from datetime import datetime, timedelta, time

from flask import current_app
from notifications_utils.timezones import convert_bst_to_utc
from sqlalchemy import func
from sqlalchemy.dialects.postgresql import insert
from sqlalchemy.sql.expression import literal, extract
from sqlalchemy.types import DateTime, Integer

from app import db
from app.models import Notification, NotificationHistory, FactNotificationStatus, KEY_TYPE_TEST, Service, Template
from app.utils import get_london_midnight_in_utc, midnight_n_days_ago, get_london_month_from_utc_column


def fetch_notification_status_for_day(process_day, service_id=None):
    start_date = convert_bst_to_utc(datetime.combine(process_day, time.min))
    end_date = convert_bst_to_utc(datetime.combine(process_day + timedelta(days=1), time.min))
    # use notification_history if process day is older than 7 days
    # this is useful if we need to rebuild the ft_billing table for a date older than 7 days ago.
    current_app.logger.info("Fetch ft_notification_status for {} to {}".format(start_date, end_date))
    table = Notification
    if start_date < datetime.utcnow() - timedelta(days=7):
        table = NotificationHistory

    transit_data = db.session.query(
        table.template_id,
        table.service_id,
        func.coalesce(table.job_id, '00000000-0000-0000-0000-000000000000').label('job_id'),
        table.notification_type,
        table.key_type,
        table.status,
        func.count().label('notification_count')
    ).filter(
        table.created_at >= start_date,
        table.created_at < end_date
    ).group_by(
        table.template_id,
        table.service_id,
        'job_id',
        table.notification_type,
        table.key_type,
        table.status
    )

    if service_id:
        transit_data = transit_data.filter(table.service_id == service_id)

    return transit_data.all()


def update_fact_notification_status(data, process_day):
    table = FactNotificationStatus.__table__
    FactNotificationStatus.query.filter(
        FactNotificationStatus.bst_date == process_day.date()
    ).delete()
    for row in data:
        stmt = insert(table).values(
            bst_date=process_day.date(),
            template_id=row.template_id,
            service_id=row.service_id,
            job_id=row.job_id,
            notification_type=row.notification_type,
            key_type=row.key_type,
            notification_status=row.status,
            notification_count=row.notification_count,
        )
        db.session.connection().execute(stmt)
        db.session.commit()


def fetch_notification_status_for_service_by_month(start_date, end_date, service_id):
    return db.session.query(
        func.date_trunc('month', FactNotificationStatus.bst_date).label('month'),
        FactNotificationStatus.notification_type,
        FactNotificationStatus.notification_status,
        func.sum(FactNotificationStatus.notification_count).label('count')
    ).filter(
        FactNotificationStatus.service_id == service_id,
        FactNotificationStatus.bst_date >= start_date,
        FactNotificationStatus.bst_date < end_date,
        FactNotificationStatus.key_type != KEY_TYPE_TEST
    ).group_by(
        func.date_trunc('month', FactNotificationStatus.bst_date).label('month'),
        FactNotificationStatus.notification_type,
        FactNotificationStatus.notification_status
    ).all()


def fetch_notification_status_for_service_for_day(bst_day, service_id):
    return db.session.query(
        # return current month as a datetime so the data has the same shape as the ft_notification_status query
        literal(bst_day.replace(day=1), type_=DateTime).label('month'),
        Notification.notification_type,
        Notification.status.label('notification_status'),
        func.count().label('count')
    ).filter(
        Notification.created_at >= get_london_midnight_in_utc(bst_day),
        Notification.created_at < get_london_midnight_in_utc(bst_day + timedelta(days=1)),
        Notification.service_id == service_id,
        Notification.key_type != KEY_TYPE_TEST
    ).group_by(
        Notification.notification_type,
        Notification.status
    ).all()


def fetch_notification_status_for_service_for_today_and_7_previous_days(service_id, limit_days=7):
    start_date = midnight_n_days_ago(limit_days)
    now = datetime.utcnow()
    stats_for_7_days = db.session.query(
        FactNotificationStatus.notification_type.label('notification_type'),
        FactNotificationStatus.notification_status.label('status'),
        FactNotificationStatus.notification_count.label('count')
    ).filter(
        FactNotificationStatus.service_id == service_id,
        FactNotificationStatus.bst_date >= start_date,
        FactNotificationStatus.key_type != KEY_TYPE_TEST
    )

