# Copyright (c) 2006-2012 Mitch Garnaat http://garnaat.org/
# Copyright (c) 2010, Eucalyptus Systems, Inc.
# Copyright (c) 2012 Amazon.com, Inc. or its affiliates.
# All rights reserved.
#
# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish, dis-
# tribute, sublicense, and/or sell copies of the Software, and to permit
# persons to whom the Software is furnished to do so, subject to the fol-
# lowing conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABIL-
# ITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
# SHALL THE AUTHOR BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
# IN THE SOFTWARE.

#
# Parts of this code were copied or derived from sample code supplied by AWS.
# The following notice applies to that code.
#
#  This software code is made available "AS IS" without warranties of any
#  kind.  You may copy, display, modify and redistribute the software
#  code either by itself or as incorporated into your code; provided that
#  you do not remove any proprietary notices.  Your use of this software
#  code is at your own risk and you waive any claim against Amazon
#  Digital Services, Inc. or its affiliates with respect to your use of
#  this software code. (c) 2006 Amazon Digital Services, Inc. or its
#  affiliates.

"""
Some handy utility functions used by several classes.
"""

import subprocess
import time
import logging.handlers
import boto
import boto.provider
import tempfile
import random
import smtplib
import datetime
import re
import email.mime.multipart
import email.mime.base
import email.mime.text
import email.utils
import email.encoders
import gzip
import threading
import locale
from boto.compat import six, StringIO, urllib, encodebytes

from contextlib import contextmanager

from hashlib import md5, sha512
_hashfn = sha512

from boto.compat import json

try:
    from boto.compat.json import JSONDecodeError
except ImportError:
    JSONDecodeError = ValueError

# List of Query String Arguments of Interest
qsa_of_interest = ['acl', 'cors', 'defaultObjectAcl', 'location', 'logging',
                   'partNumber', 'policy', 'requestPayment', 'torrent',
                   'versioning', 'versionId', 'versions', 'website',
                   'uploads', 'uploadId', 'response-content-type',
                   'response-content-language', 'response-expires',
                   'response-cache-control', 'response-content-disposition',
                   'response-content-encoding', 'delete', 'lifecycle',
                   'tagging', 'restore',
                   # storageClass is a QSA for buckets in Google Cloud Storage.
                   # (StorageClass is associated to individual keys in S3, but
                   # having it listed here should cause no problems because
                   # GET bucket?storageClass is not part of the S3 API.)
                   'storageClass',
                   # websiteConfig is a QSA for buckets in Google Cloud
                   # Storage.
                   'websiteConfig',
                   # compose is a QSA for objects in Google Cloud Storage.
                   'compose',
                   # billing is a QSA for buckets in Google Cloud Storage.
                   'billing',
                   # userProject is a QSA for requests in Google Cloud Storage.
                   'userProject',
                   # encryptionConfig is a QSA for requests in Google Cloud
                   # Storage.
                   'encryptionConfig']


_first_cap_regex = re.compile('(.)([A-Z][a-z]+)')
_number_cap_regex = re.compile('([a-z])([0-9]+)')
_end_cap_regex = re.compile('([a-z0-9])([A-Z])')


def unquote_v(nv):
    if len(nv) == 1:
        return nv
    else:
        return (nv[0], urllib.parse.unquote(nv[1]))


def canonical_string(method, path, headers, expires=None,
                     provider=None):
    """
    Generates the aws canonical string for the given parameters
    """
    if not provider:
        provider = boto.provider.get_default()
    interesting_headers = {}
    for key in headers:
        lk = key.lower()
        if headers[key] is not None and \
                (lk in ['content-md5', 'content-type', 'date'] or
                 lk.startswith(provider.header_prefix)):
            interesting_headers[lk] = str(headers[key]).strip()

    # these keys get empty strings if they don't exist
    if 'content-type' not in interesting_headers:
        interesting_headers['content-type'] = ''
    if 'content-md5' not in interesting_headers:
        interesting_headers['content-md5'] = ''

