"""OHLCV resampling — replaces `technical.util.resample_to_interval`.

That was the only symbol this project imported from `technical`, which in turn
pulled in the freqtrade dependency chain. Behaviour is preserved exactly,
including the left-labelled bins (rows are candle *open* times) and the
`dropna()` that drops empty intervals.
"""

from __future__ import annotations

import pandas as pd

__all__ = ["TICKER_INTERVAL_MINUTES", "resample_to_interval"]

TICKER_INTERVAL_MINUTES: dict[str, int] = {
    "1m": 1,
    "5m": 5,
    "15m": 15,
    "30m": 30,
    "1h": 60,
    "60m": 60,
    "2h": 120,
    "4h": 240,
    "6h": 360,
    "12h": 720,
    "1d": 1440,
    "1w": 10080,
}

_OHLC_AGG = {
    "open": "first",
    "high": "max",
    "low": "min",
    "close": "last",
    "volume": "sum",
}


def resample_to_interval(dataframe: pd.DataFrame, interval: int | str) -> pd.DataFrame:
    """Resample OHLCV rows to `interval` minutes (or a timeframe string).

    Merging the result back onto a finer frame requires care to avoid lookahead
    bias; this function only resamples.
    """
    if isinstance(interval, str):
        interval = TICKER_INTERVAL_MINUTES[interval]

    df = dataframe.copy()
    df = df.set_index(pd.DatetimeIndex(df["date"]))
    df = df.resample(f"{interval}min", label="left").agg(_OHLC_AGG).dropna()
    df.reset_index(inplace=True)
    return df