package api

import (
	"code.gitea.io/sdk/gitea"
	"context"
	"fmt"
	"git.lumeweb.com/LumeWeb/gitea-github-proxy/config"
	"github.com/golang-jwt/jwt"
	"go.uber.org/zap"
	"golang.org/x/oauth2"
	"time"
)

type oauth struct {
	cfg              *config.Config
	logger           *zap.Logger
	token            *oauth2.Token
	refresher        oauth2.TokenSource
	keepAliveRunning bool
}

func newOauth(cfg *config.Config, logger *zap.Logger) *oauth {
	return &oauth{cfg: cfg, logger: logger}
}

func (o oauth) config() *oauth2.Config {
	cfg := &oauth2.Config{
		ClientID:     o.cfg.Oauth.ClientId,
		ClientSecret: o.cfg.Oauth.ClientSecret,
		Scopes:       []string{"admin"},
		RedirectURL:  fmt.Sprintf("https://%s/setup/callback", o.cfg.Domain),
		Endpoint: oauth2.Endpoint{
			TokenURL: fmt.Sprintf("%s/login/oauth/access_token", o.cfg.GiteaUrl),
			AuthURL:  fmt.Sprintf("%s/login/oauth/authorize", o.cfg.GiteaUrl),
		},
	}

	o.loadToken(cfg)
	o.keepAlive()

	return cfg
}

func (o oauth) authUrl() string {
	return o.config().AuthCodeURL("state")
}

func (o oauth) loadToken(config *oauth2.Config) {
	token := &oauth2.Token{}

	if o.cfg.Oauth.Token != "" {
		o.token = &oauth2.Token{AccessToken: o.cfg.Oauth.Token}
	}

	if o.cfg.Oauth.RefreshToken != "" {
		o.token.RefreshToken = o.cfg.Oauth.RefreshToken
	}

	if o.token != nil {
		parsedToken, err := jwt.Parse(o.cfg.Oauth.Token, func(token *jwt.Token) (interface{}, error) {
			return nil, nil
		})

		if err != nil {
			o.logger.Fatal("Error parsing token", zap.Error(err))
		}

		valid := false

		if claims, ok := parsedToken.Claims.(jwt.MapClaims); ok && parsedToken.Valid {
			if exp, ok := claims["exp"].(float64); ok {
				expirationTime := time.Unix(int64(exp), 0)
				if time.Now().Before(expirationTime) {
					valid = true
					o.token.Expiry = expirationTime
				}
			}
		}

		if valid {
			token = o.token
		} else {
			o.logger.Info("Token is expired, ignoring")
		}
	}

	o.refresher = config.TokenSource(context.Background(), token)
}

func (o oauth) keepAlive() {
	if o.cfg.Oauth.Token == "" || o.cfg.Oauth.RefreshToken == "" {
		o.logger.Error("No token or refresh token provided.")
		return
	}

	if o.keepAliveRunning {
		return
	}

	ticker := time.NewTicker(30 * time.Minute)

	o.keepAliveRunning = true

	go func() {
		for {
			select {
			case <-ticker.C:
				if !o.isTokenValid() {
					if err := o.refreshToken(); err != nil {
						o.logger.Error("Error refreshing token", zap.Error(err))
					}
				}
			}
		}
	}()
}
func (o *oauth) isTokenValid() bool {
	if o.token == nil {
		return false
	}

	return o.token.Valid()
}

func (o *oauth) refreshToken() error {
	o.logger.Info("Refreshing token...")

	token, err := o.refresher.Token()
	if err != nil {
		return err
	}

	o.token = token

	return nil
}

func (o *oauth) exchange(code string) (*oauth2.Token, error) {
	cfg := o.config()
	token, err := o.config().Exchange(context.Background(), code)
	if err != nil {
		return nil, err
	}

	o.cfg.Oauth.Token = token.AccessToken
	o.cfg.Oauth.RefreshToken = token.RefreshToken
	err = config.SaveConfig(o.cfg)
	if err != nil {
		return nil, err
	}

	o.loadToken(cfg)
	o.keepAlive()

	return token, nil
}

func (o *oauth) client() *gitea.Client {
	client, err := getClient(ClientParams{
		Config: o.cfg,
	})
	if err != nil {
		o.logger.Fatal("Error creating gitea client", zap.Error(err))
	}

	return client
}