# Copyright (c) 2018 Cisco and/or its affiliates.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at:
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import smtplib
import logging

from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from os.path import isdir

from errors import PresentationError


class AlertingError(PresentationError):
    """Exception(s) raised by the alerting module.

    When raising this exception, put this information to the message in this
    order:
     - short description of the encountered problem (parameter msg),
     - relevant messages if there are any collected, e.g., from caught
       exception (optional parameter details),
     - relevant data if there are any collected (optional parameter details).
    """

    def __init__(self, msg, details='', level="CRITICAL"):
        """Sets the exception message and the level.

        :param msg: Short description of the encountered problem.
        :param details: Relevant messages if there are any collected, e.g.,
            from caught exception (optional parameter details), or relevant data
            if there are any collected (optional parameter details).
        :param level: Level of the error, possible choices are: "DEBUG", "INFO",
            "WARNING", "ERROR" and "CRITICAL".
        :type msg: str
        :type details: str
        :type level: str
        """

        super(AlertingError, self).__init__(
            "Alerting: {0}".format(msg), details, level)

    def __repr__(self):
        return (
            "AlertingError(msg={msg!r},details={dets!r},level={level!r})".
            format(msg=self._msg, dets=self._details, level=self._level))


class Alerting(object):
    """Class implementing the alerting mechanism.
    """

    def __init__(self, spec):
        """Initialization.

        :param spec: The CPTA specification.
        :type spec: Specification
        """

        # Implemented alerts:
        self._ALERTS = ("failed-tests", )

        self._spec = spec.alerting
        self._path_failed_tests = spec.environment["paths"]["DIR[STATIC,VPP]"]

        # Verify and validate input specification:
        self.configs = self._spec.get("configurations", None)
        if not self.configs:
            raise AlertingError("No alert configuration is specified.")
        for config_type, config_data in self.configs.iteritems():
            if config_type == "email":
                if not config_data.get("server", None):
                    raise AlertingError("Parameter 'server' is missing.")
                if not config_data.get("address-to", None):
                    raise AlertingError("Parameter 'address-to' (recipient) is "
                                        "missing.")
                if not config_data.get("address-from", None):
                    raise AlertingError("Parameter 'address-from' (sender) is "
                                        "missing.")
            elif config_type == "jenkins":
                if not isdir(config_data.get("output-dir", "")):
                    raise AlertingError("Parameter 'output-dir' is "
                                        "missing or it is not a directory.")
                if not config_data.get("output-file", None):
                    raise AlertingError("Parameter 'output-file' is missing.")
            else:
                raise AlertingError("Alert of type '{0}' is not implemented.".
                                    format(config_type))

        self.alerts = self._spec.get("alerts", None)
        if not self.alerts:
            raise AlertingError("No alert is specified.")
        for alert, alert_data in self.alerts.iteritems():
            if not alert_data.get("title", None):
                raise AlertingError("Parameter 'title' is missing.")
            if not alert_data.get("type", None) in self._ALERTS:
                raise AlertingError("Parameter 'failed-tests' is missing or "
                                    "incorrect.")
            if not alert_data.get("way", None) in self.configs.keys():
                raise AlertingError("Parameter 'way' is missing or incorrect.")
            if not alert_data.get("include", None):
                raise AlertingError("Parameter 'include' is missing or the "
                                    "list is empty.")

    def __str__(self):
        """Return string with human readable description of the alert.

        :returns: Readable description.
        :rtype: str
        """
        return "configs={configs}, alerts={alerts}".format(
            configs=self.configs, alerts=self.alerts)

    def __repr__(self):
        """Return string executable as Python constructor call.

        :returns: Executable constructor call.
        :rtype: str
        """
        return "Alerting(spec={spec})".format(
            spec=self._spec)

    def generate_alerts(self):
        """Generate alert(s) using specified way(s).
        """

        for alert, alert_data in self.alerts.iteritems():
            if alert_data["way"] == "email":
                text, html = self._create_alert_message(alert_data)
                conf = self.configs["email"]
                self._send_email(server=conf["server"],
                                 addr_from=conf["address-from"],
                                 addr_to=conf["address-to"],
                                 subject=alert_data["title"],
                                 text=text,
                                 html=html)
            elif alert_data["way"] == "jenkins":
                self._generate_files_for_jenkins(alert_data)
            else:
                raise AlertingError("Alert with way '{0}' is not implemented.".
                                    format(alert_data["way"]))

    @staticmethod
    def _send_email(server, addr_from, addr_to, subject, text=None, html=None):
        """Send an email using predefined configuration.

