import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query"
import { Link } from "@tanstack/react-router"
import { AlertCircle, Workflow } from "lucide-react"

import { type FlowRollup, type FlowSummary, FlowsService } from "@/client"
import { byRecency } from "@/components/Common/DashboardMosaic"
import type { Range } from "@/components/Common/RangePicker"
import { flowKeys, flowsQueryOptions } from "@/components/Flow/queries"
import { PANEL_SECTION } from "@/components/Flow/SidePanel"
import { Badge } from "@/components/ui/badge"
import { Skeleton } from "@/components/ui/skeleton"
import { Switch } from "@/components/ui/switch"
import useCustomToast from "@/hooks/useCustomToast"
import { dur, si } from "@/lib/utils"
import { CARD, flowRollupsQueryOptions } from "./queries"
import { Spark } from "./Spark"

/** Another tab can stop a flow, and the engine can fail one on its own. */
const REFRESH_INTERVAL = 10_000

/** About six rows. Past that the table scrolls rather than the page. */
const HEIGHT = "max-h-96"

/**
 * Every flow, with what it has been doing.
 *
 * One table rather than a list beside a rollup table: they are two halves of
 * the same question and were previously read by matching rows up by eye. The
 * join is a left one — the rollups only carry flows that ran inside the
 * window, and a flow that has never run is still a flow.
 */
export function FlowTable({ range }: { range: Range }) {
  const { data, isPending } = useQuery({
    ...flowsQueryOptions(),
    refetchInterval: REFRESH_INTERVAL,
  })
  const { data: rollups } = useQuery(flowRollupsQueryOptions(range))

  const flows = [...(data?.data ?? [])].sort(byRecency)
  const activity = new Map<string, FlowRollup>(
    (rollups ?? []).map((row: FlowRollup) => [row.flow, row]),
  )

  return (
    <section className="grid gap-3">
      <div className="flex flex-wrap items-baseline gap-x-3">
        <h2 className={PANEL_SECTION}>Flows</h2>
        <p className="text-muted-foreground text-xs">
          activity over the last {range.label}
        </p>
      </div>

      {isPending ? (
        <div className={`${CARD} grid gap-3`}>
          <Skeleton className="h-5 w-40" />
          <Skeleton className="h-5 w-28" />
        </div>
      ) : flows.length === 0 ? (
        <div
          className={`${CARD} flex flex-col items-center gap-3 py-10 text-center`}
        >
          <span className="flex size-12 items-center justify-center rounded-full bg-muted text-muted-foreground">
            <Workflow className="size-5" />
          </span>
          <p className="text-muted-foreground text-sm">
            Flows you build show up here, with what they are doing.
          </p>
          <Link to="/flows" className="font-medium text-sm underline">
            Go to flows
          </Link>
        </div>
      ) : (
        <div className={`${CARD} ${HEIGHT} overflow-auto p-0`}>
          {/* The name anchors the left, what it is doing sits beside it, and
              the numbers read down their own centre with the trend closing the
              row on the right. */}
          <table className="w-full text-sm">
            <thead className="sticky top-0 z-10 bg-card text-muted-foreground text-xs">
              <tr>
                <th className="px-4 pt-4 pb-2 text-left font-medium">Flow</th>
                <th className="px-3 pt-4 pb-2 text-left font-medium">Status</th>
                <th className="px-3 pt-4 pb-2 text-center font-medium">Run</th>
                <th className="hidden px-3 pt-4 pb-2 text-center font-medium sm:table-cell">
                  Executions
                </th>
                <th className="hidden px-3 pt-4 pb-2 text-center font-medium sm:table-cell">
                  Errors
                </th>
                <th className="hidden px-3 pt-4 pb-2 text-center font-medium sm:table-cell">
                  Avg
                </th>
                <th className="hidden px-3 pt-4 pb-2 text-center font-medium sm:table-cell">
                  Lag
                </th>
                {/* A bounded share rather than all the slack, so the numbers
                    spread across the middle instead of huddling on the left.
                    Its 128px floor is more than a phone has to spare, and a
                    curve that narrow says nothing, so it goes below `sm`. */}
                <th className="hidden w-1/4 px-4 pt-4 pb-2 text-right font-medium sm:table-cell sm:min-w-32">
                  Trend
                </th>
              </tr>
            </thead>
            <tbody>
              {flows.map((flow) => (
                <Row
                  key={flow.name}
                  flow={flow}
                  activity={activity.get(flow.name)}
                />
              ))}
            </tbody>
          </table>
        </div>
      )}
    </section>
  )
}

