import json
from datetime import datetime
from collections import namedtuple

from celery.signals import worker_process_shutdown
from flask import current_app

from notifications_utils.recipients import (
    RecipientCSV
)
from notifications_utils.statsd_decorators import statsd
from notifications_utils.template import (
    SMSMessageTemplate,
    WithSubjectTemplate,
    LetterDVLATemplate
)
from requests import (
    HTTPError,
    request,
    RequestException
)
from sqlalchemy.exc import SQLAlchemyError
from botocore.exceptions import ClientError as BotoClientError

from app import (
    create_uuid,
    create_random_identifier,
    DATETIME_FORMAT,
    notify_celery,
    encryption
)
from app.aws import s3
from app.celery import provider_tasks, letters_pdf_tasks, research_mode_tasks
from app.config import QueueNames
from app.dao.inbound_sms_dao import dao_get_inbound_sms_by_id
from app.dao.jobs_dao import (
    dao_update_job,
    dao_get_job_by_id,
    all_notifications_are_created_for_job,
    dao_get_all_notifications_for_job,
    dao_update_job_status
)
from app.dao.notifications_dao import (
    get_notification_by_id,
    dao_update_notifications_for_job_to_sent_to_dvla,
    dao_update_notifications_by_reference,
    dao_get_last_notification_added_for_job_id,
    dao_get_notification_by_reference,
    update_notification_status_by_reference,
)
from app.dao.provider_details_dao import get_current_provider
from app.dao.service_inbound_api_dao import get_service_inbound_api_for_service
from app.dao.services_dao import dao_fetch_service_by_id, fetch_todays_total_message_count
from app.dao.templates_dao import dao_get_template_by_id
from app.exceptions import DVLAException
from app.models import (
    DVLA_RESPONSE_STATUS_SENT,
    EMAIL_TYPE,
    JOB_STATUS_CANCELLED,
    JOB_STATUS_FINISHED,
    JOB_STATUS_IN_PROGRESS,
    JOB_STATUS_PENDING,
    JOB_STATUS_READY_TO_SEND,
    JOB_STATUS_SENT_TO_DVLA, JOB_STATUS_ERROR,
    KEY_TYPE_NORMAL,
    LETTER_TYPE,
    NOTIFICATION_CREATED,
    NOTIFICATION_DELIVERED,
    NOTIFICATION_SENDING,
    NOTIFICATION_TEMPORARY_FAILURE,
    NOTIFICATION_TECHNICAL_FAILURE,
    SMS_TYPE,
)
from app.notifications.process_notifications import persist_notification
from app.service.utils import service_allowed_to_send_to
from notifications_utils.s3 import s3upload


@worker_process_shutdown.connect
def worker_process_shutdown(sender, signal, pid, exitcode):
    current_app.logger.info('Tasks worker shutdown: PID: {} Exitcode: {}'.format(pid, exitcode))


@notify_celery.task(name="process-job")
@statsd(namespace="tasks")
def process_job(job_id):
    start = datetime.utcnow()
    job = dao_get_job_by_id(job_id)

    if job.job_status != JOB_STATUS_PENDING:
        return

    service = job.service

    if not service.active:
        job.job_status = JOB_STATUS_CANCELLED
        dao_update_job(job)
        current_app.logger.warn(
            "Job {} has been cancelled, service {} is inactive".format(job_id, service.id))
        return

    if __sending_limits_for_job_exceeded(service, job, job_id):
        return

    job.job_status = JOB_STATUS_IN_PROGRESS
    job.processing_started = start
    dao_update_job(job)

    db_template = dao_get_template_by_id(job.template_id, job.template_version)

