from pathlib import Path
from typing import List, Optional


def ensure_has_columns(df: "pandas.DataFrame", columns: List[str]):
    # We don't want to import pandas too soon
    import pandas as pd

    all_columns = columns
    #    print("all_columns={}".format(all_columns))
    #    print("df={}".format(df.columns.tolist()))
    for c in reversed(columns):
        if not c in df.columns.tolist():
            df.insert(0, column=c, value=pd.Series())
    #    print("df={}".format(df.columns.tolist()))
    return df


def run_filters(filters, obj):
    for f in filters:
        if not f(obj):
            return False
    return True


def any(filters):
    def f(obj):
        for f in filters:
            if f(obj):
                return True
        return False

    return f


def all(filters):
    def f(obj):
        for f in filters:
            if not f(obj):
                return False
        return True

    return f


class HttpCache(object):
    def __init__(self, path: Path, ext="html"):
        self.path = path
        self.ext = ext

    def lookup(self, key):
        cache_path = self._make_path(key)

        if cache_path.exists():
            with open(str(cache_path), "r") as f:
                return f.read()

    def save(self, key, value):
        cache_path = self._make_path(key)
        cache_path.parent.mkdir(parents=True, exist_ok=True)

        with cache_path.open("w") as f:
            f.write(value)

    def _make_path(self, key) -> Path:
        return self.path / "{}.{}".format(key, self.ext)


class EmptyHttpCache(object):
    @staticmethod
    def lookup(key):
        return None

    def save(self, key, value):
        pass


def maybe_cache(path: Optional[Path], **kwargs) -> HttpCache:
    return HttpCache(path, **kwargs) if path is not None else EmptyHttpCache()