package dbhandler

import (
	"context"
	"crypto/rand"
	"encoding/base64"
	"fmt"
	"log"

	"git.acooldomain.co/server-manager/backend/models"
	"github.com/coreos/go-oidc"
	"golang.org/x/oauth2"
)

type CallbackRequest struct {
	Code string `json:"code"`
}

type OidcClaims struct {
	Email       string
	Profile     string
	Permissions models.Permission
}

type OidcAuthenticationDbHandler struct {
	provider     *oidc.Provider
	oauth2Config *oauth2.Config
}

func GenerateOidcState() string {
	b := make([]byte, 16)
	_, err := rand.Read(b)
	if err != nil {
		log.Fatal(err)
	}

	return base64.URLEncoding.EncodeToString(b)
}

func (self *OidcAuthenticationDbHandler) AuthenticateUser(ctx context.Context, request CallbackRequest) (models.Permission, error) {
	token, err := self.oauth2Config.Exchange(ctx, request.Code)
	if err != nil {
		return 0, err
	}

	verifier := self.provider.Verifier(&oidc.Config{ClientID: self.oauth2Config.ClientID})
	idToken, ok := token.Extra("id_token").(string)

	if !ok {
		return 0, fmt.Errorf("Failed to convert id_token to string")
	}

	tokenObj, err := verifier.Verify(ctx, idToken)
	var claims OidcClaims

	if err := tokenObj.Claims(&claims); err != nil {
		return 0, err
	}

	return claims.Permissions, nil
}

func NewOidcAuthenticationDbHamdler(config models.OidcAuthConfig) (*OidcAuthenticationDbHandler, error) {
	provider, err := oidc.NewProvider(context.Background(), config.IssuerUrl)
	if err != nil {
		return nil, err
	}

	return &OidcAuthenticationDbHandler{
		provider: provider,
		oauth2Config: &oauth2.Config{
			ClientID:     config.ClientId,
			ClientSecret: config.ClientSecret,
			Endpoint:     provider.Endpoint(),
			Scopes:       []string{oidc.ScopeOpenID, "email", "name", "profile"},
		},
	}, nil
}