/**
 * Extension skill installation.
 *
 * Copies extension skill directories into the global pi agent dir
 * so pi discovers them inside containers. Also installs built-in
 * skills shipped with Mercury.
 */

import fs from "node:fs";
import path from "node:path";
import type { Logger } from "../logger.js";
import type { ExtensionMeta } from "./types.js";

/**
 * Install extension skills into the global pi agent dir.
 *
 * - Copies each extension's skill directory to `<globalDir>/skills/<name>/`
 * - Removes stale skill directories for extensions that no longer exist
 * - Preserves all files (scripts, references, assets) — not just SKILL.md
 */
export function installExtensionSkills(
  extensions: ExtensionMeta[],
  globalDir: string,
  log: Logger,
): void {
  const skillsDir = path.join(globalDir, "skills");
  fs.mkdirSync(skillsDir, { recursive: true });

  // Track which extension names have skills
  const activeSkillNames = new Set(
    extensions.filter((e) => e.skillDir).map((e) => e.name),
  );

  // Clean up stale skill directories
  for (const entry of fs.readdirSync(skillsDir, { withFileTypes: true })) {
    if (!entry.isDirectory()) continue;
    if (!activeSkillNames.has(entry.name)) {
      const stale = path.join(skillsDir, entry.name);
      fs.rmSync(stale, { recursive: true });
      log.info(`Removed stale skill: ${entry.name}`);
    }
  }

  // Copy skill directories
  for (const ext of extensions) {
    if (!ext.skillDir) continue;
    const dst = path.join(skillsDir, ext.name);
    fs.rmSync(dst, { recursive: true, force: true });
    fs.cpSync(ext.skillDir, dst, { recursive: true });
    log.info(`Installed skill: ${ext.name}`);
  }
}

/**
 * Install built-in skills shipped with Mercury.
 *
 * Copies from `resources/skills/` into `<globalDir>/skills/`.
 * Built-in skills are for mrctl built-in commands (tasks, roles, etc.).
 */
export function installBuiltinSkills(
  builtinSkillsDir: string,
  globalDir: string,
  log: Logger,
): void {
  if (!fs.existsSync(builtinSkillsDir)) {
    log.debug(`No built-in skills directory: ${builtinSkillsDir}`);
    return;
  }

  const skillsDir = path.join(globalDir, "skills");
  fs.mkdirSync(skillsDir, { recursive: true });

  for (const entry of fs.readdirSync(builtinSkillsDir, {
    withFileTypes: true,
  })) {
    if (!entry.isDirectory()) continue;
    const src = path.join(builtinSkillsDir, entry.name);
    const dst = path.join(skillsDir, entry.name);
    fs.cpSync(src, dst, { recursive: true });
    log.debug(`Installed built-in skill: ${entry.name}`);
  }
}