# Copyright (c) 2013-2016 Hewlett Packard Enterprise Development LP
#
# Redistribution and use of this software in source and binary forms,
# with or without modification, are permitted provided that the following
# conditions are met:
#
#   Redistributions of source code must retain the above copyright notice,
#   this list of conditions and the following disclaimer.
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#   Redistributions in binary form must reproduce the above copyright
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#   documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "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 COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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import hashlib
import os.path
import sys

from requestbuilder import Arg
from requestbuilder.exceptions import ArgumentError
from requestbuilder.mixins import FileTransferProgressBarMixin
import six

from euca2ools.commands.s3 import S3Request
import euca2ools.bundle.pipes


class GetObject(S3Request, FileTransferProgressBarMixin):
    DESCRIPTION = 'Retrieve objects from the server'
    ARGS = [Arg('source', metavar='BUCKET/KEY', route_to=None,
                help='the object to download (required)'),
            Arg('-o', dest='dest', metavar='PATH', route_to=None,
                default='.', help='''where to download to.  If this names a
                directory the object will be written to a file inside of that
                directory.  If this is is "-" the object will be written to
                stdout.  Otherwise it will be written to a file with the name
                given.  (default:  current directory)''')]

    def configure(self):
        S3Request.configure(self)

        bucket, _, key = self.args['source'].partition('/')
        if not bucket:
            raise ArgumentError('source must contain a bucket name')
        if not key:
            raise ArgumentError('source must contain a key name')

        if isinstance(self.args.get('dest'), six.string_types):
            # If it is not a string we assume it is a file-like object
            if self.args['dest'] == '-':
                self.args['dest'] = sys.stdout
            elif os.path.isdir(self.args['dest']):
                basename = os.path.basename(key)
                if not basename:
                    raise ArgumentError("specify a complete file path with -o "
                                        "to download objects that end in '/'")
                dest_path = os.path.join(self.args['dest'], basename)
                self.args['dest'] = open(dest_path, 'w')
            else:
                self.args['dest'] = open(self.args['dest'], 'w')

    def preprocess(self):
        self.path = self.args['source']

    def main(self):
        # Note that this method does not close self.args['dest']
        self.preprocess()
        bytes_written = 0
        md5_digest = hashlib.md5()
        sha_digest = hashlib.sha1()
        response = self.send()
        content_length = response.headers.get('Content-Length')
        if content_length:
            pbar = self.get_progressbar(label=self.args['source'],
                                        maxval=int(content_length))
        else:
            pbar = self.get_progressbar(label=self.args['source'])
        pbar.start()
        for chunk in response.iter_content(chunk_size=euca2ools.BUFSIZE):
            self.args['dest'].write(chunk)
            bytes_written += len(chunk)
            md5_digest.update(chunk)
            sha_digest.update(chunk)
            if pbar is not None:
                pbar.update(bytes_written)
        self.args['dest'].flush()
        pbar.finish()

        # Integrity checks
        if content_length and bytes_written != int(content_length):
            self.log.error('rejecting download due to Content-Length size '
                           'mismatch (expected: %i, actual: %i)',
                           content_length, bytes_written)
            raise RuntimeError('downloaded file appears to be corrupt '
                               '(expected size: {0}, actual: {1})'
                               .format(content_length, bytes_written))
        etag = response.headers.get('ETag', '').lower().strip('"')
        if (len(etag) == 32 and
                all(char in '0123456789abcdef' for char in etag)):
            # It looks like an MD5 hash
            if md5_digest.hexdigest() != etag:
                self.log.error('rejecting download due to ETag MD5 mismatch '
                               '(expected: %s, actual: %s)',
                               etag, md5_digest.hexdigest())
                raise RuntimeError('downloaded file appears to be corrupt '
                                   '(expected MD5: {0}, actual: {1})'
                                   .format(etag, md5_digest.hexdigest()))

        return {self.args['source']: {'md5': md5_digest.hexdigest(),
                                      'sha1': sha_digest.hexdigest(),
                                      'size': bytes_written}}