// <AlertsPage> — `/alerts`' content: the alerts the swarm's Grafana holds
// now, from swarm-controller's `GET /api/alerts`. Only the firing ones show at
// first; a button in the header adds the pending, no-data and errored ones.
// Same shape as `HivesPage`: one fetch on a `RefreshIntervalPicker` cadence,
// rendered as a `Table`.
import { useState } from "preact/hooks";
import { ApiErrorPanel } from "@hive/shared/api-error-panel.js";
import { Badge, type BadgeTone } from "@hive/shared/badge.js";
import { Button } from "../ui/button/Button.js";
import { Panel } from "../ui/panel/Panel.js";
import { RelativeTime } from "../ui/relative-time/RelativeTime.js";
import {
  RefreshIntervalPicker,
  type RefreshIntervalMs,
} from "../ui/refresh-interval/RefreshInterval.js";
import { fetchJson, usePolled } from "../ui/polled/usePolled.js";
import { Table, type TableColumn } from "../ui/table/Table.js";
import { activeSinceMs, alertKey, listedAlerts, type Alert } from "./alerts.js";

const STATE_TONE: Record<string, BadgeTone> = {
  Alerting: "negative",
  Error: "negative",
  NoData: "warning",
  Pending: "warning",
};

// Grafana's own alert list, for what this page does not show.
const GRAFANA_ALERTS_URL =
  "https://grafana.constellation.darkest.space/alerting/groups";

const COLUMNS: TableColumn<Alert>[] = [
  {
    key: "name",
    header: "alert",
    render: (a) => a.name,
    sortBy: (a) => a.name,
    filterValue: (a) => a.name,
  },
  {
    key: "state",
    header: "state",
    render: (a) => {
      const since = activeSinceMs(a);
      return (
        <Badge
          tone={STATE_TONE[a.state] ?? "neutral"}
          value={
            since !== null ? (
              <>
                {a.state} (<RelativeTime epochMs={since} />)
              </>
            ) : (
              a.state
            )
          }
        />
      );
    },
    sortBy: (a) => a.state,
    filterValues: (a) => [a.state],
    filterMode: "multiselect",
  },
  {
    key: "summary",
    header: "summary",
    render: (a) => a.summary ?? "—",
    sortBy: (a) => a.summary ?? "",
    filterValue: (a) => a.summary ?? "",
  },
];

const DEFAULT_INTERVAL_MS: RefreshIntervalMs = 30_000;

export function AlertsPage() {
  const [showAll, setShowAll] = useState(false);
  const [intervalMs, setIntervalMs] =
    useState<RefreshIntervalMs>(DEFAULT_INTERVAL_MS);
  const { data: alerts, error } = usePolled(intervalMs, (signal) =>
    fetchJson<Alert[]>("/api/alerts", signal),
  );
  const listed = alerts ? listedAlerts(alerts, showAll) : null;
  const hidden = alerts && listed ? alerts.length - listed.length : 0;

  return (
    <Panel
      title="alerts"
      icon="🚨"
      actions={
        <>
          <a
            href={GRAFANA_ALERTS_URL}
            target="_blank"
            rel="noopener noreferrer"
          >
            Grafana's alert list
          </a>
          {showAll || hidden > 0 ? (
            <Button onClick={() => setShowAll(!showAll)}>
              {showAll ? "only firing" : `show ${hidden} more`}
            </Button>
          ) : null}
          <RefreshIntervalPicker
            id="alerts-refresh"
            value={intervalMs}
            onChange={setIntervalMs}
          />
        </>
      }
    >
      {error ? (
        <ApiErrorPanel
          context="failed to load Grafana's alerts"
          problem={error}
        />
      ) : null}
      {!error && alerts === null ? <p>loading…</p> : null}
      {listed && listed.length === 0 ? (
        <p>{showAll ? "no alerts." : "nothing is alerting."}</p>
      ) : null}
      {listed && listed.length > 0 ? (
        <Table
          columns={COLUMNS}
          rows={listed}
          rowKey={alertKey}
          storageKey="swarm-ui:alerts:table-filters"
        />
      ) : null}
    </Panel>
  );
}