Clean up much of the Kotlin usage and remove RxJava

app/build.gradle

@@ -39,7 +39,6 @@ android {
         applicationId "com.wbrawner.simplemarkdown"
         minSdkVersion 21
         targetSdkVersion 28
-        multiDexEnabled true
         versionCode 20
         versionName "0.7.0"
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
@@ -75,7 +74,6 @@ android {
 }
 
 dependencies {
-    def lifecycle_version = "2.0.0"
     testImplementation 'junit:junit:4.12'
     testImplementation 'org.robolectric:robolectric:4.2'
     implementation fileTree(include: ['*.jar'], dir: 'libs')
@@ -95,18 +93,14 @@ dependencies {
     annotationProcessor 'com.google.dagger:dagger-compiler:2.22.1'
     kapt 'com.google.dagger:dagger-android-processor:2.22.1'
     kapt 'com.google.dagger:dagger-compiler:2.22.1'
-    implementation 'com.jakewharton.rxbinding2:rxbinding:2.0.0'
-    implementation 'com.jakewharton.rxbinding2:rxbinding-design:2.0.0'
-    implementation 'io.reactivex.rxjava2:rxandroid:2.1.1'
-    implementation 'io.reactivex.rxjava2:rxjava:2.2.7'
     implementation 'com.google.firebase:firebase-core:17.0.1'
     implementation 'com.android.billingclient:billing:1.2'
     implementation 'com.crashlytics.sdk.android:crashlytics:2.10.1'
-    implementation 'androidx.multidex:multidex:2.0.1'
-    implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:$lifecycle_version"
-    implementation "androidx.lifecycle:lifecycle-common-java8:$lifecycle_version"
     implementation "androidx.core:core-ktx:1.0.2"
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+    def coroutines_version = "1.3.0-RC2"
+    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutines_version"
+    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:$coroutines_version"
     implementation 'androidx.lifecycle:lifecycle-extensions:2.0.0'
     implementation 'eu.crydee:syllable-counter:4.0.2'
 }

app/src/main/java/com/wbrawner/simplemarkdown/presentation/MarkdownPresenter.kt

@@ -3,37 +3,37 @@ package com.wbrawner.simplemarkdown.presentation
 import android.content.Context
 import android.net.Uri
 
-import com.wbrawner.simplemarkdown.view.MarkdownEditView
-import com.wbrawner.simplemarkdown.view.MarkdownPreviewView
-
 import java.io.InputStream
 import java.io.OutputStream
 
 interface MarkdownPresenter {
     var fileName: String
     var markdown: String
-    fun loadFromUri(context: Context, fileUri: Uri)
-
-    fun loadMarkdown(
+    var editView: MarkdownEditView?
+    var previewView: MarkdownPreviewView?
+    suspend fun loadFromUri(context: Context, fileUri: Uri): String?
+    suspend fun loadMarkdown(
             fileName: String,
             `in`: InputStream,
-            listener: FileLoadedListener? = null,
             replaceCurrentFile: Boolean = true
-    )
-
+    ): String?
     fun newFile(newName: String)
-    fun setEditView(editView: MarkdownEditView)
-    fun setPreviewView(previewView: MarkdownPreviewView)
-    fun saveMarkdown(listener: MarkdownSavedListener, name: String, outputStream: OutputStream)
+    suspend fun saveMarkdown(name: String, outputStream: OutputStream): Boolean
     fun onMarkdownEdited(markdown: String? = null)
-    fun generateHTML(markdown: String? = null): String
-
-    interface FileLoadedListener {
-        fun onSuccess(markdown: String)
-        fun onError()
-    }
-
-    interface MarkdownSavedListener {
-        fun saveComplete(success: Boolean)
-    }
+    fun generateHTML(markdown: String = ""): String
 }
+
+interface MarkdownEditView {
+    var markdown: String
+    fun setTitle(title: String)
+
+    fun onFileSaved(success: Boolean)
+
+    fun onFileLoaded(success: Boolean)
+}
+
+interface MarkdownPreviewView {
+    fun updatePreview(html: String)
+}
+
+

app/src/main/java/com/wbrawner/simplemarkdown/presentation/MarkdownPresenterImpl.kt

