# -*- coding: utf-8 -*-
#
# python-json-pointer - An implementation of the JSON Pointer syntax
# https://github.com/stefankoegl/python-json-pointer
#
# Copyright (c) 2011 Stefan Kögl <stefan@skoegl.net>
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
# 3. The name of the author may not be used to endorse or promote products
#    derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#

""" Identify specific nodes in a JSON document (according to draft 07) """

# http://tools.ietf.org/html/draft-ietf-appsawg-json-pointer-07

# Will be parsed by setup.py to determine package metadata
__author__ = 'Stefan Kögl <stefan@skoegl.net>'
__version__ = '0.6'
__website__ = 'https://github.com/stefankoegl/python-json-pointer'
__license__ = 'Modified BSD License'


try:
    from urllib import unquote
    from itertools import izip
except ImportError: # Python 3
    from urllib.parse import unquote
    izip = zip

from itertools import tee
import re


# array indices must not contain signs, spaces, decimal parts, etc
RE_ARRAY_INDEX=re.compile('^[0-9]+$')


class JsonPointerException(Exception):
    pass


class EndOfList(object):
    """ Result of accessing element "-" of a list """

    def __init__(self, list_):
        self.list_ = list_


    def __repr__(self):
        return '{cls}({lst})'.format(cls=self.__class__.__name__,
                lst=repr(self.list_))


_nothing = object()


def resolve_pointer(doc, pointer, default=_nothing):
    """
    Resolves pointer against doc and returns the referenced object

    >>> obj = {"foo": {"anArray": [ {"prop": 44}], "another prop": {"baz": "A string" }}}

    >>> resolve_pointer(obj, '') == obj
    True

    >>> resolve_pointer(obj, '/foo') == obj['foo']
    True

    >>> resolve_pointer(obj, '/foo/another%20prop') == obj['foo']['another prop']
    True

    >>> resolve_pointer(obj, '/foo/another%20prop/baz') == obj['foo']['another prop']['baz']
    True

    >>> resolve_pointer(obj, '/foo/anArray/0') == obj['foo']['anArray'][0]
    True

    >>> resolve_pointer(obj, '/some/path', None) == None
    True

    """

    pointer = JsonPointer(pointer)
    return pointer.resolve(doc, default)


class JsonPointer(object):
    """ A JSON Pointer that can reference parts of an JSON document """

    def __init__(self, pointer):
        parts = pointer.split('/')
        if parts.pop(0) != '':
            raise JsonPointerException('location must starts with /')

        parts = map(unquote, parts)
        parts = [part.replace('~1', '/') for part in parts]
        parts = [part.replace('~0', '~') for part in parts]
        self.parts = parts


    def to_last(self, doc, default=_nothing):
        """ Resolves ptr until the last step, returns (sub-doc, last-step) """

        if not self.parts:
            return doc, None

        for part in self.parts[:-1]:
            doc = self.walk(doc, part)

        return doc, self.get_part(doc, self.parts[-1])


    def resolve(self, doc, default=_nothing):
        """Resolves the pointer against doc and returns the referenced object"""

        for part in self.parts:

            try:
                doc = self.walk(doc, part)
            except JsonPointerException:
                if default is _nothing:
                    raise
                else:
                    return default

        return doc


    get = resolve


    def get_part(self, doc, part):
        """ Returns the next step in the correct type """

        if isinstance(doc, dict):
            return part

        elif isinstance(doc, list):

            if part == '-':
                return part

            if not RE_ARRAY_INDEX.match(str(part)):
                raise JsonPointerException("'%s' is not a valid list index" % (part, ))

            return int(part)

        else:
            raise JsonPointerException("Unknown document type '%s'" % (doc.__class__,))


    def walk(self, doc, part):
        """ Walks one step in doc and returns the referenced part """

        part = self.get_part(doc, part)

        if isinstance(doc, dict):
            try:
                return doc[part]

            except KeyError:
                raise JsonPointerException("member '%s' not found in %s" % (part, doc))

        elif isinstance(doc, list):

            if part == '-':
                return EndOfList(doc)

            try:
                return doc[part]

            except IndexError:
                raise JsonPointerException("index '%s' is out of bounds" % (part, ))


        else:
            raise JsonPointerException("can not go beyond '%s' (type '%s')" % (part, doc.__class__))



    def contains(self, ptr):
        """" Returns True if self contains the given ptr """
        return len(self.parts) > len(ptr.parts) and \
             self.parts[:len(ptr.parts)] == ptr.parts


def pairwise(iterable):
    "s -> (s0,s1), (s1,s2), (s2, s3), ..."
    a, b = tee(iterable)
    for _ in b:
        break
    return izip(a, b)