    # just in case someone used this.  it's not necessary in this lib.
    if provider.date_header in interesting_headers:
        interesting_headers['date'] = ''

    # if you're using expires for query string auth, then it trumps date
    # (and provider.date_header)
    if expires:
        interesting_headers['date'] = str(expires)

    sorted_header_keys = sorted(interesting_headers.keys())

    buf = "%s\n" % method
    for key in sorted_header_keys:
        val = interesting_headers[key]
        if key.startswith(provider.header_prefix):
            buf += "%s:%s\n" % (key, val)
        else:
            buf += "%s\n" % val

    # don't include anything after the first ? in the resource...
    # unless it is one of the QSA of interest, defined above
    t = path.split('?')
    buf += t[0]

    if len(t) > 1:
        qsa = t[1].split('&')
        qsa = [a.split('=', 1) for a in qsa]
        qsa = [unquote_v(a) for a in qsa if a[0] in qsa_of_interest]
        if len(qsa) > 0:
            qsa.sort(key=lambda x: x[0])
            qsa = ['='.join(a) for a in qsa]
            buf += '?'
            buf += '&'.join(qsa)

    return buf


def merge_meta(headers, metadata, provider=None):
    if not provider:
        provider = boto.provider.get_default()
    metadata_prefix = provider.metadata_prefix
    final_headers = headers.copy()
    for k in metadata.keys():
        if k.lower() in boto.s3.key.Key.base_user_settable_fields:
            final_headers[k] = metadata[k]
        else:
            final_headers[metadata_prefix + k] = metadata[k]

    return final_headers


def get_aws_metadata(headers, provider=None):
    if not provider:
        provider = boto.provider.get_default()
    metadata_prefix = provider.metadata_prefix
    metadata = {}
    for hkey in headers.keys():
        if hkey.lower().startswith(metadata_prefix):
            val = urllib.parse.unquote(headers[hkey])
            if isinstance(val, bytes):
                try:
                    val = val.decode('utf-8')
                except UnicodeDecodeError:
                    # Just leave the value as-is
                    pass
            metadata[hkey[len(metadata_prefix):]] = val
            del headers[hkey]
    return metadata


def retry_url(url, retry_on_404=True, num_retries=10, timeout=None):
    """
    Retry a url.  This is specifically used for accessing the metadata
    service on an instance.  Since this address should never be proxied
    (for security reasons), we create a ProxyHandler with a NULL
    dictionary to override any proxy settings in the environment.
    """
    for i in range(0, num_retries):
        try:
            proxy_handler = urllib.request.ProxyHandler({})
            opener = urllib.request.build_opener(proxy_handler)
            req = urllib.request.Request(url)
            r = opener.open(req, timeout=timeout)
            result = r.read()

            if(not isinstance(result, six.string_types) and
                    hasattr(result, 'decode')):
                result = result.decode('utf-8')

            return result
        except urllib.error.HTTPError as e:
            code = e.getcode()
            if code == 404 and not retry_on_404:
                return ''
        except Exception as e:
            boto.log.exception('Caught exception reading instance data')
        # If not on the last iteration of the loop then sleep.
        if i + 1 != num_retries:
            boto.log.debug('Sleeping before retrying')
            time.sleep(min(2 ** i,
                           boto.config.get('Boto', 'max_retry_delay', 60)))
    boto.log.error('Unable to read instance data, giving up')
    return ''


def _get_instance_metadata(url, num_retries, timeout=None):
    return LazyLoadMetadata(url, num_retries, timeout)


class LazyLoadMetadata(dict):
    def __init__(self, url, num_retries, timeout=None):
        self._url = url
        self._num_retries = num_retries
        self._leaves = {}
        self._dicts = []
        self._timeout = timeout
        data = boto.utils.retry_url(self._url, num_retries=self._num_retries, timeout=self._timeout)
        if data:
            fields = data.split('\n')
            for field in fields:
                if field.endswith('/'):
                    key = field[0:-1]
                    self._dicts.append(key)
                else:
                    p = field.find('=')
                    if p > 0:
                        key = field[p + 1:]
                        resource = field[0:p] + '/openssh-key'
                    else:
                        key = resource = field
                    self._leaves[key] = resource
                self[key] = None

    def _materialize(self):
        for key in self:
            self[key]

    def __getitem__(self, key):
        if key not in self:
            # allow dict to throw the KeyError
            return super(LazyLoadMetadata, self).__getitem__(key)

