/**
 * Config management — persists agent config to ~/.tip-agent/config.json
 */
import * as fs from "fs";
import * as path from "path";
import * as os from "os";

const CONFIG_DIR = path.join(os.homedir(), ".tip-agent");
const CONFIG_FILE = path.join(CONFIG_DIR, "config.json");

export interface AgentConfig {
  token: string;
  port: number;
  maxGb: number;
  name: string;
  serverUrl: string;
  pid?: number;
  startedAt?: string;
}

const DEFAULTS: Partial<AgentConfig> = {
  port: 1080,
  maxGb: 10,
  name: os.hostname(),
  serverUrl: "https://transceiver-db.context-x.org",
};

export function loadConfig(): AgentConfig | null {
  if (!fs.existsSync(CONFIG_FILE)) return null;
  try {
    const raw = fs.readFileSync(CONFIG_FILE, "utf8");
    return JSON.parse(raw) as AgentConfig;
  } catch {
    return null;
  }
}

export function saveConfig(cfg: Partial<AgentConfig>): AgentConfig {
  if (!fs.existsSync(CONFIG_DIR)) {
    fs.mkdirSync(CONFIG_DIR, { recursive: true });
  }
  const existing = loadConfig() ?? {};
  const merged = { ...DEFAULTS, ...existing, ...cfg } as AgentConfig;
  fs.writeFileSync(CONFIG_FILE, JSON.stringify(merged, null, 2), "utf8");
  return merged;
}

export function clearConfig(): void {
  if (fs.existsSync(CONFIG_FILE)) {
    fs.unlinkSync(CONFIG_FILE);
  }
}

export function getPidFile(): string {
  return path.join(CONFIG_DIR, "agent.pid");
}

export function savePid(pid: number): void {
  if (!fs.existsSync(CONFIG_DIR)) {
    fs.mkdirSync(CONFIG_DIR, { recursive: true });
  }
  fs.writeFileSync(getPidFile(), String(pid), "utf8");
}

export function loadPid(): number | null {
  const pidFile = getPidFile();
  if (!fs.existsSync(pidFile)) return null;
  const raw = fs.readFileSync(pidFile, "utf8").trim();
  const pid = parseInt(raw, 10);
  return isNaN(pid) ? null : pid;
}

export function clearPid(): void {
  const pidFile = getPidFile();
  if (fs.existsSync(pidFile)) fs.unlinkSync(pidFile);
}