#!/usr/bin/env python
# This file is part of Xpra.
# Copyright (C) 2011-2016 Antoine Martin <antoine@devloop.org.uk>
# Copyright (C) 2008, 2009, 2010 Nathaniel Smith <njs@pobox.com>
# Xpra is released under the terms of the GNU GPL v2, or, at your option, any
# later version. See the file COPYING for details.

from xpra.log import Logger
log = Logger("network", "protocol")
from xpra.net.header import FLAGS_RENCODE, FLAGS_YAML, FLAGS_BENCODE

from xpra.util import envbool
#those are also modified from the command line switch:
use_rencode = envbool("XPRA_USE_RENCODER", True)
use_bencode = envbool("XPRA_USE_BENCODER", True)
use_yaml    = envbool("XPRA_USE_YAML", True)


has_rencode = None
rencode_dumps, rencode_loads, rencode_version = None, None, None
def init_rencode():
    global use_rencode, has_rencode, rencode_dumps, rencode_loads, rencode_version
    try:
        from rencode import dumps as rencode_dumps, loads as rencode_loads, __version__ as rencode_version
    except ImportError as e:
        log("init_rencode()", exc_info=True)
        if use_rencode:
            log.warn("Warning: rencode import failed:")
            log.warn(" %s", e)
    except Exception as e:
        log.error("error loading rencode", exc_info=True)
    has_rencode = rencode_dumps is not None and rencode_loads is not None and rencode_version is not None
    use_rencode = has_rencode and use_rencode
    log("packet_encoding.init_rencode() has_rencode=%s, use_rencode=%s, version=%s", has_rencode, use_rencode, rencode_version)


has_bencode = None
bencode, bdecode, bencode_version = None, None, None
def init_bencode():
    global use_bencode, has_bencode, bencode, bdecode, bencode_version
    try:
        from xpra.net.bencode import bencode, bdecode, __version__ as bencode_version
    except ImportError as e:
        log("init_bencode()", exc_info=True)
        if use_bencode:
            log.warn("Warning: bencode import failed:")
            log.warn(" %s", e)
    except Exception as e:
        log.error("error loading bencoder", exc_info=True)
    has_bencode = bencode is not None and bdecode is not None
    use_bencode = has_bencode and use_bencode
    log("packet_encoding.init_bencode() has_bencode=%s, use_bencode=%s, version=%s", has_bencode, use_bencode, bencode_version)

has_yaml = None
yaml_encode, yaml_decode, yaml_version = None, None, None
def init_yaml():
    global use_yaml, has_yaml, yaml_encode, yaml_decode, yaml_version
    try:
        #json messes with strings and unicode (makes it unusable for us)
        import yaml
        yaml_encode = yaml.dump
        yaml_decode = yaml.load
        yaml_version = yaml.__version__
    except ImportError:
        log("yaml not found")
    has_yaml = yaml_encode is not None and yaml_decode is not None
    use_yaml = has_yaml and use_yaml
    log("packet encoding: has_yaml=%s, use_yaml=%s, version=%s", has_yaml, use_yaml, yaml_version)

def init():
    init_rencode()
    init_bencode()
    init_yaml()
init()

def do_bencode(data):
    return bencode(data), FLAGS_BENCODE

def do_rencode(data):
    return  rencode_dumps(data), FLAGS_RENCODE

def do_yaml(data):
    return yaml_encode(data), FLAGS_YAML


def get_packet_encoding_caps():
    r = {"" : use_rencode}
    if has_rencode:
        assert rencode_version is not None
        r["version"]    = rencode_version
    b = {"" : use_bencode}
    if has_bencode:
        assert bencode_version is not None
        b["version"] = bencode_version
    y = {"" : use_yaml}
    if has_yaml:
        assert yaml_version is not None
        y["version"] = yaml_version
    return {
            "rencode"               : r,
            "bencode"               : b,
            "yaml"                  : y,
           }


#all the encoders we know about, in best compatibility order:
ALL_ENCODERS = ["bencode", "rencode", "yaml"]

#order for performance:
PERFORMANCE_ORDER = ["rencode", "bencode", "yaml"]

_ENCODERS = {
             "rencode"   : do_rencode,
             "bencode"   : do_bencode,
             "yaml"      : do_yaml,
             }

def get_enabled_encoders(order=ALL_ENCODERS):
    enabled = [x for x,b in {
                "rencode"               : use_rencode,
                "bencode"               : use_bencode,
                "yaml"                  : use_yaml,
                }.items() if b]
    log("get_enabled_encoders(%s) enabled=%s", order, enabled)
    #order them:
    return [x for x in order if x in enabled]


def get_encoder(e):
    assert e in ALL_ENCODERS, "invalid encoder name: %s" % e
    assert e in get_enabled_encoders(), "%s is not available" % e
    return _ENCODERS[e]

def get_encoder_name(e):
    assert e in _ENCODERS.values(), "invalid encoder: %s" % e
    for k,v in _ENCODERS.items():
        if v==e:
            return k
    raise Exception("impossible bug!")


def get_packet_encoding_type(protocol_flags):
    if protocol_flags & FLAGS_RENCODE:
        return "rencode"
    elif protocol_flags & FLAGS_YAML:
        return "yaml"
    else:
        return "bencode"


def sanity_checks():
    if not use_rencode:
        log.warn("Warning: 'rencode' packet encoder not found")
        log.warn(" the other packet encoders are much slower")


class InvalidPacketEncodingException(Exception):
    pass


def decode(data, protocol_flags):
    if protocol_flags & FLAGS_RENCODE:
        if not has_rencode:
            raise InvalidPacketEncodingException("rencode is not available")
        if not use_rencode:
            raise InvalidPacketEncodingException("rencode is disabled")
        return list(rencode_loads(data))
    elif protocol_flags & FLAGS_YAML:
        if not has_yaml:
            raise InvalidPacketEncodingException("yaml is not available")
        if not use_yaml:
            raise InvalidPacketEncodingException("yaml is disabled")
        return list(yaml_decode(data))
    else:
        if not has_bencode:
            raise InvalidPacketEncodingException("bencode is not available")
        if not use_bencode:
            raise InvalidPacketEncodingException("bencode is disabled")
        packet, l = bdecode(data)
        assert l==len(data)
        return packet


def main():
    from xpra.util import print_nested_dict
    from xpra.platform import program_context
    with program_context("Packet Encoding", "Packet Encoding Info"):
        print_nested_dict(get_packet_encoding_caps())


if __name__ == "__main__":
    main()
