import py
defaultconftestpath = py.magic.autopath().dirpath('defaultconftest.py')

class Conftest(object):
    """ the single place for accessing values and interacting 
        towards conftest modules from py.test objects. 

        Note that triggering Conftest instances to import 
        conftest.py files may result in added cmdline options. 
        XXX
    """ 
    def __init__(self, path=None):
        self._path2confmods = {}
        if path is not None:
            self.setinitial([path])

    def setinitial(self, args):
        """ try to find a first anchor path for looking up global values
            from conftests. This function is usually called _before_  
            argument parsing.  conftest files may add command line options
            and we thus have no completely safe way of determining
            which parts of the arguments are actually related to options
            and which are file system paths.  We just try here to get 
            bootstrapped ... 
        """
        current = py.path.local()
        for arg in args + [current]:
            anchor = current.join(arg, abs=1)
            if anchor.check(): # we found some file object 
                self._path2confmods[None] = self.getconftestmodules(anchor)
                break

    def getconftestmodules(self, path):
        """ return a list of imported conftest modules for the given path.  """ 
        try:
            clist = self._path2confmods[path]
        except KeyError:
            dp = path.dirpath()
            if dp == path: 
                return [importconfig(defaultconftestpath)]
            clist = self.getconftestmodules(dp)
            conftestpath = path.join("conftest.py")
            if conftestpath.check(file=1):
                clist.append(importconfig(conftestpath))
            self._path2confmods[path] = clist
        # be defensive: avoid changes from caller side to
        # affect us by always returning a copy of the actual list 
        return clist[:]

    def rget(self, name, path=None):
        mod, value = self.rget_with_confmod(name, path)
        return value

    def rget_with_confmod(self, name, path=None):
        modules = self.getconftestmodules(path)
        modules.reverse()
        for mod in modules:
            try:
                return mod, getattr(mod, name)
            except AttributeError:
                continue
        raise KeyError, name

def importconfig(configpath):
    # We could have used caching here, but it's redundant since
    # they're cached on path anyway, so we use it only when doing rget_path
    assert configpath.check(), configpath
    if not configpath.dirpath('__init__.py').check(file=1): 
        # HACK: we don't want any "globally" imported conftest.py, 
        #       prone to conflicts and subtle problems 
        modname = str(configpath).replace('.', configpath.sep)
        mod = configpath.pyimport(modname=modname)
    else:
        mod = configpath.pyimport()
    return mod