    stats_for_today = db.session.query(
        Notification.notification_type.cast(db.Text),
        Notification.status,
        func.count().label('count')
    ).filter(
        Notification.created_at >= get_london_midnight_in_utc(now),
        Notification.service_id == service_id,
        Notification.key_type != KEY_TYPE_TEST
    ).group_by(
        Notification.notification_type,
        Notification.status
    )
    all_stats_table = stats_for_7_days.union_all(stats_for_today).subquery()
    return db.session.query(
        all_stats_table.c.notification_type,
        all_stats_table.c.status,
        func.cast(func.sum(all_stats_table.c.count), Integer).label('count'),
    ).group_by(
        all_stats_table.c.notification_type,
        all_stats_table.c.status,
    ).all()


def fetch_notification_status_totals_for_all_services(start_date, end_date):
    stats = db.session.query(
        FactNotificationStatus.notification_type.label('notification_type'),
        FactNotificationStatus.notification_status.label('status'),
        FactNotificationStatus.key_type.label('key_type'),
        func.sum(FactNotificationStatus.notification_count).label('count')
    ).filter(
        FactNotificationStatus.bst_date >= start_date,
        FactNotificationStatus.bst_date <= end_date
    ).group_by(
        FactNotificationStatus.notification_type,
        FactNotificationStatus.notification_status,
        FactNotificationStatus.key_type,
    )
    today = get_london_midnight_in_utc(datetime.utcnow())
    if start_date <= today.date() <= end_date:
        stats_for_today = db.session.query(
            Notification.notification_type.cast(db.Text).label('notification_type'),
            Notification.status,
            Notification.key_type,
            func.count().label('count')
        ).filter(
            Notification.created_at >= today
        ).group_by(
            Notification.notification_type.cast(db.Text),
            Notification.status,
            Notification.key_type,
        )
        all_stats_table = stats.union_all(stats_for_today).subquery()
        query = db.session.query(
            all_stats_table.c.notification_type,
            all_stats_table.c.status,
            all_stats_table.c.key_type,
            func.cast(func.sum(all_stats_table.c.count), Integer).label('count'),
        ).group_by(
            all_stats_table.c.notification_type,
            all_stats_table.c.status,
            all_stats_table.c.key_type,
        ).order_by(
            all_stats_table.c.notification_type
        )
    else:
        query = stats.order_by(
            FactNotificationStatus.notification_type
        )
    return query.all()


def fetch_notification_statuses_for_job(job_id):
    return db.session.query(
        FactNotificationStatus.notification_status.label('status'),
        func.sum(FactNotificationStatus.notification_count).label('count'),
    ).filter(
        FactNotificationStatus.job_id == job_id,
    ).group_by(
        FactNotificationStatus.notification_status
    ).all()


def fetch_stats_for_all_services_by_date_range(start_date, end_date, include_from_test_key=True):
    stats = db.session.query(
        FactNotificationStatus.service_id.label('service_id'),
        Service.name.label('name'),
        Service.restricted.label('restricted'),
        Service.research_mode.label('research_mode'),
        Service.active.label('active'),
        Service.created_at.label('created_at'),
        FactNotificationStatus.notification_type.label('notification_type'),
        FactNotificationStatus.notification_status.label('status'),
        func.sum(FactNotificationStatus.notification_count).label('count')
    ).filter(
        FactNotificationStatus.bst_date >= start_date,
        FactNotificationStatus.bst_date <= end_date,
        FactNotificationStatus.service_id == Service.id,
    ).group_by(
        FactNotificationStatus.service_id.label('service_id'),
        Service.name,
        Service.restricted,
        Service.research_mode,
        Service.active,
        Service.created_at,
        FactNotificationStatus.notification_type,
        FactNotificationStatus.notification_status,
    ).order_by(
        FactNotificationStatus.service_id,
        FactNotificationStatus.notification_type
    )
    if not include_from_test_key:
        stats = stats.filter(FactNotificationStatus.key_type != KEY_TYPE_TEST)

    if start_date <= datetime.utcnow().date() <= end_date:
        today = get_london_midnight_in_utc(datetime.utcnow())
        subquery = db.session.query(
            Notification.notification_type.cast(db.Text).label('notification_type'),
            Notification.status.label('status'),
            Notification.service_id.label('service_id'),
            func.count(Notification.id).label('count')
        ).filter(
            Notification.created_at >= today
        ).group_by(
            Notification.notification_type,
            Notification.status,
            Notification.service_id
        )
        if not include_from_test_key:
            subquery = subquery.filter(Notification.key_type != KEY_TYPE_TEST)
        subquery = subquery.subquery()

