"""Seqan Doc Links for Trac.

Version 0.1.

Copyright (C) 2010 Manuel Holtgrewe

Install by copying this file into the plugins directory of your trac
work directory.  In your trac.ini, you can use something like this
(the following also shows the defaults).

  [seqan_doc_links]
  prefix = seqan
  base_url = http://www.seqan.de/dddoc/html/

Use something like this to test the plugin:

  * {{{[seqan:Page.Sequences]}}} [seqan:Page.Sequences]
  * {{{seqan:Class.Finder}}} seqan:Class.Finder
  * {{{seqan:"Concept.Simple Type"}}} seqan:"Concept.Simple Type"
  * {{{seqan:"Spec.Chunk Pool Allocator}}} seqan:"Spec.Chunk Pool Allocator"
"""
import urllib
import sys

import trac.wiki
import genshi.builder as gb


def getFilename(cat, item):
    """Get the filename that dddoc would create.

    Args:
      cat   String, category of the link.
      item  String, name of the item.

    Returns:
      File name of the categorized item.
    """
    return cat.upper() + escapeFiles(item) + ".html"


def escapeFiles(text):
    """Escape the file name as dddoc would do it.

    Args:
      text  String with the text to escape.

    Returns:
      Escaped text.
    """
    text = text.replace("_", "__")

    ret = ""
    for i in range(len(text)):
    	if (text[i] >= 'A') and (text[i] <= 'Z'):
    		ret += "_"
    	ret += text[i]

    ret = ret.replace("\t", "_09")
    ret = ret.replace("\n", "_0a")
    ret = ret.replace("!", "_21")
    ret = ret.replace("\"", "_22")
    ret = ret.replace("#", "_23")
    ret = ret.replace("$", "_24")
    ret = ret.replace("%", "_25")
    ret = ret.replace("&", "_26")
    ret = ret.replace("'", "_27")
    ret = ret.replace("(", "_28")
    ret = ret.replace(")", "_29")
    ret = ret.replace("*", "_2a")
    ret = ret.replace("+", "_2b")
    ret = ret.replace("/", "_2f")
    ret = ret.replace(":", "_3a")
    ret = ret.replace(",", "_2c")
    ret = ret.replace("<", "_3c")
    ret = ret.replace(">", "_3e")
    ret = ret.replace("?", "_3f")
    ret = ret.replace("\\", "_5c")
    ret = ret.replace("|", "_7c")
    ret = ret.replace(" ", "+")

    if (len(ret) == 0) or (ret[0] == '_'): return ret
    else: return '.'+ret


class SeqanDocsSyntaxProvider(trac.core.Component):
    """Expands seqan:<Category>.<EntryName> links."""
    trac.core.implements(trac.wiki.IWikiSyntaxProvider)

    SECTION_NAME = 'seqan_doc_links'
    DEFAULT_PREFIX = 'seqan'
    DEFAULT_BASE_URL = 'http://www.seqan.de/dddoc/html/'

    def __init__(self):
        # Set defaults.
        self.prefix = self.DEFAULT_PREFIX
        self.base_url = self.DEFAULT_BASE_URL
        # Parse configuration from trac.ini config file.
        for option in self.config.options(self.SECTION_NAME):
            if option[0] == 'prefix':
                self.prefix = option[1]
            if option[0] == 'base_url':
                self.base_url = option[1]

    def get_wiki_syntax(self):
        """Method from IWikiSyntaxProvider.

        Returns empty list, we do not implement any."""
        return []

    def get_link_resolvers(self):
        """Method from IWikiSyntaxProvider.

        Returns iterable (list) of (prefix, function) pairs.
        """
        return [(self.prefix, self.format_doc_link)]

    def format_doc_link(self, formatter, ns, target, label):
        """Function to perform formatting for seqan:XYZ links.

        This roughly follows [1].

        [1] http://trac.edgewall.org/wiki/TracDev/IWikiSyntaxProviderExample
        """
        # The following is a heuristic for "no alternative label".
        if ns in label and target in label:
          if '.' in target:
            category, item = tuple(target.split('.', 1))
            label = item
          else:
            label = target
        # Ignore if the target does not contain a dot.
        if not '.' in target:
          return target
        # Now, use dddoc's logic to generate the appropriate file name for
        file_name = getFilename(*target.split('.', 1))
        span = [gb.tag.span(' ', class_='icon'), label]
        title = ' "%s" in SeqAn documentation.' % target
        return gb.tag.a(span, class_='ext-link',
                        href=self.base_url + file_name, title=title)