        :param server: SMTP server used to send email.
        :param addr_from: Sender address.
        :param addr_to: Recipient address(es).
        :param subject: Subject of the email.
        :param text: Message in the ASCII text format.
        :param html: Message in the HTML format.
        :type server: str
        :type addr_from: str
        :type addr_to: list
        :type subject: str
        :type text: str
        :type html: str
        """

        if not text and not html:
            raise AlertingError("No text/data to send.")

        msg = MIMEMultipart('alternative')
        msg['Subject'] = subject
        msg['From'] = addr_from
        msg['To'] = ", ".join(addr_to)

        if text:
            msg.attach(MIMEText(text, 'plain'))
        if html:
            msg.attach(MIMEText(html, 'html'))

        smtp_server = None
        try:
            logging.info("Trying to send alert '{0}' ...".format(subject))
            logging.debug("SMTP Server: {0}".format(server))
            logging.debug("From: {0}".format(addr_from))
            logging.debug("To: {0}".format(", ".join(addr_to)))
            logging.debug("Message: {0}".format(msg.as_string()))
            smtp_server = smtplib.SMTP(server)
            smtp_server.sendmail(addr_from, addr_to, msg.as_string())
        except smtplib.SMTPException as err:
            raise AlertingError("Not possible to send the alert via email.",
                                str(err))
        finally:
            if smtp_server:
                smtp_server.quit()

    def _create_alert_message(self, alert):
        """Create the message which is used in the generated alert.

        :param alert: Message is created for this alert.
        :type alert: dict
        :returns: Message in the ASCII text and HTML format.
        :rtype: tuple(str, str)
        """

        if alert["type"] == "failed-tests":
            text = ""
            html = "<html><body>"
            for item in alert["include"]:
                file_name = "{path}/{name}".format(
                    path=self._path_failed_tests, name=item)
                try:
                    with open("{0}.txt".format(file_name), 'r') as txt_file:
                        text += "{0}:\n\n".format(
                            item.replace("failed-tests-", ""))
                        text += txt_file.read() + "\n" * 2
                except IOError:
                    logging.error("Not possible to read the file '{0}.txt'.".
                                  format(file_name))
                try:
                    with open("{0}.rst".format(file_name), 'r') as rst_file:
                        html += "<h2>{0}:</h2>".format(
                            item.replace("failed-tests-", ""))
                        html += rst_file.readlines()[2].\
                            replace("../trending", alert.get("url", ""))
                        html += "<br>" * 3
                except IOError:
                    logging.error("Not possible to read the file '{0}.rst'.".
                                  format(file_name))
            html += "</body></html>"
        else:
            raise AlertingError("Alert of type '{0}' is not implemented.".
                                format(alert["type"]))
        return text, html

    def _generate_files_for_jenkins(self, alert):
        """Create the file which is used in the generated alert.

        :param alert: Files are created for this alert.
        :type alert: dict
        """

        config = self.configs[alert["way"]]

        if alert["type"] == "failed-tests":
            text, html = self._create_alert_message(alert)
            file_name = "{0}/{1}".format(config["output-dir"],
                                         config["output-file"])
            logging.info("Writing the file '{0}.txt' ...".format(file_name))
            try:
                with open("{0}.txt".format(file_name), 'w') as txt_file:
                    txt_file.write(text)
            except IOError:
                logging.error("Not possible to write the file '{0}.txt'.".
                              format(file_name))
            logging.info("Writing the file '{0}.html' ...".format(file_name))
            try:
                with open("{0}.html".format(file_name), 'w') as html_file:
                    html_file.write(html)
            except IOError:
                logging.error("Not possible to write the file '{0}.html'.".
                              format(file_name))
        else:
            raise AlertingError("Alert of type '{0}' is not implemented.".
                                format(alert["type"]))