package auth

import (
	"bytes"
	"database/sql"
	"encoding/json"
	"fmt"
	"git.minhas.io/asara/sudoscientist-go-backend/packages/middleware"
	"git.minhas.io/asara/sudoscientist-go-backend/packages/users"
	"github.com/badoux/checkmail"
	"github.com/dgrijalva/jwt-go"
	"github.com/go-chi/chi"
	"github.com/go-chi/jwtauth"
	"github.com/go-chi/render"
	"golang.org/x/crypto/bcrypt"
	"net/http"
	"os"
	"strings"
	"time"
)

var (
	DB            *sql.DB
	TokenAuth     *jwtauth.JWTAuth
	EmailAuth     *jwtauth.JWTAuth
	PostalEnabled bool
	PostalKey     string
	PostalAPI     string
	PostalEmail   string
)

func Init() {
	if postal_key, ok := os.LookupEnv("POSTAL_KEY"); ok {
		if postal_api, ok := os.LookupEnv("POSTAL_API"); ok {
			if email_src, ok := os.LookupEnv("POSTAL_SRC_EMAIL"); ok {
				if email_auth, ok := os.LookupEnv("EMAIL_SECRET"); ok {
					EmailAuth = jwtauth.New("HS256", []byte(email_auth), nil)
					PostalKey = postal_key
					PostalAPI = postal_api
					PostalEmail = email_src
					PostalEnabled = true
					fmt.Println("Postal Enabled")
				}
			}
		}
	}
}

type ReturnMessage struct {
	Message string `json:"msg"`
	Error   bool   `json:"error"`
}

type SignUpCredentials struct {
	Username string `json:"username", db:"username"`
	Email    string `json:"email", db:"email"`
	Password string `json:"password", db:"password"`
}

type UserCredentials struct {
	Username string `json:"username", db:"username"`
	Password string `json:"password", db:"password"`
}

type Claims struct {
	Username string `json:"username", db:"username"`
	Admin    bool   `json:"admin", db:"admin"`
	Verified bool   `json:"verified", db:"verified"`
	jwt.StandardClaims
}

type JWT struct {
	JWT string `json:"jwt"`
}

type ComposedEmail struct {
	To         [1]string `json:"to"`
	From       string    `json:"from"`
	Subject    string    `json:"subject"`
	Plain_body string    `json:"plain_body"`
}

func Routes() *chi.Mux {
	r := chi.NewRouter()
	r.Group(func(r chi.Router) {
		r.Use(jwtauth.Verify(EmailAuth, auth_middleware.TokenFromUrl))
		r.Use(jwtauth.Authenticator)
		r.Get("/verify/{token}", verify)
	})
	r.Post("/signin", signin)
	r.Post("/register", register)
	r.Group(func(r chi.Router) {
		r.Use(jwtauth.Verify(TokenAuth, auth_middleware.TokenFromSplitCookie))
		r.Use(jwtauth.Authenticator)
		r.Post("/refresh", refresh)
	})
	return r
}

func verify(w http.ResponseWriter, r *http.Request) {
	returnMessage := ReturnMessage{}
	returnMessage.Error = false
	_, claims, _ := jwtauth.FromContext(r.Context())
	sqlStatement := `
	UPDATE users
	SET verified = $1
	WHERE username = $2;`
	_, err := DB.Exec(sqlStatement, true, claims["username"])
	if err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		returnMessage.Message = "unexpected error verifying account. please contact the administrator"
		returnMessage.Error = true
		render.JSON(w, r, returnMessage)
		return
	}
	w.WriteHeader(http.StatusOK)
	returnMessage.Message = "your email has been verified!"
	render.JSON(w, r, returnMessage)
	return
}