function Row({
  flow,
  activity,
}: {
  flow: FlowSummary
  /** Absent when the flow did not run inside the selected window. */
  activity?: FlowRollup
}) {
  const queryClient = useQueryClient()
  const { showErrorToast } = useCustomToast()
  const enabled = flow.enabled ?? true

  const toggle = useMutation({
    mutationFn: (next: boolean) =>
      next
        ? FlowsService.startFlow({ name: flow.name })
        : FlowsService.stopFlow({ name: flow.name }),
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: flowKeys.all })
      queryClient.invalidateQueries({ queryKey: flowKeys.detail(flow.name) })
    },
    onError: () => showErrorToast("The flow could not be started or stopped."),
  })

  // Nothing to report is not zero: a flow that never ran in this window and a
  // flow that ran and did nothing are different answers.
  const idle = <span className="text-muted-foreground">—</span>

  return (
    <tr className="border-border border-t" data-testid="home-flow-row">
      {/* `max-w-0` is what lets a cell truncate at all: without it the table
          sizes to the longest name and pushes the page sideways. */}
      <td className="max-w-0 px-4 py-2 sm:min-w-40">
        <Link
          to="/flows/$flowName"
          params={{ flowName: flow.name }}
          className="block min-w-0"
        >
          <p className="truncate font-medium">{flow.title || flow.name}</p>
          <p className="truncate text-muted-foreground text-xs">
            {flow.node_count === 1 ? "1 node" : `${flow.node_count} nodes`}
            {flow.has_draft ? " · unpublished changes" : ""}
          </p>
        </Link>
      </td>

      <td className="whitespace-nowrap px-3 py-2">
        <span className="flex items-center gap-1.5">
          {(flow.error_count ?? 0) > 0 ? (
            <Badge variant="destructive" className="gap-1">
              <AlertCircle />
              {flow.error_count}
            </Badge>
          ) : null}
          <Badge
            variant="outline"
            className={
              enabled
                ? flow.paused
                  ? "border-transparent bg-primary/15 text-primary"
                  : "border-transparent bg-status-success/15 text-status-success"
                : "text-muted-foreground"
            }
          >
            {enabled ? (flow.paused ? "Paused" : "Running") : "Stopped"}
          </Badge>
        </span>
      </td>

      <td className="px-3 py-2 text-center">
        <Switch
          checked={enabled}
          disabled={toggle.isPending}
          onCheckedChange={(next) => toggle.mutate(next)}
          aria-label={`Run ${flow.title || flow.name}`}
          data-testid="flow-enabled-switch"
        />
      </td>

      <td className="hidden px-3 py-2 text-center sm:table-cell">
        {activity ? si(activity.executions) : idle}
      </td>
      <td className="hidden px-3 py-2 text-center sm:table-cell">
        {!activity ? (
          idle
        ) : activity.errors ? (
          <Badge variant="destructive">{si(activity.errors)} failed</Badge>
        ) : (
          <span className="text-muted-foreground">none</span>
        )}
      </td>
      <td className="hidden whitespace-nowrap px-3 py-2 text-center sm:table-cell">
        {activity ? dur(activity.avg_ms) : idle}
      </td>
      <td className="hidden whitespace-nowrap px-3 py-2 text-center sm:table-cell">
        {activity ? dur(activity.avg_lag_ms) : idle}
      </td>
      {/* The dot straddles the curve's right edge, so the cell keeps a little
          room for the half that hangs out. */}
      <td className="hidden py-2 pr-3 pl-3 text-right sm:table-cell">
        {activity ? <Spark counts={activity.spark} /> : idle}
      </td>
    </tr>
  )
}