import sys, os
import zipfile
from datetime import datetime
from email import message_from_file
from tempfile import TemporaryDirectory
from lxml.etree import parse as parse_xml
from dmarcreceiver.model import DBSession, Report, ReportError, ReportRecord, OverrideReason, DKIMResult, SPFResult, metadata, init_model
import transaction

from .util import sendmail
from .config import config

def parse_metadata(tree):
    org_name, = tree.xpath('org_name/text()')
    email, = tree.xpath('email/text()')
    extra_contact_info = tree.xpath('extra_contact_info/text()')
    if len(extra_contact_info) == 0:
        extra_contact_info = None
    else:
        extra_contact_info = extra_contact_info[0]
    report_id, = tree.xpath('report_id/text()')
    date_begin, = tree.xpath('date_range/begin/text()')
    date_begin = datetime.fromtimestamp(int(date_begin))
    date_end, = tree.xpath('date_range/end/text()')
    date_end = datetime.fromtimestamp(int(date_end))
    return Report(
        org_name=org_name,
        email=email,
        extra_contact_info=extra_contact_info,
        report_id=report_id,
        date_begin=date_begin,
        date_end=date_end
    )

def scoop_elements(obj, tree, *elements):
    for elt in elements:
        try:
            value, = tree.xpath('./' + elt + '/text()')
        except ValueError:
            value = None
        else:
            if all([ c.isdigit() for c in value ]):
                value = int(value)
        setattr(obj, elt, value)

def parse_report(f):
    tree = parse_xml(f)

    metadata_tree, = tree.xpath('/feedback/report_metadata')
    report = parse_metadata(metadata_tree)
    scoop_elements(report, tree.xpath('/feedback/policy_published')[0], 'domain', 'adkim', 'aspf', 'p', 'sp', 'pct')
    for record_node in tree.xpath('/feedback/record'):
        record = ReportRecord()
        scoop_elements(record, record_node.xpath('./row')[0], 'source_ip', 'count')
        scoop_elements(record, record_node.xpath('./row/policy_evaluated')[0], 'disposition', 'dkim', 'spf')
        for reason_node in record_node.xpath('./row/policy_evaluated/reason'):
            reason = OverrideReason()
            reason.policy_override_type, = reason_node.xpath('./type/text()')
            comment = reason_node.xpath('./comment/text()')
            if len(comment) > 0:
                reason.comment = comment[0]
            record.override_reasons.append(reason)
        scoop_elements(record, record_node.xpath('./identifiers')[0], 'envelope_to', 'header_from')
        for dkim_node in record_node.xpath('./auth_results/dkim'):
            dkim = DKIMResult()
            scoop_elements(dkim, dkim_node, 'domain', 'result', 'human_result')
            t = dkim_node.xpath('./selector/text()')
            if len(t) > 0:
                dkim.human_result = t[0]
            record.dkim_results.append(dkim)
        for spf_node in record_node.xpath('./auth_results/spf'):
            spf = SPFResult()
            scoop_elements(spf, spf_node, 'domain', 'result')
            record.spf_results.append(spf)
        report.records.append(record)
    DBSession.add(report)
    transaction.commit()

def read_config_if_present(args):
    if args.config_file:
        if os.access(args.config_file, os.R_OK):
            config.read_file(open(args.config_file, 'rt'))

def receive_report(args):
    read_config_if_present(args)
    init_model()

    # read email message from stdin
    msg = message_from_file(sys.stdin)

    # check for zip file
    content_type = msg['content-type']
    if content_type.find(';') != -1:
        content_type = content_type.split(';',1)[0]

    if content_type != 'application/zip':
        # not a zip file - bounce to postmaster
        bounce_address = config.get('bounce_address')
        if args.bounce_address:
            bounce_address = args.bounce_address
        if bounce_address:
            msg['To'] = bounce_address
            sendmail(msg)
        return

    with TemporaryDirectory(
        prefix=os.path.splitext(os.path.basename(sys.argv[0]))[0] + '-'
    ) as tempdir:
        filename = msg.get_filename()
        if filename is None:
            filename = 'report.zip'
        fn = os.path.join(tempdir, filename)
        with open(fn, 'wb') as f:
            f.write(msg.get_payload(decode=True))
        with zipfile.ZipFile(fn, 'r') as z:
            namelist = z.namelist()
            report_fn = os.path.join(tempdir, os.path.basename(namelist[0]))
            z.extract(namelist[0], path=tempdir)
        with open(report_fn, 'rb') as f:
            parse_report(f)

def init(args):
    read_config_if_present(args)
    init_model()
    metadata.create_all()