        # already loaded
        val = super(LazyLoadMetadata, self).__getitem__(key)
        if val is not None:
            return val

        if key in self._leaves:
            resource = self._leaves[key]
            last_exception = None

            for i in range(0, self._num_retries):
                try:
                    val = boto.utils.retry_url(
                        self._url + urllib.parse.quote(resource,
                                                       safe="/:"),
                        num_retries=self._num_retries,
                        timeout=self._timeout)
                    if val and val[0] == '{':
                        val = json.loads(val)
                        break
                    else:
                        p = val.find('\n')
                        if p > 0:
                            val = val.split('\n')
                        break

                except JSONDecodeError as e:
                    boto.log.debug(
                        "encountered '%s' exception: %s" % (
                            e.__class__.__name__, e))
                    boto.log.debug(
                        'corrupted JSON data found: %s' % val)
                    last_exception = e

                except Exception as e:
                    boto.log.debug("encountered unretryable" +
                                   " '%s' exception, re-raising" % (
                                       e.__class__.__name__))
                    last_exception = e
                    raise

                boto.log.error("Caught exception reading meta data" +
                               " for the '%s' try" % (i + 1))

                if i + 1 != self._num_retries:
                    next_sleep = min(
                        random.random() * 2 ** i,
                        boto.config.get('Boto', 'max_retry_delay', 60))
                    time.sleep(next_sleep)
            else:
                boto.log.error('Unable to read meta data, giving up')
                boto.log.error(
                    "encountered '%s' exception: %s" % (
                        last_exception.__class__.__name__, last_exception))
                raise last_exception

            self[key] = val
        elif key in self._dicts:
            self[key] = LazyLoadMetadata(self._url + key + '/',
                                         self._num_retries)

        return super(LazyLoadMetadata, self).__getitem__(key)

    def get(self, key, default=None):
        try:
            return self[key]
        except KeyError:
            return default

    def values(self):
        self._materialize()
        return super(LazyLoadMetadata, self).values()

    def items(self):
        self._materialize()
        return super(LazyLoadMetadata, self).items()

    def __str__(self):
        self._materialize()
        return super(LazyLoadMetadata, self).__str__()

    def __repr__(self):
        self._materialize()
        return super(LazyLoadMetadata, self).__repr__()


def _build_instance_metadata_url(url, version, path):
    """
    Builds an EC2 metadata URL for fetching information about an instance.

    Example:

        >>> _build_instance_metadata_url('http://169.254.169.254', 'latest', 'meta-data/')
        http://169.254.169.254/latest/meta-data/

    :type url: string
    :param url: URL to metadata service, e.g. 'http://169.254.169.254'

    :type version: string
    :param version: Version of the metadata to get, e.g. 'latest'

    :type path: string
    :param path: Path of the metadata to get, e.g. 'meta-data/'. If a trailing
                 slash is required it must be passed in with the path.

    :return: The full metadata URL
    """
    return '%s/%s/%s' % (url, version, path)


def get_instance_metadata(version='latest', url='http://169.254.169.254',
                          data='meta-data/', timeout=None, num_retries=5):
    """
    Returns the instance metadata as a nested Python dictionary.
    Simple values (e.g. local_hostname, hostname, etc.) will be
    stored as string values.  Values such as ancestor-ami-ids will
    be stored in the dict as a list of string values.  More complex
    fields such as public-keys and will be stored as nested dicts.

    If the timeout is specified, the connection to the specified url
    will time out after the specified number of seconds.

