#!/usr/bin/env python

import os
import sys
import urllib2

from ConfigParser import ConfigParser
from ConfigParser import InterpolationMissingOptionError
from ConfigParser import MissingSectionHeaderError
from ConfigParser import NoOptionError
from StringIO import StringIO

def file_pointer(resource):
    """returns a file-like object given a string"""
    # XXX could go in utils.py 

    if not isinstance(resource, basestring):
        # assume resource is already a file-like object
        return resource

    if os.path.exists(resource):
        return file(resource)
    if sum([resource.startswith(http) for http in 'http://', 'https://']):
        return urllib2.urlopen(resource)
    return StringIO(resource)


class ConfigMunger(ConfigParser):
    """combine configuration from .ini files"""
    
    def __init__(self, *conf, **kw):
        ConfigParser.__init__(self, kw.get('defaults',{}))
        self.read(*conf)
    
    def __getitem__(self, section):
        """
        return an object with __getitem__ defined appropriately
        to allow referencing like self['foo']['bar']
        """
        return dict(self.items(section))

    def get(self, section, option, default=None, raw=False, vars=None):
        try:
            value = ConfigParser.get(self, section, option, raw, vars)
        except NoOptionError:
            return default
        return value

    def set(self, section, option, value):
        if section not in self.sections():
            self.add_section(section)
        ConfigParser.set(self, section, option, value)

    def move_section(self, section, newname):
        if self.has_section(section):
            _section = self[section]
            self.remove_section(section)
        else:
            _section = {}
        self.read({newname: _section})
    
    def dict(self):
        """return a dictionary of dictionaries; 
        the outer with keys of section names;
        the inner with keys, values of the section"""
        return dict([(section, self[section])
                     for section in self.sections()])

    def read(self, *ini):
        for _ini in ini:
            if isinstance(_ini, dict):
                for section, contents in _ini.items():
                    for option, value in contents.items():
                        self.set(section, option, value)
            elif isinstance(_ini, list) or isinstance(_ini, tuple):

                # ensure list or tuple of 3-tuples
                assert len([option for option in _ini
                            if isinstance(option, tuple) 
                            and len(option) == 3])

                for section, option, value in _ini:
                    self.set(section, option, value)                
            else:
                fp = file_pointer(_ini)
                try:
                    self.readfp(fp)
                except MissingSectionHeaderError:
                    fp.seek(0)
                    fp = StringIO("[DEFAULTS]\n" + fp.read())
                    self.readfp(fp)
            
    def missing(self):
        """returns missing variable names"""
        missing = set()        

        for section in self.sections():
            for key, val in self.items(section, raw=True):
                try:
                    self.get(section, key)
                except InterpolationMissingOptionError, e:
                    missing.add(e.reference)
        return missing

    def tuples(self):
        """
        return options in format appropriate to trac:
        [ (section, option, value) ]
        """
        options = []
        for section in self.sections():
            options.extend([(section,) + item 
                            for item in self.items(section)])
        return options

    def write(self, fp=sys.stdout, raw=False, sorted=True, vars=None):
        sections = self.sections()
        if sorted:
            sections.sort()

        for section in sections:
            print >> fp, '[%s]' % section
            options = self.options(section)
            if sorted:
                options.sort()
            for option in options:
                print >> fp, "%s = %s" % (option, self.get(section, option, raw, vars))
            if section != sections[-1]:
                print >> fp

if __name__ == '__main__':
    import sys
    from optparse import OptionParser
    parser = OptionParser()
    parser.add_option('--missing', action="store_true", default=False,
                      help="list missing template variables")
    munger = ConfigMunger()
    options, args = parser.parse_args()
    munger.read(*args)
    if options.missing:
        for missing in munger.missing():
            print missing
    else:
        munger.write(sys.stdout)