// The hub's copy lines for /ask and the scope chips — the operator's words,
// ruled 2026-09-28. Change them here and nowhere else: the components render
// these values and the hub e2e asserts them.
//
// To edit a line:
//   - change the words inside the backticks;
//   - the phrase wrapped in ${link("…")} is a link to the hub's front page —
//     move the wrapper to link other words, or drop it (keep the words) for no
//     link. One link per line at most: a second one throws when this module
//     loads;
//   - ASK_SCOPE_LINE may return null to show no line at all (e.g.
//     `inScope === total ? null : copy`…`` to show it only when some archives
//     are switched off).
// A line with no link can be a plain string (LIVE_CHAT_MISSING).

// A copy line: its words, with at most one phrase linked to the hub's front
// page. `text` is the line as a reader reads it; `before` + `link` + `after`
// is the same line split around the link (`link` absent, and `after` empty,
// when there is none).
export type Copy = { before: string; link?: string; after: string; text: string };

export class CopyLink {
  constructor(readonly words: string) {}
}

// The linked phrase of a copy line (see `copy`).
export function link(words: string): CopyLink {
  return new CopyLink(words);
}

// The tag for a copy line. Plain interpolations (numbers, strings) are text;
// only a link(…) value becomes the link. Nothing is parsed out of the words.
export function copy(strings: TemplateStringsArray, ...values: unknown[]): Copy {
  let before = "";
  let after = "";
  let linked: string | undefined;
  const add = (s: string) => {
    if (linked === undefined) before += s;
    else after += s;
  };
  strings.forEach((s, i) => {
    add(s);
    if (i >= values.length) return;
    const v = values[i];
    if (v instanceof CopyLink) {
      if (linked !== undefined) {
        throw new Error(
          `A copy line links one phrase at most: "${linked}" and "${v.words}" (hubScopeCopy.ts)`,
        );
      }
      linked = v.words;
    } else {
      add(String(v));
    }
  });
  return linked === undefined
    ? { before, after: "", text: before }
    : { before, link: linked, after, text: before + linked + after };
}

// /ask, for a browser that has switched EVERY archive off with the front
// page's scope chips: the chat has nothing to search, so its composer is
// disabled and this one line says why. The link goes to the chips.
export const NO_ARCHIVES_IN_SCOPE = copy`No archives selected. Choose some on the ${link("hub's front page")} to ask.`;

// /ask, on a hub with NO archives at all: its /hub-sites.json lists none (a
// fresh self-hosted hub) or could not be read, and this browser has added
// none. The composer is disabled and this line says why, instead of "Loading
// transcripts…" forever. The link goes to the form that adds an archive.
export const NO_ARCHIVES_ON_HUB = copy`This hub has no archives yet. Add one on the ${link("hub's front page")} to ask.`;

// The note on a hub scope chip (the front page) when that archive's live chat
// could not be read: its videos are searched, its live chat is not. A Retry
// for the live chat alone sits beside it. Chip notes are lower case, like the
// chip's own "loading…" and "failed".
export const LIVE_CHAT_MISSING = "live chat didn't load";

// The one line at the top of the hub's /ask that says what the chat searches:
// `inScope` of the hub's `total` archives, the rest switched off with the
// front page's scope chips. Not shown when none are in scope
// (NO_ARCHIVES_IN_SCOPE says so instead).
export const ASK_SCOPE_LINE = (inScope: number, total: number): Copy | null =>
  copy`Searching ${inScope} of ${total} ${total === 1 ? "archive" : "archives"} — ${link("change on the front page")}.`;

// Evaluated once here, so a second link in it throws when this module loads
// rather than when /ask renders.
ASK_SCOPE_LINE(1, 2);