from dataclasses import dataclass
import pandas as pd
from scipy.stats import skew
from string import Template
import time

from util.dev_util import str_int_list_no_bracket
from util.data_prepare import (
    COL_VALUE, DAY_OF_WEEK_NAME, DEFAULT_Z, DEFAULT_SENSITIVITY_MULTIPLIER,
    down_sample, get_resolution, remove_super_spikes
    )
from util.pattern_evaluate import (
    THRESHOLD_SILHOUETTE_LOW, THRESHOLD_SILHOUETTE_HIGH,
    check_weekly_pattern, evaluate_half_day, evaluate_hour_block
    )
from util.threshold_utils import sub_sequences_groupby
from util.itsi_at_threshold import calc_history_normal_behavior, VARIATION_BUFFER
from util.outlier_exclusion_recommend import calc_sensitivity
from util.csc_output import THR_DIR_BOTH, THR_DIR_LO, THR_DIR_UP

from util import setup_logging
from six.moves import zip

logger = setup_logging.get_logger()

DAYS_IN_WEEK = [0, 1, 2, 3, 4, 5, 6]

DAY_IN_MINUTES = 1440
WEEK_IN_MINUTES = 10080
NO_RECOMMENDATION = 'No Recommendation'
INSUFFICIENT_DATA = 'INSUFFICIENT_DATA'
NO_PATTERN = 'NO_PATTERN'
PATTERN_SWITCH = 'PATTERN_SWITCH'
SUCCESSFUL = 'SUCCESSFUL'

DEFAULT_RESOLUTION = pd.Timedelta('15min')
COEF_FAVOR_WEEKLY = 1.1
THRESHOLD_SKEW = 2.0

CRON_TEMPLATE_DAILY_PATTERN  = Template('0 $start_hour * * *')
CRON_TEMPLATE_WEEKLY_PATTERN = Template('0 $start_hour * * $dow_list')

def get_output_no_pattern(mean, std):
    return {0: CronOutputItem('0 0 * * 0', WEEK_IN_MINUTES, DEFAULT_Z, mean, std)}

@dataclass(frozen=True)
class TimepolicyOutput:
    cron_dict           : dict
    time_policy_desc    : str
    time_policy_score   : float
    threshold_direction : str
    value_collections   : tuple

@dataclass(frozen=True)
class CronOutputItem:
    cron_expression : str
    time_length     : int
    z_value         : float
    mean            : float = 0.0
    std             : float = 0.0
    sensitivity     : float = DEFAULT_SENSITIVITY_MULTIPLIER

    def __str__(self):
        return f'({self.cron_expression}, {self.time_length}, z={self.z_value:.3f}, m={self.mean:.3f}, s={self.std:.3f}, {self.sensitivity:.3f})'
    
    def update_cron_expression(self, cron_expression):
        return CronOutputItem(
            cron_expression = cron_expression,
            time_length = self.time_length,
            z_value = self.z_value,
            mean = self.mean,
            std = self.std,
        )
    
    def update_mean_std_sensitivity(self, mean, std, sensitivity):
        return CronOutputItem(
            cron_expression = self.cron_expression,
            time_length = self.time_length,
            z_value = self.z_value,
            mean = mean,
            std = std,
            sensitivity = sensitivity
        )

    def update_numeric_stats(self, mean, std, z_value, sensitivity):
        return CronOutputItem(
            cron_expression = self.cron_expression,
            time_length = self.time_length,
            z_value = max(z_value, self.z_value) * (1.0 + VARIATION_BUFFER),
            mean = mean,
            std = std,
            sensitivity = sensitivity
        )
    
class TimePolicy:
    def __init__(self, hour_block_length, offset, has_weekend, offdays_start=5, score=-2.0, label_method=None) -> None:
        self.hour_block_length = hour_block_length
        self.offset = offset
        self.has_weekend = has_weekend
        self.offdays_start = offdays_start
        self.score = score
        self.label_method = label_method

    def __str__(self) -> str:
        offset_str = '' if self.offset == 0 else f', offset={self.offset}h'
        if self.has_weekend:
            offdays_str = '' if self.offdays_start == 5 else f', {DAY_OF_WEEK_NAME[self.offdays_start]} {DAY_OF_WEEK_NAME[(self.offdays_start + 1) % 7]} off'
            return 'weekly seasonality' + offset_str + offdays_str

        if self.hour_block_length == 12: # half-day pattern
            return 'half-day pattern' + offset_str
        
        if self.hour_block_length > 0:
            return f'daily {self.hour_block_length}-hour block' + offset_str 

        return 'no pattern'

def _dict_key_for_weekly_cron(dow, start_hour):
    return dow * 100 + start_hour

def detect_threshold_direction(values):
    skew_score = skew(values)
    if skew_score > THRESHOLD_SKEW:
        return THR_DIR_UP
    if skew_score < - THRESHOLD_SKEW:
        return THR_DIR_LO
    
    return THR_DIR_BOTH

def generate_cron_output(df, filter_config, choose_direction=True, compare_thresholds=False):
    
    df_resolution = get_resolution(df)
    df = down_sample(df, resolution=df_resolution, df_resolution=df_resolution) # don't change resolution but fill na

