'use strict';

const logger = require('../logger');
const nantum = require('../modules/nantum');
const { vtnId } = require('../config');

function calculateEventStatus(notificationTime, startTime, endTime) {
  const nowMillis = new Date().getTime();
  if (nowMillis < new Date(startTime).getTime()) {
    return 'far';
  }
  if (nowMillis > new Date(endTime).getTime()) {
    return 'completed';
  }

  return 'active';
}

function calculateDurationSeconds(startTime, endTime) {
  return Math.round(
    (new Date(endTime).getTime() - new Date(startTime).getTime()) / 1000,
  );
}

function calculateDuration(startTime, endTime) {
  return `PT${calculateDurationSeconds(startTime, endTime)}S`;
}

function calculateNotificationDuration(notificationTime, startTime) {
  if (!notificationTime) {
    return 'PT0S';
  }
  return calculateDuration(notificationTime, startTime);
}

function calculateEventIntervals(eventInfoValues, eventDurationSeconds) {
  //TODO: this is likely incorrect. Get more details on the event_info_value data model.

  let result = [];

  for (let i = 0; i < eventInfoValues.length; i++) {
    const eventInfoValue = eventInfoValues[i];
    const nextOffset =
      i === eventInfoValues.length - 1
        ? eventDurationSeconds - eventInfoValue.timeOffset
        : eventInfoValues[i + 1].timeOffset;
    result.push({
      signalPayloads: [eventInfoValue.value],
      duration: `PT${nextOffset}S`,
      uid: `${i + 1}`,
    });
  }
  return result;
}

function calculateEventSignals(eventInstances, eventDurationSeconds) {
  return eventInstances.map(eventInstance => {
    return {
      signalName: eventInstance.event_type_id,
      signalId: '112233445566',
      signalType: 'level',
      intervals: calculateEventIntervals(
        eventInstance.event_info_values,
        eventDurationSeconds,
      ),
    };
  });
}

function convertToOadrEvents(nantumEvent) {
  if (!nantumEvent.dr_event_data) {
    // no event
    return [];
  }
  const nowMillis = new Date().getTime();
  if (
    nowMillis < new Date(nantumEvent.dr_event_data.notification_time).getTime()
  ) {
    return []; // not in the notification period yet
  }

  return [
    {
      eventDescriptor: {
        eventId: nantumEvent.event_identifier,
        modificationNumber: nantumEvent.event_mod_number,
        marketContext: 'http://MarketContext1',
        createdDateTime: '2020-04-14T16:06:39.000Z',
        eventStatus: calculateEventStatus(
          nantumEvent.dr_event_data.notification_time,
          nantumEvent.dr_event_data.start_time,
          nantumEvent.dr_event_data.end_time,
        ),
        testEvent: nantumEvent.test_event,
        priority: 0,
      },
      activePeriod: {
        startDate: nantumEvent.dr_event_data.start_time,
        duration: calculateDuration(
          nantumEvent.dr_event_data.start_time,
          nantumEvent.dr_event_data.end_time,
        ),
        notificationDuration: calculateNotificationDuration(
          nantumEvent.dr_event_data.notification_time,
          nantumEvent.dr_event_data.start_time,
        ),
      },
      signals: {
        event: calculateEventSignals(
          nantumEvent.dr_event_data.event_instance,
          calculateDurationSeconds(
            nantumEvent.dr_event_data.start_time,
            nantumEvent.dr_event_data.end_time,
          ),
        ),
      },
      target: {
        venId: [nantumEvent.client_id],
      },
      responseRequired: 'always',
    },
  ];
}

async function retrieveEvents(
  oadrRequestEvent,
  clientCertificateCn,
  clientCertificateFingerprint,
) {
  logger.info(
    'retrieveEvents',
    oadrRequestEvent,
    clientCertificateCn,
    clientCertificateFingerprint,
  );

  const requestVenId = oadrRequestEvent.venId;

  if (!requestVenId) {
    const error = new Error('No VenID in request');
    error.responseCode = 452;
    throw error;
  }

  if (requestVenId !== clientCertificateFingerprint) {
    // as per certification item #512, venId MUST be case-sensitive
    const error = new Error('VenID does not match certificate');
    error.responseCode = 452;
    throw error;
  }

  if (!clientCertificateCn) {
    const error = new Error('Could not determine CN from client certificate');
    error.responseCode = 452;
    throw error;
  }

  const event = await nantum.fetchEvent(requestVenId);

  return {
    responseCode: '200',
    responseDescription: 'OK',
    responseRequestId: oadrRequestEvent.requestId || '',
    requestId: oadrRequestEvent.requestId || '',
    vtnId: vtnId,
    events: convertToOadrEvents(event),
  };
}

