"""RSS 2.0 Generator

This library encapsulates the generation of an RSS (2.0) feed


You may freely use this code in any way you can think of.
"""
import xml.sax.saxutils
class RSS:
    """ 
    RSS
    
    This class encapsulates the creation of an RSS 2.0 feed
    
    The RSS2.0 spec can be found here: 
    http://blogs.law.harvard.edu/tech/rss
    
    
    RSS validator :  http://rss.scripting.com


    The generation of an RSS feed is simple, the following is a
    sample:
        from rsslib import RSS, Item, Namespace
        rss = RSS()
        rss.channel.link = "http://channel.com"
        rss.channel.title = "my channel title"
        rss.channel.description = "my channel description"
        
        ns = Namespace( "foobar", "http://foobar.baz" )
        rss.channel.namespaces.append( ns )
        
        item = Item()
        item.link = "http://link.com"
        item.description = "my link description"
        item.title ="my item title"
        item.nsItems[ns.name + ":foo"] = "bar"
        rss.channel.items.append( item )
        
        item = Item()
        item.link = "http://link2.com"
        item.description = "my link2 description"
        item.title ="my item2 title"
        item.nsItems[ns.name +":foo"] = "foo bar baz"
        rss.channel.items.append( item )
        
        print rss.write()
  
    output:
        <?xml version="1.0" encoding="UTF-8"?>
        <rss version="2.0" xmlns:foobar=http://foobar.baz >
        <channel>
        <title>my channel title</title>
        <link>http://channel.com</link>
        <description>my channel description</description>
        
        <item><title>my item title</title>
        <link>http://link.com</link>
        <description>my link description</description>
        <foobar:foo>bar</foobar:foo>
        </item>
        
        <item><title>my item2 title</title>
        <link>http://link2.com</link>
        <description>my link2 description</description>
        <foobar:foo>foo bar baz</foobar:foo>
        </item>
        
        </channel>
        </rss>
     
    author: cmallory /a t/ berserk /dot/ o r g
    """ 
    def __init__(self):
        self.channel = Channel()
        self.version = "2.0"
        self.contents = None
                
    if __name__ == "__main__" :
        from rsslib import RSS, Item, Namespace
        rss = RSS()
        rss.channel.link = "http://channel.com"
        rss.channel.title = "my channel title"
        rss.channel.description = "my channel description"
        
        ns = Namespace( "foobar", "http://foobar.baz" )
        rss.addNamespace( ns )
        
        item = Item()
        item.link = "http://link.com"
        item.description = "my link description"
        item.title ="my item title"
        
        item.enclosure.url = "http://enclosure.url.com"
        item.enclosure.length = 12345
        item.enclosure.type = "audio/mpeg"
        
        item.nsItems[ns.name + ":foo"] = "bar"
        rss.addItem( item )
        
        item = Item()
        item.link = "http://link2.com"
        item.description = "my link2 description"
        item.title ="my item2 title"
        item.nsItems[ns.name +":foo"] = "foo bar baz"
        rss.addItem( item )
        
        print rss.write()
   

    """
    Write out the rss document
    """
    def write( self ):
    
        self.contents = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
        #contents += "<!--\n Last " + cnt + " urls to be shrunk \n-->\n"
        
        self.contents += "<rss version=\"" + self.version + "\" "
        if ( self.channel is not None and self.channel.namespaces is not None ):
            for ns in self.channel.namespaces :
                self.contents += "xmlns:" + ns.name + "=\"" +  ns.url + "\" "
        self.contents += ">\n"     
        self.contents += self.generateChannel()
        self.contents += "</rss>\n";
        return self.contents
            
    """
    Generates everything contained in a <channel> element
    """        
    def generateChannel( self ):
        contents = ""
        if ( self.channel.initialized() ):
            contents += "<channel>\n"
            contents += self.optionalWrite("title", self.channel.title );
            contents += self.optionalWrite("link", self.channel.link );
            contents += self.optionalWrite("description", self.channel.description );
            
            contents += self.optionalWrite("language", self.channel.language );
            contents += self.optionalWrite("copyright", self.channel.copyright );
            contents += self.optionalWrite("category", self.channel.category );
            contents += self.optionalWrite("managingEditor", self.channel.managingEditor );
            contents += self.optionalWrite("webMaster", self.channel.webMaster );
            contents += self.optionalWrite("pubDate", self.channel.pubDate );
            contents += self.optionalWrite("lastBuildDate", self.channel.lastBuildDate );
            contents += self.optionalWrite("docs", self.channel.docs );
            contents += self.optionalWrite("cloud", self.channel.cloud );
            contents += self.optionalWrite("ttl", self.channel.ttl );
            contents += self.optionalWrite("generator", self.channel.generator );     
            contents += self.optionalWrite("image", self.channel.image );
            contents += self.optionalWrite("rating", self.channel.rating );
            contents += self.optionalWrite("textInput", self.channel.textInput );
            contents += self.optionalWrite("skipHours", self.channel.skipHours );
            contents += self.optionalWrite("skipDays", self.channel.skipDays );
 
