/**
 * Turning edited clips into a snippet library. Each included onset is
 * refined to the foot of its energy rise (the project's one definition of
 * event time) and a fixed window [t - pre, t + post) is cut. Onsets whose
 * window would run off either end of the clip are skipped rather than
 * padded, so every snippet is honest audio.
 */
import { refineOnset } from '../analysis/onsets.ts';
import type { EventType } from '../store.ts';
import { FS, type SnippetLibrary } from './types.ts';

export interface ClipAudioLookup {
  (clipId: string): { samples: Float32Array; sr: number } | null;
}

export function extractLibrary(
  types: EventType[],
  preMs: number,
  postMs: number,
  getAudio: ClipAudioLookup,
): SnippetLibrary {
  const pre = Math.round((preMs / 1000) * FS);
  const post = Math.round((postMs / 1000) * FS);
  const lib: SnippetLibrary = { names: types.map((t) => t.name), pre, post, snippets: [] };
  types.forEach((type, typeIndex) => {
    for (const clip of type.clips) {
      const audio = getAudio(clip.id);
      if (!audio) continue;
      const excluded = new Set(clip.excluded);
      clip.onsets.forEach((t, i) => {
        if (excluded.has(i)) return;
        const s = refineOnset(audio.samples, audio.sr, t);
        if (s - pre < 0 || s + post > audio.samples.length) return;
        lib.snippets.push({
          typeIndex,
          samples: audio.samples.slice(s - pre, s + post),
        });
      });
    }
  });
  return lib;
}

/** Usable snippet count per type id, for the UI. */
export function snippetCounts(
  types: EventType[],
  preMs: number,
  postMs: number,
  getAudio: ClipAudioLookup,
): Map<string, number> {
  const lib = extractLibrary(types, preMs, postMs, getAudio);
  const counts = new Map<string, number>();
  types.forEach((t, i) => {
    counts.set(t.id, lib.snippets.filter((s) => s.typeIndex === i).length);
  });
  return counts;
}