"""
Signals Tab — live scrolling monitor of all bus events.

Subscribes to every topic ("**") and appends new events to a scrollable
RichLog widget, styled to resemble an oscilloscope or signal analyser.
"""

from __future__ import annotations

import json
from datetime import datetime, timezone
from typing import Any

from textual.app import ComposeResult
from textual.binding import Binding
from textual.widget import Widget
from textual.widgets import Label, RichLog, Static


def _preview(data: Any, max_len: int = 80) -> str:
    """Produce a compact single-line preview of event data."""
    if data is None:
        return "null"
    try:
        raw = json.dumps(data, default=str)
    except Exception:
        raw = str(data)
    if len(raw) > max_len:
        raw = raw[:max_len] + "…"
    return raw


class SignalsTab(Widget):
    """
    Live event signal monitor.

    Every event published on the bus appears here with:
      - Timestamp (HH:MM:SS.mmm)
      - Topic (colour-coded by namespace)
      - Data preview (truncated JSON)
    """

    DEFAULT_CSS = """
    SignalsTab {
        layout: vertical;
        height: 1fr;
        padding: 1 2;
    }
    SignalsTab .tab-title {
        color: $primary;
        text-style: bold;
        height: 1;
        margin-bottom: 1;
    }
    SignalsTab RichLog {
        height: 1fr;
        border: round $primary;
        background: $surface;
        scrollbar-gutter: stable;
    }
    SignalsTab .hint {
        height: 1;
        color: $text-muted;
        margin-top: 1;
    }
    """

    BINDINGS = [
        Binding("c", "clear_log", "Clear"),
        Binding("p", "toggle_pause", "Pause"),
    ]

    # Colour map per topic namespace
    TOPIC_COLOURS = {
        "network": "cyan",
        "dns": "blue",
        "firewall": "red",
        "system": "green",
        "state": "yellow",
        "registry": "magenta",
    }

    def __init__(self, **kwargs) -> None:
        super().__init__(**kwargs)
        self._paused = False
        self._event_count = 0
        self._sub_id: str | None = None

    def compose(self) -> ComposeResult:
        yield Static("//  SIGNALS  —  Live Event Monitor", classes="tab-title")
        yield RichLog(id="signal-log", highlight=True, markup=True, max_lines=500)
        yield Static(
            "Press [bold]c[/bold] to clear  |  [bold]p[/bold] to pause",
            classes="hint",
        )

    def on_mount(self) -> None:
        app = self.app
        if hasattr(app, "bus"):
            self._sub_id = app.bus.subscribe("**", self._on_any_event)

    def on_unmount(self) -> None:
        app = self.app
        if hasattr(app, "bus") and self._sub_id:
            app.bus.unsubscribe(self._sub_id)

    def _on_any_event(self, topic: str, data: Any) -> None:
        if self._paused:
            return
        self.call_from_thread(self._append_event, topic, data)

    def _append_event(self, topic: str, data: Any) -> None:
        self._event_count += 1
        log_widget = self.query_one("#signal-log", RichLog)

        now = datetime.now(timezone.utc)
        ts = now.strftime("%H:%M:%S") + f".{now.microsecond // 1000:03d}"

        namespace = topic.split(".")[0]
        colour = self.TOPIC_COLOURS.get(namespace, "white")
        preview = _preview(data)

        # Format: [dim]HH:MM:SS.mmm[/]  [colour]topic[/]  data
        line = (
            f"[dim]{ts}[/dim]  "
            f"[{colour} bold]{topic:<35}[/{colour} bold]  "
            f"[dim]{preview}[/dim]"
        )
        log_widget.write(line)

    def action_clear_log(self) -> None:
        log_widget = self.query_one("#signal-log", RichLog)
        log_widget.clear()
        self._event_count = 0

    def action_toggle_pause(self) -> None:
        self._paused = not self._paused
        log_widget = self.query_one("#signal-log", RichLog)
        status = "[yellow]PAUSED[/yellow]" if self._paused else "[green]LIVE[/green]"
        log_widget.write(f"  ── {status} ──")