        stats_for_today = db.session.query(
            Service.id.label('service_id'),
            Service.name.label('name'),
            Service.restricted.label('restricted'),
            Service.research_mode.label('research_mode'),
            Service.active.label('active'),
            Service.created_at.label('created_at'),
            subquery.c.notification_type.label('notification_type'),
            subquery.c.status.label('status'),
            subquery.c.count.label('count')
        ).outerjoin(
            subquery,
            subquery.c.service_id == Service.id
        )

        all_stats_table = stats.union_all(stats_for_today).subquery()
        query = db.session.query(
            all_stats_table.c.service_id,
            all_stats_table.c.name,
            all_stats_table.c.restricted,
            all_stats_table.c.research_mode,
            all_stats_table.c.active,
            all_stats_table.c.created_at,
            all_stats_table.c.notification_type,
            all_stats_table.c.status,
            func.cast(func.sum(all_stats_table.c.count), Integer).label('count'),
        ).group_by(
            all_stats_table.c.service_id,
            all_stats_table.c.name,
            all_stats_table.c.restricted,
            all_stats_table.c.research_mode,
            all_stats_table.c.active,
            all_stats_table.c.created_at,
            all_stats_table.c.notification_type,
            all_stats_table.c.status,
        ).order_by(
            all_stats_table.c.name,
            all_stats_table.c.notification_type,
            all_stats_table.c.status
        )
    else:
        query = stats
    return query.all()


def fetch_monthly_template_usage_for_service(start_date, end_date, service_id):
    # services_dao.replaces dao_fetch_monthly_historical_usage_by_template_for_service
    stats = db.session.query(
        FactNotificationStatus.template_id.label('template_id'),
        Template.name.label('name'),
        Template.template_type.label('template_type'),
        Template.is_precompiled_letter.label('is_precompiled_letter'),
        extract('month', FactNotificationStatus.bst_date).label('month'),
        extract('year', FactNotificationStatus.bst_date).label('year'),
        func.sum(FactNotificationStatus.notification_count).label('count')
    ).join(
        Template, FactNotificationStatus.template_id == Template.id
    ).filter(
        FactNotificationStatus.service_id == service_id,
        FactNotificationStatus.bst_date >= start_date,
        FactNotificationStatus.bst_date <= end_date,
    ).group_by(
        FactNotificationStatus.template_id,
        Template.name,
        Template.template_type,
        Template.is_precompiled_letter,
        extract('month', FactNotificationStatus.bst_date).label('month'),
        extract('year', FactNotificationStatus.bst_date).label('year'),
    )

    if start_date <= datetime.utcnow() <= end_date:
        today = get_london_midnight_in_utc(datetime.utcnow())
        month = get_london_month_from_utc_column(Notification.created_at)

        stats_for_today = db.session.query(
            Notification.template_id.label('template_id'),
            Template.name.label('name'),
            Template.template_type.label('template_type'),
            Template.is_precompiled_letter.label('is_precompiled_letter'),
            extract('month', month).label('month'),
            extract('year', month).label('year'),
            func.count().label('count')
        ).join(
            Template, Notification.template_id == Template.id,
        ).filter(
            Notification.created_at >= today,
            Notification.service_id == service_id,
            # we don't want to include test keys
            Notification.key_type != KEY_TYPE_TEST
        ).group_by(
            Notification.template_id,
            Template.hidden,
            Template.name,
            Template.template_type,
            month
        )

        all_stats_table = stats.union_all(stats_for_today).subquery()
        query = db.session.query(
            all_stats_table.c.template_id,
            all_stats_table.c.name,
            all_stats_table.c.is_precompiled_letter,
            all_stats_table.c.template_type,
            func.cast(all_stats_table.c.month, Integer).label('month'),
            func.cast(all_stats_table.c.year, Integer).label('year'),
            func.cast(func.sum(all_stats_table.c.count), Integer).label('count'),
        ).group_by(
            all_stats_table.c.template_id,
            all_stats_table.c.name,
            all_stats_table.c.is_precompiled_letter,
            all_stats_table.c.template_type,
            all_stats_table.c.month,
            all_stats_table.c.year,
        ).order_by(
            all_stats_table.c.year,
            all_stats_table.c.month,
            all_stats_table.c.name
        )
    else:
        query = stats
    return query.all()