package auth

import (
	"context"
	"fmt"
	"net/http"
	"time"

	"github.com/coreos/go-oidc/v3/oidc"
	"github.com/gravitl/netmaker/logger"
	"github.com/gravitl/netmaker/logic"
	"github.com/gravitl/netmaker/models"
	"github.com/gravitl/netmaker/servercfg"
	"golang.org/x/oauth2"
)

const OIDC_TIMEOUT = 10 * time.Second

var oidc_functions = map[string]interface{}{
	init_provider:   initOIDC,
	get_user_info:   getOIDCUserInfo,
	handle_callback: handleOIDCCallback,
	handle_login:    handleOIDCLogin,
	verify_user:     verifyOIDCUser,
}

var oidc_verifier *oidc.IDTokenVerifier

// == handle OIDC authentication here ==

func initOIDC(redirectURL string, clientID string, clientSecret string, issuer string) {
	ctx, cancel := context.WithTimeout(context.Background(), OIDC_TIMEOUT)
	defer cancel()

	provider, err := oidc.NewProvider(ctx, issuer)
	if err != nil {
		logger.Log(1, "error when initializing OIDC provider with issuer \""+issuer+"\"", err.Error())
		return
	}

	oidc_verifier = provider.Verifier(&oidc.Config{ClientID: clientID})
	auth_provider = &oauth2.Config{
		ClientID:     clientID,
		ClientSecret: clientSecret,
		RedirectURL:  redirectURL,
		Endpoint:     provider.Endpoint(),
		Scopes:       []string{oidc.ScopeOpenID, "profile", "email"},
	}
}

func handleOIDCLogin(w http.ResponseWriter, r *http.Request) {
	var oauth_state_string = logic.RandomString(user_signin_length)
	if auth_provider == nil && servercfg.GetFrontendURL() != "" {
		http.Redirect(w, r, servercfg.GetFrontendURL()+"/login?oauth=callback-error", http.StatusTemporaryRedirect)
		return
	} else if auth_provider == nil {
		fmt.Fprintf(w, "%s", []byte("no frontend URL was provided and an OAuth login was attempted\nplease reconfigure server to use OAuth or use basic credentials"))
		return
	}

	if err := logic.SetState(oauth_state_string); err != nil {
		http.Redirect(w, r, servercfg.GetFrontendURL()+"/login?oauth=callback-error", http.StatusTemporaryRedirect)
		return
	}
	var url = auth_provider.AuthCodeURL(oauth_state_string)
	http.Redirect(w, r, url, http.StatusTemporaryRedirect)
}

func handleOIDCCallback(w http.ResponseWriter, r *http.Request) {

	var rState, rCode = getStateAndCode(r)

	var content, err = getOIDCUserInfo(rState, rCode)
	if err != nil {
		logger.Log(1, "error when getting user info from callback:", err.Error())
		http.Redirect(w, r, servercfg.GetFrontendURL()+"/login?oauth=callback-error", http.StatusTemporaryRedirect)
		return
	}
	_, err = logic.GetUser(content.Email)
	if err != nil { // user must not exists, so try to make one
		if err = addUser(content.Email); err != nil {
			return
		}
	}
	var newPass, fetchErr = fetchPassValue("")
	if fetchErr != nil {
		return
	}
	// send a netmaker jwt token
	var authRequest = models.UserAuthParams{
		UserName: content.Email,
		Password: newPass,
	}

	var jwt, jwtErr = logic.VerifyAuthRequest(authRequest)
	if jwtErr != nil {
		logger.Log(1, "could not parse jwt for user", authRequest.UserName, jwtErr.Error())
		return
	}

	logger.Log(1, "completed OIDC OAuth signin in for", content.Email)
	http.Redirect(w, r, servercfg.GetFrontendURL()+"/login?login="+jwt+"&user="+content.Email, http.StatusPermanentRedirect)
}

func getOIDCUserInfo(state string, code string) (u *OAuthUser, e error) {
	oauth_state_string, isValid := logic.IsStateValid(state)
	logger.Log(3, "using oauth state string:,", oauth_state_string)
	logger.Log(3, "            state string:,", state)
	if (!isValid || state != oauth_state_string) && !isStateCached(state) {
		return nil, fmt.Errorf("invalid oauth state")
	}

	defer func() {
		if p := recover(); p != nil {
			e = fmt.Errorf("getOIDCUserInfo panic: %v", p)
		}
	}()

	ctx, cancel := context.WithTimeout(context.Background(), OIDC_TIMEOUT)
	defer cancel()

	oauth2Token, err := auth_provider.Exchange(ctx, code)
	if err != nil {
		return nil, fmt.Errorf("failed to exchange oauth2 token using code \"%s\"", code)
	}

	rawIDToken, ok := oauth2Token.Extra("id_token").(string)
	if !ok {
		return nil, fmt.Errorf("failed to get raw id_token from oauth2 token")
	}

	idToken, err := oidc_verifier.Verify(ctx, rawIDToken)
	if err != nil {
		return nil, fmt.Errorf("failed to verify raw id_token: \"%s\"", err.Error())
	}

	u = &OAuthUser{}
	if err := idToken.Claims(u); err != nil {
		e = fmt.Errorf("error when claiming OIDCUser: \"%s\"", err.Error())
	}

	return
}

func verifyOIDCUser(token *oauth2.Token) bool {
	return token.Valid()
}