# Copyright (c) Streamlit Inc. (2018-2022) Snowflake Inc. (2022)
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""A bunch of useful utilities."""

from __future__ import annotations

import dataclasses
import functools
import hashlib
import os
import subprocess
from typing import Any, Dict, Iterable, List, Mapping, Set, TypeVar, Union, cast

from typing_extensions import Final

from streamlit import env_util

# URL of Streamlit's help page.
HELP_DOC: Final = "https://docs.streamlit.io/"
FLOAT_EQUALITY_EPSILON: Final[float] = 0.000000000005


def memoize(func):
    """Decorator to memoize the result of a no-args func."""
    result: List[Any] = []

    @functools.wraps(func)
    def wrapped_func():
        if not result:
            result.append(func())
        return result[0]

    return wrapped_func


def open_browser(url):
    """Open a web browser pointing to a given URL.

    We use this function instead of Python's `webbrowser` module because this
    way we can capture stdout/stderr to avoid polluting the terminal with the
    browser's messages. For example, Chrome always prints things like "Created
    new window in existing browser session", and those get on the user's way.

    url : str
        The URL. Must include the protocol.

    """
    # Treat Windows separately because:
    # 1. /dev/null doesn't exist.
    # 2. subprocess.Popen(['start', url]) doesn't actually pop up the
    #    browser even though 'start url' works from the command prompt.
    # Fun!
    # Also, use webbrowser if we are on Linux and xdg-open is not installed.
    #
    # We don't use the webbrowser module on Linux and Mac because some browsers
    # (ahem... Chrome) always print "Opening in existing browser session" to
    # the terminal, which is spammy and annoying. So instead we start the
    # browser ourselves and send all its output to /dev/null.

    if env_util.IS_WINDOWS:
        _open_browser_with_webbrowser(url)
        return
    if env_util.IS_LINUX_OR_BSD:
        if env_util.is_executable_in_path("xdg-open"):
            _open_browser_with_command("xdg-open", url)
            return
        _open_browser_with_webbrowser(url)
        return
    if env_util.IS_DARWIN:
        _open_browser_with_command("open", url)
        return

    import platform

    raise Error('Cannot open browser in platform "%s"' % platform.system())


def _open_browser_with_webbrowser(url):
    import webbrowser

    webbrowser.open(url)


def _open_browser_with_command(command, url):
    cmd_line = [command, url]
    with open(os.devnull, "w") as devnull:
        subprocess.Popen(cmd_line, stdout=devnull, stderr=subprocess.STDOUT)


def _maybe_tuple_to_list(item: Any) -> Any:
    """Convert a tuple to a list. Leave as is if it's not a tuple."""
    if isinstance(item, tuple):
        return list(item)
    return item


def repr_(self: Any) -> str:
    """A clean repr for a class, excluding both values that are likely defaults,
    and those explicitly default for dataclasses.
    """
    classname = self.__class__.__name__
    # Most of the falsey value, but excluding 0 and 0.0, since those often have
    # semantic meaning within streamlit.
    defaults: list[Any] = [None, "", False, [], set(), dict()]
    if dataclasses.is_dataclass(self):
        fields_vals = (
            (f.name, getattr(self, f.name))
            for f in dataclasses.fields(self)
            if f.repr
            and getattr(self, f.name) != f.default
            and getattr(self, f.name) not in defaults
        )
    else:
        fields_vals = ((f, v) for (f, v) in self.__dict__.items() if v not in defaults)

    field_reprs = ", ".join(f"{field}={value!r}" for field, value in fields_vals)
    return f"{classname}({field_reprs})"


_Value = TypeVar("_Value")


def index_(iterable: Iterable[_Value], x: _Value) -> int:
    """Return zero-based index of the first item whose value is equal to x.
    Raises a ValueError if there is no such item.

    We need a custom implementation instead of the built-in list .index() to
    be compatible with NumPy array and Pandas Series.

    Parameters
    ----------
    iterable : list, tuple, numpy.ndarray, pandas.Series
    x : Any

    Returns
    -------
    int
    """
    for i, value in enumerate(iterable):
        if x == value:
            return i
        elif isinstance(value, float) and isinstance(x, float):
            if abs(x - value) < FLOAT_EQUALITY_EPSILON:
                return i
    raise ValueError("{} is not in iterable".format(str(x)))


_Key = TypeVar("_Key", bound=str)


def lower_clean_dict_keys(dict: Mapping[_Key, _Value]) -> Dict[str, _Value]:
    return {k.lower().strip(): v for k, v in dict.items()}


# TODO: Move this into errors.py? Replace with StreamlitAPIException?
class Error(Exception):
    pass


def calc_md5(s: Union[bytes, str]) -> str:
    """Return the md5 hash of the given string."""
    h = hashlib.new("md5")

    # mypy seems to have trouble inferring that the type of the if/else expression is
    # always bytes.
    b = cast(bytes, s.encode("utf-8") if type(s) is str else s)

    h.update(b)
    return h.hexdigest()


def exclude_key_query_params(
    query_params: Dict[str, List[str]], keys_to_exclude: List[str]
) -> Dict[str, List[str]]:
    """Returns new object query_params : Dict[str, List[str]], but without keys defined with keys_to_drop : List[str]."""
    return {
        key: value
        for key, value in query_params.items()
        if key.lower() not in keys_to_exclude
    }


def extract_key_query_params(
    query_params: Dict[str, List[str]], param_key: str
) -> Set[str]:
    """Extracts key (case-insensitive) query params from Dict, and returns them as Set of str."""
    return set(
        [
            item.lower()
            for sublist in [
                [value.lower() for value in query_params[key]]
                for key in query_params.keys()
                if key.lower() == param_key and query_params.get(key)
            ]
            for item in sublist
        ]
    )