import sys
import sysconfig
from os.path import dirname, abspath, join
import shutil
from typing import List, Optional, Tuple, Union
import shlex


def is_command_available(command_name):
    """
    Use `shutil.which` to determine whether a command is available.

    Args:
    command_name (str): The name of the command to check.

    Returns:
    bool: True if the command is available, False otherwise.
    """

    return shutil.which(command_name) is not None


def find_parameter(parameters: List[str], param_names: List[str]) -> Optional[str]:
    """
    Find specified parameter by name from the parameters.
    Return the value of the parameter if found, otherwise return None.
    """
    if parameters is None:
        return None

    for i, param in enumerate(parameters):
        # Strip whitespace from the parameter
        param_stripped = param.strip()

        if '=' in param_stripped:
            key, value = param_stripped.split('=', 1)
            if key.strip().lstrip('-') in param_names:
                return value
        elif ' ' in param_stripped:
            key, value = param_stripped.split(' ', 1)
            if key.strip().lstrip('-') in param_names:
                split_values = shlex.split(value)
                if len(split_values) == 1:
                    return split_values[0]
                return value
        else:
            if param_stripped.lstrip('-') in param_names:
                if i + 1 < len(parameters):
                    return parameters[i + 1]
    return None


def find_int_parameter(parameters: List[str], param_names: List[str]) -> Optional[int]:
    """
    Find specified integer parameter by name from the parameters.
    Return the integer value of the parameter if found, otherwise return None.
    """
    value = find_parameter(parameters, param_names)
    if value is not None:
        try:
            return int(value)
        except ValueError:
            return None
    return None


def find_bool_parameter(parameters: List[str], param_names: List[str]) -> bool:
    """
    Find specified boolean parameter by name from the parameters.
    Return True if the parameter is set, otherwise return False.
    """
    if parameters is None:
        return False

    for i, param in enumerate(parameters):
        param_stripped = param.strip()
        if param_stripped.lstrip('-') in param_names:
            return True
    return False


def get_versioned_command(command_name: str, version: str) -> str:
    """
    Get the versioned command name.
    """
    if command_name.endswith(".exe"):
        return f"{command_name[:-4]}_{version}.exe"

    return f"{command_name}_{version}"


def get_command_path(command_name: str) -> str:
    """
    Return the full path of sepcified command. Supports both frozen and python base environments.
    """
    base_path = (
        dirname(sys.executable)
        if getattr(sys, 'frozen', False)
        else sysconfig.get_path("scripts")
    )
    return abspath(join(base_path, command_name))


def extend_args_no_exist(
    arguments: List[str], *args: Union[str, Tuple[str, str]]
) -> None:
    """
    Extend arguments list with key-value pairs only if the key is not already present.

    This function prevents duplicate parameters when user-defined backend parameters
    may conflict with system-generated ones.

    Args:
        arguments: The list of arguments to extend (modified in place)
        *args: Variable number of arguments, each can be:
               - A tuple of (key, value) like ("--host", "127.0.0.1")
               - A single string key like "--enable-metrics" (flag without value)

    Examples:
        extend_args_no_exist(args, ("--host", "127.0.0.1"), ("--port", "8080"))
        extend_args_no_exist(args, "--enable-metrics")
    """
    for arg in args:
        if isinstance(arg, tuple):
            key, value = arg
            if not any(
                existing_arg == key or existing_arg.startswith(f"{key}=")
                for existing_arg in arguments
            ):
                arguments.extend([key, value])
        else:
            # Single flag without value
            if arg not in arguments:
                arguments.append(arg)


def format_backend_parameters(parameters: Optional[List[str]]) -> List[str]:
    """
    Format flattened command-line tokens as backend parameter entries.

    Examples:
        ["--max-model-len", "8192", "--enable-prefix-caching"]
            -> ["--max-model-len=8192", "--enable-prefix-caching"]
        ["--dtype=float16"] -> ["--dtype=float16"]
    """
    if not parameters:
        return []

    formatted = []
    index = 0
    while index < len(parameters):
        parameter = parameters[index]
        if not parameter.startswith("-") or "=" in parameter:
            formatted.append(parameter)
            index += 1
            continue

        if index + 1 < len(parameters) and not _looks_like_parameter(
            parameters[index + 1]
        ):
            formatted.append(f"{parameter}={parameters[index + 1]}")
            index += 2
            continue

        formatted.append(parameter)
        index += 1

    return formatted


def _looks_like_parameter(value: str) -> bool:
    if not value.startswith("-"):
        return False

    # Negative numeric values are parameter values, not flags.
    try:
        float(value)
        return False
    except ValueError:
        return True