// Text shaping for the paper — isomorphic (no Node, no DB, no LLM).
// Imported by server routes AND client components, so keep it dependency-free.
//
// Why this file exists (Daniel, 2026-08-31): the edition used to slice summaries with a
// bare `.slice(0, 150)`, which cut copy mid-WORD — "the Department of T", "recently in Q".
// A newspaper never breaks a word to fit a box; it breaks at a sentence, then at a word,
// then says "more". clipText() encodes that order of preference.

const ELLIPSIS = "\u2026"; // …

// Sentence-ish endings, including closing quotes/brackets and common abbreviations guard.
// With the `$` anchor: "the text ends here" counts as a sentence end (firstSentence).
// Without it: used while CLIPPING, where the end of the allowed window is an artifact of
// the budget, not a sentence end — including `$` there made clipText believe a cut that
// landed mid-word was a finished sentence and print it with no ellipsis at all.
// (Caught by tests/text-test.mjs: "…concerns an" — the word "and", severed.)
const SENT_END = /(?:[.!?…]["'”’)»]\s|[.!?…]\s|$)/;
const SENT_END_CLIP = /(?:[.!?…]["'”’)»]\s|[.!?…]\s)/;
const ABBREV = /(?:\b(?:mr|mrs|ms|dr|prof|sr|jr|st|no|vs|etc|e\.g|i\.e|u\.s|u\.k|ph|jan|feb|mar|apr|jun|jul|aug|sep|sept|oct|nov|dec)\.)\s*$/i;

// Prefer a sentence boundary, then a word boundary. Never cuts inside a word.
export function clipText(s, max = 160, { ellipsis = true } = {}) {
  const t = String(s || "").replace(/\s+/g, " ").trim();
  if (!t) return "";
  if (t.length <= max) return t;

  // Look for a sentence end in the tail of the allowed window — a cut that lands
  // mid-first-sentence is only acceptable when the first sentence is longer than the box.
  const window = t.slice(0, max + 1);
  let cut = -1;
  const re = new RegExp(SENT_END_CLIP.source, "g");
  let m;
  while ((m = re.exec(window))) {
    // ignore a terminal that is really an abbreviation ("U.S.", "St.")
    if (ABBREV.test(window.slice(0, m.index + 1))) continue;
    cut = m.index + m[0].trimEnd().length;
    if (cut > max * 0.5) break; // take a boundary in the back half of the window
  }
  if (cut > 0) {
    // We landed on a real sentence end: the teaser is a complete thought, so it gets NO
    // ellipsis. Hanging "…" off a finished sentence is the same lie as cutting mid-word.
    return t.slice(0, cut).trim();
  }

  // No sentence end in range: cut at the last word boundary and say so with "…".
  const sp = window.lastIndexOf(" ");
  const hard = sp > max * 0.4 ? sp : max;
  const out = t.slice(0, hard).replace(/[,;:\-–—)]+$/, "").trim();
  return ellipsis ? out + " " + ELLIPSIS : out;
}

// The line under a headline: 1-2 complete sentences when they fit the box.
export function dek(summary, max = 180) {
  return clipText(summary, max);
}

// First complete sentence, for the "lede" slot.
export function firstSentence(s, max = 260) {
  const t = String(s || "").replace(/\s+/g, " ").trim();
  if (!t) return "";
  const m = SENT_END.exec(t);
  const end = m ? m.index + m[0].trimEnd().length : t.length;
  const one = t.slice(0, Math.max(end, t.indexOf(" ") + 1)).trim();
  return one.length <= max ? one : clipText(one, max);
}

export function wordCount(s) {
  return String(s || "").trim().split(/\s+/).filter(Boolean).length;
}

// Does the card's copy actually run out? Drives the "read on" affordance so we never
// advertise more text than exists.
export function isClipped(s, max = 180) {
  const t = String(s || "").replace(/\s+/g, " ").trim();
  return t.length > max;
}

export { ELLIPSIS };