import { existsSync, mkdirSync } from "node:fs";
import { join } from "node:path";
import { homedir } from "node:os";
import type { Config } from "./types";

const DEFAULT_CONFIG: Config = {
  apiKey: "",
  apiBase: "https://api.deepseek.com/v1",
  model: "deepseek-v4-flash",
  maxTokens: 500,
  temperature: 0.7,
};

const CONFIG_DIR = join(homedir(), ".config", "gai");
const CONFIG_PATH = join(CONFIG_DIR, "config.json");

export async function loadConfig(): Promise<Config> {
  let config = { ...DEFAULT_CONFIG };

  if (existsSync(CONFIG_PATH)) {
    try {
      const file = Bun.file(CONFIG_PATH);
      const json = (await file.json()) as Partial<Config>;
      config = { ...config, ...json };
    } catch {}
  }

  if (process.env.GAI_API_KEY) config.apiKey = process.env.GAI_API_KEY;
  if (process.env.GAI_API_BASE) config.apiBase = process.env.GAI_API_BASE;
  if (process.env.GAI_MODEL) config.model = process.env.GAI_MODEL;
  if (process.env.GAI_MAX_TOKENS)
    config.maxTokens = parseInt(process.env.GAI_MAX_TOKENS);
  if (process.env.GAI_TEMPERATURE)
    config.temperature = parseFloat(process.env.GAI_TEMPERATURE);

  return config;
}

export async function saveConfig(partial: Partial<Config>): Promise<void> {
  if (!existsSync(CONFIG_DIR)) {
    mkdirSync(CONFIG_DIR, { recursive: true });
  }

  const current = await loadConfig();
  const merged = { ...current, ...partial };

  await Bun.write(CONFIG_PATH, JSON.stringify(merged, null, 2));
}