    TemplateClass = get_template_class(db_template.template_type)
    template = TemplateClass(db_template.__dict__)

    current_app.logger.debug("Starting job {} processing {} notifications".format(job_id, job.notification_count))

    for row_number, recipient, personalisation in RecipientCSV(
            s3.get_job_from_s3(str(service.id), str(job_id)),
            template_type=template.template_type,
            placeholders=template.placeholders
    ).enumerated_recipients_and_personalisation:
        process_row(row_number, recipient, personalisation, template, job, service)

    job_complete(job, start=start)


def job_complete(job, resumed=False, start=None):
    job.job_status = JOB_STATUS_FINISHED

    finished = datetime.utcnow()
    job.processing_finished = finished
    dao_update_job(job)

    if resumed:
        current_app.logger.info(
            "Resumed Job {} completed at {}".format(job.id, job.created_at)
        )
    else:
        current_app.logger.info(
            "Job {} created at {} started at {} finished at {}".format(job.id, job.created_at, start, finished)
        )


def process_row(row_number, recipient, personalisation, template, job, service):
    template_type = template.template_type
    encrypted = encryption.encrypt({
        'template': str(template.id),
        'template_version': job.template_version,
        'job': str(job.id),
        'to': recipient,
        'row_number': row_number,
        'personalisation': dict(personalisation)
    })

    send_fns = {
        SMS_TYPE: save_sms,
        EMAIL_TYPE: save_email,
        LETTER_TYPE: save_letter
    }

    send_fn = send_fns[template_type]

    send_fn.apply_async(
        (
            str(service.id),
            create_uuid(),
            encrypted,
        ),
        queue=QueueNames.DATABASE if not service.research_mode else QueueNames.RESEARCH_MODE
    )


def __sending_limits_for_job_exceeded(service, job, job_id):
    total_sent = fetch_todays_total_message_count(service.id)

    if total_sent + job.notification_count > service.message_limit:
        job.job_status = 'sending limits exceeded'
        job.processing_finished = datetime.utcnow()
        dao_update_job(job)
        current_app.logger.info(
            "Job {} size {} error. Sending limits {} exceeded".format(
                job_id, job.notification_count, service.message_limit)
        )
        return True
    return False


@notify_celery.task(bind=True, name="save-sms", max_retries=5, default_retry_delay=300)
@statsd(namespace="tasks")
def save_sms(self,
             service_id,
             notification_id,
             encrypted_notification,
             api_key_id=None,
             key_type=KEY_TYPE_NORMAL):
    notification = encryption.decrypt(encrypted_notification)
    service = dao_fetch_service_by_id(service_id)
    template = dao_get_template_by_id(notification['template'], version=notification['template_version'])

    if not service_allowed_to_send_to(notification['to'], service, key_type):
        current_app.logger.debug(
            "SMS {} failed as restricted service".format(notification_id)
        )
        return

    try:
        saved_notification = persist_notification(
            template_id=notification['template'],
            template_version=notification['template_version'],
            recipient=notification['to'],
            service=service,
            personalisation=notification.get('personalisation'),
            notification_type=SMS_TYPE,
            api_key_id=api_key_id,
            key_type=key_type,
            created_at=datetime.utcnow(),
            job_id=notification.get('job', None),
            job_row_number=notification.get('row_number', None),
            notification_id=notification_id,
            reply_to_text=template.get_reply_to_text()
        )

        provider_tasks.deliver_sms.apply_async(
            [str(saved_notification.id)],
            queue=QueueNames.SEND_SMS if not service.research_mode else QueueNames.RESEARCH_MODE
        )

        current_app.logger.debug(
            "SMS {} created at {} for job {}".format(
                saved_notification.id,
                saved_notification.created_at,
                notification.get('job', None))
        )

    except SQLAlchemyError as e:
        handle_exception(self, notification, notification_id, e)


@notify_celery.task(bind=True, name="save-email", max_retries=5, default_retry_delay=300)
@statsd(namespace="tasks")
def save_email(self,
               service_id,
               notification_id,
               encrypted_notification,
               api_key_id=None,
               key_type=KEY_TYPE_NORMAL):
    notification = encryption.decrypt(encrypted_notification)

    service = dao_fetch_service_by_id(service_id)
    template = dao_get_template_by_id(notification['template'], version=notification['template_version'])

    if not service_allowed_to_send_to(notification['to'], service, key_type):
        current_app.logger.info("Email {} failed as restricted service".format(notification_id))
        return

    try:
        saved_notification = persist_notification(
            template_id=notification['template'],
            template_version=notification['template_version'],
            recipient=notification['to'],
            service=service,
            personalisation=notification.get('personalisation'),
            notification_type=EMAIL_TYPE,
            api_key_id=api_key_id,
            key_type=key_type,
            created_at=datetime.utcnow(),
            job_id=notification.get('job', None),
            job_row_number=notification.get('row_number', None),
            notification_id=notification_id,
            reply_to_text=template.get_reply_to_text()
        )

        provider_tasks.deliver_email.apply_async(
            [str(saved_notification.id)],
            queue=QueueNames.SEND_EMAIL if not service.research_mode else QueueNames.RESEARCH_MODE
        )

        current_app.logger.debug("Email {} created at {}".format(saved_notification.id, saved_notification.created_at))
    except SQLAlchemyError as e:
        handle_exception(self, notification, notification_id, e)


