package auth

import (
	"crypto/sha512"
	"encoding/hex"
	"log"
	"strconv"
	"strings"
	"time"

	"git.xdrm.io/example/aicra/storage"
	"git.xdrm.io/go/aicra"
	"git.xdrm.io/go/aicra/api"
)

// Service manages the url shortener
type Service struct {
	storage *storage.Client
}

// New returns a bare service
func New(storage *storage.Client) *Service {
	log.Printf("[service.auth] created")
	return &Service{
		storage: storage,
	}
}

// Wire to the aicra server
func (svc *Service) Wire(server *aicra.Server) {
	log.Printf("[service.auth] wired")
	server.HandleFunc("POST", "/token", svc.generateToken)
}

// generateToken generates a token valid for 5 mintes
func (svc *Service) generateToken(req api.Request, res *api.Response) {

	// 1. extract input
	role, err := req.Param.GetString("role")
	if err != nil {
		res.SetError(api.ErrorInvalidParam(), "role", err.Error())
		return
	}

	// 2. generate token
	hasher := sha512.New()
	defer hasher.Reset()
	hasher.Write([]byte(strconv.FormatInt(time.Now().Unix(), 5)))
	token := hex.EncodeToString(hasher.Sum(nil))

	// 3. store token
	if !svc.storage.Set(storage.TOKEN, token, role, 5*time.Minute) {
		res.SetError(api.ErrorFailure())
		return
	}

	// 4. return data
	res.Data["token"] = token
	res.SetError(api.ErrorSuccess())

}

// CheckToken returns whether a token is valid
func (svc *Service) CheckToken(handler api.HandlerFunc) api.HandlerFunc {
	return func(req api.Request, res *api.Response) {

		// success if no scope [['admin']]
		if req.Scope == nil || len(req.Scope) < 1 {
			handler(req, res)
			return
		}

		headerToken := req.Request.Header.Get("Authorization")

		// fail if invalid header
		if len(headerToken) != 128 || strings.ContainsAny(headerToken, "$-_") {
			res.SetError(api.ErrorPermission())
			return
		}

		tokenRole := svc.storage.Get(storage.TOKEN, headerToken)

		// fail if the role of the token does not match any scope
		for _, scope := range req.Scope {
			if scope == nil || len(scope) != 1 {
				continue
			}

			// success
			if scope[0] == string(tokenRole) {
				handler(req, res)
				return
			}
		}

		// failure
		res.SetError(api.ErrorPermission())
		return
	}
}