#!/usr/bin/env python 
import sys
from xml import sax

class Block(object):
    pass

class BasicTextBlock(Block):
    def __init__(self, text = ""):
        self.text = text
        
    def __str__(self):
        return self.text
        
class Para(BasicTextBlock):
    def __str__(self):
        return "\n.PP\n" + self.text.lstrip()

class Lpara(BasicTextBlock):
    def __str__(self):
        return "\n.IP\n" + self.text.lstrip()

class ProgramListing(BasicTextBlock):
    def __str__(self):
        return "\n.nf\n%s\n.fi\n" % self.text.lstrip()

class ListItem(Block):
    def __init__(self):
        self.paras = []
        
    def __str__(self):
        ret = ""
        for p in self.paras:
            ret += str(p)
        return ret    
    
class VariableList(Block):
    def __init__(self):
        self.entries = []

    def __str__(self):
        ret = ""
        for p in self.entries:
            ret += str(p)
        return ret
    
class Variable(Block):
    def __init__(self):
        self.term = None
        self.listitem = None

    def __str__(self):
        return "\n.TP \n.B %s\n%s\n" % (self.term, str(self.listitem))
    
class RefSection(Block):
    def __init__(self, id):
        self.id = id
        self.title = None
        self.elements = []
        
    def first(self, vtype):
        for o in self.elements:
            if isinstance(o, vtype):
                return o
        return None
        
    def last(self, vtype):
        for o in reversed(self.elements):
            if isinstance(o, vtype):
                return o
        return None
        
    def __str__(self):
        ret = ".SH %s \n" % self.title
        for p in self.elements:
            ret += str(p)
        return ret

class DocBookToNroffHandler(sax.ContentHandler):
    def __init__(self, out=sys.stdout):
        ###########################################################################################
        self.out = out
        self.stack = []
        ###########################################################################################
        
        self.refentryinfo = {}
        self.refmeta = {}
        self.refnamediv = {}
        self.synopsis = {}
        self.elementcount = 0
        self.formatting = []
        self.justformatted = False

    def is_formatting(self, what):
        return what in [ "command", "option", "parameter", "replaceable", "filename", "emphasis" ]

    def translate_formatting(self, what):
        if what in ["command", "option", "parameter", "filename"]:
            return "B"
        elif what in ["emphasis", "replaceable"]:
            return "I"
        return ""
        
    def startElement(self, name, attrs):
        ###########################################################################################
        #print >> self.out, "+" + name
        name = name.lower()    
        self.stack.append(name)
        self.elementcount += 1
        #print >> self.out, self.stack
        ###########################################################################################
        if "refsection" == name:
            self.refsection = RefSection(attrs["id"])

        if "para" == name:
            if "listitem" in self.stack:
                self.refsection.last(VariableList).entries[-1].listitem.paras.append(Lpara())
            elif "refsection" in self.stack:
                self.refsection.elements.append(Para())
                
        if "variablelist" == name:
            self.refsection.elements.append(VariableList())
        
        if "varlistentry" == name:
            self.refsection.last(VariableList).entries.append(Variable())

        if "listitem" == name:
            self.refsection.last(VariableList).entries[-1].listitem = ListItem()

        if "programlisting" == name:
            self.refsection.elements.append(ProgramListing())

        if self.is_formatting(name):
            self.formatting.append(self.translate_formatting(name))

    def characters(self, content):
        ###########################################################################################
        name = self.stack[-1]
        #print >> self.out, content
        ###########################################################################################
        
        #TODO this should always use += content instead of = content, in case content is incomplete
        
        if "refentryinfo" in self.stack:
            if "refentrytitle" == name:
               self.refentryinfo["refentrytitle"] = content
            if "manvolnum" == name:
                self.refentryinfo["manvolnum"] = content
            if "productname" == name:
                self.refentryinfo["productname"] = content
            if "date" == name:
                self.refentryinfo["date"] = content
              
        elif "refmeta" in self.stack:
            if "refentrytitle" == name:
                self.refmeta["refentrytitle"] = content
            if "manvolnum" == name:
                self.refmeta["manvolnum"] = content
                
        elif "refnamediv" in self.stack:
            if "refname" == name:
                self.refnamediv["refname"] = content
            if "refpurpose" == name:
                self.refnamediv["refpurpose"] = content

        elif "cmdsynopsis" in self.stack:
            if "command" == name:
                self.synopsis["command"] = content
            #don't check more explicitly, take all text content under the arg
            elif "arg" in self.stack:
                if not self.synopsis.has_key("args"):
                    self.synopsis["args"] = []
                self.synopsis["args"].append(content) 

        elif "refsection" in self.stack:
            if "title" in self.stack:
                self.refsection.title = content
            elif "varlistentry" in self.stack:
                if "term" == name:
                    self.refsection.last(VariableList).entries[-1].term = content
                elif "listitem" in self.stack:
                    if "para" in self.stack:
                        self._add_formatted_text(self.refsection.last(VariableList).entries[-1].listitem.paras[-1], content)
            elif "programlisting" in self.stack:
                self.refsection.last(ProgramListing).text += content
            elif "para" in self.stack:
                self._add_formatted_text(self.refsection.last(Para), content)
                    
    def _add_formatted_text(self, mypara, content):
        if self.formatting:
            mypara.text += "\n.%s %s\n" % ("".join(self.formatting), content)
            self.justformatted = True
        else:
            if self.justformatted:
                mypara.text += content.lstrip()
            else:
                mypara.text += content
            self.justformatted = False        
    
    
    def endElement(self, name):
        ###########################################################################################
        #print >> self.out, "-" + name
        name = name.lower()
        self.stack.pop()
        #print >> self.out, self.stack
        ###########################################################################################
        
        if "refentryinfo" == name:
            print >> self.out, ".TH %(refentrytitle)s %(manvolnum)s \"%(date)s\" \"USER COMMANDS\"" % self.refentryinfo

        if "refnamediv" == name:
            print >> self.out, ".SH NAME \n %(refname)s \- %(refpurpose)s" % self.refnamediv

        if "cmdsynopsis" == name:
            self.synopsis["argcombo"] = " ".join(self.synopsis["args"])
            print >> self.out, ".SH Synopsis \n.B %(command)s \n%(argcombo)s" % self.synopsis

        if "refsection" == name:
            print >> self.out, str(self.refsection)

        if self.is_formatting(name):
            self.formatting.pop()

parser = sax.make_parser()
parser.setContentHandler(DocBookToNroffHandler())
parser.parse(open(sys.argv[1], "r"))