@@ -2,163 +2,126 @@ package com.wbrawner.simplemarkdown.presentation
 
 import android.content.Context
 import android.net.Uri
-import android.os.Handler
 import android.provider.OpenableColumns
 import com.commonsware.cwac.anddown.AndDown
 import com.wbrawner.simplemarkdown.model.MarkdownFile
 import com.wbrawner.simplemarkdown.utility.ErrorHandler
-import com.wbrawner.simplemarkdown.view.MarkdownEditView
-import com.wbrawner.simplemarkdown.view.MarkdownPreviewView
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
 import java.io.InputStream
 import java.io.OutputStream
 import javax.inject.Inject
 import javax.inject.Singleton
 
 @Singleton
-class MarkdownPresenterImpl @Inject
-constructor(private val errorHandler: ErrorHandler) : MarkdownPresenter {
-    private val fileLock = Any()
-    private var file: MarkdownFile? = null
+class MarkdownPresenterImpl @Inject constructor(private val errorHandler: ErrorHandler) : MarkdownPresenter {
     @Volatile
-    private var editView: MarkdownEditView? = null
+    private var file: MarkdownFile = MarkdownFile()
     @Volatile
-    private var previewView: MarkdownPreviewView? = null
-    private val fileHandler = Handler()
+    override var editView: MarkdownEditView? = null
+        set(value) {
+            field = value
+            onMarkdownEdited(null)
+        }
+    @Volatile
+    override var previewView: MarkdownPreviewView? = null
 
     override var fileName: String
-        get() = synchronized(fileLock) {
-            return file!!.name
-        }
-        set(name) = synchronized(fileLock) {
-            file!!.name = name
+        get() = file.name
+        set(name) {
+            file.name = name
         }
 
     override var markdown: String
-        get() = synchronized(fileLock) {
-            return file!!.content
-        }
-        set(markdown) = synchronized(fileLock) {
-            file!!.content = markdown
+        get() = file.content
+        set(markdown) {
+            file.content = markdown
         }
 
-    init {
-        synchronized(fileLock) {
-            this.file = MarkdownFile()
-        }
-    }
-
-    override fun loadMarkdown(
+    override suspend fun loadMarkdown(
             fileName: String,
             `in`: InputStream,
-            listener: MarkdownPresenter.FileLoadedListener?,
             replaceCurrentFile: Boolean
-    ) {
-        fileHandler.post {
-            val tmpFile = MarkdownFile()
-            if (tmpFile.load(fileName, `in`)) {
-                if (listener != null) {
-                    val html = generateHTML(tmpFile.content)
-                    listener.onSuccess(html)
-                }
-                if (replaceCurrentFile) {
-                    synchronized(fileLock) {
-                        this.file = tmpFile
-                        val currentEditView = editView
-                        if (currentEditView != null) {
-                            currentEditView.onFileLoaded(true)
-                            currentEditView.setTitle(fileName)
-                            currentEditView.markdown = this.file!!.content
-                            onMarkdownEdited(null)
-                        }
-                    }
-                }
-            } else {
-                listener?.onError()
+    ): String? {
+        val tmpFile = MarkdownFile()
+        withContext(Dispatchers.IO) {
+            if (!tmpFile.load(fileName, `in`)) {
+                throw RuntimeException("Failed to load markdown")
             }
         }
+        if (replaceCurrentFile) {
+            this.file = tmpFile
+            editView?.let {
+                it.onFileLoaded(true)
+                it.setTitle(fileName)
+                it.markdown = file.content
+                onMarkdownEdited(file.content)
+            }
+        }
+        return generateHTML(tmpFile.content)
     }
 
     override fun newFile(newName: String) {
-        synchronized(fileLock) {
-            val currentEditView = editView
-            if (currentEditView != null) {
-                file!!.content = currentEditView.markdown
-                currentEditView.setTitle(newName)
-                currentEditView.markdown = ""
-            }
-            file = MarkdownFile(newName, "")
+        editView?.let {
+            file.content = it.markdown
+            it.setTitle(newName)
+            it.markdown = ""
         }
+        file = MarkdownFile(newName, "")
     }
 
