# -*- coding: utf-8 -*-

# Copyright © 2012-2018 Roberto Alsina and others.

# Permission is hereby granted, free of charge, to any
# person obtaining a copy of this software and associated
# documentation files (the "Software"), to deal in the
# Software without restriction, including without limitation
# the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the
# Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice
# shall be included in all copies or substantial portions of
# the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
# PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS
# OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
# OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

"""Page compiler plugin for Markdown."""


import io
import os
import threading

try:
    from markdown import Markdown
except ImportError:
    Markdown = None  # NOQA
    nikola_extension = None
    gist_extension = None
    podcast_extension = None

from nikola import shortcodes as sc
from nikola.plugin_categories import PageCompiler
from nikola.utils import makedirs, req_missing, write_metadata, LocaleBorg, map_metadata


class ThreadLocalMarkdown(threading.local):
    """Convert Markdown to HTML using per-thread Markdown objects.

    See discussion in #2661.
    """

    def __init__(self, extensions):
        """Create a Markdown instance."""
        self.markdown = Markdown(extensions=extensions, output_format="html5")

    def convert(self, data):
        """Convert data to HTML and reset internal state."""
        result = self.markdown.convert(data)
        try:
            meta = {}
            for k in self.markdown.Meta:  # This reads everything as lists
                meta[k.lower()] = ','.join(self.markdown.Meta[k])
        except Exception:
            meta = {}
        self.markdown.reset()
        return result, meta


class CompileMarkdown(PageCompiler):
    """Compile Markdown into HTML."""

    name = "markdown"
    friendly_name = "Markdown"
    demote_headers = True
    site = None
    supports_metadata = False

    def set_site(self, site):
        """Set Nikola site."""
        super(CompileMarkdown, self).set_site(site)
        self.config_dependencies = []
        extensions = []
        for plugin_info in self.get_compiler_extensions():
            self.config_dependencies.append(plugin_info.name)
            extensions.append(plugin_info.plugin_object)
            plugin_info.plugin_object.short_help = plugin_info.description

        site_extensions = self.site.config.get("MARKDOWN_EXTENSIONS")
        self.config_dependencies.append(str(sorted(site_extensions)))
        extensions.extend(site_extensions)
        if Markdown is not None:
            self.converter = ThreadLocalMarkdown(extensions)
        self.supports_metadata = 'markdown.extensions.meta' in extensions

    def compile_string(self, data, source_path=None, is_two_file=True, post=None, lang=None):
        """Compile Markdown into HTML strings."""
        if Markdown is None:
            req_missing(['markdown'], 'build this site (compile Markdown)')
        if not is_two_file:
            _, data = self.split_metadata(data, post, lang)
        new_data, shortcodes = sc.extract_shortcodes(data)
        output, _ = self.converter.convert(new_data)
        output, shortcode_deps = self.site.apply_shortcodes_uuid(output, shortcodes, filename=source_path, extra_context={'post': post})
        return output, shortcode_deps

    def compile(self, source, dest, is_two_file=True, post=None, lang=None):
        """Compile the source file into HTML and save as dest."""
        if Markdown is None:
            req_missing(['markdown'], 'build this site (compile Markdown)')
        makedirs(os.path.dirname(dest))
        with io.open(dest, "w+", encoding="utf8") as out_file:
            with io.open(source, "r", encoding="utf8") as in_file:
                data = in_file.read()
            output, shortcode_deps = self.compile_string(data, source, is_two_file, post, lang)
            out_file.write(output)
        if post is None:
            if shortcode_deps:
                self.logger.error(
                    "Cannot save dependencies for post {0} (post unknown)",
                    source)
        else:
            post._depfile[dest] += shortcode_deps

    def create_post(self, path, **kw):
        """Create a new post."""
        content = kw.pop('content', None)
        onefile = kw.pop('onefile', False)
        # is_page is not used by create_post as of now.
        kw.pop('is_page', False)

        metadata = {}
        metadata.update(self.default_metadata)
        metadata.update(kw)
        makedirs(os.path.dirname(path))
        if not content.endswith('\n'):
            content += '\n'
        with io.open(path, "w+", encoding="utf8") as fd:
            if onefile:
                fd.write(write_metadata(metadata, comment_wrap=True, site=self.site, compiler=self))
            fd.write(content)

    def read_metadata(self, post, lang=None):
        """Read the metadata from a post, and return a metadata dict."""
        if not self.supports_metadata:
            return {}
        if Markdown is None:
            req_missing(['markdown'], 'build this site (compile Markdown)')
        if lang is None:
            lang = LocaleBorg().current_lang
        source = post.translated_source_path(lang)
        with io.open(source, 'r', encoding='utf-8') as inf:
            # Note: markdown meta returns lowercase keys
            data = inf.read()
            # If the metadata starts with "---" it's actually YAML and
            # we should not let markdown parse it, because it will do
            # bad things like setting empty tags to "''"
            if data.startswith('---\n'):
                return {}
            _, meta = self.converter.convert(data)
        # Map metadata from other platforms to names Nikola expects (Issue #2817)
        map_metadata(meta, 'markdown_metadata', self.site.config)
        return meta
