# -*- encoding: utf-8 -*-

import json
import os
import sys
import email
import hashlib
import tempfile
import uuid
import smtplib
import subprocess
import traceback

import redminelib
from redminelib import Redmine

REDMINE_URL = os.environ.get('REDMINE_URL', 'https://dev.entrouvert.org')
REDMINE_KEY = os.environ.get('REDMINE_KEY')
TRACKER_ID = os.environ.get('REDMINE_TRACKER', '3')
PROJECT_ID = os.environ.get('PROJECT')
TECH_MANAGER_ROLE_ID = os.environ.get('TECH_MANAGER_ROLE_ID', 10)
FALLBACK_EMAIL = os.environ.get('FALLBACK_EMAIL', 'support@entrouvert.com')
ATTACHMENTS_BLACKLIST = os.environ.get('ATTACHMENTS_BLACKLIST', None)


class UnknownUser(Exception):
    pass

def parse_header(header_text):
    if not header_text:
        return ''
    default_charset = 'ascii'
    try:
        headers = email.header.decode_header(header_text)
    except email.errors.HeaderParseError:
        return header_text.encode(default_charset, 'replace').decode(default_charset)
    else:
        res = ''
        for i, (text, charset) in enumerate(headers):
            if isinstance(text, str):
                res += text
            else:
                res += text.decode(charset or default_charset, errors='replace')
        return res
    return ''


def parse_attachment(data, blacklist=None):
    if data.get('Content-type', '').startswith('multipart/'):
        return None
    if data.get('Content-type', '').startswith('text/plain') and not (
            data.get('Content-Disposition', '').startswith('attachment')):
        return None
    file_data = data.get_payload(decode=True)
    if not file_data:
        return None
    if blacklist and hashlib.sha1(file_data).hexdigest() in blacklist.get('sha1sums'):
        return None
    with tempfile.NamedTemporaryFile(delete=False) as attachment:
        attachment.write(file_data)
        attachment.flush()

    attachment = {'path': attachment.name,
                  'content_type': data.get_content_type(),
                  'filename': parse_header(data.get_filename())}
    return attachment


def send_mail(to, subject, message):
    s = smtplib.SMTP('localhost')
    from_mail = 'noreply@entrouvert.com'
    msg = email.mime.Text.MIMEText(message, 'plain', 'utf-8')
    msg['From'] = from_mail
    msg['To'] = to
    msg['Subject'] = subject
    s.sendmail(from_mail, to, msg.as_string())
    s.quit()


def create_ticket(mail):
    mail = email.message_from_string(mail)
    r = Redmine(REDMINE_URL, key=REDMINE_KEY)
    from_name, from_email = email.utils.parseaddr(mail['From'])
    users = r.user.filter(name=from_email)
    if not users:
        raise UnknownUser

    blacklist = {'sha1sums': []}
    if ATTACHMENTS_BLACKLIST:
        try:
            blacklist = json.load(open(ATTACHMENTS_BLACKLIST))
        except (IOError, ValueError):
            pass

    r = Redmine(REDMINE_URL, key=REDMINE_KEY, impersonate=users[0].login)

    attachments = []

    body = u''
    for data in mail.walk():
        attachment = parse_attachment(data, blacklist)
        if attachment:
            attachments.append(attachment)
        elif data.get_content_type() == "text/plain":
            body = data.get_payload()

    # get project tech manager
    tech_manager = None
    for membership in r.project_membership.filter(project_id=PROJECT_ID):
        try:
            if membership.roles.get(TECH_MANAGER_ROLE_ID):
                tech_manager = membership.user
                break
        except redminelib.resources.ResourceAttrError:
            continue

    issue_data = {'project_id': PROJECT_ID,
                  'subject': parse_header(mail['Subject']),
                  'tracker_id': TRACKER_ID,
                  'description': body,
                  'uploads': attachments}
    if tech_manager:
        issue_data['assigned_to_id'] = tech_manager.id

    issue = r.issue.create(**issue_data)

    message = u"""[ Ce courriel est envoyé par un automate. Merci de ne pas y répondre, votre message ne serait pas pris en compte. ]


Bonjour,

Votre demande a bien été prise en compte et enregistrée dans notre système sous
le numéro %s.

Vous pouvez suivre son évolution à l'adresse : %s .

Cordialement,

L'équipe Entr'ouvert"""
    message = message % (issue.id, issue.url)
    send_mail(mail['From'], u'Votre demande a été bien prise en compte', message)
    # cleanup temporary attachment files
    for attachment in attachments:
        if os.path.exists(attachment['path']):
            os.unlink(attachment['path'])


if __name__ == '__main__':
    mail = sys.stdin.read()
    mail_dumps_dir = '/var/tmp'
    if not os.path.exists(mail_dumps_dir):
        os.mkdir(mail_dumps_dir)
    file_id = uuid.uuid4()
    filename = os.path.join(mail_dumps_dir, '%s.mail' % file_id)
    with open(filename, 'w') as mail_dump:
        mail_dump.write(mail)
    try:
        create_ticket(mail)
    except Exception as e:
        exim = subprocess.Popen(['/usr/sbin/exim', FALLBACK_EMAIL], stdin=file(filename))
        trace = traceback.format_exc()
        filename = os.path.join(mail_dumps_dir, '%s.trace' % file_id)
        with open(filename, 'w') as mail_dump:
            mail_dump.write(trace)