#!/usr/bin/env python3
"""Add, list and remove Media Centre dashboard accounts.

Passwords are prompted for interactively (never echoed, never taken as a
command-line argument, so they don't land in shell history) and only ever
stored as a salted pbkdf2 hash in settings.json. Nothing here writes a
plaintext password anywhere.

Run it inside the container, where Werkzeug and the real settings.json are:

    docker exec -it arr-summary python3 manage_users.py list
    docker exec -it arr-summary python3 manage_users.py add <username>
    docker exec -it arr-summary python3 manage_users.py passwd <username>
    docker exec -it arr-summary python3 manage_users.py remove <username>

The first `add` switches the dashboard from its single shared password to
per-user logins. Until then the old LOGIN_PASSWORD keeps working, so you
can't lock yourself out by deploying this.
"""

import sys
import getpass

from app import (
    SETTINGS_FILE,
    PASSWORD_HASH_METHOD,
    save_settings,
    load_users,
    generate_password_hash,
)

MIN_LEN = 6


def _prompt_new_password(username):
    """Ask twice, confirm they match, never echo. None if aborted."""
    pw = getpass.getpass(f"New password for {username!r}: ")
    if not pw:
        print("Aborted: empty password.", file=sys.stderr)
        return None
    if len(pw) < MIN_LEN:
        print(f"Aborted: must be at least {MIN_LEN} characters.", file=sys.stderr)
        return None
    if pw != getpass.getpass("Confirm: "):
        print("Aborted: passwords don't match.", file=sys.stderr)
        return None
    return pw


def cmd_list(_args):
    users = load_users()
    if not users:
        print("No accounts configured — the dashboard is still using the")
        print("single shared password (LOGIN_PASSWORD / settings.json).")
        return 0
    print(f"{len(users)} account(s) in {SETTINGS_FILE}:")
    for name in sorted(users):
        print(f"  {name}")
    return 0


def _set_password(username, require_existing):
    users = load_users()
    exists = username in users
    if require_existing and not exists:
        print(f"No such account: {username!r}. Use `add` to create it.", file=sys.stderr)
        return 1
    if not require_existing and exists:
        print(f"Account {username!r} already exists. Use `passwd` to change it.",
              file=sys.stderr)
        return 1

    pw = _prompt_new_password(username)
    if pw is None:
        return 1

    users[username] = generate_password_hash(pw, method=PASSWORD_HASH_METHOD)
    save_settings({"users": users})
    print(f"{'Updated' if exists else 'Created'} {username!r} in {SETTINGS_FILE}.")
    if not exists and len(users) == 1:
        print()
        print("This is the first account, so the dashboard has just switched to")
        print("per-user logins. The old shared password no longer signs in —")
        print("make sure you can log in as this user before closing this shell.")
    return 0


def cmd_add(args):
    if not args:
        print("Usage: manage_users.py add <username>", file=sys.stderr)
        return 2
    return _set_password(args[0].strip(), require_existing=False)


def cmd_passwd(args):
    if not args:
        print("Usage: manage_users.py passwd <username>", file=sys.stderr)
        return 2
    return _set_password(args[0].strip(), require_existing=True)


def cmd_remove(args):
    if not args:
        print("Usage: manage_users.py remove <username>", file=sys.stderr)
        return 2
    username = args[0].strip()
    users = load_users()
    if username not in users:
        print(f"No such account: {username!r}", file=sys.stderr)
        return 1
    if len(users) == 1:
        print("Refusing to remove the last account — that would drop the dashboard",
              file=sys.stderr)
        print("back to the shared password, which is probably not what you meant.",
              file=sys.stderr)
        print("Add another account first, or clear `users` from settings.json by hand.",
              file=sys.stderr)
        return 1
    del users[username]
    save_settings({"users": users})
    print(f"Removed {username!r}. {len(users)} account(s) remain.")
    return 0


COMMANDS = {"list": cmd_list, "add": cmd_add, "passwd": cmd_passwd, "remove": cmd_remove}


def main(argv):
    if len(argv) < 2 or argv[1] not in COMMANDS:
        print(__doc__.strip())
        return 2
    return COMMANDS[argv[1]](argv[2:])


if __name__ == "__main__":
    sys.exit(main(sys.argv))