import { useQuery } from "@tanstack/react-query"
import { Link } from "@tanstack/react-router"

import type { FlowRollup, HistoryPoint } from "@/client"
import { type Range, RangePicker } from "@/components/Common/RangePicker"
import { Sparkline } from "@/components/Common/Sparkline"
import { PANEL_SECTION } from "@/components/Flow/SidePanel"
import { Badge } from "@/components/ui/badge"
import { si } from "@/lib/utils"
import {
  ago,
  CARD,
  failuresQueryOptions,
  flowRollupsQueryOptions,
  summaryQueryOptions,
} from "./queries"

function Tile({
  label,
  value,
  note,
}: {
  label: string
  value: string
  note?: string
}) {
  return (
    <div className={CARD}>
      <div className={PANEL_SECTION}>{label}</div>
      <div className="mt-1 text-2xl">{value}</div>
      {note ? (
        <div className="text-xs text-muted-foreground">{note}</div>
      ) : null}
    </div>
  )
}

/**
 * A flow's execution trend, drawn from the 60 slices the rollup carries.
 *
 * Sixty slices of whatever window is selected, so the curve stays the same
 * width and only its resolution moves. The same curve the node panel and the
 * edge popover draw, dot included, in the chart ramp this page's other graphs
 * use. The dot marks the newest slice rather than this instant — the rollups
 * are polled, so that slice is the last complete one.
 */
function Spark({ counts }: { counts: number[] }) {
  const points: HistoryPoint[] = counts.map((value, index) => ({
    ts: index,
    value,
  }))
  if (points.every((point) => point.value === 0)) {
    return <span className="text-xs text-muted-foreground">nothing yet</span>
  }
  return (
    <Sparkline
      points={points}
      color="var(--chart-1)"
      height="h-6"
      readout={false}
    />
  )
}

/**
 * How the engine is doing, and how each flow has been doing over the window.
 *
 * The tiles are the standing state; the table below is the same window the
 * charts cover, one row per flow. The range control sits on this heading
 * because it governs the whole health block, the activity below included —
 * one window, not one per card.
 */
export function HealthOverview({
  range,
  onRangeChange,
}: {
  range: Range
  onRangeChange: (range: Range) => void
}) {
  const { data: summary } = useQuery(summaryQueryOptions())
  const { data: flows } = useQuery(flowRollupsQueryOptions(range))
  // Shares the list below's cache entry, for the one tile that dates them.
  const { data: failures } = useQuery(failuresQueryOptions(range))

  const queue = (summary?.queue ?? {}) as Record<string, number>
  const degraded = summary?.status === "degraded"
  const errors = (flows ?? []).reduce((total, row) => total + row.errors, 0)

  return (
    <>
      <section className="grid gap-3">
        <div className="flex flex-wrap items-center gap-3">
          <h2 className={PANEL_SECTION}>Health</h2>
          <Badge variant={degraded ? "destructive" : "secondary"}>
            {degraded ? "Degraded" : "Running normally"}
          </Badge>
          <div className="ml-auto">
            <RangePicker value={range} onChange={onRangeChange} />
          </div>
        </div>
        {summary?.problems.length ? (
          <p className="text-sm text-muted-foreground">
            {summary.problems.join(" · ")}
          </p>
        ) : null}

        <div className="grid gap-3 sm:grid-cols-2 lg:grid-cols-5">
          <Tile
            label="Nodes"
            value={String(summary?.nodes.total ?? 0)}
            note={
              summary?.nodes.error
                ? `${summary.nodes.error} failed to load`
                : "all loaded"
            }
          />
          <Tile
            label="Flows running"
            value={`${summary?.flows.running ?? 0}/${summary?.flows.total ?? 0}`}
            // Worst first: the engine gave up on a quarantined flow, a flow
            // validation blocks never started, and a paused one is deliberate.
            note={
              summary?.flows.quarantined
                ? `${summary.flows.quarantined} quarantined`
                : summary?.flows.invalid
                  ? `${summary.flows.invalid} cannot run`
                  : summary?.flows.paused
                    ? `${summary.flows.paused} paused`
                    : "none paused"
            }
          />
          <Tile
            label={`Failures (${range.label})`}
            // Summed from the rollups the table below is drawn from, so the
            // tile, the Errors column and the chart's error line all count the
            // same thing over the same window. Narrower than the list beside
            // it, which also carries quarantines and crashed tasks.
            value={si(errors)}
            note={
              failures?.length
                ? `latest ${ago(failures[0].ts)}`
                : "nothing recorded"
            }
          />
          <Tile
            label="Queue in flight"
            value={String(queue.pending ?? 0)}
            note={`${queue.delayed ?? 0} waiting · ${queue.parked ?? 0} parked`}
          />
          <Tile
            label="Loop lag"
            value={`${si(summary?.loop_lag.ewma ?? 0)} ms`}
            note={`peak ${si(summary?.loop_lag.max_60s ?? 0)} ms in the last minute`}
          />
        </div>
      </section>

      <section className="grid gap-3">
        <h2 className={PANEL_SECTION}>Flow activity ({range.label})</h2>
        <div className={`${CARD} overflow-x-auto`}>
          {/* The name anchors the left, the numbers read down their own
              centre, and the trend closes the row on the right. */}
          <table className="w-full text-sm">
            <thead className="text-xs text-muted-foreground">
              <tr>
                <th className="pb-2 text-left font-medium">Flow</th>
                <th className="px-3 pb-2 text-center font-medium">
                  Executions
                </th>
                <th className="px-3 pb-2 text-center font-medium">Errors</th>
                <th className="px-3 pb-2 text-center font-medium">Avg</th>
                <th className="px-3 pb-2 text-center font-medium">Lag</th>
                {/* A bounded share rather than all the slack: the columns
                    beside it grow with their own content, so the numbers
                    spread across the middle instead of huddling on the left. */}
                <th className="w-1/3 min-w-32 pb-2 pl-3 text-right font-medium">
                  Trend
                </th>
              </tr>
            </thead>
            <tbody>
              {(flows ?? []).map((row: FlowRollup) => (
                <tr key={row.flow} className="border-t border-border">
                  <td className="py-2 pr-3">
                    <Link
                      to="/flows/$flowName"
                      params={{ flowName: row.flow }}
                      className="font-mono hover:underline"
                    >
                      {row.flow || "—"}
                    </Link>
                  </td>
                  <td className="px-3 py-2 text-center">
                    {si(row.executions)}
                  </td>
                  <td className="px-3 py-2 text-center">
                    {row.errors ? (
                      <Badge variant="destructive">
                        {si(row.errors)} failed
                      </Badge>
                    ) : (
                      <span className="text-muted-foreground">none</span>
                    )}
                  </td>
                  <td className="whitespace-nowrap px-3 py-2 text-center">
                    {si(row.avg_ms)} ms
                  </td>
                  <td className="whitespace-nowrap px-3 py-2 text-center">
                    {si(row.avg_lag_ms)} ms
                  </td>
                  {/* The dot straddles the curve's right edge, so the cell
                      keeps a little room for the half that hangs out. */}
                  <td className="py-2 pr-2 pl-3 text-right">
                    <Spark counts={row.spark} />
                  </td>
                </tr>
              ))}
              {flows?.length === 0 ? (
                <tr>
                  <td
                    colSpan={6}
                    className="py-6 text-center text-muted-foreground"
                  >
                    No flow has run in the last {range.label}.
                  </td>
                </tr>
              ) : null}
            </tbody>
          </table>
        </div>
      </section>
    </>
  )
}