DMA32
  #   	ˆl–Ðz¾”ji?u4 \¸î*bÑ¿Àƒy×Ÿ¿ÄÃ "U    	# Copyright (C) 2012 Yahoo! Inc.
# Copyright (C) 2014 Amazon.com, Inc. or its affiliates.
#
# Author: Joshua Harlow <harlowja@yahoo-inc.com>
# Author: Andrew Jorgensen <ajorgens@amazon.com>
#
# This file is part of cloud-init. See LICENSE file for license information.

import functools
import json
import logging

from cloudinit import url_helper, util

LOG = logging.getLogger(__name__)
SKIP_USERDATA_CODES = frozenset([url_helper.NOT_FOUND])


class MetadataLeafDecoder:
    """Decodes a leaf blob into something meaningful."""

    def _maybe_json_object(self, text):
        if not text:
            return False
        text = text.strip()
        if text.startswith("{") and text.endswith("}"):
            return True
        return False

    def __call__(self, field, blob):
        if not blob:
            return ""
        try:
            blob = util.decode_binary(blob)
        except UnicodeDecodeError:
            return blob
        if self._maybe_json_object(blob):
            try:
                # Assume it's json, unless it fails parsing...
                return json.loads(blob)
            except (ValueError, TypeError) as e:
                LOG.warning(
                    "Field %s looked like a json object, but it was not: %s",
                    field,
                    e,
                )
        if blob.find("\n") != -1:
            return blob.splitlines()
        return blob


# See: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/
#         ec2-instance-metadata.html
class MetadataMaterializer:
    def __init__(self, blob, base_url, caller, leaf_decoder=None):
        self._blob = blob
        self._md = None
        self._base_url = base_url
        self._caller = caller
        if leaf_decoder is None:
            self._leaf_decoder = MetadataLeafDecoder()
        else:
            self._leaf_decoder = leaf_decoder

    def _parse(self, blob):
        leaves = {}
        children = []
        blob = util.decode_binary(blob)

        if not blob:
            return (leaves, children)

        def has_children(item):
            if item.endswith("/"):
                return True
            else:
                return False

        def get_name(item):
            if item.endswith("/"):
                return item.rstrip("/")
            return item

        for field in blob.splitlines():
            field = field.strip()
            field_name = get_name(field)
            if not field or not field_name:
                continue
            # Don't materialize credentials
            if field_name == "security-credentials":
                continue
            if has_children(field):
                if field_name not in children:
                    children.append(field_name)
            else:
                contents = field.split("=", 1)
                resource = field_name
                if len(contents) > 1:
                    # What a PITA...
                    (ident, sub_contents) = contents
                    ident = util.safe_int(ident)
                    if ident is not None:
                        resource = "%s/openssh-key" % (ident)
                        field_name = sub_contents
                leaves[field_name] = resource
        return (leaves, children)

    def materialize(self):
        if self._md is not None:
            return self._md
        self._md = self._materialize(self._blob, self._base_url)
        return self._md

    def _materialize(self, blob, base_url):
        (leaves, children) = self._parse(blob)
        child_contents = {}
        for c in children:
            child_url = url_helper.combine_url(base_url, c)
            if not child_url.endswith("/"):
                child_url += "/"
            child_blob = self._caller(child_url)
            child_contents[c] = self._materialize(child_blob, child_url)
        leaf_contents = {}
        for field, resource in leaves.items():
            leaf_url = url_helper.combine_url(base_url, resource)
            leaf_blob = self._caller(leaf_u