    """
    try:
        metadata_url = _build_instance_metadata_url(url, version, data)
        return _get_instance_metadata(metadata_url, num_retries=num_retries, timeout=timeout)
    except urllib.error.URLError:
        boto.log.exception("Exception caught when trying to retrieve "
                           "instance metadata for: %s", data)
        return None


def get_instance_identity(version='latest', url='http://169.254.169.254',
                          timeout=None, num_retries=5):
    """
    Returns the instance identity as a nested Python dictionary.
    """
    iid = {}
    base_url = _build_instance_metadata_url(url, version,
                                            'dynamic/instance-identity/')
    try:
        data = retry_url(base_url, num_retries=num_retries, timeout=timeout)
        fields = data.split('\n')
        for field in fields:
            val = retry_url(base_url + '/' + field + '/', num_retries=num_retries, timeout=timeout)
            if val[0] == '{':
                val = json.loads(val)
            if field:
                iid[field] = val
        return iid
    except urllib.error.URLError:
        return None


def get_instance_userdata(version='latest', sep=None,
                          url='http://169.254.169.254', timeout=None, num_retries=5):
    ud_url = _build_instance_metadata_url(url, version, 'user-data')
    user_data = retry_url(ud_url, retry_on_404=False, num_retries=num_retries, timeout=timeout)
    if user_data:
        if sep:
            l = user_data.split(sep)
            user_data = {}
            for nvpair in l:
                t = nvpair.split('=')
                user_data[t[0].strip()] = t[1].strip()
    return user_data

ISO8601 = '%Y-%m-%dT%H:%M:%SZ'
ISO8601_MS = '%Y-%m-%dT%H:%M:%S.%fZ'
RFC1123 = '%a, %d %b %Y %H:%M:%S %Z'
LOCALE_LOCK = threading.Lock()


@contextmanager
def setlocale(name):
    """
    A context manager to set the locale in a threadsafe manner.
    """
    with LOCALE_LOCK:
        saved = locale.setlocale(locale.LC_ALL)

        try:
            yield locale.setlocale(locale.LC_ALL, name)
        finally:
            locale.setlocale(locale.LC_ALL, saved)


def get_ts(ts=None):
    if not ts:
        ts = time.gmtime()
    return time.strftime(ISO8601, ts)


def parse_ts(ts):
    with setlocale('C'):
        ts = ts.strip()
        try:
            dt = datetime.datetime.strptime(ts, ISO8601)
            return dt
        except ValueError:
            try:
                dt = datetime.datetime.strptime(ts, ISO8601_MS)
                return dt
            except ValueError:
                dt = datetime.datetime.strptime(ts, RFC1123)
                return dt


def find_class(module_name, class_name=None):
    if class_name:
        module_name = "%s.%s" % (module_name, class_name)
    modules = module_name.split('.')
    c = None

    try:
        for m in modules[1:]:
            if c:
                c = getattr(c, m)
            else:
                c = getattr(__import__(".".join(modules[0:-1])), m)
        return c
    except:
        return None


def update_dme(username, password, dme_id, ip_address):
    """
    Update your Dynamic DNS record with DNSMadeEasy.com
    """
    dme_url = 'https://www.dnsmadeeasy.com/servlet/updateip'
    dme_url += '?username=%s&password=%s&id=%s&ip=%s'
    s = urllib.request.urlopen(dme_url % (username, password, dme_id, ip_address))
    return s.read()


