"""
Guild Journal Extension for Python-Markdown
======================================

Converts [[NPC/Frankie]] to links.

Original code Copyright [Waylan Limberg](http://achinghead.com/).

All changes Copyright The Python Markdown Project

License: [BSD](https://opensource.org/licenses/bsd-license.php)

"""

from markdown.extensions import Extension
from markdown.inlinepatterns import InlineProcessor
from guild.models import NPC, Character
import xml.etree.ElementTree as etree


def build_url(category: str, name):
    """Build a URL from the label, a base, and an end."""
    if category.lower() == "char":
        try:
            return Character.get_by_name(name).get_absolute_url()
        except Character.DoesNotExist:
            return ""
    elif category.lower() == "npc":
        try:
            return NPC.get_by_name(name).get_absolute_url()
        except NPC.DoesNotExist:
            return ""
    return ""


class GuildLinkExtension(Extension):
    def extendMarkdown(self, md):
        self.md = md

        # append to end of inline patterns
        GUILD_RE = r"\[\[([\w0-9_ -]+)\/([\w0-9_ -]+)\]\]"
        wikilinkPattern = GuildLinksInlineProcessor(GUILD_RE, self.getConfigs())
        wikilinkPattern.md = md
        md.inlinePatterns.register(wikilinkPattern, "guildlinks", 75)


class GuildLinksInlineProcessor(InlineProcessor):
    def __init__(self, pattern, config):
        super().__init__(pattern)
        self.config = config

    def handleMatch(self, m, data):
        if m.group(1).strip() and m.group(2).strip():
            category = m.group(1).strip()
            name = m.group(2).strip()
            url = build_url(category, name)
            a = etree.Element("a")
            a.text = name
            a.set("href", url)
            if url == "":
                a.set("class", "invalid-url")
        else:
            a = ""
        return a, m.start(0), m.end(0)


def makeExtension(**kwargs):  # pragma: no cover
    return GuildLinkExtension(**kwargs)