package main

import (
	"bytes"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"net/http"
	"net/url"
	"syscall/js"
	"time"

	"golang.org/x/crypto/argon2"
)

var currentInputType = 0

func hashPassword(password string, salt []byte) string {
	return base64.StdEncoding.EncodeToString(
		argon2.IDKey(
			[]byte(password),
			salt,
			32,
			19264,
			1,
			32,
		),
	)
}

func showInput(inputType int, inputContainer js.Value, usernameBox js.Value, signupButton js.Value, passwordBox js.Value, backButton js.Value, inputNameBox js.Value, statusBox js.Value, nextButton js.Value) {
	if inputType == 0 {
		// Show login
		inputContainer.Get("classList").Call("remove", "hidden")
		usernameBox.Get("classList").Call("remove", "hidden")
		signupButton.Get("classList").Call("remove", "hidden")
		passwordBox.Get("classList").Call("add", "hidden")
		backButton.Get("classList").Call("add", "hidden")
		inputNameBox.Set("innerText", "Username:")
		// Get the current service name
		serviceName := js.Global().Get("document").Call("getElementById", "passThrough").Get("innerText").String()

		// Set the service name
		statusBox.Set("innerText", "Login to your "+serviceName+" account!")

		// Set the current input type
		currentInputType = 0
	} else if inputType == 1 {
		inputContainer.Get("classList").Call("remove", "hidden")
		signupButton.Get("classList").Call("add", "hidden")
		usernameBox.Get("classList").Call("add", "hidden")
		passwordBox.Get("classList").Call("remove", "hidden")
		backButton.Get("classList").Call("remove", "hidden")
		inputNameBox.Get("classList").Call("remove", "hidden")
		nextButton.Get("classList").Call("remove", "hidden")
		inputNameBox.Get("classList").Call("remove", "hidden")
		inputNameBox.Set("innerText", "Password:")
		currentInputType = 1
	} else if inputType == 2 {
		signupButton.Get("classList").Call("add", "hidden")
		nextButton.Get("classList").Call("add", "hidden")
		backButton.Get("classList").Call("add", "hidden")
		inputContainer.Get("classList").Call("add", "hidden")
		inputNameBox.Get("classList").Call("add", "hidden")
		passwordBox.Get("classList").Call("add", "hidden")
		usernameBox.Get("classList").Call("add", "hidden")
		currentInputType = 2
	}
}

func main() {
	// Redirect to app if already signed in
	localStorage := js.Global().Get("localStorage")
	if !localStorage.Call("getItem", "DONOTSHARE-secretKey").IsNull() {
		js.Global().Get("window").Get("location").Call("replace", "/authorize"+js.Global().Get("window").Get("location").Get("search").String())
	}

	var usernameBox = js.Global().Get("document").Call("getElementById", "usernameBox")
	var passwordBox = js.Global().Get("document").Call("getElementById", "passwordBox")
	var statusBox = js.Global().Get("document").Call("getElementById", "statusBox")
	var nextButton = js.Global().Get("document").Call("getElementById", "nextButton")
	var backButton = js.Global().Get("document").Call("getElementById", "backButton")
	var signupButton = js.Global().Get("document").Call("getElementById", "signupButton")
	var inputNameBox = js.Global().Get("document").Call("getElementById", "inputNameBox")
	var inputContainer = js.Global().Get("document").Call("getElementById", "inputContainer")

	// Show the login screen
	showInput(0, inputContainer, usernameBox, signupButton, passwordBox, backButton, inputNameBox, statusBox, nextButton)

	nextButton.Call("addEventListener", "click", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
		go func() {
			if currentInputType == 0 {
				if usernameBox.Get("value").IsNull() {
					statusBox.Set("innerText", "A username is required!")
					return
				} else {
					statusBox.Set("innerText", "Welcome back, "+usernameBox.Get("value").String()+"!")
					showInput(1, inputContainer, usernameBox, signupButton, passwordBox, backButton, inputNameBox, statusBox, nextButton)
				}
			} else if currentInputType == 1 {
				password := passwordBox.Get("value").String()
				username := usernameBox.Get("value").String()

				if passwordBox.Get("value").IsNull() {
					statusBox.Set("innerText", "A password is required!")
					return
				}

				showInput(2, inputContainer, usernameBox, signupButton, passwordBox, backButton, inputNameBox, statusBox, nextButton)

				// Hash the password
				statusBox.Set("innerText", "Hashing password...")
				fmt.Println("Hashing password...")

