import { existsSync, mkdirSync, readFileSync, writeFileSync } from "fs";
import { homedir } from "os";
import { join } from "path";

export interface CliConfig {
  token: string;
  registryUrl: string;
  savedAt: string;
}

const CONFIG_DIR = join(homedir(), ".paperclip-skills");
const CONFIG_FILE = join(CONFIG_DIR, "config.json");

const DEFAULT_REGISTRY_URL = "https://www.paperclipskills.com";

export function readConfig(): Partial<CliConfig> {
  if (!existsSync(CONFIG_FILE)) return {};
  try {
    const raw = readFileSync(CONFIG_FILE, "utf-8");
    return JSON.parse(raw) as Partial<CliConfig>;
  } catch {
    return {};
  }
}

export function writeConfig(config: Partial<CliConfig>): void {
  if (!existsSync(CONFIG_DIR)) {
    mkdirSync(CONFIG_DIR, { recursive: true, mode: 0o700 });
  }
  const current = readConfig();
  const merged: Partial<CliConfig> = { ...current, ...config };
  writeFileSync(CONFIG_FILE, JSON.stringify(merged, null, 2), {
    encoding: "utf-8",
    mode: 0o600,
  });
}

export function getToken(): string | undefined {
  return process.env.PAPERCLIP_SKILLS_TOKEN ?? readConfig().token;
}

export function getRegistryUrl(): string {
  return (
    process.env.PAPERCLIP_REGISTRY_URL ??
    readConfig().registryUrl ??
    DEFAULT_REGISTRY_URL
  );
}

export function requireToken(): string {
  const token = getToken();
  if (!token) {
    throw new Error(
      "No auth token found. Run `npx paperclip-skills login` to authenticate, " +
        "or set PAPERCLIP_SKILLS_TOKEN in your environment."
    );
  }
  return token;
}