import itertools
from datetime import (datetime)

from flask import current_app
from monotonic import monotonic
from notifications_utils.recipients import (
    RecipientCSV,
    allowed_to_send_to
)
from notifications_utils.template import Template
from sqlalchemy.exc import SQLAlchemyError

from app import clients, statsd_client
from app import (
    create_uuid,
    DATETIME_FORMAT,
    DATE_FORMAT,
    notify_celery,
    encryption
)
from app.aws import s3
from app.celery.provider_tasks import send_sms_to_provider
from app.celery.research_mode_tasks import send_email_response
from app.clients.email import EmailClientException
from app.dao.jobs_dao import (
    dao_update_job,
    dao_get_job_by_id
)
from app.dao.notifications_dao import (
    dao_create_notification,
    dao_update_notification,
    dao_get_notification_statistics_for_service_and_day,
    update_provider_stats
)
from app.dao.provider_details_dao import get_provider_details_by_notification_type
from app.dao.services_dao import dao_fetch_service_by_id
from app.dao.templates_dao import dao_get_template_by_id
from app.models import (
    Notification,
    TEMPLATE_TYPE_EMAIL,
    TEMPLATE_TYPE_SMS
)


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

    service = job.service

    stats = dao_get_notification_statistics_for_service_and_day(
        service_id=service.id,
        day=job.created_at.strftime(DATE_FORMAT)
    )

    total_sent = 0
    if stats:
        total_sent = stats.emails_requested + stats.sms_requested

    if total_sent + job.notification_count > service.message_limit:
        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

    job.status = 'in progress'
    dao_update_job(job)

    template = Template(
        dao_get_template_by_id(job.template_id, job.template_version).__dict__
    )

    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:

        encrypted = encryption.encrypt({
            'template': str(template.id),
            'template_version': job.template_version,
            'job': str(job.id),
            'to': recipient,
            'row_number': row_number,
            'personalisation': {
                key: personalisation.get(key)
                for key in template.placeholders
                }
        })

        if template.template_type == 'sms':
            send_sms.apply_async((
                str(job.service_id),
                create_uuid(),
                encrypted,
                datetime.utcnow().strftime(DATETIME_FORMAT)),
                queue='bulk-sms'
            )

        if template.template_type == 'email':
            send_email.apply_async((
                str(job.service_id),
                create_uuid(),
                encrypted,
                datetime.utcnow().strftime(DATETIME_FORMAT)),
                {'reply_to_addresses': service.reply_to_email_address},
                queue='bulk-email')

    finished = datetime.utcnow()
    job.status = 'finished'
    job.processing_started = start
    job.processing_finished = finished
    dao_update_job(job)
    remove_job.apply_async((str(job_id),), queue='remove-job')
    current_app.logger.info(
        "Job {} created at {} started at {} finished at {}".format(job_id, job.created_at, start, finished)
    )
    statsd_client.incr("notifications.tasks.process-job")
    statsd_client.timing("notifications.tasks.process-job.task-time", monotonic() - task_start)


@notify_celery.task(name="remove-job")
def remove_job(job_id):
    job = dao_get_job_by_id(job_id)
    s3.remove_job_from_s3(job.service.id, str(job_id))
    current_app.logger.info("Job {} has been removed from s3.".format(job_id))


@notify_celery.task(bind=True, name="send-sms", max_retries=5, default_retry_delay=5)
def send_sms(self, service_id, notification_id, encrypted_notification, created_at):
    task_start = monotonic()
    notification = encryption.decrypt(encrypted_notification)
    service = dao_fetch_service_by_id(service_id)