func register(w http.ResponseWriter, r *http.Request) {
	returnMessage := ReturnMessage{}
	returnMessage.Error = false
	creds := &SignUpCredentials{}
	err := json.NewDecoder(r.Body).Decode(creds)
	if err != nil {
		fmt.Println(err)
		w.WriteHeader(http.StatusBadRequest)
		returnMessage.Message = "bad data provided"
		returnMessage.Error = true
		render.JSON(w, r, returnMessage)
		return
	}
	if creds.Username == "" {
		returnMessage.Message = "username is required"
		returnMessage.Error = true
		w.WriteHeader(http.StatusBadRequest)
		render.JSON(w, r, returnMessage)
		return
	}
	if creds.Password == "" {
		returnMessage.Message = "password is required"
		returnMessage.Error = true
		w.WriteHeader(http.StatusBadRequest)
		render.JSON(w, r, returnMessage)
		return
	}
	if creds.Email == "" {
		returnMessage.Message = "email is required"
		returnMessage.Error = true
		w.WriteHeader(http.StatusBadRequest)
		render.JSON(w, r, returnMessage)
		return
	}
	err = checkmail.ValidateFormat(creds.Email)
	if err != nil {
		returnMessage.Message = "email not valid"
		returnMessage.Error = true
		w.WriteHeader(http.StatusBadRequest)
		render.JSON(w, r, returnMessage)
		return
	}

	hashedPassword, err := bcrypt.GenerateFromPassword([]byte(creds.Password), 10)
	s := `INSERT INTO users (username, email, password, admin, verified)
          VALUES ($1, $2, $3, $4, $5)`
	if _, err = DB.Exec(s, creds.Username, creds.Email, string(hashedPassword), false, false); err != nil {
		fmt.Println(err)
		returnMessage.Message = "unexpected error. please contact the administrator"
		returnMessage.Error = true
		w.WriteHeader(http.StatusInternalServerError)
		render.JSON(w, r, returnMessage)
		return
	}
	users.CreateProfile(creds.Username, creds.Email)
	expirationTime := time.Now().Add(24 * time.Hour)
	claims := &Claims{
		Username: creds.Username,
		Admin:    false,
		Verified: false,
		StandardClaims: jwt.StandardClaims{
			ExpiresAt: expirationTime.Unix(),
		},
	}
	if PostalEnabled {
		_, emailToken, _ := EmailAuth.Encode(claims)
		returnMessage, ok := sendEmailToken(w, emailToken, creds.Username, creds.Email)
		if !ok {
			w.WriteHeader(http.StatusInternalServerError)
			render.JSON(w, r, returnMessage)
			return
		}
		w.WriteHeader(http.StatusCreated)
		render.JSON(w, r, returnMessage)
		return
	}
	_, tokenString, _ := TokenAuth.Encode(claims)
	setCookies(w, tokenString, expirationTime)
	w.WriteHeader(http.StatusCreated)
	returnMessage.Message = "User created! Welcome to the site!"
	render.JSON(w, r, returnMessage)
	return
}

func signin(w http.ResponseWriter, r *http.Request) {
	returnMessage := ReturnMessage{}
	returnMessage.Error = false
	creds := &UserCredentials{}
	err := json.NewDecoder(r.Body).Decode(creds)
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		returnMessage.Message = "bad data provided"
		returnMessage.Error = true
		render.JSON(w, r, returnMessage)
		return
	}
	verify_pw, ok := checkPassword(w, *creds)
	if !ok {
		w.WriteHeader(http.StatusBadRequest)
		returnMessage.Message = verify_pw
		returnMessage.Error = true
		render.JSON(w, r, returnMessage)
		return
	}
	expirationTime := time.Now().Add(24 * time.Hour)
	user_claims := &Claims{}
	user_claims_query := DB.QueryRow("SELECT username, admin, verified FROM users WHERE username=$1", creds.Username)
	err = user_claims_query.Scan(&user_claims.Username, &user_claims.Admin, &user_claims.Verified)
	claims := &Claims{
		Username: user_claims.Username,
		Admin:    user_claims.Admin,
		Verified: user_claims.Verified,
		StandardClaims: jwt.StandardClaims{
			ExpiresAt: expirationTime.Unix(),
		},
	}
	_, tokenString, _ := TokenAuth.Encode(claims)
	setCookies(w, tokenString, expirationTime)
	w.WriteHeader(http.StatusOK)
	render.JSON(w, r, returnMessage)
}

