import urllib

from zope.interface import classProvides
from zope.interface import implements
from zope.location.location import located
from zope.location.interfaces import ILocation

from repoze.bfg.interfaces import IPublishTraverser
from repoze.bfg.interfaces import IPublishTraverserFactory

def split_path(path):
    if path.startswith('/'):
        path = path[1:]
    if path.endswith('/'):
        path = path[:-1]
    clean=[]
    for segment in path.split('/'):
        segment = urllib.unquote(segment) # deal with spaces in path segment
        if not segment or segment=='.':
            continue
        elif segment == '..':
            del clean[-1]
        else:
            clean.append(segment)
    return clean

def step(ob, name, default):
    if name.startswith('@@'):
        return name[2:], default
    if not hasattr(ob, '__getitem__'):
        return name, default
    try:
        return name, ob[name]
    except KeyError:
        return name, default

_marker = ()

class NaivePublishTraverser(object):
    classProvides(IPublishTraverserFactory)
    implements(IPublishTraverser)
    def __init__(self, root, request):
        self.root = root
        self.locatable = ILocation.providedBy(root)
        self.request = request

    def __call__(self, path):
        root = self.root
        path = split_path(path)

        ob = self.root
        name = ''

        while path:
            segment = path.pop(0)
            segment, next = step(ob, segment, _marker)
            if next is _marker:
                name = segment
                break
            if self.locatable:
                next = located(next, ob, segment)
            ob = next

        return ob, name, path