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

    try:

        sent_at = datetime.utcnow()
        notification_db_object = Notification(
            id=notification_id,
            template_id=notification['template'],
            template_version=notification['template_version'],
            to=notification['to'],
            service_id=service_id,
            job_id=notification.get('job', None),
            job_row_number=notification.get('row_number', None),
            status='created',
            created_at=datetime.strptime(created_at, DATETIME_FORMAT),
            personalisation=notification.get('personalisation')
        )
        dao_create_notification(notification_db_object, TEMPLATE_TYPE_SMS)

        send_sms_to_provider.apply_async((service_id, notification_id, encrypted_notification), queue='sms')

        current_app.logger.info(
            "SMS {} created at {} sent at {}".format(notification_id, created_at, sent_at)
        )

        statsd_client.incr("notifications.tasks.send-sms")
        statsd_client.timing("notifications.tasks.send-sms.task-time", monotonic() - task_start)
    except SQLAlchemyError as e:
        current_app.logger.exception(e)
        raise self.retry(queue="retry", exc=e)


@notify_celery.task(name="send-email")
def send_email(service_id, notification_id, encrypted_notification, created_at, reply_to_addresses=None):
    task_start = monotonic()
    notification = encryption.decrypt(encrypted_notification)
    service = dao_fetch_service_by_id(service_id)

    provider = provider_to_use('email', notification_id)

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

    try:
        sent_at = datetime.utcnow()
        notification_db_object = Notification(
            id=notification_id,
            template_id=notification['template'],
            template_version=notification['template_version'],
            to=notification['to'],
            service_id=service_id,
            job_id=notification.get('job', None),
            job_row_number=notification.get('row_number', None),
            status='sending',
            created_at=datetime.strptime(created_at, DATETIME_FORMAT),
            sent_at=sent_at,
            sent_by=provider.get_name(),
            personalisation=notification.get('personalisation')
        )

        dao_create_notification(notification_db_object, TEMPLATE_TYPE_EMAIL)
        statsd_client.timing_with_dates(
            "notifications.tasks.send-email.queued-for",
            sent_at,
            datetime.strptime(created_at, DATETIME_FORMAT)
        )

        try:
            template = Template(
                dao_get_template_by_id(notification['template'], notification['template_version']).__dict__,
                values=notification.get('personalisation', {})
            )

            if service.research_mode:
                reference = create_uuid()
                send_email_response.apply_async(
                    (provider.get_name(), str(reference), notification['to']), queue='research-mode'
                )
            else:
                from_address = '"{}" <{}@{}>'.format(service.name, service.email_from,
                                                     current_app.config['NOTIFY_EMAIL_DOMAIN'])
                reference = provider.send_email(
                    from_address,
                    notification['to'],
                    template.replaced_subject,
                    body=template.replaced_govuk_escaped,
                    html_body=template.as_HTML_email,
                    reply_to_addresses=reply_to_addresses,
                )

                update_provider_stats(
                    notification_id,
                    'email',
                    provider.get_name()
                )

            notification_db_object.reference = reference
            dao_update_notification(notification_db_object)

        except EmailClientException as e:
            current_app.logger.exception(e)
            notification_db_object.status = 'technical-failure'
            dao_update_notification(notification_db_object)

        current_app.logger.info(
            "Email {} created at {} sent at {}".format(notification_id, created_at, sent_at)
        )
        statsd_client.incr("notifications.tasks.send-email")
        statsd_client.timing("notifications.tasks.send-email.task-time", monotonic() - task_start)
    except SQLAlchemyError as e:
        current_app.logger.exception(e)


def service_allowed_to_send_to(recipient, service):
    if not service.restricted:
        return True

    return allowed_to_send_to(
        recipient,
        itertools.chain.from_iterable(
            [user.mobile_number, user.email_address] for user in service.users
        )
    )


def provider_to_use(notification_type, notification_id):
    active_providers_in_order = [
        provider for provider in get_provider_details_by_notification_type(notification_type) if provider.active
        ]

    if not active_providers_in_order:
        current_app.logger.error(
            "{} {} failed as no active providers".format(notification_type, notification_id)
        )
        raise Exception("No active {} providers".format(notification_type))

    return clients.get_client_by_name_and_type(active_providers_in_order[0].identifier, notification_type)