#!/usr/bin/env python
# -*- coding: utf-8 -*-

import glob
import importlib
import logging
import os

from songbook_core.errors import SongbookError

LOGGER = logging.getLogger(__name__)

class Content:
    """Content item of type 'example'."""

    def render(self):
        """Render this content item.

        Returns a string, to be placed verbatim in the generated .tex file.
        """
        return ""

    # Block management

    def begin_new_block(self, previous):
        """Return a boolean stating if a new block is to be created.

        # Arguments

        - previous: the songbook.content.Content object of the previous item.

        # Return

        True if the renderer has to close previous block, and begin a new one,
        False otherwise.

        # Default

        The default behavior of this method (if not defined in this child
        class) is: begin a new block if the previous item is not an instance of
        the same class.
        """
        return False

    def begin_block(self):
        """Return the string to begin a block."""
        return ""

    def end_block(self):
        """Return the string to end a block."""
        return ""

class ContentError(SongbookError):
    def __init__(self, keyword, message):
        self.keyword = keyword
        self.message = message

    def __str__(self):
        return "Content: {}: {}".format(self.keyword, self.message)

def load_plugins():
    """Load all content plugins, and return a dictionary of those plugins.

    Return value: a dictionary where:
    - keys are the keywords ;
    - values are functions triggered when this keyword is met.
    """
    plugins = {}
    for name in glob.glob(os.path.join(os.path.dirname(__file__), "*.py")):
        if name.endswith(".py") and os.path.basename(name) != "__init__.py":
            plugin = importlib.import_module(
                    'songbook_core.content.{}'.format(os.path.basename(name[:-len('.py')]))
                )
            for (key, value) in plugin.CONTENT_PLUGINS.items():
                if key in plugins:
                    LOGGER.warning("File %s: Keyword '%s' is already used. Ignored.", os.path.relpath(name), key)
                    continue
                plugins[key] = value
    return plugins