#!/opt/cloudlinux/venv/bin/python3

import errno
import html
import os
import base64
import time
from dataclasses import dataclass
from datetime import timedelta, datetime

from email.header import Header
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText

from prettytable import PrettyTable, ALL

from wmt.common.const import WMT_TEMPLATES_DIR, LICENSE_EXPIRED_FAREWELL_LETTER_MARKER, JWT_TOKEN
from wmt.common.exceptions import WmtEmailException
from clcommon import clemail
from clcommon.mail_helper import MailHelper
from clcommon.lib.network import get_hostname, get_ip_addr


HEADERS_REPORT_MAPPING = {
    'summary_report': ['All',
                       'Successful',
                       'Failed',
                       'Undone',
                       'Average time (ms)'],
    'error_report': ['URL',
                     'Errors',
                     'Error codes'],
    'duration_report': ['URL',
                        'Average time (ms)']
}


class SupportedNotificationTypes:
    ALERT = 'alert'
    REPORT = 'report'
    FAREWELL = 'farewell'


@dataclass
class Email:
    subject: str
    text_sample: str
    html_sample: str


@dataclass
class EmailReport:
    text_option: str
    html_option: str


@dataclass
class EmailTemplate:

    target_mail: str
    from_mail: str

    summary_report: EmailReport = None
    error_report: EmailReport = None
    duration_report: EmailReport = None
    target_name: str = 'Administrator'
    locale: str = 'en_US'

    @staticmethod
    def _get_hostname():
        return get_hostname() or 'UNKNOWN'

    @staticmethod
    def get_ip_addr(hostname):
        if not hostname:
            return 'UNKNOWN'
        return get_ip_addr(hostname) or 'UNKNOWN'

    @staticmethod
    def _get_logo():
        logo_path = os.path.join(WMT_TEMPLATES_DIR, 'logo.png')
        with open(logo_path, 'rb') as logo:
            logo_img_encoded = base64.b64encode(logo.read()).decode('utf-8')
        return logo_img_encoded

    def to_text_template(self, date, notify_type):
        """
        Convert to txt template keys
        see wmt_notify.txt
        """
        hostname = self._get_hostname()
        template = {
            'TONAME': self.target_name,
            'DATE': date,
            'HOSTNAME': hostname,
            'IP_ADDR': self.get_ip_addr(hostname)
        }
        if notify_type in [SupportedNotificationTypes.REPORT, SupportedNotificationTypes.ALERT]:
            template.update({
                'ERROR_REPORT': self.error_report.text_option
            })
        if notify_type == SupportedNotificationTypes.REPORT:
            template.update({
                'SUMMARY_REPORT': self.summary_report.text_option,
                'DURATION_REPORT': self.duration_report.text_option,
            })
        return template

    def to_html_template(self, date, notify_type):
        """
        Convert to html template keys
        see wmt_notify.html
        """
        hostname = self._get_hostname()
        template = {
            'TONAME': self.target_name,
            'DATE': date,
            'LOGO': self._get_logo(),
            'HOSTNAME': hostname,
            'IP_ADDR': self.get_ip_addr(hostname)
        }
        if notify_type in [SupportedNotificationTypes.REPORT, SupportedNotificationTypes.ALERT]:
            template.update({
                'ERROR_HTML_REPORT': self.error_report.html_option
            })
        if notify_type == SupportedNotificationTypes.REPORT:
            template.update({
                'SUMMARY_HTML_REPORT': self.summary_report.html_option,
                'DURATION_HTML_REPORT': self.duration_report.html_option
            })
        return template


@dataclass
class Notifier:
    target_email: str
    from_email: str
    report: dict
    notification_type: str

    @property
    def period(self) -> str:
        if self.notification_type == SupportedNotificationTypes.REPORT:
            return datetime.strftime(datetime.now() - timedelta(days=1), '%Y-%m-%d')
        elif self.notification_type == SupportedNotificationTypes.ALERT:
            return datetime.strftime(datetime.now(), '%Y-%m-%d %H:%M:%S')
        elif self.notification_type == SupportedNotificationTypes.FAREWELL:
            if not os.path.exists(JWT_TOKEN):
                return ''
            seconds = time.time() - os.path.getmtime(JWT_TOKEN)
            days = int(seconds // (3600 * 24))
            if days > 0:
                return f'{str(days)} day(s) ago'
            else:
                hours = int(seconds // 3600)
                return f'{str(hours)} hour(s) ago'
        else:
            raise NotImplementedError(f'unexpected notifier type: {self.notification_type}')

