"""

    This file is part of the Ventoo program.

    This is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    It is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this software.  If not, see <http://www.gnu.org/licenses/>.

    Copyright 2010 Christopher Harvey

"""

import os.path as osp
from lxml import etree
import augeas_utils
import search_paths

class VentooModule:
    def __init__(self, moduleName):
        #see if we can find the module files
        found = False;
        for p in search_paths.modules:
            thisPath = osp.join(p,moduleName,"main.xml")
            if osp.isfile(thisPath):
                self.pathFound = thisPath
                found = True
                self.docRoot = osp.join(p, moduleName)
                break
        if not found:
            raise RuntimeError('Could not find '+moduleName+' Module')
        self.xmlTree = etree.parse(self.pathFound)
        #validate the module main.xml file.
        #make sure it starts with <VentooModule>
        self.xmlRoot = self.xmlTree.getroot()
        if self.xmlRoot.tag != "VentooModule":
            raise RuntimeError('Ventoo modules need to start with <VentooModule>')
        
        
    def getChildrenOf(self, xPath):
        children = self.xmlTree.xpath(osp.join(xPath, '*'))
        ret = []
        for i in range(len(children)):
            if not children[i].tag.startswith('ventoo_'):
                ret.extend([children[i]])
        return ret

    def getMultOf(self, xPath):
        elem = self.xmlTree.xpath(osp.join(xPath))
        if len(elem) >= 1:
            return elem[0].get("mult")
        else:
            return '0'

    def getDocURLOf(self, xPath): 
        try:
            elem = self.xmlTree.xpath(osp.join(xPath))
            if len(elem) >= 1 and not elem[0].get("docurl") == None:
                return "file:///"+osp.abspath(osp.join(self.docRoot, augeas_utils.stripBothSlashes(elem[0].get("docurl"))))
        except etree.XPathEvalError:
            pass
        return None


    """
    Returns true if a comes before b
    Raise ValueError if either a or b are not in the xml file.
    a and b must both have the same parent node.
    a and b are both tags, not paths.
    """
    def comesBefore(self, a, b):
        try:
            elemAlist = self.xmlTree.xpath("//"+a)
            elemBlist = self.xmlTree.xpath("//"+b)
        except etree.XPathEvalError:
            raise ValueError("Could not find one of "+b)
        if len(elemBlist) != 1:
            return ValueError("Could not find one of "+b)
        if len(elemAlist) != 1:
            return ValueError("Could not find one of "+a)
        elemAparent = elemAlist[0].getparent()
        elemBparent = elemBlist[0].getparent()
        if elemBparent.tag != elemAparent.tag:
            raise ValueError(a+" and "+b+" do not have the same parent.")
        for child in elemAparent:
            if child.tag == elemBlist[0].tag:
                return False
            if child.tag == elemAlist[0].tag:
                return True
        raise RuntimeError("Something is wrong in comesBefore in VentooModule...")