import hashlib
import json
import os
from pathlib import PurePosixPath
import subprocess
import tempfile


class WorkspaceError(Exception):
    pass


def run(args, cwd, env=None, check=True):
    result = subprocess.run(args, cwd=cwd, env=env, text=True, capture_output=True,
                            timeout=180)
    if check and result.returncode:
        raise WorkspaceError(f"{args[0]} failed ({result.returncode}): {result.stderr.strip() or result.stdout.strip()}")
    return result


def relative_path(value, allow_dot=False):
    if not isinstance(value, str) or not value or "\\" in value or any(ord(c) < 32 for c in value):
        raise WorkspaceError("invalid relative path")
    path = PurePosixPath(value)
    if path.is_absolute() or ".." in path.parts or (value == "." and not allow_dot):
        raise WorkspaceError(f"unsafe relative path: {value}")
    return path


def safe_path(root, value, allow_dot=False):
    relative_path(value, allow_dot)
    path = root / value
    # Refuse symlink path components even when a link currently points inside root.
    # This avoids creating a second apparent owner and later retargeting escapes.
    current = root
    for part in PurePosixPath(value).parts:
        current /= part
        if current.is_symlink():
            raise WorkspaceError(f"symlink path is not owned by this workspace: {value}")
    if not path.resolve().is_relative_to(root.resolve()):
        raise WorkspaceError(f"path escapes workspace: {value}")
    return path


def read_json(path):
    if path.is_symlink():
        raise WorkspaceError(f"refusing symlink metadata: {path}")
    try:
        return json.loads(path.read_text())
    except (OSError, ValueError) as error:
        raise WorkspaceError(f"cannot read {path.name}: {error}") from error


def atomic_write(path, content):
    if path.is_symlink():
        raise WorkspaceError(f"refusing symlink output: {path}")
    path.parent.mkdir(parents=True, exist_ok=True)
    descriptor, temporary = tempfile.mkstemp(prefix="." + path.name + "-", dir=path.parent)
    try:
        with os.fdopen(descriptor, "w") as stream:
            stream.write(content)
            stream.flush()
            os.fsync(stream.fileno())
        os.replace(temporary, path)
    finally:
        if os.path.exists(temporary):
            os.unlink(temporary)


def write_json(path, value):
    atomic_write(path, json.dumps(value, indent=2, sort_keys=True) + "\n")


def digest(path):
    return hashlib.sha256(path.read_bytes()).hexdigest()