PixelDroid-App-Android/app/src/main/java/com/h/pixeldroid/LoginActivity.kt

package com.h.pixeldroid

import android.content.ActivityNotFoundException
import android.content.Context
import android.content.Intent
import android.content.SharedPreferences
import android.net.Uri
import android.os.Bundle
import android.view.View
import androidx.appcompat.app.AppCompatActivity
import androidx.browser.customtabs.CustomTabsIntent
import com.h.pixeldroid.api.PixelfedAPI
import com.h.pixeldroid.objects.Application
import com.h.pixeldroid.objects.Token
import kotlinx.android.synthetic.main.activity_login.*
import okhttp3.HttpUrl
import retrofit2.Call
import retrofit2.Callback
import retrofit2.Response

class LoginActivity : AppCompatActivity() {

    private lateinit var OAUTH_SCHEME: String
    private val PACKAGE_ID = BuildConfig.APPLICATION_ID
    private val SCOPE = "read write follow"
    private lateinit var APP_NAME: String
    private lateinit var preferences: SharedPreferences

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_login)

        connect_instance_button.setOnClickListener { onClickConnect() }
        APP_NAME = getString(R.string.app_name)
        OAUTH_SCHEME = getString(R.string.auth_scheme)
        preferences = getSharedPreferences(
            "$PACKAGE_ID.pref", Context.MODE_PRIVATE
        )
    }

    override fun onStart(){
        super.onStart()

        val url = intent.data

        //Check if the activity was started after the authentication
        if (url == null || !url.toString().startsWith("$OAUTH_SCHEME://$PACKAGE_ID")) return

        loadingAnimation(true)

        val code = url.getQueryParameter("code")
        authenticate(code)

    }

    override fun onStop() {
        super.onStop()
        loadingAnimation(false)
    }

    override fun onBackPressed() {
    }

    private fun onClickConnect() {

        val normalizedDomain = normalizeDomain(editText.text.toString())

        try{
            HttpUrl.Builder().host(normalizedDomain).scheme("https").build()
        } catch (e: IllegalArgumentException) {
            return failedRegistration(getString(R.string.invalid_domain))
        }

        loadingAnimation(true)

        preferences.edit()
            .putString("domain", "https://$normalizedDomain")
            .apply()
        registerAppToServer("https://$normalizedDomain")

    }

    private fun normalizeDomain(domain: String): String {
        var d = domain.replace("http://", "")
        d = d.replace("https://", "")
        return d.trim(Char::isWhitespace)
    }

    private fun registerAppToServer(normalizedDomain: String) {
        val callback = object : Callback<Application> {
            override fun onResponse(call: Call<Application>, response: Response<Application>) {
                if (!response.isSuccessful) {
                    return failedRegistration()
                }

                val credentials = response.body()
                val clientId = credentials?.client_id ?: return failedRegistration()
                val clientSecret = credentials.client_secret

                preferences.edit()
                    .putString("clientID", clientId)
                    .putString("clientSecret", clientSecret)
                    .apply()

                promptOAuth(normalizedDomain, clientId)
            }

            override fun onFailure(call: Call<Application>, t: Throwable) {
                return failedRegistration()
            }
        }
        PixelfedAPI.create(normalizedDomain).registerApplication(
            APP_NAME,"$OAUTH_SCHEME://$PACKAGE_ID", SCOPE
        ).enqueue(callback)
    }

    private fun promptOAuth(normalizedDomain: String, client_id: String) {

        val url = "$normalizedDomain/oauth/authorize?" +
                "client_id" + "=" + client_id + "&" +
                "redirect_uri" + "=" + "$OAUTH_SCHEME://$PACKAGE_ID" + "&" +
                "response_type=code" + "&" +
                "scope=$SCOPE"

        val intent = CustomTabsIntent.Builder().build()

        try {
            intent.launchUrl(this, Uri.parse(url))
        } catch (e: ActivityNotFoundException) {
            val browserIntent = Intent(Intent.ACTION_VIEW, Uri.parse(url))
            if (browserIntent.resolveActivity(packageManager) != null) {
                startActivity(browserIntent)
            } else {
                return failedRegistration(getString(R.string.browser_launch_failed))
            }
        }
    }

    private fun authenticate(code: String?) {

        // Get previous values from preferences
        val domain = preferences.getString("domain", "")
        val clientId = preferences.getString("clientID", "")
        val clientSecret = preferences.getString("clientSecret", "")

        if (code == null || domain.isNullOrEmpty() || clientId.isNullOrEmpty() || clientSecret.isNullOrEmpty()) {
            return failedRegistration(getString(R.string.auth_failed))
        }

        //Successful authorization
        val callback = object : Callback<Token> {
            override fun onResponse(call: Call<Token>, response: Response<Token>) {
                if (!response.isSuccessful || response.body() == null) {
                    return failedRegistration(getString(R.string.token_error))
                }
                authenticationSuccessful(domain, response.body()!!.access_token)
            }

            override fun onFailure(call: Call<Token>, t: Throwable) {
                return failedRegistration(getString(R.string.token_error))
            }
        }

        PixelfedAPI.create("$domain")
            .obtainToken(
            clientId, clientSecret, "$OAUTH_SCHEME://$PACKAGE_ID", SCOPE, code,
            "authorization_code"
        ).enqueue(callback)
    }

    private fun authenticationSuccessful(domain: String, accessToken: String) {
        preferences.edit().putString("accessToken", accessToken).apply()
        val intent = Intent(this, MainActivity::class.java)
        startActivity(intent)
        finish()
    }

    private fun failedRegistration(message: String =
                                       getString(R.string.registration_failed)){
        loadingAnimation(false)
        editText.error = message
    }

    private fun loadingAnimation(on: Boolean){
        if(on) {
            domainTextInputLayout.visibility = View.GONE
            progressLayout.visibility = View.VISIBLE
        }
        else {
            domainTextInputLayout.visibility = View.VISIBLE
            progressLayout.visibility = View.GONE
        }
    }

}