from __future__ import annotations

import json
import time

import click

from browser_cli.commands import client_from_ctx, handle_errors

@click.group("watch")
def watch_group():
    """Watch browser state and print changes."""

@watch_group.command("tabs")
@click.option("--interval", type=float, default=1.0, show_default=True)
@click.option("--once", is_flag=True)
@handle_errors
def watch_tabs(interval, once):
    """Watch the tab list as JSON snapshots."""
    client = client_from_ctx()
    previous = None
    while True:
        current = [t.__dict__ for t in client.tabs.list()]
        if current != previous:
            click.echo(json.dumps({"type": "tabs", "tabs": current}, default=str), flush=True)
            previous = current
        if once:
            return
        time.sleep(interval)

@watch_group.command("page")
@click.option("--field", default=None, help="Only print a single page.info field")
@click.option("--interval", type=float, default=1.0, show_default=True)
@handle_errors
def watch_page(field, interval):
    """Watch page.info for the active tab."""
    client = client_from_ctx()
    previous = object()
    while True:
        info = client.page.info()
        current = info.get(field) if field else info
        if current != previous:
            click.echo(json.dumps({"type": "page", "field": field, "value": current}, default=str), flush=True)
            previous = current
        time.sleep(interval)

@watch_group.command("dom")
@click.argument("selector")
@click.option("--interval", type=float, default=1.0, show_default=True)
@handle_errors
def watch_dom(selector, interval):
    """Watch textContent for a selector."""
    client = client_from_ctx()
    previous = object()
    while True:
        current = client.dom.text(selector)
        if current != previous:
            click.echo(json.dumps({"type": "dom", "selector": selector, "text": current}, default=str), flush=True)
            previous = current
        time.sleep(interval)