from __future__ import annotations

import argparse
import getpass
import sys
from collections.abc import Sequence
from dataclasses import replace

from host_agent.app import create_application
from host_agent.config import load_host_agent_config
from host_agent.instance_lock import InstanceAlreadyRunningError
from host_agent.local_account import LocalAccountStore
from host_agent.mcp_token import McpTokenStore


class LocalAccountSetupError(RuntimeError):
    """Raised when local account bootstrap cannot proceed."""


def main(argv: Sequence[str] | None = None) -> None:
    parser = argparse.ArgumentParser(description="Run the Device Host Agent")
    subparsers = parser.add_subparsers(dest="command")
    subparsers.add_parser("setup", help="Create the local operator account")
    subparsers.add_parser(
        "mcp-token",
        help="Print the MCP server bearer token (generating if missing)",
    )
    args = parser.parse_args(argv)

    if args.command == "mcp-token":
        _print_mcp_token()
        return

    try:
        if args.command == "setup":
            _run_setup()
            return
        config = _resolve_config_with_local_account()
    except LocalAccountSetupError as exc:
        print(f"error: {exc}", file=sys.stderr)
        raise SystemExit(1) from exc

    try:
        create_application(config=config).run()
    except InstanceAlreadyRunningError as exc:
        print(f"error: {exc}", file=sys.stderr)
        raise SystemExit(1) from exc


def _run_setup() -> None:
    config = load_host_agent_config()
    store = LocalAccountStore(config.local_account_path)
    if store.load() is not None:
        confirm = (
            input("A local account already exists. Overwrite it? [y/N] ")
            .strip()
            .lower()
        )
        if confirm != "y":
            print("Setup cancelled; existing account left unchanged.")
            return
    account = _prompt_and_create(store)
    print(f"Local account '{account.username}' created.")


def _print_mcp_token() -> None:
    config = load_host_agent_config()
    store = McpTokenStore(config.identity_path.parent / "host_mcp_token.json")
    print(store.load_or_create().token)


def _resolve_config_with_local_account():
    config = load_host_agent_config()
    store = LocalAccountStore(config.local_account_path)
    account = store.load()
    if account is None:
        if not sys.stdin.isatty():
            raise LocalAccountSetupError(
                "no local account configured; run `device-host-agent setup` "
                "on an interactive terminal to create one"
            )
        account = _prompt_and_create(store)
    if not config.display_name:
        config = replace(config, display_name=account.username)
    return config


def _prompt_and_create(store: LocalAccountStore):
    username = input("Username: ").strip()
    if not username:
        raise LocalAccountSetupError("username must not be empty")
    password = getpass.getpass("Password: ")
    confirm = getpass.getpass("Confirm password: ")
    if not password:
        raise LocalAccountSetupError("password must not be empty")
    if password != confirm:
        raise LocalAccountSetupError("passwords do not match")
    return store.create(username, password)