import { readFile } from 'node:fs/promises';
import { existsSync } from 'node:fs';
import { join, resolve } from 'node:path';

/**
 * Bridge from the inert Seedance prompt-skill knowledge (Track A) to the live
 * code path (Track B).
 *
 * `references/video/seedance-skills/NN-*.md` are verbatim copies of the upstream
 * `beshuaxian/higgsfield-seedance2-jineng` skill files. They are rich but
 * machine-inert: no code parses their prose. This module is the single place
 * that maps a canonical category id to its reference file, so the id used by
 * {@link CATEGORY_REGISTRY} stays in lockstep with the on-disk knowledge doc.
 *
 * Intentionally structured-only: this resolves the id ⇄ file relationship and
 * reads the markdown for human/audit use. It does NOT parse prose into prompt
 * output — the discrete, selectable techniques (hooks, beat templates, style
 * lines, sound profiles) live in typed registers, keeping output deterministic.
 */
export interface SeedanceSkillReference {
  /** Canonical category id — matches the keys of CATEGORY_REGISTRY. */
  id: string;
  /** Human-readable label. */
  label: string;
  /** File name under references/video/seedance-skills/. */
  file: string;
}

const SEEDANCE_SKILLS_SUBDIR = ['references', 'video', 'seedance-skills'] as const;

export const SEEDANCE_SKILL_REGISTRY: readonly SeedanceSkillReference[] = [
  { id: 'cinematic', label: 'Cinematic / Narrative', file: '01-cinematic.md' },
  { id: '3d-cgi', label: '3D / CGI', file: '02-3d-cgi.md' },
  { id: 'cartoon', label: 'Cartoon', file: '03-cartoon.md' },
  { id: 'comic-to-video', label: 'Comic to Video', file: '04-comic-to-video.md' },
  { id: 'fight-scenes', label: 'Fight Scenes', file: '05-fight-scenes.md' },
  { id: 'motion-design-ad', label: 'Motion Design Ad', file: '06-motion-design-ad.md' },
  { id: 'ecommerce-ad', label: 'E-commerce Ad', file: '07-ecommerce-ad.md' },
  { id: 'anime-action', label: 'Anime Action', file: '08-anime-action.md' },
  { id: 'product-360', label: 'Product 360 / Turntable', file: '09-product-360.md' },
  { id: 'music-video', label: 'Music Video', file: '10-music-video.md' },
  { id: 'social-hook', label: 'Social Hook', file: '11-social-hook.md' },
  { id: 'brand-story', label: 'Brand Story', file: '12-brand-story.md' },
  { id: 'fashion-lookbook', label: 'Fashion Lookbook', file: '13-fashion-lookbook.md' },
  { id: 'food-beverage', label: 'Food & Beverage', file: '14-food-beverage.md' },
  { id: 'real-estate', label: 'Real Estate', file: '15-real-estate.md' },
] as const;

export const SEEDANCE_SKILL_IDS: string[] = SEEDANCE_SKILL_REGISTRY.map((s) => s.id);

function seedanceSkillsDir(root = process.cwd()): string {
  return join(resolve(root), ...SEEDANCE_SKILLS_SUBDIR);
}

/**
 * Resolve a canonical category id to its skill-reference descriptor.
 *
 * Throws on an unknown id (no silent fallback), matching `resolveCategory` in
 * {@link category-registry}.
 */
export function categoryReferenceDoc(id: string): SeedanceSkillReference {
  const entry = SEEDANCE_SKILL_REGISTRY.find((s) => s.id === id);
  if (!entry) {
    throw new Error(`unknown seedance skill category: ${id}`);
  }
  return entry;
}

/**
 * Read the on-disk markdown for a category. Returns null for an unknown id or a
 * missing file (graceful, mirroring `readPromptReference`).
 */
export async function readCategoryReference(
  id: string,
  root = process.cwd(),
): Promise<(SeedanceSkillReference & { content: string }) | null> {
  const entry = SEEDANCE_SKILL_REGISTRY.find((s) => s.id === id);
  if (!entry) return null;
  const path = join(seedanceSkillsDir(root), entry.file);
  if (!existsSync(path)) return null;
  const content = await readFile(path, 'utf-8');
  return { ...entry, content };
}