package main

import (
	"encoding/json"
	"fmt"
	"os"

	"golang.org/x/oauth2"
)

func readConfig(filePath string) (*oauth2.Token, error) {
	if _, err := os.Stat(filePath); os.IsNotExist(err) {
		f, err := os.Create(filePath)
		if err != nil {
			return nil, fmt.Errorf("failed to create config file: %v", err)
		}
		if _, err := f.Write([]byte("{}")); err != nil {
			return nil, fmt.Errorf("failed to write empty object: %v", err)
		}
		return &oauth2.Token{}, nil
	}

	f, err := os.OpenFile(filePath, os.O_RDWR, 0644)
	if err != nil {
		return nil, fmt.Errorf("failed to open config file: %v", err)
	}
	defer f.Close()

	token := new(oauth2.Token)
	if err := json.NewDecoder(f).Decode(token); err != nil {
		return nil, fmt.Errorf("failed to decode json from config file: %v", err)
	}

	return token, nil
}

func writeConfig(filePath string, token *oauth2.Token) error {
	f, err := os.OpenFile(filePath, os.O_WRONLY, 0644)
	if err != nil {
		return fmt.Errorf("failed to open config file: %v", err)
	}
	defer f.Close()

	if err := json.NewEncoder(f).Encode(token); err != nil {
		return fmt.Errorf("failed to encode json to config file: %v", err)
	}

	return nil
}