##############################################################################

#

# Copyright (c) 2009 Zope Corporation and Contributors.

# All Rights Reserved.

#

# This software is subject to the provisions of the Zope Public License,

# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.

# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED

# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS

# FOR A PARTICULAR PURPOSE.

#

##############################################################################

"""Buildout download infrastructure"""

try:

    from hashlib import md5

except ImportError:

    from md5 import new as md5

from zc.buildout.easy_install import realpath

import logging

import os

import os.path

import re

import shutil

import tempfile

import urllib

import urlparse

import zc.buildout

class URLOpener(urllib.FancyURLopener):

    http_error_default = urllib.URLopener.http_error_default

class ChecksumError(zc.buildout.UserError):

    pass

url_opener = URLOpener()

class Download(object):

    """Configurable download utility.

    Handles the download cache and offline mode.

    Download(options=None, cache=None, namespace=None, hash_name=False)

    options: mapping of buildout options (e.g. a ``buildout`` config section)

    cache: path to the download cache (excluding namespaces)

    namespace: namespace directory to use inside the cache

    hash_name: whether to use a hash of the URL as cache file name

    logger: an optional logger to receive download-related log messages

    """

    def __init__(self, options={}, cache=-1, namespace=None,

                 offline=-1, fallback=False, hash_name=False, logger=None):

        self.directory = options.get('directory', '')

        self.cache = cache

        if cache == -1:

            self.cache = options.get('download-cache')

        self.namespace = namespace

        self.offline = offline

        if offline == -1:

            self.offline = (options.get('offline') == 'true'

                            or options.get('install-from-cache') == 'true')

        self.fallback = fallback

        self.hash_name = hash_name

        self.logger = logger or logging.getLogger('zc.buildout')

    @property

    def download_cache(self):

        if self.cache is not None:

            return realpath(os.path.join(self.directory, self.cache))

    @property

    def cache_dir(self):

        if self.download_cache is not None:

            return os.path.join(self.download_cache, self.namespace or '')

    def __call__(self, url, md5sum=None, path=None):

        """Download a file according to the utility's configuration.

        url: URL to download

        md5sum: MD5 checksum to match

        path: where to place the downloaded file

        Returns the path to the downloaded file.

        """

        if self.cache:

            local_path, is_temp = self.download_cached(url, md5sum)

        else:

            local_path, is_temp = self.download(url, md5sum, path)

        return locate_at(local_path, path), is_temp

    def download_cached(self, url, md5sum=None):

        """Download a file from a URL using the cache.

        This method assumes that the cache has been configured. Optionally, it

        raises a ChecksumError if a cached copy of a file has an MD5 mismatch,

        but will not remove the copy in that case.

        """

        if not os.path.exists(self.download_cache):

            raise zc.buildout.UserError(

                'The directory:\n'

                '%r\n'

                "to be used as a download cache doesn't exist.\n"

                % self.download_cache)

        cache_dir = self.cache_dir

        if not os.path.exists(cache_dir):

            os.mkdir(cache_dir)

        cache_key = self.filename(url)

        cached_path = os.path.join(cache_dir, cache_key)

        self.logger.debug('Searching cache at %s' % cache_dir)

        if os.path.isfile(cached_path):

            is_temp = False

            if self.fallback:

                try:

                    _, is_temp = self.download(url, md5sum, cached_path)

                except ChecksumError:

                    raise

                except Exception:

                    pass

            if not check_md5sum(cached_path, md5sum):

                raise ChecksumError(

                    'MD5 checksum mismatch for cached download '

                    'from %r at %r' % (url, cached_path))

            self.logger.debug('Using cache file %s' % cached_path)

        else:

            self.logger.debug('Cache miss; will cache %s as %s' %

                              (url, cached_path))

            _, is_temp = self.download(url, md5sum, cached_path)

        return cached_path, is_temp

    def download(self, url, md5sum=None, path=None):

        """Download a file from a URL to a given or temporary path.

        An online resource is always downloaded to a temporary file and moved

        to the specified path only after the download is complete and the

        checksum (if given) matches. If path is None, the temporary file is

        returned and the client code is responsible for cleaning it up.

        """

        if re.match(r"^[A-Za-z]:\\", url):

            url = 'file:' + url

        parsed_url = urlparse.urlparse(url, 'file')

        url_scheme, _, url_path = parsed_url[:3]

        if url_scheme == 'file':

            self.logger.debug('Using local resource %s' % url)

            if not check_md5sum(url_path, md5sum):

                raise ChecksumError(

                    'MD5 checksum mismatch for local resource at %r.' %

                    url_path)

            return locate_at(url_path, path), False

        if self.offline:

            raise zc.buildout.UserError(

                "Couldn't download %r in offline mode." % url)

        self.logger.info('Downloading %s' % url)

        urllib._urlopener = url_opener

        handle, tmp_path = tempfile.mkstemp(prefix='buildout-')

        try:

            try:

                tmp_path, headers = urllib.urlretrieve(url, tmp_path)

                if not check_md5sum(tmp_path, md5sum):

                    raise ChecksumError(

                        'MD5 checksum mismatch downloading %r' % url)

            finally:

                os.close(handle)

        except:

            os.remove(tmp_path)

            raise

        if path:

            shutil.move(tmp_path, path)

            return path, False

        else:

            return tmp_path, True

    def filename(self, url):

        """Determine a file name from a URL according to the configuration.

        """

        if self.hash_name:

            return md5(url).hexdigest()

        else:

            if re.match(r"^[A-Za-z]:\\", url):

                url = 'file:' + url

            parsed = urlparse.urlparse(url, 'file')

            url_path = parsed[2]

            if parsed[0] == 'file':

                while True:

                    url_path, name = os.path.split(url_path)

                    if name:

                        return name

                    if not url_path:

                        break

            else:

                for name in reversed(url_path.split('/')):

                    if name:

                        return name

            url_host, url_port = parsed[-2:]

            return '%s:%s' % (url_host, url_port)

def check_md5sum(path, md5sum):

    """Tell whether the MD5 checksum of the file at path matches.

    No checksum being given is considered a match.

    """

    if md5sum is None:

        return True

    f = open(path, 'rb')

    checksum = md5()

    try:

        chunk = f.read(2**16)

        while chunk:

            checksum.update(chunk)

            chunk = f.read(2**16)

        return checksum.hexdigest() == md5sum

    finally:

        f.close()

def remove(path):

    if os.path.exists(path):

        os.remove(path)

def locate_at(source, dest):

    if dest is None or realpath(dest) == realpath(source):

        return source

    try:

        os.link(source, dest)

    except (AttributeError, OSError):

        shutil.copyfile(source, dest)

    return dest