# -*- coding: utf-8 -*-
"""
bitmapist.cohort
~~~~~~~~~~~~~~~~
Implements cohort analytics on top of the data stored in bitmapist.

This library makes it possible to implement real-time, highly scalable analytics that can answer following questions:

* Generate a cohort table over real-time data stored in bitmapist
* How many % of users that were active last [days, weeks, months] are still active?
* How many % of users that performed action X also performed action Y (and this over time)

A screenshot of the library in action:
https://d2dq6e731uoz0t.cloudfront.net/d5b299fafecc15eb3ea9f7f12f70a061/as/cohort.png

If you want to read more about cohort please read following:
* http://en.wikipedia.org/wiki/Cohort_(statistics)
* https://mixpanel.com/docs/learn-the-features/retention-overview [ I was inspired by this, but didn't want to pay the steep price ]


Examples
========

Mark user 123 as active and mark some other events::

    from bitmapist import mark_event

    mark_event('active', 123)
    mark_event('song:add', 123)
    mark_event('song:play', 123)

Generate the form that makes it easy to query the bitmapist database::

    html_form = bitmapist_cohort.render_html_form(
        action_url='/_Cohort',
        selections1=[ ('Are Active', 'active'), ],
        selections2=[ ('Played song', 'song:play'), ],
        time_group='days',
        select1='active',
        select2='song:play'
    )

    # action_url is the action URL of the <form> element
    # selections1, selections2 specifies the events that the user can select in the form
    # time_group can be `days`, `weeks` or `months`
    # select1, select2 specifies the current selected events in the <form>

Get the data and render it via HTML::

    dates_data = bitmapist_cohort.get_dates_data(select1='active',
                                                 select2='song:play',
                                                 time_group='days',
                                                 system='default')

    html_data = bitmapist_cohort.render_html_data(dates_data,
                                                  time_group='days')

    # All the arguments should come from the FORM element (html_form)
    # but to make things more clear I have filled them in directly

:copyright: 2012 by Doist Ltd.
:developer: Amir Salihefendic ( http://amix.dk )
:license: BSD
"""
from datetime import date, datetime, timedelta
from os import path
from typing import Any, Callable, Optional

from dateutil.relativedelta import relativedelta
from mako.lookup import TemplateLookup

from bitmapist import (
    BitOpAnd,
    DayEvents,
    GenericPeriodEvents,
    MonthEvents,
    WeekEvents,
    YearEvents,
    delete_runtime_bitop_keys,
)

# --- HTML rendering


def render_html_form(
    action_url,
    selections1,
    selections1b=None,
    selections2=None,
    selections2b=None,
    time_group="days",
    select1=None,
    select1b=None,
    select2=None,
    select2b=None,
    as_precent=1,
    num_results=31,
    num_of_rows=12,
    start_date=None,
):
    """
    Render a HTML form that can be used to query the data in bitmapist.

    :param :action_url The action URL of the <form> element. The form will always to a GET request.
    :param :selections1 A list of selections that the user can filter by, example `[ ('Are Active', 'active'), ]`
    :param :selections1b Extra selections, used with the first selection, example `[ ('in US', 'country:US'), ]`
    :param :selections2 A list of selections that the user can filter by, example `[ ('Played song', 'song:play'), ]`
    :param :selections2b Extra selections, used with the second selection, example `[ ('Playlist', 'playlist:new'), ]`
    :param :time_group What data should be clustered by, can be `days`, `weeks`, `months`, `years`
    :param :select1 What is the current selected filter (first)
    :param :select1b What is the current selected filter (extra, optional)
    :param :select2 What is the current selected filter (second)
    :param :select2b What is the current selected filter (extra, optional)

    """
    # mandatory
    selections2 = selections2 or selections1[:]

    # optional
    selections1b_c = selections1b[:] if selections1b else selections1[:]
    selections1b_c.insert(0, ("------", ""))

    selections2b_c = selections2b[:] if selections2b else selections2[:]
    selections2b_c.insert(0, ("------", ""))

    return (
        get_lookup()
        .get_template("form_data.mako")
        .render(
            selections1=selections1,
            selections1b=selections1b_c,
            selections2=selections2,
            selections2b=selections2b_c,
            time_group=time_group,
            select1=select1,
            select1b=select1b,
            select2=select2,
            select2b=select2b,
            action_url=action_url,
            as_precent=as_precent,
            num_results=int(num_results),
            num_of_rows=int(num_of_rows),
            start_date=start_date,
        )
    )


def render_html_data(
    dates_data,
    as_precent=True,
    time_group="days",
    num_results: int = 31,
    num_of_rows: int = 12,
    start_date=None,
):
    """
    Render's data as HTML, inside a TABLE element.

    :param :dates_data The data that's returned by `get_dates_data`
    :param :as_precent Should the data be shown as percents or as counts. Defaults to `True`
    :param :time_group What is the data grouped by? Can be `days`, `weeks`, `months`, `years`
    """
    return (
        get_lookup()
        .get_template("table_data.mako")
        .render(
            dates_data=dates_data,
            as_precent=as_precent,
            time_group=time_group,
            num_results=num_results,
            num_of_rows=num_of_rows,
            start_date=start_date,
        )
    )


def render_csv_data(
    dates_data,
    as_precent=True,
    time_group="days",
    num_results: int = 31,
    num_of_rows: int = 12,
    start_date=None,
):
    """
    Render's data as CSV.
    """
    return (
        get_lookup()
        .get_template("table_data_csv.mako")
        .render(
            dates_data=dates_data,
            as_precent=as_precent,
            time_group=time_group,
            num_results=num_results,
            num_of_rows=num_of_rows,
            start_date=start_date,
        )
    )


# --- Data rendering


def get_dates_data(
    select1,
    select2,
    select1b=None,
    select2b=None,
    time_group="days",
    system="default",
    as_precent=1,
    num_results=31,
    num_of_rows=12,
    start_date=None,
):
    """
    Fetch the data from bitmapist.

