import { readFileSync } from "node:fs";
import type { Metadata } from "next";
import { getPaths } from "yt-dlp-transcript-common/lib/paths";
import { inspectChannelMedia } from "yt-dlp-transcript-common/lib/channelMedia";
import { getSettings } from "yt-dlp-transcript-common/lib/settings";
import { locationLabelOfDataDir } from "yt-dlp-transcript-common/lib/storageLocations";
import {
  getSite,
  listSiteIds,
  siteChannelSlugs,
} from "yt-dlp-transcript-common/lib/site";
import {
  getActionableSummary,
  widgetActionableRows,
} from "./lib/actionable/loadActionable";
import { readActiveSite } from "./lib/activeSiteServer";
import { buildActiveJobsPayload } from "./jobs/active/buildActiveJobs";
import { buildWorkersPayload } from "./workers/buildWorkers";
import { buildWidgetSyncPayload } from "yt-dlp-transcript-common/views/widgetSync";
import { widgetSyncInputs } from "./widget/lib/syncInputs";
import { DashboardCockpit } from "./components/dashboard/DashboardCockpit";
import {
  buildChannelRowView,
  channelVolumeOf,
  neutralChannelPriority,
  type ChannelRowView,
} from "yt-dlp-transcript-common/views/channelRow";
import { buildWidgetActionablePayload } from "yt-dlp-transcript-common/views/widgetActionable";
import type { ActionableRow } from "./lib/actionable/loadActionable";

export const dynamic = "force-dynamic";

// Next.js title.template defined in app/layout.tsx applies to *child* route
// segments, not the root page. Build the templated form ourselves so the home
// page still gets the site name in its document title.
export async function generateMetadata(): Promise<Metadata> {
  const settings = getSettings();
  return { title: `Dashboard — ${settings.adminTitle}` };
}

function loadChangelog(): string | null {
  try {
    return readFileSync(getPaths().editorChangelogFile, "utf8");
  } catch {
    return null;
  }
}

export default async function Dashboard({
  searchParams,
}: {
  searchParams: Promise<{ site?: string }>;
}) {
  const paths = getPaths();
  // The active site: a `?site=` link's for this request, else the cookie's.
  const { site } = await searchParams;
  const active = await readActiveSite(site, listSiteIds(paths));
  const summary = await getActionableSummary(paths);

  // Scope the channel-derived data to the active site's membership. Under "all
  // sites" the full pool is shown. Job/worker state stays global (pool state).
  const inScope = (() => {
    if (active.isAll || !active.siteId) return () => true;
    const slugs = siteChannelSlugs(getSite(active.siteId, paths));
    return (r: ActionableRow) => slugs.has(r.channel.slug);
  })();
  const rows = summary.rows.filter(inScope);

  // Enriched channels table rows (pass-through, not client state, so a global
  // AutoRefresh re-seeds them live).
  // WHERE EACH CHANNEL'S MEDIA IS — two stats and a small JSON read per row,
  // with the config already in hand. Not a corpus walk. A row whose drive is
  // not mounted reports every other number as zero, which is exactly why the
  // dashboard has to be able to say so rather than drawing a confident zero.
  const mediaBySlug = new Map(
    await Promise.all(
      rows.map(
        async (r) =>
          [
            r.channel.slug,
            await inspectChannelMedia(paths, r.channel.slug, r.channel.config),
          ] as const,
      ),
    ),
  );
  // Read once for the whole table, not once per row.
  const locations = getSettings().storage.locations;
  // The shared channel row (common/views/channelRow.ts), drawn by the shared
  // table with the dashboard's six columns. No pipeline bands and a neutral
  // priority: this table draws neither.
  const channels: ChannelRowView[] = rows.map((r) => {
    const media = mediaBySlug.get(r.channel.slug) ?? null;
    return buildChannelRowView({
      slug: r.channel.slug,
      config: r.channel.config,
      // From the snapshot rather than a corpus walk, so the Videos figure lags
      // a sync by the snapshot scheduler's debounce.
      snapshot: r.snapshot,
      playlistCount: null,
      bands: [],
      priority: neutralChannelPriority(),
      media,
      volume: channelVolumeOf(r.channel.config, locations),
      // The named location, matched against the configured roots from the
      // media TARGET, as this table always has. A pure prefix match, never a
      // probe.
      mediaLocationLabel: media
        ? locationLabelOfDataDir(media.target, locations)
        : undefined,
    });
  });

  // "Needs work" payload, same shape (and the same two functions) the
  // /api/view/widgetActionable handler the cockpit polls serves, scoped to the
  // active site for the SSR seed.
  const actionable = buildWidgetActionablePayload(widgetActionableRows(rows));

  const [jobs, sync] = await Promise.all([
    buildActiveJobsPayload(),
    widgetSyncInputs().then(buildWidgetSyncPayload),
  ]);
  const workers = buildWorkersPayload();
  const changelogSource = loadChangelog();

  return (
    <DashboardCockpit
      initial={{
        jobs,
        workers,
        actionable,
        sync,
        channels,
        changelogSource,
      }}
    />
  );
}