package main

import (
	"auth-server/logic"
	"context"
	"net/url"
	"os"
	"strconv"

	"github.com/go-oauth2/oauth2/v4/errors"
	"github.com/go-oauth2/oauth2/v4/manage"
	"github.com/go-oauth2/oauth2/v4/server"
	"github.com/go-oauth2/oauth2/v4/store"
	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
	"github.com/nspcc-dev/neo-go/pkg/rpcclient"
	"github.com/nspcc-dev/neo-go/pkg/rpcclient/actor"
	"github.com/nspcc-dev/neo-go/pkg/util"
	"github.com/nspcc-dev/neo-go/pkg/wallet"

	"log"
	"log/slog"
	"net/http"
)

func main() {
	config, err := logic.LoadConfig("./config.json")
	if err != nil {
		log.Fatalf("Error while reading config: %s", err)
		return
	}

	slog.Info("ContractCheckSum: " + config.ContractCheckSum)
	slog.Info("AuthServerPort: " + strconv.Itoa(config.AuthServerPort))
	slog.Info("WalletFile: " + config.WalletFile)
	slog.Info("EndpointUrl: " + config.EndpointUrl)
	slog.Info("AccountSecret: " + config.AccountSecret)

	manager := manage.NewDefaultManager()
	manager.SetAuthorizeCodeTokenCfg(manage.DefaultAuthorizeCodeTokenCfg)

	// contract integration
	fileWallet, err := wallet.NewWalletFromFile(config.WalletFile)
	if err != nil {
		log.Fatalln("Wallet loading failed.", err)
	}

	acc := fileWallet.Accounts[0]
	if err := acc.Decrypt(config.AccountSecret, keys.NEP2ScryptParams()); err != nil {
		log.Fatal("Wallet decryption failed")
	}
	defer fileWallet.Close()

	// In idea we need an rpc-server(?)
	rpcClient, _ := rpcclient.New(context.Background(), config.EndpointUrl, rpcclient.Options{})
	rpcActor, _ := actor.NewSimple(rpcClient, fileWallet.Accounts[0])

	// smart contract check sum
	var contractHash, _ = util.Uint160DecodeStringLE(config.ContractCheckSum)

	// using blockchain storage
	blockchainStorage := logic.NewBlockchainStorage(rpcActor, contractHash)

	// using default in memory token storage
	manager.MustTokenStorage(store.NewMemoryTokenStore())

	manager.MapClientStorage(blockchainStorage)

	srv := server.NewDefaultServer(manager)
	srv.SetAllowGetAccessRequest(true)
	srv.SetClientInfoHandler(server.ClientFormHandler)
	manager.SetRefreshTokenCfg(manage.DefaultRefreshTokenCfg)

	srv.SetInternalErrorHandler(func(err error) (re *errors.Response) {
		log.Println("Internal Error:", err.Error())
		return
	})

	srv.SetResponseErrorHandler(func(re *errors.Response) {
		log.Println("Response Error:", re.Error.Error())
	})

	http.HandleFunc("/login", func(w http.ResponseWriter, r *http.Request) {
		id := r.URL.Query().Get("client_id")
		secret := r.URL.Query().Get("client_secret")
		secret_hash := logic.HashSecret(secret)

		_, err := blockchainStorage.CheckPassword(id, secret_hash)
		if err != nil {
			msg := "Credentials verification failed"
			slog.Warn(msg + " for client with id: " + id)
			w.WriteHeader(http.StatusForbidden)
			w.Write([]byte(msg))
		}

		r.Form = make(url.Values)
		r.Form.Add("client_id", id)
		r.Form.Add("client_secret", secret_hash)
		r.Form.Add("grant_type", r.URL.Query().Get("grant_type"))
		r.Form.Add("scope", r.URL.Query().Get("scope"))

		srv.HandleTokenRequest(w, r) // verifying secret
	})

	http.HandleFunc("/register", func(writer http.ResponseWriter, request *http.Request) {
		id := request.Header.Get("client_id")
		secret := request.Header.Get("client_secret")

		// check whether client exists
		_, err := blockchainStorage.GetByID(context.Background(), id)
		if err == nil {
			msg := "Client already exists with id: " + id
			slog.Warn(msg)
			writer.WriteHeader(http.StatusBadRequest)
			writer.Write([]byte(msg))
			return
		}

