"""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

"""

__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 Publisher

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

    cw = context._cw

    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((cw.lang, cw.vreg.property_value('ui.language')),

                      cw.vreg.config.available_languages()):

        rid = '%s_%s.rst' % (fid, lang)

        resourcedir = cw.vreg.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()

# XXX docutils keep a ref on context, can't find a correct way to remove it

class CWReSTPublisher(Publisher):

    def __init__(self, context, settings, **kwargs):

        Publisher.__init__(self, **kwargs)

        self.set_components('standalone', 'restructuredtext', 'pseudoxml')

        self.process_programmatic_settings(None, settings, None)

        self.settings.context = context

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(),

                # 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:

        pub = CWReSTPublisher(context, settings,

                              parser=CubicWebReSTParser(),

                              writer=Writer(base_url=base_url),

                              source_class=io.StringInput,

                              destination_class=io.StringOutput)

        pub.set_source(data)

        pub.set_destination()

        res = pub.publish(enable_exit_status=None)

        # necessary for proper garbage collection, else a ref is kept somewhere in docutils...

        del pub.settings.context

        return res

    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)