from __future__ import print_function
import os
import sys

class BasePlugin(object):
    def __init__(self, src):
        self.source = src

    def lookup(self, token):
        return None


class ReadOnlyTokenFile(BasePlugin):
    # source is a token file with lines like
    #   token: host:port
    # or a directory of such files
    def __init__(self, *args, **kwargs):
        super(ReadOnlyTokenFile, self).__init__(*args, **kwargs)
        self._targets = None

    def _load_targets(self):
        if os.path.isdir(self.source):
            cfg_files = [os.path.join(self.source, f) for
                         f in os.listdir(self.source)]
        else:
            cfg_files = [self.source]

        self._targets = {}
        index = 1
        for f in cfg_files:
            for line in [l.strip() for l in open(f).readlines()]:
                if line and not line.startswith('#'):
                    try:
                        tok, target = line.split(': ')
                        self._targets[tok] = target.strip().rsplit(':', 1)
                    except ValueError:
                        print >>sys.stderr, "Syntax error in %s on line %d" % (self.source, index)
                index += 1

    def lookup(self, token):
        if self._targets is None:
            self._load_targets()

        if token in self._targets:
            return self._targets[token]
        else:
            return None


# the above one is probably more efficient, but this one is
# more backwards compatible (although in most cases
# ReadOnlyTokenFile should suffice)
class TokenFile(ReadOnlyTokenFile):
    # source is a token file with lines like
    #   token: host:port
    # or a directory of such files
    def lookup(self, token):
        self._load_targets()

        return super(TokenFile, self).lookup(token)


class BaseTokenAPI(BasePlugin):
    # source is a url with a '%s' in it where the token
    # should go

    # we import things on demand so that other plugins
    # in this file can be used w/o unecessary dependencies

    def process_result(self, resp):
        return resp.text.split(':')

    def lookup(self, token):
        import requests

        resp = requests.get(self.source % token)

        if resp.ok:
            return self.process_result(resp)
        else:
            return None


class JSONTokenApi(BaseTokenAPI):
    # source is a url with a '%s' in it where the token
    # should go

    def process_result(self, resp):
        resp_json = resp.json()
        return (resp_json['host'], resp_json['port'])


class JWTTokenApi(BasePlugin):
    # source is a JWT-token, with hostname and port included
    # Both JWS as JWE tokens are accepted. With regards to JWE tokens, the key is re-used for both validation and decryption.

    def lookup(self, token):
        try:
            from jwcrypto import jwt
            import json

            key = jwt.JWK()
            
            try:
                with open(self.source, 'rb') as key_file:
                    key_data = key_file.read()
            except Exception as e:
                print("Error loading key file: %s" % str(e), file=sys.stderr)
                return None

            try:
                key.import_from_pem(key_data)
            except:
                try:
                    key.import_key(k=key_data.decode('utf-8'),kty='oct')
                except:
                    print('Failed to correctly parse key data!', file=sys.stderr)
                    return None

            try:
                token = jwt.JWT(key=key, jwt=token)
                parsed_header = json.loads(token.header)

                if 'enc' in parsed_header:
                    # Token is encrypted, so we need to decrypt by passing the claims to a new instance
                    token = jwt.JWT(key=key, jwt=token.claims)

                parsed = json.loads(token.claims)

                return (parsed['host'], parsed['port'])
            except Exception as e:
                print("Failed to parse token: %s" % str(e), file=sys.stderr)
                return None
        except ImportError as e:
            print("package jwcrypto not found, are you sure you've installed it correctly?", file=sys.stderr)
            return None