    @staticmethod
    def create_farewell_letter_marker():
        # O_NOFOLLOW refuses a symlink at the marker path so a planted link
        # cannot redirect this root-run truncate; mirrors get_domains.py.
        # If a symlink is squatting the path the open fails with ELOOP. We
        # must still end up with a real marker file, otherwise the send-once
        # guard in manage_license_farewell() (which checks os.path.exists,
        # False for a dangling link) keeps re-sending the farewell email
        # every license-expiry cycle. Drop the offending directory entry and
        # retry once: unlink removes the link itself, never its target, so
        # the symlink victim is left intact (Bugbot 7f754fdf).
        flags = os.O_WRONLY | os.O_CREAT | os.O_TRUNC | os.O_NOFOLLOW
        try:
            fd = os.open(LICENSE_EXPIRED_FAREWELL_LETTER_MARKER, flags, 0o600)
        except OSError as err:
            if err.errno != errno.ELOOP:
                raise
            os.unlink(LICENSE_EXPIRED_FAREWELL_LETTER_MARKER)
            fd = os.open(LICENSE_EXPIRED_FAREWELL_LETTER_MARKER, flags, 0o600)
        try:
            os.fchmod(fd, 0o600)
        finally:
            os.close(fd)

    def notify(self):
        mail_manager = MailHelper()
        template = self._generate_template_data()
        message = self._generate_final_message(template)
        mail_manager.sendmail(template.from_mail, [template.target_mail], message)
        if self.notification_type == SupportedNotificationTypes.FAREWELL:
            self.create_farewell_letter_marker()

    def _get_templates(self):
        if self.notification_type == SupportedNotificationTypes.REPORT:
            return os.path.join(WMT_TEMPLATES_DIR, 'wmt_notify.txt'), \
                   os.path.join(WMT_TEMPLATES_DIR, 'wmt_notify.html')
        elif self.notification_type == SupportedNotificationTypes.ALERT:
            return os.path.join(WMT_TEMPLATES_DIR, 'wmt_alert.txt'), \
                   os.path.join(WMT_TEMPLATES_DIR, 'wmt_alert.html')
        elif self.notification_type == SupportedNotificationTypes.FAREWELL:
            return os.path.join(WMT_TEMPLATES_DIR, 'wmt_farewell_solo.txt'), \
                   os.path.join(WMT_TEMPLATES_DIR, 'wmt_farewell_solo.html')
        else:
            raise NotImplementedError(f'unexpected notifier type: {self.notification_type}')

    @staticmethod
    def _get_table_headers(section):
        return HEADERS_REPORT_MAPPING[section]

    def _generate_tables(self, section) -> EmailReport:
        no_domains_message = f'No domains for {self.period}'
        text_table = self._get_table('text', section)
        html_table = self._get_table('html', section)

        text_final_str = text_table.get_string() if text_table else no_domains_message
        html_final_str = html_table.get_html_string(format=True,
                                                    border=True,
                                                    hrules=ALL,
                                                    vrules=ALL) if html_table else no_domains_message
        return EmailReport(
            text_option=text_final_str,
            html_option=html.unescape(html_final_str.replace('text-align: center', 'text-align: left'))
        )

    def _get_table(self, alternative, section):
        table_data = self.report[section]
        if not table_data:
            return None
        table = PrettyTable(self._get_table_headers(section))
        table.align = 'l'
        if not isinstance(table_data, list):
            table_data = [table_data]
        for row in table_data:
            table.add_row(row.to_template(alternative))
        return table

    def _generate_template_data(self) -> EmailTemplate:
        template = {
            'target_mail': self.target_email,
            'from_mail': self.from_email
        }
        if self.notification_type in [SupportedNotificationTypes.REPORT, SupportedNotificationTypes.ALERT]:
            template.update({
                'error_report': self._generate_tables('error_report'),
            })
        if self.notification_type == SupportedNotificationTypes.REPORT:
            template.update({
                'summary_report': self._generate_tables('summary_report'),
                'duration_report': self._generate_tables('duration_report')
            })
        return EmailTemplate(**template)

    def _generate_email(self, report: EmailTemplate):
        text_template, html_template = self._get_templates()
        if not os.path.exists(text_template) or not os.path.exists(html_template):
            raise WmtEmailException(f'unable to find email templates: {text_template}, {html_template}. '
                                    'Try to reinstall package')

        try:
            period = self.period
            subject = f'Web Monitoring Tool {self.notification_type} for {period} from server {get_hostname()}'
            if self.notification_type == SupportedNotificationTypes.ALERT:
                subject = f'[{self.notification_type.upper()}] {subject}'
            if self.notification_type == SupportedNotificationTypes.FAREWELL:
                subject = f'[EXPIRED CloudLinux LICENSE] Web Monitoring Tool {self.notification_type}'
            subject, text_body = clemail.ClEmail.generate_mail_jinja2(
                text_template, templ_data=report.to_text_template(period, self.notification_type),
                subject=subject)

            _, html_body = clemail.ClEmail.generate_mail_jinja2(
                html_template, templ_data=report.to_html_template(period, self.notification_type),
                subject=subject)

        except clemail.jinja2.exceptions.TemplateError as e:
            raise WmtEmailException(f'cannot generate email, reason: {e}')

        return Email(subject=subject, text_sample=text_body, html_sample=html_body)

    def _generate_final_message(self, template_data: EmailTemplate):
        email = self._generate_email(template_data)
        text_body = email.text_sample.encode('utf-8', 'xmlcharrefreplace').decode('utf-8')
        html_body = email.html_sample.encode('utf-8', 'xmlcharrefreplace').decode('utf-8')
        message = MIMEMultipart('alternative')
        message.attach(MIMEText(text_body, 'plain', 'utf-8'))
        message.attach(MIMEText(html_body, 'html', 'utf-8'))

        message['Subject'] = Header(email.subject, 'utf-8').encode()
        message['From'] = template_data.from_mail
        message['To'] = template_data.target_mail
        return message