import copy
import os
from collections.abc import MutableMapping
from pathlib import Path


def add_spec_env(
    env: MutableMapping[str, str],
    spec_dir: Path,
) -> MutableMapping[str, str]:
    """
    Add SPEC-specific configurations to an environment mapping.

    This function updates the provided environment mapping with SPEC-specific
    settings. It sets the 'SPEC' environment variable to the provided directory
    path and prepends the SPEC binary directory to the system PATH.

    Parameters
    ----------
    env : MutableMapping[str, str]
        The environment dictionary to update.
    spec_dir : Path
        The path to the SPEC directory.

    Returns
    -------
    MutableMapping[str, str]
        The updated environment dictionary.

    Examples
    --------
    >>> import pathlib
    >>> env = {"PATH": "/usr/bin:/usr/local/bin"}
    >>> updated_env = add_spec_env(env, pathlib.Path("/path/to/spec"))
    >>> updated_env["SPEC"]
    '/path/to/spec'
    >>> updated_env["PATH"].startswith("/path/to/spec/bin:")
    True
    """
    env["SPEC"] = str(spec_dir)
    env["PATH"] = os.pathsep.join(
        [
            str(spec_dir / "bin"),
            *env["PATH"].split(os.pathsep),
        ]
    )
    return env


def create_spec_env(spec_dir: Path) -> MutableMapping[str, str]:
    """
    Create a new environment with SPEC-specific configurations.

    This function creates a copy of the current environment variables and updates
    it with SPEC-specific settings using add_spec_env.

    Parameters
    ----------
    spec_dir : Path
        The path to the SPEC directory.

    Returns
    -------
    dict
        A dictionary containing the updated environment variables.

    Examples
    --------
    >>> import pathlib
    >>> import os
    >>> os.environ["PATH"] = "/usr/bin:/usr/local/bin"
    >>> env = create_spec_env(pathlib.Path("/path/to/spec"))
    >>> env["SPEC"]
    '/path/to/spec'
    >>> "/path/to/spec/bin" in env["PATH"]
    True
    """
    new_env = copy.deepcopy(os.environ)
    return add_spec_env(new_env, spec_dir)

def find_build(build_dir: Path) -> Path:
    entries = list(sorted(os.listdir(build_dir)))
    for entry in entries:
        if entry.startswith("build"):
            return build_dir / entry
    raise RuntimeError(f"SPEC build directory not found at {build_dir}")


class SPEC:
    dir: Path

    def __init__(self, dir: Path):
        self.dir = dir

    @property
    def config_dir(self) -> Path:
        return self.dir / "config"

    def env(self):
        return create_spec_env(self.dir)

    def mkcmd_runcpu(
        self,
        config: str,
        benchmarks: list[str],
        setprocgroup: bool = True,
        workload: str = "ref",
        output_root: Path | None = None,
    ):
        return [
            "runcpu",
            *(["--setprocgroup"] if setprocgroup else []),
            "-i",
            workload,
            "-c",
            config,
            *(["--outputdir", str(output_root)] if output_root else []),
            *benchmarks,
        ]