# (c) 2015, Jan-Piet Mens <jpmens(at)gmail.com>
#
# This file is part of Ansible
#
# Ansible is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Ansible 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 Ansible.  If not, see <http://www.gnu.org/licenses/>.
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type

from ansible.errors import AnsibleError
from ansible.plugins.lookup import LookupBase
import socket

try:
    import dns.resolver
    import dns.reversename
    from dns.rdatatype import *
    from dns.exception import DNSException
    HAVE_DNS = True
except ImportError:
    HAVE_DNS = False

def make_rdata_dict(rdata):
    ''' While the 'dig' lookup plugin supports anything which dnspython supports
        out of the box, the following supported_types list describes which
        DNS query types we can convert to a dict.

        Note: adding support for RRSIG is hard work. :)
    '''
    supported_types = {
            A           : ['address'],
            AAAA        : ['address'],
            CNAME       : ['target'],
            DNAME       : ['target'],
            DLV         : ['algorithm', 'digest_type', 'key_tag', 'digest'],
            DNSKEY      : ['flags', 'algorithm', 'protocol', 'key'],
            DS          : ['algorithm', 'digest_type', 'key_tag', 'digest'],
            HINFO       : ['cpu', 'os'],
            LOC         : ['latitude', 'longitude', 'altitude', 'size', 'horizontal_precision', 'vertical_precision'],
            MX          : ['preference', 'exchange'],
            NAPTR       : ['order', 'preference', 'flags', 'service', 'regexp', 'replacement'],
            NS          : ['target'],
            NSEC3PARAM  : ['algorithm', 'flags', 'iterations', 'salt'],
            PTR         : ['target'],
            RP          : ['mbox', 'txt'],
            # RRSIG       : ['algorithm', 'labels', 'original_ttl', 'expiration', 'inception', 'signature'],
            SOA         : ['mname', 'rname', 'serial', 'refresh', 'retry', 'expire', 'minimum'],
            SPF         : ['strings'],
            SRV         : ['priority', 'weight', 'port', 'target'],
            SSHFP       : ['algorithm', 'fp_type', 'fingerprint'],
            TLSA        : ['usage', 'selector', 'mtype', 'cert'],
            TXT         : ['strings'],
        }

    rd = {}

    if rdata.rdtype in supported_types:
        fields = supported_types[rdata.rdtype]
        for f in fields:
            val     = rdata.__getattribute__(f)

            if type(val) == dns.name.Name:
                val = dns.name.Name.to_text(val)

            if rdata.rdtype == DLV and f == 'digest':
                val = dns.rdata._hexify(rdata.digest).replace(' ', '')
            if rdata.rdtype == DS and f == 'digest':
                val = dns.rdata._hexify(rdata.digest).replace(' ', '')
            if rdata.rdtype == DNSKEY and f == 'key':
                val = dns.rdata._base64ify(rdata.key).replace(' ', '')
            if rdata.rdtype == NSEC3PARAM and f == 'salt':
                val = dns.rdata._hexify(rdata.salt).replace(' ', '')
            if rdata.rdtype == SSHFP and f == 'fingerprint':
                val = dns.rdata._hexify(rdata.fingerprint).replace(' ', '')
            if rdata.rdtype == TLSA and f == 'cert':
                val = dns.rdata._hexify(rdata.cert).replace(' ', '')


            rd[f]   = val

    return rd

# ==============================================================
# dig: Lookup DNS records
#
# --------------------------------------------------------------

class LookupModule(LookupBase):

    def run(self, terms, variables=None, **kwargs):

        '''
        terms contains a string with things to `dig' for. We support the
        following formats:
            example.com                                     # A record
            example.com  qtype=A                            # same
            example.com/TXT                                 # specific qtype
            example.com  qtype=txt                          # same
            192.168.1.2/PTR                                 # reverse PTR
              ^^ shortcut for 2.1.168.192.in-addr.arpa/PTR
            example.net/AAAA  @nameserver                   # query specified server
                               ^^^ can be comma-sep list of names/addresses

            ... flat=0                                      # returns a dict; default is 1 == string
        '''

        if HAVE_DNS == False:
            raise AnsibleError("Can't LOOKUP(dig): module dns.resolver is not installed")

        # Create Resolver object so that we can set NS if necessary
        myres = dns.resolver.Resolver()
        edns_size = 4096
        myres.use_edns(0, ednsflags=dns.flags.DO, payload=edns_size)

        domain = None
        qtype  = 'A'
        flat   = True

        for t in terms:
            if t.startswith('@'):       # e.g. "@10.0.1.2,192.168.1.1" is ok.
                nsset = t[1:].split(',')
                nameservers = []
                for ns in nsset:
                    # Check if we have a valid IP address. If so, use that, otherwise
                    # try to resolve name to address using system's resolver. If that
                    # fails we bail out.
                    try:
                        socket.inet_aton(ns)
                        nameservers.append(ns)
                    except:
                        try:
                            nsaddr = dns.resolver.query(ns)[0].address
                            nameservers.append(nsaddr)
                        except Exception as e:
                            raise AnsibleError("dns lookup NS: ", str(e))
                    myres.nameservers = nameservers
                continue
            if '=' in t:
                try:
                    opt, arg = t.split('=')
                except:
                    pass

                if opt == 'qtype':
                    qtype = arg.upper()
                elif opt == 'flat':
                    flat = int(arg)

                continue

            if '/' in t:
                try:
                    domain, qtype = t.split('/')
                except:
                    domain = t
            else:
                domain = t

        # print "--- domain = {0} qtype={1}".format(domain, qtype)

        ret = []

        if qtype.upper() == 'PTR':
            try:
                n = dns.reversename.from_address(domain)
                domain = n.to_text()
            except dns.exception.SyntaxError:
                pass
            except Exception as e:
                raise AnsibleError("dns.reversename unhandled exception", str(e))

        try:
            answers = myres.query(domain, qtype)
            for rdata in answers:
                s = rdata.to_text()
                if qtype.upper() == 'TXT':
                    s = s[1:-1]  # Strip outside quotes on TXT rdata

                if flat:
                    ret.append(s)
                else:
                    try:
                        rd = make_rdata_dict(rdata)
                        rd['owner']     = answers.canonical_name.to_text()
                        rd['type']      = dns.rdatatype.to_text(rdata.rdtype)
                        rd['ttl']       = answers.rrset.ttl

                        ret.append(rd)
                    except Exception as e:
                        ret.append(str(e))

        except dns.resolver.NXDOMAIN:
            ret.append('NXDOMAIN')
        except dns.resolver.NoAnswer:
            ret.append("")
        except dns.resolver.Timeout:
            ret.append('')
        except dns.exception.DNSException as e:
            raise AnsibleError("dns.resolver unhandled exception", e)

        return ret
