package users

import (
	"encoding/json"
	"net/http"
	"os"
	"time"

	"github.com/dustinpianalto/errors"
	"github.com/dustinpianalto/quartermaster"
	"github.com/dustinpianalto/quartermaster/pkg/services"
	"github.com/golang-jwt/jwt"
	"golang.org/x/crypto/bcrypt"
)

var jwtKey = []byte(os.Getenv("JWT_KEY"))

func loginHandler(w http.ResponseWriter, r *http.Request) error {
	const method errors.Method = "users/login"
	var userReq quartermaster.User
	err := json.NewDecoder(r.Body).Decode(&userReq)
	if err != nil {
		return errors.E(method, errors.Malformed, "failed to decode user request", err)
	}

	user, err := services.UserService.User(userReq.Username)
	if err != nil {
		return errors.E(method, errors.Username(userReq.Username), errors.Incorrect, "user not found", err)
	}

	if err := bcrypt.CompareHashAndPassword([]byte(user.Password), []byte(userReq.Password)); err != nil {
		return errors.E(method, errors.Username(userReq.Username), errors.Incorrect, "incorrect password", err)
	}

	expires := time.Now().Add(10 * time.Minute)
	claims := &quartermaster.Claims{
		ID:       user.ID,
		Username: user.Username,
		StandardClaims: jwt.StandardClaims{
			ExpiresAt: expires.Unix(),
		},
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS512, claims)
	tokenString, err := token.SignedString(jwtKey)
	if err != nil {
		return errors.E(method, errors.Username(user.Username), errors.Internal, "error signing token", err)
	}

	http.SetCookie(w, &http.Cookie{
		Name:    "token",
		Value:   tokenString,
		Expires: expires,
	})

	return nil
}

func registerHandler(w http.ResponseWriter, r *http.Request) error {
	const method errors.Method = "users/register"
	var user *quartermaster.User
	err := json.NewDecoder(r.Body).Decode(&user)
	if err != nil {
		return errors.E(method, errors.Malformed, "failed to decode user request", err)
	}

	p, err := bcrypt.GenerateFromPassword([]byte(user.Password), 5)
	if err != nil {
		return errors.E(method, errors.Username(user.Username), errors.Internal, "error hashing password", err)
	}
	user.Password = string(p)

	user, err = services.UserService.AddUser(user)
	if err != nil {
		return errors.E(method, errors.Username(user.Username), errors.Conflict, "user already exists", err)
	}

	return nil
}

func refreshHandler(w http.ResponseWriter, r *http.Request) error {
	const method errors.Method = "users/refresh"
	c, err := r.Cookie("token")
	if err != nil {
		if err == http.ErrNoCookie {
			return errors.E(method, errors.Incorrect, "cookie not found", err)
		}
		return errors.E(method, errors.Malformed, "failed to get cookie data", err)
	}
	tknStr := c.Value
	claims := &quartermaster.Claims{}
	tkn, err := jwt.ParseWithClaims(tknStr, claims, func(token *jwt.Token) (interface{}, error) {
		return jwtKey, nil
	})
	if err != nil {
		if err == jwt.ErrSignatureInvalid {
			return errors.E(method, errors.Incorrect, "cookie is invalid", err)
		}
		e, _ := err.(*jwt.ValidationError)
		if e.Inner == jwt.ErrInvalidKeyType {
			return errors.E(method, errors.Internal, err)
		} else if e.Inner == jwt.ErrHashUnavailable {
			return errors.E(method, errors.Internal, err)
		}
		return errors.E(method, errors.Malformed, "failed to parse cookie", err)
	}
	if !tkn.Valid {
		return errors.E(method, errors.Incorrect, "cookie is invalid", err)
	}

	// We ensure that a new token is not issued until enough time has elapsed
	// In this case, a new token will only be issued if the old token is within
	// 2 minutes of expiry. Otherwise, return a bad request status
	if time.Until(time.Unix(claims.StandardClaims.ExpiresAt, 0)) >= 2*time.Minute {
		return errors.E(method, errors.Malformed, "not enough time passed")
	}

	// Now, create a new token for the current use, with a renewed expiration time
	expirationTime := time.Now().Add(10 * time.Minute)
	claims.StandardClaims.ExpiresAt = expirationTime.Unix()
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	tokenString, err := token.SignedString(jwtKey)
	if err != nil {
		return errors.E(method, errors.Internal, "error signing token", err)
	}

	// Set the new token as the users `token` cookie
	http.SetCookie(w, &http.Cookie{
		Name:    "token",
		Value:   tokenString,
		Expires: expirationTime,
	})

	return nil
}