@notify_celery.task(bind=True, name="save-letter", max_retries=5, default_retry_delay=300)
@statsd(namespace="tasks")
def save_letter(
    self,
    service_id,
    notification_id,
    encrypted_notification,
):
    notification = encryption.decrypt(encrypted_notification)

    # we store the recipient as just the first item of the person's address
    recipient = notification['personalisation']['addressline1']

    service = dao_fetch_service_by_id(service_id)
    template = dao_get_template_by_id(notification['template'], version=notification['template_version'])

    try:
        # if we don't want to actually send the letter, then start it off in SENDING so we don't pick it up
        status = NOTIFICATION_CREATED if not service.research_mode else NOTIFICATION_SENDING

        saved_notification = persist_notification(
            template_id=notification['template'],
            template_version=notification['template_version'],
            recipient=recipient,
            service=service,
            personalisation=notification['personalisation'],
            notification_type=LETTER_TYPE,
            api_key_id=None,
            key_type=KEY_TYPE_NORMAL,
            created_at=datetime.utcnow(),
            job_id=notification['job'],
            job_row_number=notification['row_number'],
            notification_id=notification_id,
            reference=create_random_identifier(),
            reply_to_text=template.get_reply_to_text(),
            status=status
        )

        if not service.research_mode:
            letters_pdf_tasks.create_letters_pdf.apply_async(
                [str(saved_notification.id)],
                queue=QueueNames.CREATE_LETTERS_PDF
            )
        elif current_app.config['NOTIFY_ENVIRONMENT'] in ['preview', 'development']:
            research_mode_tasks.create_fake_letter_response_file.apply_async(
                (saved_notification.reference,),
                queue=QueueNames.RESEARCH_MODE
            )
        else:
            update_notification_status_by_reference(saved_notification.reference, 'delivered')

        current_app.logger.debug("Letter {} created at {}".format(saved_notification.id, saved_notification.created_at))
    except SQLAlchemyError as e:
        handle_exception(self, notification, notification_id, e)


@notify_celery.task(bind=True, name="build-dvla-file", countdown=60, max_retries=15, default_retry_delay=300)
@statsd(namespace="tasks")
def build_dvla_file(self, job_id):
    try:
        if all_notifications_are_created_for_job(job_id):
            file_contents = create_dvla_file_contents_for_job(job_id)
            s3upload(
                filedata=file_contents + '\n',
                region=current_app.config['AWS_REGION'],
                bucket_name=current_app.config['DVLA_BUCKETS']['job'],
                file_location="{}-dvla-job.text".format(job_id)
            )
            dao_update_job_status(job_id, JOB_STATUS_READY_TO_SEND)
        else:
            msg = "All notifications for job {} are not persisted".format(job_id)
            current_app.logger.info(msg)
            self.retry(queue=QueueNames.RETRY)
    # specifically don't catch celery.retry errors
    except (SQLAlchemyError, BotoClientError):
        current_app.logger.exception("build_dvla_file threw exception")
        self.retry(queue=QueueNames.RETRY)


@notify_celery.task(bind=True, name='update-letter-job-to-sent')
@statsd(namespace="tasks")
def update_job_to_sent_to_dvla(self, job_id):
    # This task will be called by the FTP app to update the job to sent to dvla
    # and update all notifications for this job to sending, provider = DVLA
    provider = get_current_provider(LETTER_TYPE)

    updated_count = dao_update_notifications_for_job_to_sent_to_dvla(job_id, provider.identifier)
    dao_update_job_status(job_id, JOB_STATUS_SENT_TO_DVLA)

    current_app.logger.info("Updated {} letter notifications to sending. "
                            "Updated {} job to {}".format(updated_count, job_id, JOB_STATUS_SENT_TO_DVLA))