            contents += "\n" + self.generateItems() + "</channel>\n"
        else :
            contents = "[Channel not properly initialized.  "
            contents +="A required field is not set.(title/link/description]"
        
        return contents

    """
    Generates all items within a channel
    """            
    def generateItems( self ):
        c = ""
        for i in self.channel.items :

            c += "<item>"

            c += self.optionalWrite("title", i.title);
            c += self.optionalWrite("link", i.link );
            c += self.optionalWrite("description", i.description);
            c += self.optionalWrite("author", i.author );
            c += self.optionalWrite("pubDate", str(i.pubDate) )
            c += self.optionalWrite("category", i.category )
            c += self.optionalWrite("comments", i.comments )
            c += self.optionalWrite("guid", i.guid )
            c += self.optionalWrite("source", i.source )
            
            if ( i.enclosure.url != "" ):
                c+= "<enclosure url=\"" + i.enclosure.url + "\" "
                c+= "length=\"" + str(i.enclosure.length )+ "\" "
                c+= "type=\"" + i.enclosure.type + "\"/>\n"
                
            for k in i.nsItems.keys():
                c += self.optionalWrite( k , i.nsItems[ k ] )
            
            c += "</item>\n\n"
            
        return c


    def addNamespace( self, ns ):
        if ( self.channel.namespaces is not None ):
            self.channel.namespaces.append( ns )

    def addItem( self, item ):
        if ( self.channel is not None):
            self.channel.items.append( item )
            
            
    def optionalWrite( self, key, val ):
        if ( val is not None and val != "" ):
            return "<" + key + ">" + xml.sax.saxutils.escape(val) + "</" + key + ">\n"
        else:
            return ""


"""
Namespace
"""
class Namespace:
    def __init__( self, name, url ):
        self.url = url
        self.name = name

   
class Channel:
    """
    Channel
    
	(http://blogs.law.harvard.edu/tech/rss)
	 
	This object represents an RSS channel (as of ver2.0)
    """
    
    def __init__( self ):
        #
        # Required Fields
        #
        self.title= None
        self.link= None
        self.description= None
        #
        #  Optional Fields
        #
        self.language = ""
        self.copyright = ""
        self.managingEditor = ""
        self.webMaster = ""
        self.pubDate = ""
        self.lastBuildDate = ""
        self.category = ""
        self.generator = ""
        self.docs = ""
        self.cloud = ""
        self.ttl = ""
        self.image = ""
        self.rating = ""
        self.textInput = ""
        self.skipHours = ""
        self.skipDays = ""
        
        self.items = []
        self.namespaces = []

    def initialized( self ):
        return self.title is not None and self.link is not None and self.description is not None
            
class Item:
    """
    Item
     
    http://blogs.law.harvard.edu/tech/rss#hrelementsOfLtitemgt
     
    A channel may contain any number of &lt;item&gt;s. An item may 
    represent a "story" -- much like a story in a newspaper or magazine; 
    if so its description is a synopsis of the story, and the link 
    points to the full story. An item may also be complete in itself, 
    if so, the description contains the text (entity-encoded HTML is 
    allowed; see examples), and the link and title may be omitted. 
    All elements of an item are optional, however at least one of 
    title or description must be present.
    """
    def __init__( self ):

        self.title = ""
        self.link = ""
        self.description = ""
        self.author = ""
        self.category = ""
        self.comments = ""
        self.enclosure = ""
        self.guid = ""
        self.pubDate = ""
        self.source = ""
        self.enclosure = Enclosure()
        
        self.nsItems = {}
        
        
class Enclosure:

    """
    Enclosure
    
    <enclosure> sub-element of <item> 

    <enclosure> is an optional sub-element of <item>.

    It has three required attributes:
    
        url:     says where the enclosure is located, 
        length:  says how big it is in bytes, and 
        type:    says what its type is, a standard MIME type.

        The url must be an http url.

    Example: <enclosure url="http://www.scripting.com/mp3s/weatherReportSuite.mp3" length="12216320" type="audio/mpeg" />
    
    """
    def __init__(self):
        self.url = ""
        self.length = 0
        self.type = ""