    # make a copy of the df values before calling recommend_time_policy, b/c
    # df values may get modified there, for example, in remove_super_spikes
    df_values = df[COL_VALUE].copy() 

    if choose_direction:
        detected_threshold_direction = detect_threshold_direction(df_values)
    else:
        detected_threshold_direction = None

    # Time policy by seasonality pattern detection
    time_policy = recommend_time_policy(df)

    if time_policy.score < THRESHOLD_SILHOUETTE_LOW: # no pattern detected
        logger.warning(f'The Silhouette Score is {time_policy.score:.3f}, which is less than the minimum threshold of {THRESHOLD_SILHOUETTE_LOW}.')
        return TimepolicyOutput(
            cron_dict           = get_output_no_pattern(df[COL_VALUE].mean(), df[COL_VALUE].std()),
            time_policy_desc    = NO_PATTERN,
            time_policy_score   = round(time_policy.score, 3),
            threshold_direction = detected_threshold_direction,
            value_collections   = None
        )

    history_normal_dict, subs, label_method = calc_history_normal_behavior(df, time_policy, filter_config)

    if not time_policy.has_weekend:
        hour_block_length = time_policy.hour_block_length
    output_dict = {}

    day_offset = time_policy.offset
    weekly_with_offset = time_policy.has_weekend and time_policy.offset > 0
    if weekly_with_offset:
        # reset day_offset to re-use the code in the for-loop below
        # put the logic of day_offset adjustment for the case of weekly-pattern-w-day-offset in isolation after that
        day_offset = 0 
    for label, subs_group in list(sub_sequences_groupby(subs, label_method).items()):
        history_normal = history_normal_dict[label]

        if time_policy.has_weekend: # in this case, subsequence is 1-day length
            dow_set = sorted(set([sub.dayofweek() for sub in subs_group]))
            dow_disp = str_int_list_no_bracket(dow_set)

            if history_normal.split_pnts is None:
                key = _dict_key_for_weekly_cron(dow_set[0], day_offset)
                output_dict[key] = CronOutputItem(
                    cron_expression = CRON_TEMPLATE_WEEKLY_PATTERN.substitute(start_hour=day_offset, dow_list=dow_disp),
                    time_length = DAY_IN_MINUTES,
                    z_value = history_normal.zs[0], 
                )
            else:
                left = 0
                split_pnts = history_normal.split_pnts + [24]
                for split_pnt, z in zip(split_pnts, history_normal.zs):
                    start_hour=(day_offset + left) % 24
                    key = _dict_key_for_weekly_cron(dow_set[0], start_hour)
                    output_dict[key] = CronOutputItem(
                        cron_expression = CRON_TEMPLATE_WEEKLY_PATTERN.substitute(start_hour=start_hour, dow_list=dow_disp),
                        time_length = (split_pnt - left)*60,
                        z_value = z,
                    )
                    left = split_pnt
                
        else: # no weekly pattern
            hour_set = sorted(set([sub.hour() for sub in subs_group]))
            if history_normal.split_pnts is None:
                for start_hour in hour_set:
                    output_dict[start_hour] = CronOutputItem(
                        cron_expression = CRON_TEMPLATE_DAILY_PATTERN.substitute(start_hour=start_hour),
                        time_length = hour_block_length * 60,
                        z_value = history_normal.zs[0],
                    )
            else:
                left = 0
                split_pnts = history_normal.split_pnts + [hour_block_length]
                for split_pnt, z in zip(split_pnts, history_normal.zs):
                    for start_hour in hour_set:
                        key = (start_hour + left) % 24
                        output_dict[key] = CronOutputItem(
                            cron_expression = CRON_TEMPLATE_DAILY_PATTERN.substitute(start_hour=key),
                            time_length = (split_pnt - left) * 60,
                            z_value = z,
                        )
                    left = split_pnt

    if weekly_with_offset:
        output_dict = compensate_weekly_with_offset(output_dict, time_policy.offset)

    # recommend sensitivity for IQR method of ITSI outlier exclusion
    output_dict, value_collections = calc_sensitivity(
        df, 
        df_values, 
        time_policy, 
        history_normal_dict, 
        output_dict, 
        subs, 
        label_method, 
        compare_thresholds=compare_thresholds
    )

    return TimepolicyOutput(
            cron_dict           = output_dict,
            time_policy_desc    = str(time_policy),
            time_policy_score   = round(time_policy.score, 3),
            threshold_direction = detected_threshold_direction,
            value_collections   = value_collections
        )
    
