import argparse
import dataclasses
import os
import typing

from app import PKG_NAME


@dataclasses.dataclass(frozen=True, slots=True)
class Parameters:
    debug: bool = False
    quiet: bool = False
    env: str = "production"
    bind: str = "0.0.0.0"
    port: int = 5000
    workers: int = 4
    timeout: int = 120
    db_url: str = "postgres://postgres:5432/tout-doux"

    @classmethod
    def from_namespace(cls, args: argparse.Namespace) -> Parameters:
        return Parameters(**vars(args))


def __get_env_str(var: str, default: str) -> str:
    if (result := os.getenv(var)) is None:
        return default
    return result


def __get_env_int(var: str, default: int) -> int:
    value = __get_env_str(var, str(default))
    if value.isdecimal():
        return int(value)
    return default


def __add_arg_str(
    parser: argparse.ArgumentParser,
    *flags: str,
    env_var: str,
    default: str,
    help_txt: str,
) -> None:
    parser.add_argument(
        *flags,
        metavar=env_var,
        default=__get_env_str(env_var, default),
        help=f"{help_txt} (default: {default})" if len(default) else help_txt,
    )


def __add_arg_int(
    parser: argparse.ArgumentParser,
    *flags: str,
    env_var: str,
    default: int,
    help_txt: str,
) -> None:
    parser.add_argument(
        *flags,
        type=int,
        metavar=env_var,
        default=__get_env_int(env_var, default),
        help=f"{help_txt} (default: {default})",
    )


def parse_parameters(args: typing.Sequence[str]) -> Parameters:
    default_values = Parameters()
    parser = argparse.ArgumentParser(
        PKG_NAME,
        suggest_on_error=True,
    )
    parser.add_argument(
        "--debug", action=argparse.BooleanOptionalAction, default=default_values.debug
    )
    parser.add_argument(
        "--quiet", action=argparse.BooleanOptionalAction, default=default_values.quiet
    )
    __add_arg_str(
        parser,
        "--env",
        env_var="APP_ENV",
        default=default_values.env,
        help_txt="environnement",
    )
    __add_arg_str(
        parser,
        "--bind",
        env_var="BIND",
        default=default_values.bind,
        help_txt="server bind address",
    )
    __add_arg_int(
        parser,
        "--port",
        env_var="PORT",
        default=default_values.port,
        help_txt="server http port",
    )
    __add_arg_int(
        parser,
        "--workers",
        env_var="WORKERS",
        default=default_values.workers,
        help_txt="WSGI workers",
    )
    __add_arg_int(
        parser,
        "--timeout",
        env_var="TIMEOUT",
        default=default_values.timeout,
        help_txt="WSGI timeout",
    )
    __add_arg_str(
        parser,
        "--db-url",
        env_var="DB_URL",
        default=default_values.db_url,
        help_txt="database connection url",
    )
    parsed_args = parser.parse_args(args)
    return Parameters.from_namespace(parsed_args)