from pathlib import Path
from typing import Optional
import subprocess

def _path_checked(path: Path, cwd=Path.cwd()) -> Optional[Path]:
    """Resolves `path`, returning `None` if it's not a subdirectory of `cwd`."""
    path = path.resolve()
    cwd = cwd.resolve()
    return path if path.is_relative_to(cwd) else None

def _path_helper(path_str: str, callback):
    path = _path_checked(Path(path_str))
    if path is None:
        return {"status": "error", "reason": f"Permission denied: {path_str}"}
    else:
        try:
            return {"status": "success", **callback(path)}
        except Exception as e:
            return {"status": "error", "reason": f"Failure: {e}"}

def ls(args):
    '{"action": "ls", "path": PATH} - list files at PATH'
    def inner(path: Path):
        return {"content": list(map(lambda s: str(s), path.iterdir()))}
    match args:
        case {"action": "ls", "path": path_str}:
            return _path_helper(path_str, inner)

def read(args):
    '{"action": "read", "path": PATH} - read file at PATH'
    def inner(path: Path):
        contents = path.read_text(encoding="utf-8")
        return {"content": contents}
    match args:
        case {"action": "read", "path": path_str}:
            return _path_helper(path_str, inner)

def write(args):
    '{"action": "write", "path": PATH, "content": CONTENT} - write CONTENT into file at PATH'
    def inner(path: Path, text: str):
        n_bytes = path.write_text(text)
        return {"bytes": n_bytes}
    match args:
        case {"action": "write", "path": path_str, "content": content}:
            return _path_helper(path_str, lambda path: inner(path, content))

def tldr(args):
    '{"action": "tldr", "program": PROGRAM} - read tldr docs for PROGRAM'
    match args:
        case {"action": "tldr", "program": program_str}:
            try:
                result = subprocess.run(
                    ["tldr", program_str],
                    capture_output=True,
                    text=True,
                    check=True
                )
                return {"status": "success", "content": result.stdout}
            except subprocess.CalledProcessError:
                return {"status": "error", "reason": f"Tldr for '{program_str}' not found."}
            except Exception as e:
                return {"status": "error", "reason": f"An unexpected error occurred: {e}"}

ALL_ACTIONS = [ls, read, write, tldr]