"""
Lines Tab — network interfaces overview.

Displays a DataTable of all network interfaces updated live via bus subscription
to the "network.interfaces" topic.
"""

from __future__ import annotations

from typing import Any, Dict

from textual.app import ComposeResult
from textual.reactive import reactive
from textual.widget import Widget
from textual.widgets import DataTable, Label, Static


def _fmt_bytes(n: int) -> str:
    """Format a byte count as a human-readable string."""
    for unit in ("B", "KB", "MB", "GB", "TB"):
        if n < 1024:
            return f"{n:.1f} {unit}"
        n /= 1024
    return f"{n:.1f} PB"


class LinesTab(Widget):
    """
    Network Interfaces tab.

    Subscribes to ``network.interfaces`` bus events and refreshes
    the DataTable in real time.
    """

    DEFAULT_CSS = """
    LinesTab {
        layout: vertical;
        height: 1fr;
        padding: 1 2;
    }
    LinesTab .tab-title {
        color: $primary;
        text-style: bold;
        height: 1;
        margin-bottom: 1;
    }
    LinesTab DataTable {
        height: 1fr;
        border: round $primary;
    }
    """

    COLUMNS = [
        ("Interface", 12),
        ("Status", 8),
        ("IPv4", 16),
        ("IPv6", 24),
        ("MAC", 18),
        ("Speed", 9),
        ("RX", 12),
        ("TX", 12),
        ("RX Err", 8),
        ("TX Err", 8),
    ]

    def compose(self) -> ComposeResult:
        yield Static("//  LINES  —  Network Interfaces", classes="tab-title")
        yield DataTable(id="lines-table", zebra_stripes=True, cursor_type="row")

    def on_mount(self) -> None:
        table = self.query_one("#lines-table", DataTable)
        for col_label, width in self.COLUMNS:
            table.add_column(col_label, width=width, key=col_label.lower().replace(" ", "_"))

        # Subscribe to the bus if app exposes one
        app = self.app
        if hasattr(app, "bus"):
            app.bus.subscribe("network.interfaces", self._on_interfaces)
            # Request immediate data
            if hasattr(app, "state"):
                interfaces = app.state.get("network.interfaces")
                if interfaces:
                    self._refresh_table(interfaces)

    def _on_interfaces(self, topic: str, data: Any) -> None:
        """Bus handler — schedule table refresh on the UI thread."""
        self.call_from_thread(self._refresh_table, data)

    def _refresh_table(self, interfaces: Dict[str, Dict]) -> None:
        table = self.query_one("#lines-table", DataTable)
        table.clear()
        for iface, info in sorted(interfaces.items()):
            status_text = info.get("status", "?")
            speed = info.get("speed", 0)
            speed_str = f"{speed} Mb" if speed else "—"
            table.add_row(
                iface,
                status_text,
                info.get("ip4", "") or "—",
                info.get("ip6", "") or "—",
                info.get("mac", "") or "—",
                speed_str,
                _fmt_bytes(info.get("rx_bytes", 0)),
                _fmt_bytes(info.get("tx_bytes", 0)),
                str(info.get("rx_errors", 0)),
                str(info.get("tx_errors", 0)),
            )