import calendar
from datetime import datetime, timedelta
from functools import partial
from itertools import groupby
from zoneinfo import ZoneInfo

from flask import abort, jsonify, render_template, request, session, url_for
from flask_login import current_user
from werkzeug.utils import redirect

from app import (
    billing_api_client,
    job_api_client,
    service_api_client,
    template_statistics_client,
)
from app.main import main
from app.main.views.user_profile import set_timezone
from app.statistics_utils import get_formatted_percentage
from app.utils import DELIVERED_STATUSES, FAILURE_STATUSES, REQUESTED_STATUSES
from app.utils.time import get_current_financial_year
from app.utils.user import user_has_permissions


@main.route("/services/<uuid:service_id>/dashboard")
@user_has_permissions("view_activity", "send_messages")
def old_service_dashboard(service_id):
    return redirect(url_for(".service_dashboard", service_id=service_id))


@main.route("/services/<uuid:service_id>")
@user_has_permissions()
def service_dashboard(service_id):

    if session.get("invited_user_id"):
        session.pop("invited_user_id", None)
        session["service_id"] = service_id

    if not current_user.has_permissions("view_activity"):
        return redirect(url_for("main.choose_template", service_id=service_id))

    job_response = job_api_client.get_jobs(service_id)["data"]
    service_data_retention_days = 7

    active_jobs = [job for job in job_response if job["job_status"] != "cancelled"]
    sorted_jobs = sorted(active_jobs, key=lambda job: job["created_at"], reverse=True)
    job_lists = [
        {**job_dict, "finished_processing": job_is_finished(job_dict)}
        for job_dict in sorted_jobs
    ]

    total_messages = service_api_client.get_service_message_ratio(service_id)
    messages_remaining = total_messages.get("messages_remaining", 0)
    messages_sent = total_messages.get("messages_sent", 0)
    all_statistics = template_statistics_client.get_template_statistics_for_service(
        service_id, limit_days=7
    )
    template_statistics = aggregate_template_usage(all_statistics)
    return render_template(
        "views/dashboard/dashboard.html",
        jobs=job_lists,
        service_data_retention_days=service_data_retention_days,
        messages_remaining=messages_remaining,
        messages_sent=messages_sent,
        template_statistics=template_statistics,
        most_used_template_count=max(
            [row["count"] for row in template_statistics] or [0]
        ),
    )


def job_is_finished(job_dict):
    done_statuses = DELIVERED_STATUSES + FAILURE_STATUSES + ["cancelled"]
    processed_count = sum(
        stat["count"]
        for stat in job_dict["statistics"]
        if stat["status"] in done_statuses
    )
    return job_dict["notification_count"] == processed_count


@main.route("/services/<uuid:service_id>/daily-stats.json")
@user_has_permissions()
def get_daily_stats(service_id):
    date_range = get_stats_date_range()
    days = date_range["days"]
    user_timezone = request.args.get("timezone", "UTC")

    stats_utc = service_api_client.get_service_notification_statistics_by_day(
        service_id,
        start_date=date_range["start_date"],
        days=days,
    )

    local_stats = get_local_daily_stats_for_last_x_days(stats_utc, user_timezone, days)
    return jsonify(local_stats)


def get_local_daily_stats_for_last_x_days(stats_utc, user_timezone, days):
    tz = ZoneInfo(user_timezone)
    today_local = datetime.now(tz).date()
    start_local = today_local - timedelta(days=days - 1)

    # Generate exactly days local dates, each with zeroed stats
    days_list = [
        (start_local + timedelta(days=i)).strftime("%Y-%m-%d") for i in range(days)
    ]
    aggregator = {
        d: {
            "sms": {"delivered": 0, "failure": 0, "pending": 0, "requested": 0},
            "email": {"delivered": 0, "failure": 0, "pending": 0, "requested": 0},
        }
        for d in days_list
    }

