from __future__ import annotations

import json
import time
from dataclasses import asdict, is_dataclass

import click
from rich.console import Console

from browser_cli.commands import client_from_ctx, handle_errors

console = Console()

def _snapshot(client):
    tabs = client.tabs.list()
    return {str(t.id): asdict(t) if is_dataclass(t) else dict(t) for t in tabs}

def _emit(event, json_output: bool):
    if json_output:
        click.echo(json.dumps(event, default=str), flush=True)
    else:
        kind = event.get("type")
        tab = event.get("tab") or {}
        console.print(f"[cyan]{kind}[/cyan] {tab.get('id', '')} {tab.get('title') or ''} [dim]{tab.get('url') or ''}[/dim]")

@click.command("events")
@click.option("--interval", type=float, default=1.0, show_default=True, help="Polling interval in seconds")
@click.option("--once", is_flag=True, help="Emit initial snapshot and exit")
@click.option("--json", "json_output", is_flag=True, default=True, help="Emit JSON Lines (default)")
@click.option("--pretty", is_flag=True, help="Render human-readable events instead of JSON")
@handle_errors
def cmd_events(interval: float, once: bool, json_output: bool, pretty: bool):
    """Stream tab events as JSON Lines using a lightweight polling watcher."""
    json_output = json_output and not pretty
    client = client_from_ctx()
    previous = _snapshot(client)
    for tab in previous.values():
        _emit({"type": "tabs.snapshot", "tab": tab}, json_output)
    if once:
        return
    while True:
        time.sleep(interval)
        current = _snapshot(client)
        for tab_id, tab in current.items():
            if tab_id not in previous:
                _emit({"type": "tabs.created", "tab": tab}, json_output)
            elif tab != previous[tab_id]:
                _emit({"type": "tabs.updated", "tab": tab, "previous": previous[tab_id]}, json_output)
        for tab_id, tab in previous.items():
            if tab_id not in current:
                _emit({"type": "tabs.closed", "tab": tab}, json_output)
        previous = current