0])
        except ValueError:
            # no lexer found
            lexer = get_lexer_by_name('text')
        parsed = highlight(u'\n'.join(content), lexer, _PYGMENTS_FORMATTER)
        # don't fail if no context set on the sourcecode directive
        try:
            context = state.document.settings.context
            context._cw.add_css('pygments.css')
        except AttributeError:
            # used outside cubicweb
            pass
        return [nodes.raw('', parsed, format='html')]

    pygments_directive.arguments = (1, 0, 1)
    pygments_directive.content = 1


class CubicWebReSTParser(Parser):
    """The (customized) reStructuredText parser."""

    def __init__(self):
        self.initial_state = 'Body'
        self.state_classes = states.state_classes
        self.inliner = states.Inliner()
        self.statemachine = states.RSTStateMachine(
              state_classes=self.state_classes,
              initial_state=self.initial_state,
              debug=0)

    def parse(self, inputstring, document):
        """Parse `inputstring` and populate `document`, a document tree."""
        self.setup_parse(inputstring, document)
        inputlines = statemachine.string2lines(inputstring,
                                               convert_whitespace=1)
        self.statemachine.run(inputlines, document, inliner=self.inliner)
        self.finish_parse()


def rest_publish(context, data):
    """publish a string formatted as ReStructured Text to HTML

    :type context: a cubicweb application object

    :type data: str
    :param data: some ReST text

    :rtype: unicode
    :return:
      the data formatted as HTML or the original data if an error occured
    """
    req = context._cw
    if isinstance(data, unicode):
        encoding = 'unicode'
        # remove unprintable characters unauthorized in xml
        data = data.translate(ESC_UCAR_TABLE)
    else:
        encoding = req.encoding
        # remove unprintable characters unauthorized in xml
        data = data.translate(ESC_CAR_TABLE)
    settings = {'input_encoding': encoding, 'output_encoding': 'unicode',
                'warning_stream': StringIO(), 'context': context,
                # dunno what's the max, severe is 4, and we never want a crash
                # (though try/except may be a better option...)
                'halt_level': 10,
                }
    if context:
        if hasattr(req, 'url'):
            base_url = req.url()
        elif hasattr(context, 'absolute_url'):
            base_url = context.absolute_url()
        else:
            base_url = req.base_url()
    else:
        base_url = None
    try:
        return publish_string(writer=Writer(base_url=base_url),
                              parser=CubicWebReSTParser(), source=data,
                              settings_overrides=settings)
    except Exception:
        LOGGER.exception('error while publishing ReST text')
        if not isinstance(data, unicode):
            data = unicode(data, encoding, 'replace')
        return xml_escape(req._('error while publishing ReST text')
                           + '\n\n' + data)


_INITIALIZED = False
def cw_rest_init():
    global _INITIALIZED
    if _INITIALIZED:
        return
    _INITIALIZED = True
    register_canonical_role('eid', eid_reference_role)
    directives.register_directive('winclude', winclude_directive)
    if pygments_directive is not None:
        directives.register_directive('sourcecode', pygments_directive)