package fileauthcache

import (
	"encoding/json"
	"os"
	"path/filepath"
	"sync"

	"git.icedream.tech/icedream/oneandone-billing-mailer/pkg/auth/authcache"
	"golang.org/x/oauth2"
)

type fileAuthCache struct {
	filePath  string
	cacheLock sync.Mutex
}

func NewFileAuthCache(filePath string) authcache.Cache {
	return &fileAuthCache{
		filePath: filePath,
	}
}

func (ts *fileAuthCache) Persist(token *oauth2.Token) (err error) {
	ts.cacheLock.Lock()
	defer ts.cacheLock.Unlock()

	f, err := os.CreateTemp(filepath.Dir(ts.filePath), "")
	if err != nil {
		return err
	}

	if err = f.Chmod(0o600); err != nil {
		f.Close()
		return err
	}

	if err = json.NewEncoder(f).Encode(token); err != nil {
		f.Close()
		return err
	}

	if err = f.Close(); err != nil {
		return err
	}

	err = os.Rename(f.Name(), ts.filePath)
	return err
}

func (ts *fileAuthCache) Fetch() (token *oauth2.Token, err error) {
	f, err := os.OpenFile(ts.filePath, os.O_RDONLY, 0o600)
	if os.IsNotExist(err) {
		// Treat as no existing token found
		return nil, nil
	}
	if err != nil {
		return nil, err
	}

	decodedToken := new(oauth2.Token)
	if err = json.NewDecoder(f).Decode(decodedToken); err != nil {
		return nil, err
	}

	return decodedToken, nil
}