				// Fetch the salt from the server
				body, err := json.Marshal(map[string]interface{}{
					"username": username,
				})

				if err != nil {
					showInput(1, inputContainer, usernameBox, signupButton, passwordBox, backButton, inputNameBox, statusBox, nextButton)
					statusBox.Set("innerText", "Error marshaling salt body: "+err.Error())
					return
				}

				requestUri, err := url.JoinPath(js.Global().Get("window").Get("location").Get("origin").String(), "/api/loginChallenge")
				if err != nil {
					showInput(1, inputContainer, usernameBox, signupButton, passwordBox, backButton, inputNameBox, statusBox, nextButton)
					statusBox.Set("innerText", "Error joining URL: "+err.Error())
					return
				}

				response, err := http.Post(requestUri, "application/json", bytes.NewReader(body))
				if err != nil {
					showInput(1, inputContainer, usernameBox, signupButton, passwordBox, backButton, inputNameBox, statusBox, nextButton)
					statusBox.Set("innerText", "Error contacting server: "+err.Error())
					return
				}

				// Get all our ducks in a row
				var responseMap map[string]interface{}

				// Read the response
				decoder := json.NewDecoder(response.Body)
				err = decoder.Decode(&responseMap)
				if err != nil {
					showInput(1, inputContainer, usernameBox, signupButton, passwordBox, backButton, inputNameBox, statusBox, nextButton)
					statusBox.Set("innerText", "Error decoding server response: "+err.Error())
					return
				}

				// Close the response body
				err = response.Body.Close()
				if err != nil {
					fmt.Println("Could not close response body: " + err.Error() + ", memory leaks may occur")
				}

				// Decode the salt
				salt, err := base64.StdEncoding.DecodeString(responseMap["salt"].(string))
				if err != nil {
					showInput(1, inputContainer, usernameBox, signupButton, passwordBox, backButton, inputNameBox, statusBox, nextButton)
					statusBox.Set("innerText", "Error decoding salt: "+err.Error())
					return
				}

				hashedPassword := hashPassword(password, salt)

				// Hashed password computed, contact server
				statusBox.Set("innerText", "Contacting server...")
				signupBody := map[string]interface{}{
					"username": username,
					"password": hashedPassword,
				}

				// Marshal the body
				body, err = json.Marshal(signupBody)
				if err != nil {
					showInput(1, inputContainer, usernameBox, signupButton, passwordBox, backButton, inputNameBox, statusBox, nextButton)
					statusBox.Set("innerText", "Error marshaling signup body: "+err.Error())
					return
				}

				// Send the password to the server
				requestUri, err = url.JoinPath(js.Global().Get("window").Get("location").Get("origin").String(), "/api/login")
				if err != nil {
					showInput(1, inputContainer, usernameBox, signupButton, passwordBox, backButton, inputNameBox, statusBox, nextButton)
					statusBox.Set("innerText", "Error joining URL: "+err.Error())
					return
				}

				// Send the request
				fmt.Println("Sending request to", requestUri)
				response, err = http.Post(requestUri, "application/json", bytes.NewReader(body))
				if err != nil {
					showInput(1, inputContainer, usernameBox, signupButton, passwordBox, backButton, inputNameBox, statusBox, nextButton)
					statusBox.Set("innerText", "Error contacting server: "+err.Error())
					return
				}

				// Read the response
				fmt.Println("Reading response...")
				decoder = json.NewDecoder(response.Body)
				err = decoder.Decode(&responseMap)
				if err != nil {
					showInput(1, inputContainer, usernameBox, signupButton, passwordBox, backButton, inputNameBox, statusBox, nextButton)
					statusBox.Set("innerText", "Error decoding server response: "+err.Error())
					return
				}

				// Close the response body
				err = response.Body.Close()
				if err != nil {
					fmt.Println("Could not close response body: " + err.Error() + ", memory leaks may occur")
				}

				if response.StatusCode == 200 {
					// Logged in
					fmt.Println("Logged in!")
					statusBox.Set("innerText", "Setting up encryption keys...")
					localStorage.Call("setItem", "DONOTSHARE-secretKey", responseMap["key"].(string))
					localStorage.Call("setItem", "DONOTSHARE-clientKey", hashPassword(password, []byte("fg-auth-client")))

					// Redirect to app
					statusBox.Set("innerText", "Welcome!")
					time.Sleep(time.Second)
					js.Global().Get("window").Get("location").Call("replace", "/authorize"+js.Global().Get("window").Get("location").Get("search").String())
				} else if response.StatusCode == 401 {
					// Login failed
					showInput(1, inputContainer, usernameBox, signupButton, passwordBox, backButton, inputNameBox, statusBox, nextButton)
					statusBox.Set("innerText", "Username or password incorrect!")
				} else {
					// Unknown error
					showInput(1, inputContainer, usernameBox, signupButton, passwordBox, backButton, inputNameBox, statusBox, nextButton)
					statusBox.Set("innerText", "Something went wrong! (error code: "+responseMap["code"].(string)+")")
				}
			}
		}()

		return nil
	}))

	backButton.Call("addEventListener", "click", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
		go func() {
			showInput(0, inputContainer, usernameBox, signupButton, passwordBox, backButton, inputNameBox, statusBox, nextButton)
			return
		}()

		return nil
	}))

	signupButton.Call("addEventListener", "click", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
		js.Global().Get("window").Get("location").Call("replace", "/signup"+js.Global().Get("window").Get("location").Get("search").String())
		return nil
	}))

	// Wait for events
	select {}
}