# -*- coding: utf-8 -*-
from ..momentum.roc import roc
from ..utils import get_drift, get_offset, verify_series

def pvt(close, volume, drift=None, offset=None, **kwargs):
    """Indicator: Price-Volume Trend (PVT)"""
    # Validate arguments
    close = verify_series(close)
    volume = verify_series(volume)
    drift = get_drift(drift)
    offset = get_offset(offset)

    # Calculate Result
    pv = roc(close=close, length=drift) * volume
    pvt = pv.cumsum()

    # Offset
    if offset != 0:
        pvt = pvt.shift(offset)

    # Handle fills
    if 'fillna' in kwargs:
        pvt.fillna(kwargs['fillna'], inplace=True)
    if 'fill_method' in kwargs:
        pvt.fillna(method=kwargs['fill_method'], inplace=True)

    # Name and Categorize it
    pvt.name = f"PVT"
    pvt.category = 'volume'

    return pvt



pvt.__doc__ = \
"""Price-Volume Trend (PVT)

The Price-Volume Trend utilizes the Rate of Change with volume to
and it's cumulative values to determine money flow.

Sources:
    https://www.tradingview.com/wiki/Price_Volume_Trend_(PVT)

Calculation:
    Default Inputs:
        drift=1
    ROC = Rate of Change
    pv = ROC(close, drift) * volume
    PVT = pv.cumsum()

Args:
    close (pd.Series): Series of 'close's
    volume (pd.Series): Series of 'volume's
    drift (int): The diff period.   Default: 1
    offset (int): How many periods to offset the result.  Default: 0

Kwargs:
    fillna (value, optional): pd.DataFrame.fillna(value)
    fill_method (value, optional): Type of fill method

Returns:
    pd.Series: New feature generated.
"""