"""
Helpers when analyzing backtest data
"""
import logging
from pathlib import Path

import numpy as np
import pandas as pd
import pytz

from freqtrade import persistence
from freqtrade.misc import json_load
from freqtrade.persistence import Trade

logger = logging.getLogger(__name__)

# must align with columns in backtest.py
BT_DATA_COLUMNS = ["pair", "profitperc", "open_time", "close_time", "index", "duration",
                   "open_rate", "close_rate", "open_at_end", "sell_reason"]


def load_backtest_data(filename) -> pd.DataFrame:
    """
    Load backtest data file.
    :param filename: pathlib.Path object, or string pointing to the file.
    :return a dataframe with the analysis results
    """
    if isinstance(filename, str):
        filename = Path(filename)

    if not filename.is_file():
        raise ValueError("File {filename} does not exist.")

    with filename.open() as file:
        data = json_load(file)

    df = pd.DataFrame(data, columns=BT_DATA_COLUMNS)

    df['open_time'] = pd.to_datetime(df['open_time'],
                                     unit='s',
                                     utc=True,
                                     infer_datetime_format=True
                                     )
    df['close_time'] = pd.to_datetime(df['close_time'],
                                      unit='s',
                                      utc=True,
                                      infer_datetime_format=True
                                      )
    df['profitabs'] = df['close_rate'] - df['open_rate']
    df = df.sort_values("open_time").reset_index(drop=True)
    return df


def evaluate_result_multi(results: pd.DataFrame, freq: str, max_open_trades: int) -> pd.DataFrame:
    """
    Find overlapping trades by expanding each trade once per period it was open
    and then counting overlaps
    :param results: Results Dataframe - can be loaded
    :param freq: Frequency used for the backtest
    :param max_open_trades: parameter max_open_trades used during backtest run
    :return: dataframe with open-counts per time-period in freq
    """
    dates = [pd.Series(pd.date_range(row[1].open_time, row[1].close_time, freq=freq))
             for row in results[['open_time', 'close_time']].iterrows()]
    deltas = [len(x) for x in dates]
    dates = pd.Series(pd.concat(dates).values, name='date')
    df2 = pd.DataFrame(np.repeat(results.values, deltas, axis=0), columns=results.columns)

    df2 = df2.astype(dtype={"open_time": "datetime64", "close_time": "datetime64"})
    df2 = pd.concat([dates, df2], axis=1)
    df2 = df2.set_index('date')
    df_final = df2.resample(freq)[['pair']].count()
    return df_final[df_final['pair'] > max_open_trades]


def load_trades_from_db(db_url: str) -> pd.DataFrame:
    """
    Load trades from a DB (using dburl)
    :param db_url: Sqlite url (default format sqlite:///tradesv3.dry-run.sqlite)
    :returns: Dataframe containing Trades
    """
    trades: pd.DataFrame = pd.DataFrame([], columns=BT_DATA_COLUMNS)
    persistence.init(db_url, clean_open_orders=False)
    columns = ["pair", "profit", "open_time", "close_time",
               "open_rate", "close_rate", "duration"]

    for x in Trade.query.all():
        logger.info("date: {}".format(x.open_date))

        trades = pd.DataFrame([(t.pair, t.calc_profit(),
                                t.open_date.replace(tzinfo=pytz.UTC),
                                t.close_date.replace(tzinfo=pytz.UTC) if t.close_date else None,
                                t.open_rate, t.close_rate,
                                t.close_date.timestamp() - t.open_date.timestamp()
                                if t.close_date else None)
                               for t in Trade.query.all()],
                              columns=columns)

    return trades


def load_trades(exportfilename: str = None, db_url: str = None) -> pd.DataFrame:
    """
    Load trades, either from a DB (using dburl) or via a backtest export file.
    :param exportfilename: Path to a file exported from backtesting
    :param db_url: Sqlite url (default format sqlite:///tradesv3.dry-run.sqlite)
    :returns: Dataframe containing Trades
    """

    trades: pd.DataFrame = pd.DataFrame([], columns=BT_DATA_COLUMNS)
    if exportfilename:
        trades = load_backtest_data(Path(exportfilename))
    elif db_url:
        trades = load_trades_from_db(db_url)

    return trades


def extract_trades_of_period(dataframe: pd.DataFrame, trades: pd.DataFrame) -> pd.DataFrame:
    """
    Compare trades and backtested pair DataFrames to get trades performed on backtested period
    :return: the DataFrame of a trades of period
    """
    trades = trades.loc[(trades['open_time'] >= dataframe.iloc[0]['date']) &
                        (trades['close_time'] <= dataframe.iloc[-1]['date'])]
    return trades