import { getPaths } from "yt-dlp-transcript-common/lib/paths";
import { isValidChannelSlug } from "yt-dlp-transcript-common/controller/channels";
import { channelCoverage } from "yt-dlp-transcript-common/controller/channelCoverage";
import { readRoute } from "../_read";
import { opsFail } from "../_lib";

export const dynamic = "force-dynamic";

// GET ?slug=<channel>[&gapDays=<n>][&from=YYYYMMDD][&to=YYYYMMDD][&list=1]
//   -> { ok, slug, titlePattern, held, dated, byRecordedDate, byUploadDate,
//        undated: [id], first, last, byYear, byMonth, gapDays,
//        gaps: [{ after, before, days }], videos?: [{ id, date, uploadDate,
//        recordedDate?, title? }] }
//
// What a channel holds, by date, and the spans with nothing held
// (controller/channelCoverage.ts): each held video dated with coverageDate —
// its recorded date when the channel has a title rule, else its upload date —
// off disk, so a video imported an hour ago counts. `gapDays` (30) is the
// shortest span reported as a gap; `from`/`to` narrow the window; `list`
// adds every dated video. Nothing is written. The MCP's channel_coverage.
const DAY = /^\d{8}$/;

export async function GET(request: Request) {
  return readRoute(request, ["slug", "gapDays", "from", "to", "list"], async (q) => {
    const slug = q.get("slug")?.trim() ?? "";
    if (!slug) return opsFail('"slug" is required');
    if (!isValidChannelSlug(slug)) return opsFail(`"${slug}" is not a valid channel slug`);
    const rawGap = q.get("gapDays");
    const gapDays = rawGap === null ? undefined : Number(rawGap);
    if (gapDays !== undefined && (!Number.isInteger(gapDays) || gapDays < 1)) {
      return opsFail('"gapDays" must be a whole number of days above zero');
    }
    const from = q.get("from") ?? undefined;
    const to = q.get("to") ?? undefined;
    for (const [k, v] of [["from", from], ["to", to]] as const) {
      if (v !== undefined && !DAY.test(v)) return opsFail(`"${k}" must be a date YYYYMMDD`);
    }
    const list = q.get("list");
    if (list !== null && list !== "1" && list !== "true") return opsFail('"list" is 1 or absent');
    try {
      const coverage = await channelCoverage(getPaths(), slug, {
        ...(gapDays !== undefined ? { gapDays } : {}),
        ...(from ? { from } : {}),
        ...(to ? { to } : {}),
        list: list !== null,
      });
      return { ok: true, ...coverage };
    } catch (e) {
      const message = (e as Error).message;
      return opsFail(message, /not found/.test(message) ? 404 : 503);
    }
  });
}