import logging
import os
import re

from django.core.exceptions import ValidationError
from django.utils.translation import ugettext_lazy as _

from orchestra.core.validators import validate_hostname
from orchestra.utils import paths
from orchestra.utils.sys import run

from .. import domains


logger = logging.getLogger(__name__)


def validate_allowed_domain(value):
    context = {
        'site_dir': paths.get_site_dir()
    }
    fname = domains.settings.DOMAINS_FORBIDDEN
    if fname:
        fname = fname % context
        with open(fname, 'r') as forbidden:
            for domain in forbidden.readlines():
                if re.match(r'^(.*\.)*%s$' % domain.strip(), value):
                    raise ValidationError(_("This domain name is not allowed"))


def validate_domain_name(value):
    # SRV, CNAME and TXT records may use '_' in the domain name
    value = value.lstrip('*.').replace('_', '')
    try:
        validate_hostname(value)
    except ValidationError:
        raise ValidationError(_("Not a valid domain name."))


def validate_zone_interval(value):
    try:
        int(value)
    except ValueError:
        value, magnitude = value[:-1], value[-1]
        if magnitude not in ('s', 'm', 'h', 'd', 'w') or not value.isdigit():
            msg = _("%s is not an appropiate zone interval value") % value
            raise ValidationError(msg)


def validate_zone_label(value):
    """
    Allowable characters in a label for a host name are only ASCII letters, digits, and the `-' character.
    Labels may not be all numbers, but may have a leading digit (e.g., 3com.com).
    Labels must end and begin only with a letter or digit. See [RFC 1035] and [RFC 1123].
    """
    if not re.match(r'^[a-z0-9][\.\-0-9a-z]*[\.0-9a-z]$', value):
        msg = _("Labels must start and end with a letter or digit, "
                "and have as interior characters only letters, digits, and hyphen.")
        raise ValidationError(msg)
    if not value.endswith('.'):
        msg = _("Use a fully expanded domain name ending with a dot.")
        raise ValidationError(msg)
    if len(value) > 63:
        raise ValidationError(_("Labels must be 63 characters or less."))


def validate_mx_record(value):
    msg = _("MX record format is 'priority domain.' tuple, with priority being a number.")
    value = value.split()
    if len(value) != 2:
        raise ValidationError(msg)
    else:
        try:
            int(value[0])
        except ValueError:
            raise ValidationError(msg)
        value = value[1]
    validate_zone_label(value)


def validate_srv_record(value):
    # 1 0 9 server.example.com.
    msg = _("%s is not an appropiate SRV record value") % value
    value = value.split()
    for i in [0,1,2]:
        try:
            int(value[i])
        except ValueError:
            raise ValidationError(msg)
    validate_zone_label(value[-1])


def validate_soa_record(value):
    # ns1.pangea.ORG. hostmaster.pangea.ORG. 2012010401 28800 7200 604800 86400
    msg = _("%s is not an appropiate SRV record value") % value
    values = value.split()
    if len(values) != 7:
        raise ValidationError(msg)
    validate_zone_label(values[0])
    validate_zone_label(values[1])
    for value in values[2:]:
        try:
            int(value)
        except ValueError:
            raise ValidationError(msg)


def validate_quoted_record(value):
    value = value.strip()
    if ' ' in value and (value[0] != '"' or value[-1] != '"'):
        raise ValidationError(
            _("This record value contains spaces, you must enclose the string in double quotes; "
              "otherwise, individual words will be separately quoted and break up the record "
              "into multiple parts.")
        )


def validate_zone(zone):
    """ Ultimate zone file validation using named-checkzone """
    zone_name = zone.split()[0][:-1]
    zone_path = os.path.join(domains.settings.DOMAINS_ZONE_VALIDATION_TMP_DIR, zone_name)
    checkzone = domains.settings.DOMAINS_CHECKZONE_BIN_PATH
    try:
        with open(zone_path, 'wb') as f:
            f.write(zone.encode('ascii'))
        # Don't use /dev/stdin becuase the 'argument list is too long' error
        check = run(' '.join([checkzone, zone_name, zone_path]), valid_codes=(0,1,127), display=False)
    finally:
        try:
            os.unlink(zone_path)
        except FileNotFoundError:
            pass
    if check.exit_code == 127:
        logger.error("Cannot validate domain zone: %s not installed." % checkzone)
    elif check.exit_code == 1:
        errors = re.compile(r'zone.*: (.*)').findall(check.stdout.decode('utf8'))[:-1]
        raise ValidationError(', '.join(errors))