    # Convert each UTC timestamp to local date and iterate
    for utc_ts, data in stats_utc.items():
        utc_dt = datetime.strptime(utc_ts, "%Y-%m-%dT%H:%M:%SZ").replace(
            tzinfo=ZoneInfo("UTC")
        )
        local_day = utc_dt.astimezone(tz).strftime("%Y-%m-%d")

        if local_day in aggregator:
            for msg_type in ["sms", "email"]:
                for status in ["delivered", "failure", "pending", "requested"]:
                    aggregator[local_day][msg_type][status] += data[msg_type][status]

    return aggregator


@main.route("/services/<uuid:service_id>/daily-stats-by-user.json")
@user_has_permissions()
def get_daily_stats_by_user(service_id):
    date_range = get_stats_date_range()
    days = date_range["days"]
    user_timezone = request.args.get("timezone", "UTC")

    stats_utc = service_api_client.get_user_service_notification_statistics_by_day(
        service_id,
        user_id=current_user.id,
        start_date=date_range["start_date"],
        days=days,
    )

    local_stats = get_local_daily_stats_for_last_x_days(stats_utc, user_timezone, days)
    return jsonify(local_stats)


@main.route("/services/<uuid:service_id>/template-usage")
@user_has_permissions("view_activity")
def template_usage(service_id):
    year, current_financial_year = requested_and_current_financial_year(request)
    stats = template_statistics_client.get_monthly_template_usage_for_service(
        service_id, year
    )

    stats = sorted(stats, key=lambda x: (x["count"]), reverse=True)

    def get_monthly_template_stats(month_name, stats):
        return {
            "name": month_name,
            "templates_used": [
                {
                    "id": stat["template_id"],
                    "name": stat["name"],
                    "type": stat["type"],
                    "requested_count": stat["count"],
                }
                for stat in stats
                if calendar.month_name[int(stat["month"])] == month_name
            ],
        }

    months = [
        get_monthly_template_stats(month, stats)
        for month in get_months_for_financial_year(year, time_format="%B")
    ]

    return render_template(
        "views/dashboard/all-template-statistics.html",
        months=months,
        stats=stats,
        most_used_template_count=max(
            (
                max(
                    (
                        template["requested_count"]
                        for template in month["templates_used"]
                    ),
                    default=0,
                )
                for month in months
            ),
            default=0,
        ),
        years=get_tuples_of_financial_years(
            partial(url_for, ".template_usage", service_id=service_id),
            start=current_financial_year - 2,
            end=current_financial_year,
        ),
        selected_year=year,
    )


@main.route("/services/<uuid:service_id>/usage")
@user_has_permissions("manage_service", allow_org_user=True)
def usage(service_id):
    year, current_financial_year = requested_and_current_financial_year(request)

    free_sms_allowance = billing_api_client.get_free_sms_fragment_limit_for_year(
        service_id
    )

    units = billing_api_client.get_monthly_usage_for_service(service_id, year)

    yearly_usage = billing_api_client.get_annual_usage_for_service(service_id, year)

    more_stats = format_monthly_stats_to_list(
        service_api_client.get_monthly_notification_stats(service_id, year)["data"]
    )
    return render_template(
        "views/usage.html",
        months=list(get_monthly_usage_breakdown(year, units, more_stats)),
        selected_year=year,
        years=get_tuples_of_financial_years(
            partial(url_for, ".usage", service_id=service_id),
            start=current_financial_year - 2,
            end=current_financial_year,
        ),
        **get_annual_usage_breakdown(yearly_usage, free_sms_allowance),
    )


def filter_out_cancelled_stats(template_statistics):
    return [s for s in template_statistics if s["status"] != "cancelled"]


def aggregate_template_usage(template_statistics, sort_key="count"):
    template_statistics = filter_out_cancelled_stats(template_statistics)
    templates = []
    for k, v in groupby(
        sorted(template_statistics, key=lambda x: x["template_id"]),
        key=lambda x: x["template_id"],
    ):
        template_stats = list(v)
        first_stat = template_stats[0] if template_stats else None
        templates.append(
            {
                "template_id": k,
                "template_name": first_stat.get("template_name"),
                "template_type": first_stat.get("template_type"),
                "count": sum(s["count"] for s in template_stats),
                "created_by": first_stat.get("created_by"),
                "created_by_id": first_stat.get("created_by_id"),
                "last_used": first_stat.get("last_used"),
                "status": first_stat.get("status"),
                "template_folder": first_stat.get("template_folder"),
                "template_folder_id": first_stat.get("template_folder_id"),
            }
        )

