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/fx"
	"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
	oauthCfg         *oauth2.Config
}

func NewOauth(lc fx.Lifecycle, cfg *config.Config, logger *zap.Logger) *Oauth {
	oa := &Oauth{cfg: cfg, logger: logger}

	lc.Append(fx.Hook{
		OnStart: func(ctx context.Context) error {
			oa.config()

			return nil
		},
	})

	return oa
}

func (o Oauth) config() *oauth2.Config {
	if o.oauthCfg == nil {
		o.oauthCfg = &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),
			},
		}

	}
	if o.loadToken(o.oauthCfg) {
		o.keepAlive()
	}

	return o.oauthCfg
}

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

func (o *Oauth) loadToken(config *oauth2.Config) bool {
	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 {
		valid := false
		parseToken, _, err := new(jwt.Parser).ParseUnverified(o.cfg.Oauth.Token, jwt.MapClaims{})

		if err != nil {
			o.logger.Error("Error parsing token", zap.Error(err))
		} else {
			// Assert the token's claims to the desired type (MapClaims in this case)
			if claims, ok := parseToken.Claims.(jwt.MapClaims); ok {
				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")
				return false
			}
		}
	}

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

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.refresher == nil {
		o.logger.Error("No refresher 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
}