/* qualifiedEvent is the combination of eventId & modificationNumber */
function eventResponseMatchesValidEvent(eventResponse, oadrEvents) {
  return (
    oadrEvents.filter(oadrEvent => {
      return (
        oadrEvent.eventDescriptor.eventId === eventResponse.eventId &&
        oadrEvent.eventDescriptor.modificationNumber ===
          eventResponse.modificationNumber &&
        oadrEvent.eventDescriptor.status !== 'cancelled' &&
        oadrEvent.eventDescriptor.status !== 'completed'
      );
    }).length > 0
  );
}

async function validateEventResponses(venId, eventResponses) {
  const event = await nantum.fetchEvent(venId);
  const oadrEvents = convertToOadrEvents(event);
  const staleResponses = eventResponses.filter(
    eventResponse => !eventResponseMatchesValidEvent(eventResponse, oadrEvents),
  );

  if (staleResponses.length > 0) {
    const error = new Error('Event response references invalid event');
    error.responseCode = '454';
    throw error;
  }
}

async function updateOptType(
  oadrCreatedEvent,
  clientCertificateCn,
  clientCertificateFingerprint,
) {
  logger.info(
    'updateOptType',
    oadrCreatedEvent,
    clientCertificateCn,
    clientCertificateFingerprint,
  );

  const requestVenId = oadrCreatedEvent.venId;
  validateVenId(requestVenId, clientCertificateFingerprint, true);

  let opted = await nantum.fetchOpted(requestVenId);

  try {
    await validateEventResponses(requestVenId, oadrCreatedEvent.eventResponses);
    for (const eventResponse of oadrCreatedEvent.eventResponses) {
      // remove existing opts for this eventId
      opted = [
        ...opted.filter(
          optedItem => optedItem.eventId !== eventResponse.eventId,
        ),
      ];
      opted.push({
        eventId: eventResponse.eventId,
        modificationNumber: eventResponse.modificationNumber,
        optType: eventResponse.optType,
      });
    }
    await nantum.updateOpted(requestVenId, opted);

    return {
      _type: 'oadrResponse',
      responseCode: '200',
      responseDescription: 'OK',
      venId: clientCertificateFingerprint,
    };
  } catch (e) {
    return {
      _type: 'oadrResponse',
      responseCode: e.responseCode || '454',
      responseDescription: e.message || 'Invalid event response received',
      venId: clientCertificateFingerprint,
    };
  }
}

async function filterOutAcknowledgedEvents(venId, events) {
  const opted = (await nantum.fetchOpted(venId)) || [];
  return events.filter(
    event =>
      opted.filter(
        optedItem =>
          optedItem.eventId === event.eventDescriptor.eventId &&
          optedItem.modificationNumber ===
            event.eventDescriptor.modificationNumber,
      ).length === 0,
  );
}

async function pollForEvents(
  oadrPoll,
  clientCertificateCn,
  clientCertificateFingerprint,
) {
  logger.info(
    'pollForEvents',
    oadrPoll,
    clientCertificateCn,
    clientCertificateFingerprint,
  );

  const requestVenId = oadrPoll.venId;
  validateVenId(requestVenId, clientCertificateFingerprint, true);

  const event = await nantum.fetchEvent(requestVenId);
  const filteredEvents = await filterOutAcknowledgedEvents(
    requestVenId,
    convertToOadrEvents(event),
  );

  if (filteredEvents.length > 0) {
    return {
      _type: 'oadrDistributeEvent',
      responseCode: '200',
      responseDescription: 'OK',
      responseRequestId: '', // required field, but empty is allowed as per spec
      requestId: '',
      vtnId: vtnId,
      events: filteredEvents,
    };
  }
  return undefined;
}

function validateVenId(requestVenId, clientCertificateFingerprint, required) {
  if (requestVenId === clientCertificateFingerprint) {
    return;
  }
  if (!required && requestVenId == null) {
    return;
  }
  if (required && requestVenId == null) {
    const error = new Error('VenID is missing');
    error.responseCode = 452;
    throw error;
  }
  const error = new Error('VenID is invalid');
  error.responseCode = 452;
  throw error;
}

module.exports = {
  pollForEvents,
  retrieveEvents,
  updateOptType,
};