    return sorted(templates, key=lambda x: x[sort_key], reverse=True)


def get_dashboard_totals(statistics):

    for msg_type in statistics.values():
        msg_type["failed_percentage"] = get_formatted_percentage(
            msg_type["failed"], msg_type["requested"]
        )
        msg_type["show_warning"] = float(msg_type["failed_percentage"]) > 3

    return statistics


def get_annual_usage_breakdown(usage, free_sms_fragment_limit):
    sms = get_usage_breakdown_by_type(usage, "sms")
    sms_chargeable_units = sum(row["chargeable_units"] for row in sms)
    sms_free_allowance = free_sms_fragment_limit
    sms_cost = sum(row["cost"] for row in sms)

    emails = get_usage_breakdown_by_type(usage, "email")
    emails_sent = sum(row["notifications_sent"] for row in emails)

    return {
        "emails_sent": emails_sent,
        "sms_free_allowance": sms_free_allowance,
        "sms_sent": sms_chargeable_units,
        "sms_allowance_remaining": max(0, (sms_free_allowance - sms_chargeable_units)),
        "sms_cost": sms_cost,
        "sms_breakdown": sms,
    }


def format_monthly_stats_to_list(historical_stats):
    return sorted(
        (
            dict(
                date=key,
                future=yyyy_mm_to_datetime(key) > datetime.utcnow(),
                name=yyyy_mm_to_datetime(key).strftime("%B"),
                **aggregate_status_types(value),
            )
            for key, value in historical_stats.items()
        ),
        key=lambda x: x["date"],
    )


def yyyy_mm_to_datetime(string):
    return datetime(int(string[0:4]), int(string[5:7]), 1)


def aggregate_status_types(counts_dict):
    return get_dashboard_totals(
        {
            "{}_counts".format(message_type): {
                "failed": sum(stats.get(status, 0) for status in FAILURE_STATUSES),
                "requested": sum(stats.get(status, 0) for status in REQUESTED_STATUSES),
            }
            for message_type, stats in counts_dict.items()
        }
    )


def get_months_for_financial_year(year, time_format="%B"):
    return [month.strftime(time_format) for month in (get_months_for_year(1, 13, year))]


def get_current_month_for_financial_year(year):
    # Setting the timezone here because we need to set it somewhere.
    set_timezone()
    current_month = datetime.now().month
    return current_month


def get_stats_date_range():
    current_financial_year = get_current_financial_year()
    current_month = get_current_month_for_financial_year(current_financial_year)
    start_date = datetime.now().strftime("%Y-%m-%d")
    days = 7
    return {
        "current_financial_year": current_financial_year,
        "current_month": current_month,
        "start_date": start_date,
        "days": days,
    }


def get_months_for_year(start, end, year):
    return [datetime(year, month, 1) for month in range(start, end)]


def get_usage_breakdown_by_type(usage, notification_type):
    return [row for row in usage if row["notification_type"] == notification_type]


def get_monthly_usage_breakdown(year, monthly_usage, more_stats):
    sms = get_usage_breakdown_by_type(monthly_usage, "sms")

    for month in get_months_for_financial_year(year):
        monthly_sms = [row for row in sms if row["month"] == month]
        sms_free_allowance_used = sum(row["free_allowance_used"] for row in monthly_sms)
        sms_cost = sum(row["cost"] for row in monthly_sms)
        sms_breakdown = [row for row in monthly_sms if row["charged_units"]]
        sms_counts = [
            row["sms_counts"]
            for row in more_stats
            if row["sms_counts"] and row["name"] == month
        ]

        yield {
            "month": month,
            "sms_free_allowance_used": sms_free_allowance_used,
            "sms_breakdown": sms_breakdown,
            "sms_cost": sms_cost,
            "sms_counts": sms_counts,
        }


def requested_and_current_financial_year(request):
    try:
        return (
            int(request.args.get("year", get_current_financial_year())),
            get_current_financial_year(),
        )
    except ValueError:
        abort(404)


def get_tuples_of_financial_years(
    partial_url,
    start=2015,
    end=None,
):
    return (
        (
            "fiscal year",
            year,
            partial_url(year=year),
            "{} to {}".format(year, year + 1),
        )
        for year in reversed(range(start, end + 1))
    )