// Skill Loader — reads .md skill files from skills/data/, caches in memory

import { readFileSync } from 'fs';
import { join } from 'path';
import { SKILL_REGISTRY, type SkillName } from './registry';

const SKILLS_DIR = join(__dirname, 'data');

// In-memory cache: filename → content
const fileCache = new Map<string, string>();

// Combined skill cache: skill name → concatenated content
const skillCache = new Map<string, string>();

function loadFile(filename: string): string {
  const cached = fileCache.get(filename);
  if (cached) return cached;

  const filePath = join(SKILLS_DIR, filename);
  const content = readFileSync(filePath, 'utf-8');
  fileCache.set(filename, content);
  return content;
}

/**
 * Get the combined skill content for a named skill.
 * Multi-file skills (builder, designer) are concatenated with separators.
 */
export function getSkill(name: string): string {
  const cached = skillCache.get(name);
  if (cached) return cached;

  const mapping = SKILL_REGISTRY[name as SkillName];
  if (!mapping) {
    throw new Error(
      `Unknown skill "${name}". Available: ${Object.keys(SKILL_REGISTRY).join(', ')}`
    );
  }

  const parts = mapping.files.map((file) => {
    const content = loadFile(file);
    return `<!-- SKILL: ${file} -->\n${content}`;
  });

  const combined = parts.join('\n\n---\n\n');
  skillCache.set(name, combined);
  return combined;
}

/**
 * Get a single raw skill file by filename.
 */
export function getSkillFile(filename: string): string {
  return loadFile(filename);
}

/**
 * Preload all skill files into cache. Call at startup for faster first requests.
 */
export function preloadSkills(): void {
  for (const mapping of Object.values(SKILL_REGISTRY)) {
    for (const file of mapping.files) {
      loadFile(file);
    }
  }
  // Also build combined caches
  for (const name of Object.keys(SKILL_REGISTRY)) {
    getSkill(name);
  }
}

/**
 * Clear all caches. Useful for development hot-reload.
 */
export function clearSkillCache(): void {
  fileCache.clear();
  skillCache.clear();
}