from __future__ import absolute_import
from util.constants import (
    DAYS_DIFFERENCE_THRESHOLD,
    LENS_DIFFERENCE_THRESHOLD,
    SECONDS_PER_DAY,
    PART_OR_WHOLE,
    DRIFT_TYPE,
    START_TIME, 
    END_TIME
)

from logger import get_logger
logger = get_logger(__name__)


def compare_drift(existing_drift_dict, new_drift_dict):
    """
    Compare two drift dictionaries to determine if they are considered the same based on defined rules.

    Parameters:
    existing_drift_dict (Dictionary): The existing drift segment containing drift information, defined in util/csc_output.py.
    This function will use the following attributes.
        {
            PART_OR_WHOLE (str): Enum [1: whole drift, 2: part drift (accumulated drift)],
            DRIFT_TYPE (str): Enum ["LEVEL", "TREND"],
            START_TIME (int): we assume this field is always epoch time,  
            END_TIME (int): we assume this field is always epoch time,
        }

    new_drift_dict (Dictionary): The new detected drift containing drift information.
    The attributes is same as existing_drift_dict.

    Returns:
    bool: True if the drifts are considered the same, False otherwise.
    """
    
    # Rule-based comparisons
    if existing_drift_dict[DRIFT_TYPE] != new_drift_dict[DRIFT_TYPE]:
        logger.debug(f"Type mismatch: {existing_drift_dict[DRIFT_TYPE]} != {new_drift_dict[DRIFT_TYPE]}")
        return False
        
    if existing_drift_dict[PART_OR_WHOLE] != new_drift_dict[PART_OR_WHOLE]:
        info = f"Finished drift mismatch: {existing_drift_dict[PART_OR_WHOLE]} != {new_drift_dict[PART_OR_WHOLE]}"
        logger.debug(info)
        return False
        
    start_day_diff = abs((existing_drift_dict[START_TIME] - new_drift_dict[START_TIME]) / SECONDS_PER_DAY)
    if start_day_diff > DAYS_DIFFERENCE_THRESHOLD:
        info = f"Start time difference is larger than threshold: {existing_drift_dict[START_TIME]} and {new_drift_dict[START_TIME]}"
        logger.debug(info)
        return False
    
    existing_diff_days = int((existing_drift_dict[END_TIME] - existing_drift_dict[START_TIME]) / SECONDS_PER_DAY)
    new_diff_days = int((new_drift_dict[END_TIME] - new_drift_dict[START_TIME]) / SECONDS_PER_DAY)
    lens_diff = abs(existing_diff_days - new_diff_days)
    if lens_diff > LENS_DIFFERENCE_THRESHOLD:
        logger.debug(f"Length difference is larger than threshold: {lens_diff}")
        return False
        
    logger.debug(f"Drift {existing_drift_dict} and {new_drift_dict} matches")
    return True