def fetch_file(uri, file=None, username=None, password=None):
    """
    Fetch a file based on the URI provided.
    If you do not pass in a file pointer a tempfile.NamedTemporaryFile,
    or None if the file could not be retrieved is returned.
    The URI can be either an HTTP url, or "s3://bucket_name/key_name"
    """
    boto.log.info('Fetching %s' % uri)
    if file is None:
        file = tempfile.NamedTemporaryFile()
    try:
        if uri.startswith('s3://'):
            bucket_name, key_name = uri[len('s3://'):].split('/', 1)
            c = boto.connect_s3(aws_access_key_id=username,
                                aws_secret_access_key=password)
            bucket = c.get_bucket(bucket_name)
            key = bucket.get_key(key_name)
            key.get_contents_to_file(file)
        else:
            if username and password:
                passman = urllib.request.HTTPPasswordMgrWithDefaultRealm()
                passman.add_password(None, uri, username, password)
                authhandler = urllib.request.HTTPBasicAuthHandler(passman)
                opener = urllib.request.build_opener(authhandler)
                urllib.request.install_opener(opener)
            s = urllib.request.urlopen(uri)
            file.write(s.read())
        file.seek(0)
    except:
        raise
        boto.log.exception('Problem Retrieving file: %s' % uri)
        file = None
    return file


class ShellCommand(object):

    def __init__(self, command, wait=True, fail_fast=False, cwd=None):
        self.exit_code = 0
        self.command = command
        self.log_fp = StringIO()
        self.wait = wait
        self.fail_fast = fail_fast
        self.run(cwd=cwd)

    def run(self, cwd=None):
        boto.log.info('running:%s' % self.command)
        self.process = subprocess.Popen(self.command, shell=True,
                                        stdin=subprocess.PIPE,
                                        stdout=subprocess.PIPE,
                                        stderr=subprocess.PIPE,
                                        cwd=cwd)
        if(self.wait):
            while self.process.poll() is None:
                time.sleep(1)
                t = self.process.communicate()
                self.log_fp.write(t[0])
                self.log_fp.write(t[1])
            boto.log.info(self.log_fp.getvalue())
            self.exit_code = self.process.returncode

            if self.fail_fast and self.exit_code != 0:
                raise Exception("Command " + self.command +
                                " failed with status " + self.exit_code)

            return self.exit_code

    def setReadOnly(self, value):
        raise AttributeError

    def getStatus(self):
        return self.exit_code

    status = property(getStatus, setReadOnly, None,
                      'The exit code for the command')

    def getOutput(self):
        return self.log_fp.getvalue()

    output = property(getOutput, setReadOnly, None,
                      'The STDIN and STDERR output of the command')


class AuthSMTPHandler(logging.handlers.SMTPHandler):
    """
    This class extends the SMTPHandler in the standard Python logging module
    to accept a username and password on the constructor and to then use those
    credentials to authenticate with the SMTP server.  To use this, you could
    add something like this in your boto config file:

    [handler_hand07]
    class=boto.utils.AuthSMTPHandler
    level=WARN
    formatter=form07
    args=('localhost', 'username', 'password', 'from@abc', ['user1@abc', 'user2@xyz'], 'Logger Subject')
    """

    def __init__(self, mailhost, username, password,
                 fromaddr, toaddrs, subject):
        """
        Initialize the handler.

        We have extended the constructor to accept a username/password
        for SMTP authentication.
        """
        super(AuthSMTPHandler, self).__init__(mailhost, fromaddr,
                                              toaddrs, subject)
        self.username = username
        self.password = password

    def emit(self, record):
        """
        Emit a record.

        Format the record and send it to the specified addressees.
        It would be really nice if I could add authorization to this class
        without having to resort to cut and paste inheritance but, no.
        """
        try:
            port = self.mailport
            if not port:
                port = smtplib.SMTP_PORT
            smtp = smtplib.SMTP(self.mailhost, port)
            smtp.login(self.username, self.password)
            msg = self.format(record)
            msg = "From: %s\r\nTo: %s\r\nSubject: %s\r\nDate: %s\r\n\r\n%s" % (
                self.fromaddr,
                ','.join(self.toaddrs),
                self.getSubject(record),
                email.utils.formatdate(), msg)
            smtp.sendmail(self.fromaddr, self.toaddrs, msg)
            smtp.quit()
        except (KeyboardInterrupt, SystemExit):
            raise
        except:
            self.handleError(record)


class LRUCache(dict):
    """A dictionary-like object that stores only a certain number of items, and
    discards its least recently used item when full.