import shlex
import shutil
import subprocess

from langchain.tools import tool

_SUPPORTED_COMMANDS = {
    # Navigation
    "open",
    "goto",
    "navigate",
    "back",
    "forward",
    "reload",
    "close",
    "quit",
    "exit",
    # Snapshots / extraction
    "snapshot",
    "get",
    "find",
    "is",
    # Interactions
    "click",
    "dblclick",
    "focus",
    "type",
    "fill",
    "press",
    "key",
    "keydown",
    "keyup",
    "hover",
    "select",
    "check",
    "uncheck",
    "scroll",
    "scrollintoview",
    "scrollinto",
    "drag",
    "upload",
    # Utilities
    "wait",
    "screenshot",
    "pdf",
    "eval",
    "session",
    "set",
    "connect",
    "help",
    "--help",
    "-h",
    "install",
}


def _resolve_agent_browser_command() -> list[str] | None:
    """Prefer installed CLI; fallback to npx for zero-setup usage."""
    if shutil.which("agent-browser"):
        return ["agent-browser"]
    if shutil.which("npx"):
        return ["npx", "-y", "agent-browser@latest"]
    return None


def _build_cmd(command: str, session: str | None, json_output: bool) -> list[str]:
    parts = shlex.split(command)
    if not parts:
        raise ValueError("command is empty")

    action = parts[0]
    if action not in _SUPPORTED_COMMANDS:
        supported = ", ".join(sorted(_SUPPORTED_COMMANDS))
        raise ValueError(f"unsupported agent-browser command: {action}. supported: {supported}")

    cmd_prefix = _resolve_agent_browser_command()
    if cmd_prefix is None:
        raise ValueError("agent-browser CLI not found. Install Node.js and run: npm i -g agent-browser && agent-browser install")

    cmd = cmd_prefix.copy()
    if session:
        cmd.extend(["--session", session])

    cmd.extend(parts)
    if json_output and "--json" not in parts:
        cmd.append("--json")
    return cmd


@tool("agent_browser", parse_docstring=True)
def agent_browser_tool(
    command: str,
    session: str | None = None,
    json_output: bool = True,
    timeout_seconds: int = 60,
) -> str:
    """Run a single agent-browser CLI command (vercel-labs/agent-browser).

    Best-practice workflow:
    1. open URL
    2. snapshot -i -c
    3. interact with refs like @e1
    4. re-snapshot after page changes

    Args:
        command: Raw agent-browser command arguments, e.g. "open https://example.com" or "snapshot -i -c".
        session: Optional isolated browser session name.
        json_output: Add --json automatically for machine-readable output.
        timeout_seconds: Max command runtime in seconds.
    """
    try:
        cmd = _build_cmd(command=command, session=session, json_output=json_output)
    except ValueError as e:
        return f"Error: {e}"

    try:
        result = subprocess.run(
            cmd,
            capture_output=True,
            text=True,
            check=False,
            timeout=timeout_seconds,
        )
    except subprocess.TimeoutExpired:
        return f"Error: agent-browser command timed out after {timeout_seconds}s"
    except Exception as e:
        return f"Error: failed to execute agent-browser command: {e}"

    if result.returncode != 0:
        stderr = (result.stderr or "").strip()
        stdout = (result.stdout or "").strip()
        detail = stderr if stderr else stdout
        return f"Error: agent-browser exited with code {result.returncode}. {detail}"

    return (result.stdout or "").strip()