def compensate_weekly_with_offset(output_dict, day_offset):
    def _dow_plus_one(dow):
        return (dow + 1) % 7
    def _cron_idx_dow(cron):
        return cron.rindex(' ') + 1
    def _cron_get_dow_head(cron):
        idx = _cron_idx_dow(cron)
        return cron[idx: idx+1]
    def _cron_get_dows(cron):
        return cron[_cron_idx_dow(cron) :]
    def _cron_update_dow(cron, dow):
        return cron[:_cron_idx_dow(cron)] + dow
    def _cron_hour_plus_offset(cron):
        idx_right = cron.index(' ', 2)
        start_hour = int(cron[2:idx_right]) + day_offset
        return cron[:2] + str(start_hour) + cron[idx_right:], start_hour
    def _cron_hour_update(cron, hour):
        idx_right = cron.index(' ', 2)
        return cron[:2] + str(hour) + cron[idx_right:]
    def _unpack_dows_str(dows):
        return [int(d) for d in dows.split(',')]
    
    adjusted_dict = {}
    
    for cron_item in list(output_dict.values()):
        cron_a, start_hour = _cron_hour_plus_offset(cron_item.cron_expression)

        if start_hour < 24: # still the same day
            key = _dict_key_for_weekly_cron(int(_cron_get_dow_head(cron_a)), start_hour)
            adjusted_dict[key] =  cron_item.update_cron_expression(cron_a)
            continue

        start_hour -= 24
        dows = _cron_get_dows(cron_a)

        if len(dows) == 1: # only one day, just move to the next day
            dows = str(_dow_plus_one(int(dows)))
            cron_a = _cron_update_dow(cron_a, dows)
            cron_a = _cron_hour_update(cron_a, start_hour)
            key = int(dows) * 100 + start_hour
            adjusted_dict[key] = cron_item.update_cron_expression(cron_a)
            continue
        
        # more than one days, besides +1, need to separate out the last day in the dow list
        dow_list = _unpack_dows_str(dows)
        dow_list = [_dow_plus_one(d) for d in dow_list]
        cron_1 = CRON_TEMPLATE_WEEKLY_PATTERN.substitute(
            start_hour=start_hour, 
            dow_list=str_int_list_no_bracket(dow_list[:-1])
            )
        key = _dict_key_for_weekly_cron(dow_list[0], start_hour)
        adjusted_dict[key] = cron_item.update_cron_expression(cron_1)
        cron_2 = CRON_TEMPLATE_WEEKLY_PATTERN.substitute(
            start_hour=start_hour, 
            dow_list=str(dow_list[-1])
            )
        key = _dict_key_for_weekly_cron(dow_list[-1], start_hour)
        adjusted_dict[key] = cron_item.update_cron_expression(cron_2)

    return adjusted_dict

def recommend_time_policy(df):
    df = remove_super_spikes(df)
    df_values = df[COL_VALUE].copy()

    # 5-point smoothing
    smoothed = df[COL_VALUE].rolling(5, center=True).mean()
    smoothed.iloc[0] = smoothed.iloc[2]
    smoothed.iloc[1] = smoothed.iloc[2]
    smoothed.iloc[-1] = smoothed.iloc[-3]
    smoothed.iloc[-2] = smoothed.iloc[-3]
    df[COL_VALUE] = smoothed

    hour_block_length, offset, has_weekend, offdays_start, score, label_method = _evaluate_seasonality_patterns(df)
        
    # keep the modifications of remove_super_spikes(), for downstream tasks, including:
    #       calculating history normal, and calculating anomaly boundary
    df[COL_VALUE] = df_values 
    return TimePolicy(hour_block_length, offset, has_weekend, offdays_start, score, label_method)

def _evaluate_seasonality_patterns(df):
    df_resolution = get_resolution(df)
    if df_resolution < DEFAULT_RESOLUTION: # downsample when the initial resolution is finer than the default
        df = down_sample(df, resolution=DEFAULT_RESOLUTION, df_resolution=df_resolution)

    time_0 = time.time()
    best_score_week, offdays_start, offset, label_method = check_weekly_pattern(df)

    logger.debug(f'weekly pattern  ({best_score_week:.3f}), time spent: {time.time() - time_0:.2f}s')

    time_0 = time.time()
    hour_block_candidate = evaluate_hour_block(df)
    logger.debug(f'hour-block pattern time spent: {time.time() - time_0:.2f}s')

    time_0 = time.time()
    score_half, workhour_start = evaluate_half_day(df)
    logger.debug(f'half-day pattern ({score_half:.3f}), time spent: {time.time() - time_0:.2f}s')

    if hour_block_candidate is None:
        hour_block_score = -2.0
    else:
        hour_block_score = hour_block_candidate.silhouette

    if best_score_week * COEF_FAVOR_WEEKLY > hour_block_score and best_score_week * COEF_FAVOR_WEEKLY > score_half:
        return 0, offset, True, offdays_start, best_score_week, label_method

    else:
        if hour_block_score >= score_half:
            offset = hour_block_candidate.offset
            best_score = hour_block_candidate.silhouette
            if best_score >= THRESHOLD_SILHOUETTE_LOW:
                hour_block_length = hour_block_candidate.hourdelta
            else:
                hour_block_length = 0
                offset = 0
        else:
            offset = workhour_start
            best_score = score_half
            if best_score >= THRESHOLD_SILHOUETTE_LOW:
                hour_block_length = 12
            else:
                hour_block_length = 0
                offset = 0

        return hour_block_length, offset, False, offdays_start, best_score, None