# vi: ts=4 expandtab
#
#    Copyright (C) 2012 Yahoo! Inc.
#
#    Author: Joshua Harlow <harlowja@yahoo-inc.com>
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License version 3, as
#    published by the Free Software Foundation.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.

import base64
import os
import six

from cloudinit.settings import PER_INSTANCE
from cloudinit import util

frequency = PER_INSTANCE

DEFAULT_OWNER = "root:root"
DEFAULT_PERMS = 0o644
UNKNOWN_ENC = 'text/plain'


def handle(name, cfg, _cloud, log, _args):
    files = cfg.get('write_files')
    if not files:
        log.debug(("Skipping module named %s,"
                   " no/empty 'write_files' key in configuration"), name)
        return
    write_files(name, files, log)


def canonicalize_extraction(encoding_type, log):
    if not encoding_type:
        encoding_type = ''
    encoding_type = encoding_type.lower().strip()
    if encoding_type in ['gz', 'gzip']:
        return ['application/x-gzip']
    if encoding_type in ['gz+base64', 'gzip+base64', 'gz+b64', 'gzip+b64']:
        return ['application/base64', 'application/x-gzip']
    # Yaml already encodes binary data as base64 if it is given to the
    # yaml file as binary, so those will be automatically decoded for you.
    # But the above b64 is just for people that are more 'comfortable'
    # specifing it manually (which might be a possiblity)
    if encoding_type in ['b64', 'base64']:
        return ['application/base64']
    if encoding_type:
        log.warn("Unknown encoding type %s, assuming %s",
                 encoding_type, UNKNOWN_ENC)
    return [UNKNOWN_ENC]


def write_files(name, files, log):
    if not files:
        return

    for (i, f_info) in enumerate(files):
        path = f_info.get('path')
        if not path:
            log.warn("No path provided to write for entry %s in module %s",
                     i + 1, name)
            continue
        path = os.path.abspath(path)
        extractions = canonicalize_extraction(f_info.get('encoding'), log)
        contents = extract_contents(f_info.get('content', ''), extractions)
        (u, g) = util.extract_usergroup(f_info.get('owner', DEFAULT_OWNER))
        perms = decode_perms(f_info.get('permissions'), DEFAULT_PERMS, log)
        util.write_file(path, contents, mode=perms)
        util.chownbyname(path, u, g)


def decode_perms(perm, default, log):
    try:
        if isinstance(perm, six.integer_types + (float,)):
            # Just 'downcast' it (if a float)
            return int(perm)
        else:
            # Force to string and try octal conversion
            return int(str(perm), 8)
    except (TypeError, ValueError):
        log.warn("Undecodable permissions %s, assuming %s", perm, default)
        return default


def extract_contents(contents, extraction_types):
    result = contents
    for t in extraction_types:
        if t == 'application/x-gzip':
            result = util.decomp_gzip(result, quiet=False, decode=False)
        elif t == 'application/base64':
            result = base64.b64decode(result)
        elif t == UNKNOWN_ENC:
            pass
    return result
