package main

import (
	"bytes"
	"time"

	"crypto/ed25519"
	"encoding/base64"
	"encoding/json"
	"syscall/js"

	"git.ailur.dev/ailur/jsFetch"
	"golang.org/x/crypto/argon2"
)

func main() {
	localStorage := js.Global().Get("localStorage")
	status := js.Global().Get("document").Call("getElementById", "status")
	loginButton := js.Global().Get("document").Call("getElementById", "login")
	username := js.Global().Get("document").Call("getElementById", "username")
	password := js.Global().Get("document").Call("getElementById", "password")

	if localStorage.Call("getItem", "server").IsNull() {
		localStorage.Call("setItem", "server", "https://chat.ailur.dev:1974")
	}

	if !localStorage.Call("getItem", "token").IsNull() {
		js.Global().Get("location").Set("href", "../")
		return
	}

	loginButton.Call("addEventListener", "click", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
		go func() {
			username.Set("disabled", true)
			password.Set("disabled", true)
			loginButton.Set("disabled", true)
			status.Set("innerText", "Generating encryption keys...")
			hash := argon2.IDKey(
				[]byte(password.Get("value").String()),
				[]byte(username.Get("value").String()),
				32,
				19264,
				1,
				32,
			)

			status.Set("innerText", "Retrieving challenge from server...")

			jsonBody, err := json.Marshal(map[string]interface{}{
				"username": username.Get("value").String(),
			})
			if err != nil {
				status.Set("innerText", "Failed to encode request: "+err.Error())
				username.Set("disabled", false)
				password.Set("disabled", false)
				loginButton.Set("disabled", false)
				return
			}

			response, err := jsFetch.Post(localStorage.Call("getItem", "server").String()+"/api/loginChallenge", "application/json", bytes.NewReader(jsonBody))
			if err != nil {
				status.Set("innerText", "Failed to contact server: "+err.Error())
				username.Set("disabled", false)
				password.Set("disabled", false)
				loginButton.Set("disabled", false)
				return
			}

			if response.StatusCode != 200 {
				if response.StatusCode == 500 {
					status.Set("innerText", "Something went wrong on our end. Please try again later.")
				} else {
					var body map[string]interface{}
					err := json.NewDecoder(response.Body).Decode(&body)
					if err != nil {
						status.Set("innerText", "Failed to decode response: "+err.Error())
					} else {
						status.Set("innerText", body["error"].(string))
					}
				}
				username.Set("disabled", false)
				password.Set("disabled", false)
				loginButton.Set("disabled", false)
				return
			}

			status.Set("innerText", "Signing challenge...")
			var body map[string]interface{}
			err = json.NewDecoder(response.Body).Decode(&body)
			if err != nil {
				status.Set("innerText", "Failed to decode response: "+err.Error())
				username.Set("disabled", false)
				password.Set("disabled", false)
				loginButton.Set("disabled", false)
				return
			}

			challenge, err := base64.StdEncoding.DecodeString(body["nonce"].(string))
			if err != nil {
				status.Set("innerText", "Failed to decode challenge: "+err.Error())
				username.Set("disabled", false)
				password.Set("disabled", false)
				loginButton.Set("disabled", false)
				return
			}

			signature := ed25519.Sign(ed25519.NewKeyFromSeed(hash), challenge)

			status.Set("innerText", "Contacting server...")

			jsonBody, err = json.Marshal(map[string]interface{}{
				"username":  username.Get("value").String(),
				"signature": base64.StdEncoding.EncodeToString(signature),
				"challenge": body["token"].(string),
			})
			if err != nil {
				status.Set("innerText", "Failed to encode request: "+err.Error())
				username.Set("disabled", false)
				password.Set("disabled", false)
				loginButton.Set("disabled", false)
				return
			}

			response, err = jsFetch.Post(localStorage.Call("getItem", "server").String()+"/api/login", "application/json", bytes.NewReader(jsonBody))
			if err != nil {
				status.Set("innerText", "Failed to contact server: "+err.Error())
				username.Set("disabled", false)
				password.Set("disabled", false)
				loginButton.Set("disabled", false)
				return
			}

			if response.StatusCode != 200 {
				if response.StatusCode == 500 {
					status.Set("innerText", "Something went wrong on our end. Please try again later.")
				} else {
					var body map[string]interface{}
					err := json.NewDecoder(response.Body).Decode(&body)
					if err != nil {
						status.Set("innerText", "Failed to decode response: "+err.Error())
					} else {
						status.Set("innerText", body["error"].(string))
					}
				}
				username.Set("disabled", false)
				password.Set("disabled", false)
				loginButton.Set("disabled", false)
				return
			}

			err = json.NewDecoder(response.Body).Decode(&body)
			if err != nil {
				status.Set("innerText", "Failed to decode response: "+err.Error())
				username.Set("disabled", false)
				password.Set("disabled", false)
				loginButton.Set("disabled", false)
				return
			}

			localStorage.Call("setItem", "token", body["token"].(string))
			localStorage.Call("setItem", "username", username.Get("value").String())
			localStorage.Call("setItem", "userId", body["userId"].(string))

			status.Set("innerText", "Welcome, "+username.Get("value").String()+", to LChat!")
			time.Sleep(300 * time.Millisecond)
			js.Global().Get("location").Set("href", "../")
		}()
		return nil
	}))

	select {}
}