#!/usr/bin/env python2

"""The Power of Greypoint

This is a tiny script that turns a ReST-formatted text into
presentation slides. In the source text, slides are delimited by a
line containing only a percent sign.

From any slide you can use the "n", "b", and "i" accesskeys (Alt-[nbi]
in Mozilla) to move one slide forward, one slide backward, or back to
the beginning of the presentation.

Presentation is handled by a 'default.css' file assumed to be in the
same directory as the slide files.

This script requires the docutils module."""

__author__ = "Leonard Richardson (leonardr@segfault.org)"
__version__ = "1.0"
__copyright__ = "Copyright (c) 2003 Leonard Richardson"
__license__ = "Public domain"

import os
import re
import string
import sys

try:
    from docutils.core import publish_string
    from docutils.writers import html4css1        
except:
    raise "Unable to import the docutils module; please check your search path (%s)" % ':'.join(sys.path)

class Presentation:

    def __init__(self, presentationFile):
        "Initializes a presentation from a source file."
        self.slides = re.split("%\n", presentationFile.read())

    def write(self, destinationDir):
        "Writes a presentation into slide files in the specified directory." 
        writer = html4css1.Writer()
        for i in range(0, len(self.slides)):
            slide = self.slides[i] + '\n.. raw:: html\n\n %s' % self.navigationText(i)
            output = open(os.path.join(destinationDir,
                                       self.getFilename(i)), 'w')
            output.write(publish_string(slide, writer=writer))
            output.close()

    def navigationText(self, ordinal):
        "Returns navigation links for the given slide."
        return '%s %s %s' % (self.nextSlideLink(ordinal), self.indexLink(),
                             self.previousSlideLink(ordinal))

    def indexLink(self):
        "Returns a link to the main slide."
        return self.getLink(0, '', 'i')

    def nextSlideLink(self, ordinal):
        "Returns a link to the slide after the given ordinal, if any."
        link = ''
        if ordinal != len(self.slides) -1:
            link = self.getLink(ordinal+1, '', 'n')
        return link

    def previousSlideLink(self, ordinal):
        "Returns a link to the slide before the given ordinal, if any."
        link = ''
        if ordinal > 0:
            link = self.getLink(ordinal-1, '', 'b')
        return link

    def getLink(self, ordinal, text, accessKey, style="navigationLink"):
        "Returns a link to the slide with the given ordinal."
        return '<a class="%s" href="%s" accesskey="%s">%s</a>' % \
               (style, self.getFilename(ordinal), accessKey, text)

    def getFilename(self, ordinal):
        """Returns the filename to which a slide with the given ordinal
        should be written."""
        if ordinal == 0:
            filename = 'index'
        else:
            filename = string.zfill(str(ordinal), 2)
        return filename + '.html'

if __name__ == '__main__':
    if len(sys.argv) < 3:
        sys.exit("Syntax: %s [source file] [destination directory]" % sys.argv[0])
    presentation = Presentation(open(sys.argv[1]))
    print "By the power of Greypoint..."
    presentation.write(sys.argv[2])