@notify_celery.task(bind=True, name='update-letter-job-to-error')
@statsd(namespace="tasks")
def update_dvla_job_to_error(self, job_id):
    dao_update_job_status(job_id, JOB_STATUS_ERROR)
    current_app.logger.info("Updated {} job to {}".format(job_id, JOB_STATUS_ERROR))


@notify_celery.task(bind=True, name='update-letter-notifications-to-sent')
@statsd(namespace="tasks")
def update_letter_notifications_to_sent_to_dvla(self, notification_references):
    # This task will be called by the FTP app to update notifications as sent to DVLA
    provider = get_current_provider(LETTER_TYPE)

    updated_count = dao_update_notifications_by_reference(
        notification_references,
        {
            'status': NOTIFICATION_SENDING,
            'sent_by': provider.identifier,
            'sent_at': datetime.utcnow(),
            'updated_at': datetime.utcnow()
        }
    )

    current_app.logger.info("Updated {} letter notifications to sending".format(updated_count))


@notify_celery.task(bind=True, name='update-letter-notifications-to-error')
@statsd(namespace="tasks")
def update_letter_notifications_to_error(self, notification_references):
    # This task will be called by the FTP app to update notifications as sent to DVLA

    updated_count = dao_update_notifications_by_reference(
        notification_references,
        {
            'status': NOTIFICATION_TECHNICAL_FAILURE,
            'updated_at': datetime.utcnow()
        }
    )

    current_app.logger.debug("Updated {} letter notifications to technical-failure".format(updated_count))


def create_dvla_file_contents_for_job(job_id):
    notifications = dao_get_all_notifications_for_job(job_id)

    return create_dvla_file_contents_for_notifications(notifications)


def create_dvla_file_contents_for_notifications(notifications):
    file_contents = '\n'.join(
        str(LetterDVLATemplate(
            notification.template.__dict__,
            notification.personalisation,
            notification_reference=notification.reference,
            contact_block=notification.reply_to_text,
            org_id=notification.service.dvla_organisation.id,
        ))
        for notification in notifications
    )
    return file_contents


def handle_exception(task, notification, notification_id, exc):
    if not get_notification_by_id(notification_id):
        retry_msg = '{task} notification for job {job} row number {row} and notification id {noti}'.format(
            task=task.__name__,
            job=notification.get('job', None),
            row=notification.get('row_number', None),
            noti=notification_id
        )
        # Sometimes, SQS plays the same message twice. We should be able to catch an IntegrityError, but it seems
        # SQLAlchemy is throwing a FlushError. So we check if the notification id already exists then do not
        # send to the retry queue.
        current_app.logger.exception('Retry' + retry_msg)
        try:
            task.retry(queue=QueueNames.RETRY, exc=exc)
        except task.MaxRetriesExceededError:
            current_app.logger.exception('Retry' + retry_msg)


def get_template_class(template_type):
    if template_type == SMS_TYPE:
        return SMSMessageTemplate
    elif template_type in (EMAIL_TYPE, LETTER_TYPE):
        # since we don't need rendering capabilities (we only need to extract placeholders) both email and letter can
        # use the same base template
        return WithSubjectTemplate


@notify_celery.task(bind=True, name='update-letter-notifications-statuses')
@statsd(namespace="tasks")
def update_letter_notifications_statuses(self, filename):
    bucket_location = '{}-ftp'.format(current_app.config['NOTIFY_EMAIL_DOMAIN'])
    response_file_content = s3.get_s3_file(bucket_location, filename)

    try:
        notification_updates = process_updates_from_file(response_file_content)
    except TypeError:
        raise DVLAException('DVLA response file: {} has an invalid format'.format(filename))
    else:
        temporary_failures = []
        for update in notification_updates:
            check_billable_units(update)
            update_letter_notification(filename, temporary_failures, update)

        if temporary_failures:
            # This will alert Notify that DVLA was unable to deliver the letters, we need to investigate
            message = "DVLA response file: {filename} has failed letters with notification.reference {failures}".format(
                filename=filename, failures=temporary_failures)
            raise DVLAException(message)


def process_updates_from_file(response_file):
    NotificationUpdate = namedtuple('NotificationUpdate', ['reference', 'status', 'page_count', 'cost_threshold'])
    notification_updates = [NotificationUpdate(*line.split('|')) for line in response_file.splitlines()]
    return notification_updates