    :param :select1 First filter (could be `active`)
    :param :select1b Second filter (could be `country:US`, optional)
    :param :select2 Second filter (could be `song:played`)
    :param :select2b Second filter (could be `playlist:created`, optional)
    :param :time_group What is the data grouped by? Can be `days`, `weeks`, `months`, `years`
    :param :system What bitmapist should be used?
    :param :as_precent If `True` then percents as calculated and shown. Defaults to `True`
    :return A list of day data, formatted like `[[datetime, count], ...]`
    """
    num_results = int(num_results)
    num_of_rows = int(num_of_rows)

    if start_date:
        now = datetime.strptime(start_date, "%Y-%m-%d")
        now = now + timedelta(days=num_results - 1)
    else:
        now = datetime.utcnow()

    # Days
    if time_group == "days":
        fn_get_events = _day_events_fn

        date_range = num_results
        now = now - timedelta(days=num_results - 1)
        timedelta_inc = lambda d: timedelta(days=d)
    # Weeks
    elif time_group == "weeks":
        fn_get_events = _weeks_events_fn

        date_range = num_results
        now = now - relativedelta(weeks=num_results - 1)
        timedelta_inc = lambda w: relativedelta(weeks=w)
    # Months
    elif time_group == "months":
        fn_get_events = _month_events_fn

        date_range = num_results
        now = now - relativedelta(months=num_results - 1)
        now -= timedelta(days=now.day - 1)
        timedelta_inc = lambda m: relativedelta(months=m)
    # Years
    elif time_group == "years":
        fn_get_events = _year_events_fn

        num_results = 3

        date_range = num_results
        now = now - relativedelta(years=num_results - 1)
        timedelta_inc = lambda m: relativedelta(years=m)

    dates = []

    for i in range(0, date_range):
        result = [now]

        # events for select1 (+select1b)
        select1_events = fn_get_events(select1, now, system)
        if select1b:
            select1b_events = fn_get_events(select1b, now, system)
            select1_events = BitOpAnd(system, select1_events, select1b_events)

        select1_count = len(select1_events)
        result.append(select1_count)

        # Move in time
        for t_delta in range(0, num_of_rows + 1):
            if select1_count == 0:
                result.append("")
                continue

            delta_now = now + timedelta_inc(t_delta)

            # events for select2 (+select2b)
            select2_events = fn_get_events(select2, delta_now, system)
            if select2b:
                select2b_events = fn_get_events(select2b, delta_now, system)
                select2_events = BitOpAnd(system, select2_events, select2b_events)

            if not select2_events.has_events_marked():
                result.append("")
                continue

            both_events = BitOpAnd(system, select1_events, select2_events)
            both_count = len(both_events)

            # Append to result
            if both_count == 0:
                result.append(float(0.0))
            else:
                if as_precent:
                    result.append((float(both_count) / float(select1_count)) * 100)
                else:
                    result.append(both_count)

        dates.append(result)
        now = now + timedelta_inc(1)

    # clean up results of BitOps
    delete_runtime_bitop_keys()

    return dates


# --- Custom handlers

CUSTOM_HANDLERS: dict[str, Callable[..., Any]] = {}


def set_custom_handler(event_name: str, callback) -> None:
    """
    Set a custom handler for `event_name`.
    This makes it possible to construct event names that are complex
    (for example looking at active & (web | ios)).

    The signature of `callback` is callback(key, cls, cls_args)
    Where cls is DayEvents, WeekEvents, MonthEvents or YearEvents and
    cls_args is the list of arguments to pass to `cls` constructor.

    For example, the code for a custom handler for all active accounts
    using web or ios, could look like::

        def active_web_ios(key, cls, cls_args):
            return cls('active', *cls_args) & (cls('web', *cls_args) | cls('ios', *cls_args))

        set_custom_handler('active_web_ios', active_web_ios)

    And then use something like::

        bitmapist_cohort.render_html_form(
            selections1=[
                ...,
                ('Active on web or iOS', 'active_web_ios')
            ],
            ...
        )
    """
    CUSTOM_HANDLERS[event_name] = callback


# --- Private


def _dispatch(key: str, cls: type[GenericPeriodEvents], cls_args):
    if key in CUSTOM_HANDLERS:
        return CUSTOM_HANDLERS[key](key, cls, cls_args)
    else:
        return cls(key, *cls_args)


def _day_events_fn(key: str, date: date, system: str):
    cls = DayEvents
    cls_args = (date.year, date.month, date.day, system)
    return _dispatch(key, cls, cls_args)


def _weeks_events_fn(key: str, date: date, system: str):
    cls = WeekEvents
    cls_args = (date.year, date.isocalendar()[1], system)
    return _dispatch(key, cls, cls_args)


def _month_events_fn(key: str, date: date, system: str):
    cls = MonthEvents
    cls_args = (date.year, date.month, system)
    return _dispatch(key, cls, cls_args)


def _year_events_fn(key: str, date: date, system: str):
    cls = YearEvents
    cls_args = (date.year, system)
    return _dispatch(key, cls, cls_args)


_LOOKUP: Optional[TemplateLookup] = None


def get_lookup() -> TemplateLookup:
    global _LOOKUP

    if not _LOOKUP:
        file_path = path.dirname(path.abspath(__file__))
        _LOOKUP = TemplateLookup(
            directories=[path.join(file_path, "tmpl")], encoding_errors="replace"
        )

    return _LOOKUP


__all__ = ["render_html_form", "render_html_data", "get_dates_data"]