		/* redundant
		// add client's credentials to in memory storage
		err = logic.AddInMemoryClient(id, "", "", false)
		if err != nil {
			slog.Error("Fault during setting client credentials", err)
			writer.WriteHeader(http.StatusInternalServerError)
			return
		}
		*/

		// add client's credentials to blockchain
		err = blockchainStorage.Set(&logic.StorageClientInfo{
			Id:     id,
			Secret: logic.HashSecret(secret), // hash with sha256
		})

		if err != nil {
			slog.Error("Failed to register user with id: "+id, err)
			writer.WriteHeader(http.StatusInternalServerError)
			return
		}

		writer.WriteHeader(http.StatusOK)
	})

	// for tests, can access only with valid token (when logged in)
	http.HandleFunc("/protected", logic.ValidateToken(func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte("Hello, I'm protected"))
	}, srv))

	// can access only with valid token (when logged in), deletes client
	http.HandleFunc("/delete", logic.ValidateToken(func(w http.ResponseWriter, r *http.Request) {
		id := r.Header.Get("client_id")
		errorMessage := "Fault during deleting client"

		// check whether client exists
		_, err := blockchainStorage.GetByID(context.Background(), id)
		if err != nil {
			msg := "Client not found with id: " + id
			slog.Warn(msg)
			w.WriteHeader(http.StatusBadRequest)
			w.Write([]byte(msg))
			return
		}

		err = blockchainStorage.Delete(id)
		if err != nil {
			slog.Error(errorMessage+" (caused by blockchain) with id: "+id, err)
			w.WriteHeader(http.StatusInternalServerError)
			w.Write([]byte(errorMessage))
		}

		/*  redundant
		logic.DeleteInMemoryClient(id)
		*/

	}, srv))

	// can access only with valid token (when logged in), deletes client and creates new one with another secret
	http.HandleFunc("/reset-secret", logic.ValidateToken(func(w http.ResponseWriter, r *http.Request) {
		id := r.Header.Get("client_id")
		secret := r.Header.Get("new_client_secret")
		errorMessage := "Fault during secret reset"

		// check whether client exists
		_, err := blockchainStorage.GetByID(context.Background(), id)
		if err != nil {
			msg := "Client not found with id: " + id
			slog.Warn(msg)
			w.WriteHeader(http.StatusBadRequest)
			w.Write([]byte(msg))
			return
		}

		err = blockchainStorage.Delete(id)
		if err != nil {
			slog.Error(errorMessage+" for client with id: "+id, err)
			w.WriteHeader(http.StatusInternalServerError)
			w.Write([]byte(errorMessage))
		}

		/* redundant
		logic.DeleteInMemoryClient(id)
		*/

		/*
			// add client with new credentials to in memory storage
			err = logic.AddInMemoryClient(id, "", "", false)
			if err != nil {
				slog.Error(errorMessage+" (caused by in memory storage) for client with id: "+id, err)
				w.WriteHeader(http.StatusInternalServerError)
				w.Write([]byte(errorMessage))
				return
			}
		*/

		// add client with new credentials to blockchain
		err = blockchainStorage.Set(&logic.StorageClientInfo{
			Id:     id,
			Secret: logic.HashSecret(secret), // hash with sha256
		})

		if err != nil {
			slog.Error(errorMessage+" (caused by blockchain storage) for client with id: "+id, err)
			w.WriteHeader(http.StatusInternalServerError)
			w.Write([]byte(errorMessage))
			return
		}
	}, srv))

	http.HandleFunc("/login.html", func(w http.ResponseWriter, r *http.Request) {
		outputHTML(w, r, "static/login.html")
	})

	http.HandleFunc("/register.html", func(w http.ResponseWriter, r *http.Request) {
		outputHTML(w, r, "static/register.html")
	})

	log.Fatal(http.ListenAndServe(":"+strconv.Itoa(config.AuthServerPort), nil))
}

func outputHTML(w http.ResponseWriter, req *http.Request, filename string) {
	file, err := os.Open(filename)
	if err != nil {
		http.Error(w, err.Error(), 500)
		return
	}
	defer file.Close()
	fi, _ := file.Stat()
	http.ServeContent(w, req, file.Name(), fi.ModTime(), file)
}