def update_letter_notification(filename, temporary_failures, update):
    if update.status == DVLA_RESPONSE_STATUS_SENT:
        status = NOTIFICATION_DELIVERED
    else:
        status = NOTIFICATION_TEMPORARY_FAILURE
        temporary_failures.append(update.reference)

    updated_count = dao_update_notifications_by_reference(
        references=[update.reference],
        update_dict={"status": status,
                     "billable_units": update.page_count,
                     "updated_at": datetime.utcnow()
                     }
    )

    if not updated_count:
        msg = "Update letter notification file {filename} failed: notification either not found " \
              "or already updated from delivered. Status {status} for notification reference {reference}".format(
                  filename=filename, status=status, reference=update.reference)
        current_app.logger.error(msg)


def check_billable_units(notification_update):
    notification = dao_get_notification_by_reference(notification_update.reference)

    if int(notification_update.page_count) != notification.billable_units:
        msg = 'Notification with id {} had {} billable_units but a page count of {}'.format(
            notification.id, notification.billable_units, notification_update.page_count)

        current_app.logger.error(msg)


@notify_celery.task(bind=True, name="send-inbound-sms", max_retries=5, default_retry_delay=300)
@statsd(namespace="tasks")
def send_inbound_sms_to_service(self, inbound_sms_id, service_id):
    inbound_api = get_service_inbound_api_for_service(service_id=service_id)
    if not inbound_api:
        # No API data has been set for this service
        return

    inbound_sms = dao_get_inbound_sms_by_id(service_id=service_id,
                                            inbound_id=inbound_sms_id)
    data = {
        "id": str(inbound_sms.id),
        # TODO: should we be validating and formatting the phone number here?
        "source_number": inbound_sms.user_number,
        "destination_number": inbound_sms.notify_number,
        "message": inbound_sms.content,
        "date_received": inbound_sms.provider_date.strftime(DATETIME_FORMAT)
    }

    try:
        response = request(
            method="POST",
            url=inbound_api.url,
            data=json.dumps(data),
            headers={
                'Content-Type': 'application/json',
                'Authorization': 'Bearer {}'.format(inbound_api.bearer_token)
            },
            timeout=60
        )
        current_app.logger.debug('send_inbound_sms_to_service sending {} to {}, response {}'.format(
            inbound_sms_id,
            inbound_api.url,
            response.status_code
        ))
        response.raise_for_status()
    except RequestException as e:
        current_app.logger.warning(
            "send_inbound_sms_to_service request failed for service_id: {} and url: {}. exc: {}".format(
                service_id,
                inbound_api.url,
                e
            )
        )
        if not isinstance(e, HTTPError) or e.response.status_code >= 500:
            try:
                self.retry(queue=QueueNames.RETRY)
            except self.MaxRetriesExceededError:
                current_app.logger.exception('Retry: send_inbound_sms_to_service has retried the max number of times')


@notify_celery.task(name='process-incomplete-jobs')
@statsd(namespace="tasks")
def process_incomplete_jobs(job_ids):
    current_app.logger.info("Resuming Job(s) {}".format(job_ids))
    for job_id in job_ids:
        process_incomplete_job(job_id)


def process_incomplete_job(job_id):

    job = dao_get_job_by_id(job_id)

    last_notification_added = dao_get_last_notification_added_for_job_id(job_id)

    if last_notification_added:
        resume_from_row = last_notification_added.job_row_number
    else:
        resume_from_row = -1  # The first row in the csv with a number is row 0

    current_app.logger.info("Resuming job {} from row {}".format(job_id, resume_from_row))

    db_template = dao_get_template_by_id(job.template_id, job.template_version)

    TemplateClass = get_template_class(db_template.template_type)
    template = TemplateClass(db_template.__dict__)

    for row_number, recipient, personalisation in RecipientCSV(
            s3.get_job_from_s3(str(job.service_id), str(job.id)),
            template_type=template.template_type,
            placeholders=template.placeholders
    ).enumerated_recipients_and_personalisation:
        if row_number > resume_from_row:
            process_row(row_number, recipient, personalisation, template, job, job.service)

    job_complete(job, resumed=True)