import Link from "next/link";
import { Badge } from "yt-dlp-transcript-common/components/ui/badge";
import type { SnapshotBuckets, StageId } from "yt-dlp-transcript-common/views/pipeline/stageStatus";

// ANOMALIES, one chip each, every one a link to the stage that owns it.
//
// Not on the line: these are not a conserved quantity moving through stages,
// they are things that went wrong at one of them. The line answers "where is the
// work"; this answers "what is broken".
//
// It renders a quiet "All clear" rather than disappearing when empty. A strip
// that vanishes is indistinguishable from a strip that failed to render, and the
// whole point of putting it on the first screen is that you can trust its
// silence.

type Chip = {
  label: string;
  count?: number;
  stage: StageId;
  tone: "warning" | "destructive";
};

const DAY_MS = 24 * 60 * 60 * 1000;
// A snapshot is regenerated on a ~1s debounce after any report-changing action,
// so a week-old one means nothing has touched this channel in a week — worth
// saying before someone reads its counts as current.
const STALE_REPORT_DAYS = 7;
// The sync cadence gate already spaces full sweeps out; a month is well past any
// of its intervals.
const STALE_SYNC_DAYS = 30;

export type AttentionInput = {
  slug: string;
  buckets: SnapshotBuckets;
  digestWarnings: string[];
  failedVideoIds: string[];
  generatedAt: string;
  lastSyncedAt?: string;
};

function ageInDays(iso: string | undefined): number | null {
  if (!iso) return null;
  const t = Date.parse(iso);
  if (Number.isNaN(t)) return null;
  return (Date.now() - t) / DAY_MS;
}

export function collectAttention(input: AttentionInput): Chip[] {
  const { buckets } = input;
  const chips: Chip[] = [];
  const add = (
    label: string,
    count: number,
    stage: StageId,
    tone: Chip["tone"] = "warning",
  ) => {
    if (count > 0) chips.push({ label, count, stage, tone });
  };

  add("failed transcriptions", input.failedVideoIds.length, "transcribe", "destructive");
  add("need cookies", buckets.needsCookies.length, "download");
  add("partial downloads", buckets.partialDownloads.length, "download");
  add("corrupt sources", buckets.corruptSource.length, "download", "destructive");
  add(
    "corrupt full sources",
    buckets.corruptFullSource.length,
    "download",
    "destructive",
  );
  add(
    "incomplete transcripts",
    buckets.incompleteTranscript.length,
    "transcribe",
  );
  add("short audio", buckets.shortAudio.length, "transcribe");
  add("duplicate dirs", buckets.duplicateDirs.length, "diagnostics");
  add("no metadata", buckets.noMetadata.length, "diagnostics");
  add("missing from archive", buckets.missingFromArchive.length, "diagnostics");
  add("digest warnings", input.digestWarnings.length, "digest");

  // Freshness. Both of these are about whether the numbers above can be trusted,
  // which is why they sit in the same strip rather than in a footnote.
  if (!input.generatedAt) {
    chips.push({ label: "no report yet", stage: "playlist", tone: "warning" });
  } else {
    const days = ageInDays(input.generatedAt);
    if (days != null && days > STALE_REPORT_DAYS) {
      chips.push({
        label: `report is ${Math.floor(days)} days old`,
        stage: "playlist",
        tone: "warning",
      });
    }
  }
  if (!input.lastSyncedAt) {
    chips.push({ label: "never synced", stage: "playlist", tone: "warning" });
  } else {
    const days = ageInDays(input.lastSyncedAt);
    if (days != null && days > STALE_SYNC_DAYS) {
      chips.push({
        label: `last synced ${Math.floor(days)} days ago`,
        stage: "playlist",
        tone: "warning",
      });
    }
  }

  return chips;
}

export function AttentionStrip(props: AttentionInput) {
  const chips = collectAttention(props);
  if (chips.length === 0) {
    return (
      <p
        aria-label="attention strip"
        data-attention="clear"
        className="text-xs text-muted-foreground"
      >
        All clear — nothing is flagged on this channel.
      </p>
    );
  }
  return (
    <div
      aria-label="attention strip"
      data-attention="flagged"
      className="flex flex-wrap items-center gap-1.5"
    >
      {chips.map((c) => (
        <Badge
          key={`${c.stage}:${c.label}`}
          asChild
          variant={c.tone === "destructive" ? "destructive" : "warning"}
        >
          <Link
            href={`/channels/${props.slug}?stage=${c.stage}`}
            aria-label={`${c.label} anomaly`}
          >
            {c.count != null && (
              <span className="tabular-nums">{c.count.toLocaleString()}</span>
            )}
            {c.label}
          </Link>
        </Badge>
      ))}
    </div>
  );
}