package auth

import (
	"encoding/json"
	"golang.org/x/oauth2"
	"io/ioutil"
	"os"
)

func FileSource(path string, token *oauth2.Token, conf *oauth2.Config) oauth2.TokenSource {
	return &fileSource{
		tokenPath:   path,
		tokenSource: conf.TokenSource(oauth2.NoContext, token),
	}
}

type fileSource struct {
	tokenPath   string
	tokenSource oauth2.TokenSource
}

func (self *fileSource) Token() (*oauth2.Token, error) {
	token, err := self.tokenSource.Token()
	if err != nil {
		return token, err
	}

	// Save token to file
	SaveToken(self.tokenPath, token)

	return token, nil
}

func ReadToken(path string) (*oauth2.Token, bool, error) {
	if !fileExists(path) {
		return nil, false, nil
	}

	content, err := ioutil.ReadFile(path)
	if err != nil {
		return nil, true, err
	}
	token := &oauth2.Token{}
	return token, true, json.Unmarshal(content, token)
}

func SaveToken(path string, token *oauth2.Token) error {
	data, err := json.MarshalIndent(token, "", "  ")
	if err != nil {
		return err
	}

	if err = mkdir(path); err != nil {
		return err
	}

	// Write to temp file first
	tmpFile := path + ".tmp"
	err = ioutil.WriteFile(tmpFile, data, 0600)
	if err != nil {
		os.Remove(tmpFile)
		return err
	}

	// Move file to correct path
	return os.Rename(tmpFile, path)
}