func refresh(w http.ResponseWriter, r *http.Request) {
	returnMessage := ReturnMessage{}
	returnMessage.Error = false
	_, claims, _ := jwtauth.FromContext(r.Context())
	w.WriteHeader(http.StatusOK)
	expirationTime := time.Now().Add(24 * time.Hour)
	user_claims := &Claims{}
	user_claims_query := DB.QueryRow("SELECT username, admin, verified FROM users WHERE username=$1", claims["username"].(string))
	err := user_claims_query.Scan(&user_claims.Username, &user_claims.Admin, &user_claims.Verified)
	if err != nil {
		fmt.Println(err)
		w.WriteHeader(http.StatusInternalServerError)
		returnMessage.Message = "unexpected error refreshing your token, please try again later"
		returnMessage.Error = true
		render.JSON(w, r, returnMessage)
		return
	}
	newClaims := &Claims{
		Username: user_claims.Username,
		Admin:    user_claims.Admin,
		Verified: user_claims.Verified,
		StandardClaims: jwt.StandardClaims{
			ExpiresAt: expirationTime.Unix(),
		},
	}
	_, tokenString, _ := TokenAuth.Encode(newClaims)
	setCookies(w, tokenString, expirationTime)
	w.WriteHeader(http.StatusOK)
	returnMessage.Message = "jwt refreshed"
	render.JSON(w, r, returnMessage)
}

func setCookies(w http.ResponseWriter, jwt string, expiration time.Time) {
	splitToken := strings.Split(jwt, ".")
	dataCookie := http.Cookie{Name: "DataCookie", Value: strings.Join(splitToken[:2], "."), Expires: expiration, HttpOnly: false, Path: "/", Domain: os.Getenv("UI_ADDR"), MaxAge: 360}
	http.SetCookie(w, &dataCookie)
	signatureCookie := http.Cookie{Name: "SignatureCookie", Value: splitToken[2], Expires: expiration, HttpOnly: true, Path: "/", Domain: os.Getenv("UI_ADDR"), MaxAge: 360}
	http.SetCookie(w, &signatureCookie)
	return
}

func sendEmailToken(w http.ResponseWriter, token string, name string, email string) (returnMessage ReturnMessage, ok bool) {
	header := "Thanks for joining sudoscientist, " + name + "!"
	body := "\n\nPlease click the following link to verify your email: "
	link := os.Getenv("API_ADDR") + "/v1/api/auth/verify/" + token
	email_array := [1]string{email}
	composed_email := ComposedEmail{
		To:         email_array,
		From:       PostalEmail,
		Subject:    "sudoscientist: Please confirm your e-mail address",
		Plain_body: header + body + link,
	}
	postal_req, err := json.Marshal(&composed_email)
	if err != nil {
		fmt.Println(err)
		returnMessage.Message = "unexpected error. your account may be in limbo. please contact the administrator"
		ok = false
		return returnMessage, ok
	}
	req, err := http.NewRequest("POST", fmt.Sprintf("%s/api/v1/send/message", PostalAPI), bytes.NewBuffer(postal_req))
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("X-Server-API-Key", PostalKey)
	if err != nil {
		fmt.Println(err)
		returnMessage.Message = "unexpected error. your account may be in limbo. please contact the administrator"
		ok = false
		return returnMessage, ok
	}
	client := &http.Client{}
	resp, err := client.Do(req)
	if err != nil {
		fmt.Println(err)
		returnMessage.Message = "unexpected error. your account may be in limbo. please contact the administrator"
		ok = false
		return returnMessage, ok
	}
	defer resp.Body.Close()
	returnMessage.Message = "verification email sent"
	ok = true
	return returnMessage, ok
}

func checkPassword(w http.ResponseWriter, creds UserCredentials) (string, bool) {
	returnMessage := ""
	result := DB.QueryRow("SELECT password FROM users WHERE username=$1", creds.Username)
	storedCreds := &UserCredentials{}
	err := result.Scan(&storedCreds.Password)
	if err != nil {
		if err == sql.ErrNoRows {
			w.WriteHeader(http.StatusUnauthorized)
			returnMessage = "username or password incorrect"
			return returnMessage, false
		}
		w.WriteHeader(http.StatusInternalServerError)
		returnMessage = "something is broken, please contact the administrator"
		return returnMessage, false
	}
	if err = bcrypt.CompareHashAndPassword([]byte(storedCreds.Password), []byte(creds.Password)); err != nil {
		w.WriteHeader(http.StatusUnauthorized)
		returnMessage = "username or password incorrect"
		return returnMessage, false
	}
	returnMessage = "user logged in"
	return returnMessage, true
}