# Copyright (C) 2017  Sébastien Gendre

# 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
from orgpython import org_to_html
from pelican import signals
from pelican.readers import BaseReader
from pelican.utils import pelican_open

class OrgReader(BaseReader):
    """Reader for Org files"""
    enabled = True
    file_extensions = ['org']

    def _separate_header_and_content(self, text_lines):
        """
        From a given Org text, return the header separate from the content.
        The given text must be separate line by line and be a list.
        The return is a list of two items: header and content.
        Theses two items are text separate line by line in format of a list
        Keyword Arguments:
        text_lines -- A list, each item is a line of the texte
        Return:
        [
          header   -- A list, each item is a line of the texte
          content  -- A list, each item is a line of the texte
        ]
        """
        no_more_header = False
        expr_metadata = re.compile(r'^#\+[a-zA-Z]+:.*')
        header = []
        content = []
        for line in text_lines:
            metadata = expr_metadata.match(line)
            if metadata and not no_more_header:
                header.append(line)
            else:
                no_more_header = True
                content.append(line)
        return header, content 

    def _parse_metadatas(self, text_lines):
        """
        From a given Org text, return the metadatas 
        Keyword Arguments:
        text_lines -- A list, each item is a line of the texte
        Return:
        A dict containing metadatas
        """
        if not text_lines:
            return {}
        expr_metadata = re.compile(r'^#\+([a-zA-Z]+):(.*)')
        return {
            expr_metadata.match(line).group(1).lower()
            : expr_metadata.match(line).group(2).strip()
            for line in text_lines
        }

    def read(self, source_path):
        """
        Parse content and metadata of Org files
        Keyword Arguments:
        source_path -- Path to the Org file to parse
        """
        self._source_path = source_path
        with pelican_open as text:
            text_lines = list(text.splitlines())

        header, content = self._separate_header_and_content(text_lines)
        metadatas = self._parse_metadatas(header)
        content_html = org_to_html("\n".join(content))
        return content_html, metadatas
    
def add_reader(readers):
    for ext in OrgReader.file_extensions:
        readers.reader_classes[ext] = OrgReader

def register():
    signals.readers_init.connect(add_reader)