166 lines
6.5 KiB
JavaScript
166 lines
6.5 KiB
JavaScript
/* ============================================================================
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* lyrics-core.js — pure helpers for synced lyrics, chapters and bookmarks
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*
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* No DOM. Used by app.js (window.LyricsCore) and unit-tested under node.
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*
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* Editor text format (a superset of LRC, so pasted .lrc files just work):
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* [0:18.00] Worthy of every song we could ever sing timed line
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* Worthy of all the praise untimed line
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* [0:18] # Verse 1 section header
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* ! Full dynamic swell into Bridge band cue
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* @ Key G, Capo 2 (Play F), 70 BPM tags
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* [00:12.00][01:30.00] repeated line LRC multi-stamp
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* [offset:+500] LRC offset (ms, + = sooner)
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* Other LRC headers ([ar:], [ti:], …) are ignored.
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*
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* Sync offset: a line is shown at (t + offset) seconds of playback, so a
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* positive offset makes the lyrics appear later.
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* ========================================================================== */
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(function (root) {
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'use strict';
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const STAMP_RE = /^\[(\d{1,3}):(\d{1,2})(?:[.:](\d{1,3}))?\]/;
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const HEADER_RE = /^\[([a-z]+):([^\]]*)\]$/i;
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function parseStamp(str) {
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const m = String(str || '').trim().match(/^(?:(\d+):)?(\d{1,3}):(\d{1,2})(?:[.:](\d{1,3}))?$/);
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if (!m) return null;
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const h = Number(m[1] || 0);
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const frac = m[4] ? Number('0.' + m[4]) : 0;
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return h * 3600 + Number(m[2]) * 60 + Number(m[3]) + frac;
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}
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// 83.456 → "1:23.46" (editor stamps keep hundredths).
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function fmtStamp(t) {
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const cs = Math.round(Math.max(0, Number(t) || 0) * 100);
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const m = Math.floor(cs / 6000);
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const s = Math.floor((cs % 6000) / 100);
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const c = cs % 100;
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return `${m}:${String(s).padStart(2, '0')}.${String(c).padStart(2, '0')}`;
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}
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// 83.9 → "1:23"; ≥1 h → "1:02:03" (YouTube chapter / display form).
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function fmtClock(t) {
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const total = Math.max(0, Math.floor(Number(t) || 0));
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const h = Math.floor(total / 3600);
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const m = Math.floor((total % 3600) / 60);
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const s = total % 60;
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return h
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? `${h}:${String(m).padStart(2, '0')}:${String(s).padStart(2, '0')}`
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: `${m}:${String(s).padStart(2, '0')}`;
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}
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function splitTags(s) {
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return String(s).split(/[,|·]/).map((x) => x.trim()).filter(Boolean);
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}
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// Editor text → { lines, tags, offset }.
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function fromText(text) {
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const lines = [];
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const tags = [];
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let offset = null;
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for (const rawLine of String(text || '').replace(/\r/g, '').split('\n')) {
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let rest = rawLine.trim();
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if (!rest) continue;
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const header = rest.match(HEADER_RE);
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if (header && !/^\d/.test(header[1])) {
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if (header[1].toLowerCase() === 'offset') {
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const ms = Number(header[2]);
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if (Number.isFinite(ms)) offset = Math.round((-ms / 1000) * 100) / 100;
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}
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continue;
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}
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const stamps = [];
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let m;
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while ((m = rest.match(STAMP_RE))) {
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const frac = m[3] ? Number('0.' + m[3]) : 0;
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stamps.push(Number(m[1]) * 60 + Number(m[2]) + frac);
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rest = rest.slice(m[0].length).trim();
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}
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if (rest.startsWith('@')) { tags.push(...splitTags(rest.slice(1))); continue; }
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let kind = 'line';
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if (rest.startsWith('#')) { kind = 'section'; rest = rest.replace(/^#+/, '').trim(); }
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else if (rest.startsWith('!')) { kind = 'cue'; rest = rest.slice(1).trim(); }
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if (!rest) continue;
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if (!stamps.length) lines.push({ t: null, text: rest, kind });
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for (const t of stamps) lines.push({ t: Math.round(t * 100) / 100, text: rest, kind });
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}
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// A fully timed sheet (typical .lrc with repeated-chorus stamps) is put in
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// time order; a partly timed one keeps the order it was written in.
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if (lines.length && lines.every((l) => l.t !== null)) {
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lines.sort((a, b) => a.t - b.t);
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}
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return { lines, tags, offset };
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}
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function toText(doc) {
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const out = [];
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if (doc && Array.isArray(doc.tags) && doc.tags.length) out.push('@ ' + doc.tags.join(', '));
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for (const l of (doc && doc.lines) || []) {
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const stamp = l.t === null || l.t === undefined ? '' : `[${fmtStamp(l.t)}] `;
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const mark = l.kind === 'section' ? '# ' : l.kind === 'cue' ? '! ' : '';
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out.push(stamp + mark + l.text);
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}
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return out.join('\n');
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}
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// Index (into lines) of the sung line playing at `time`, or -1. Sections
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// and cues are never "the active line" — the highlight follows the words.
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function activeIndex(lines, time, offset) {
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const now = Number(time) - (Number(offset) || 0);
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let best = -1;
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let bestT = -Infinity;
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(lines || []).forEach((l, i) => {
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if (l.kind !== 'line' || l.t === null || l.t === undefined) return;
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if (l.t <= now && l.t >= bestT) { best = i; bestT = l.t; }
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});
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return best;
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}
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// The section header that the active position falls under (for "Chorus in
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// progress"-style labels), or null.
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function activeSection(lines, time, offset) {
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const now = Number(time) - (Number(offset) || 0);
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let best = null;
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for (const l of lines || []) {
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if (l.kind === 'section' && l.t !== null && l.t !== undefined && l.t <= now) {
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if (!best || l.t >= best.t) best = l;
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}
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}
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return best;
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}
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function timedCount(lines) {
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return (lines || []).filter((l) => l.kind === 'line' && l.t !== null && l.t !== undefined).length;
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}
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// Chapters / bookmarks: [{t, title, note}] sorted by t.
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function activeMarker(items, time) {
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let best = null;
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for (const it of items || []) if (it.t <= time && (!best || it.t >= best.t)) best = it;
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return best;
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}
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// YouTube-description form: "0:00 Intro". YouTube only turns a list into
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// chapters when the first one is at 0:00, so an "Start" entry is added when
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// the list doesn't begin there.
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function toYouTubeTimestamps(items, { ensureZero = true } = {}) {
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const sorted = (items || []).slice().sort((a, b) => a.t - b.t);
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const rows = sorted.map((it) => `${fmtClock(it.t)} ${it.title}`);
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if (ensureZero && sorted.length && sorted[0].t >= 1) rows.unshift('0:00 Start');
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return rows.join('\n');
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}
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const LyricsCore = {
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parseStamp, fmtStamp, fmtClock, fromText, toText,
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activeIndex, activeSection, timedCount, activeMarker, toYouTubeTimestamps,
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};
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if (typeof module !== 'undefined' && module.exports) {
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module.exports = LyricsCore;
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} else {
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root.LyricsCore = LyricsCore;
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}
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})(typeof globalThis !== 'undefined' ? globalThis : this);
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