-    override fun setEditView(editView: MarkdownEditView) {
-        this.editView = editView
-        onMarkdownEdited(null)
-    }
-
-    override fun setPreviewView(previewView: MarkdownPreviewView) {
-        this.previewView = previewView
-    }
-
-    override fun saveMarkdown(listener: MarkdownPresenter.MarkdownSavedListener, name: String, outputStream: OutputStream) {
-        val fileSaver = {
-            val result: Boolean
-            synchronized(fileLock) {
-                result = file!!.save(name, outputStream)
-            }
-            listener?.saveComplete(result)
-            val currentEditView = editView
-            if (currentEditView != null) {
-                synchronized(fileLock) {
-                    currentEditView.setTitle(file!!.name)
-                }
-                currentEditView.onFileSaved(result)
-            }
+    override suspend fun saveMarkdown(name: String, outputStream: OutputStream): Boolean {
+        val result = withContext(Dispatchers.IO) {
+            file.save(name, outputStream)
         }
-        fileHandler.post(fileSaver)
+        editView?.let {
+            it.setTitle(file.name)
+            it.onFileSaved(result)
+        }
+        return result
     }
 
     override fun onMarkdownEdited(markdown: String?) {
-        this.markdown = markdown ?: file?.content ?: ""
-        fileHandler.post {
-            val currentPreviewView = previewView
-            currentPreviewView?.updatePreview(generateHTML(null))
-        }
+        this.markdown = markdown ?: file.content
+        previewView?.updatePreview(generateHTML(this.markdown))
     }
 
-    override fun generateHTML(markdown: String?): String {
-        val andDown = AndDown()
-        val HOEDOWN_FLAGS = AndDown.HOEDOWN_EXT_STRIKETHROUGH or AndDown.HOEDOWN_EXT_TABLES or
-                AndDown.HOEDOWN_EXT_UNDERLINE or AndDown.HOEDOWN_EXT_SUPERSCRIPT or
-                AndDown.HOEDOWN_EXT_FENCED_CODE
-        return andDown.markdownToHtml(markdown, HOEDOWN_FLAGS, 0)
+    override fun generateHTML(markdown: String): String {
+        return AndDown().markdownToHtml(markdown, HOEDOWN_FLAGS, 0)
     }
 
-    override fun loadFromUri(context: Context, fileUri: Uri) {
-        try {
-            val `in` = context.contentResolver.openInputStream(fileUri)
+    override suspend fun loadFromUri(context: Context, fileUri: Uri): String? {
+        return try {
             var fileName: String? = null
             if ("content" == fileUri.scheme) {
-                val retCur = context.contentResolver
-                        .query(fileUri, null, null, null, null)
-                if (retCur != null) {
-                    val nameIndex = retCur
-                            .getColumnIndex(OpenableColumns.DISPLAY_NAME)
-                    retCur.moveToFirst()
-                    fileName = retCur.getString(nameIndex)
-                    retCur.close()
-                }
+                context.contentResolver
+                        .query(
+                                fileUri,
+                                null,
+                                null,
+                                null,
+                                null
+                        )
+                        ?.use {
+                            val nameIndex = it.getColumnIndex(OpenableColumns.DISPLAY_NAME)
+                            it.moveToFirst()
+                            fileName = it.getString(nameIndex)
+                        }
             } else if ("file" == fileUri.scheme) {
                 fileName = fileUri.lastPathSegment
             }
-            if (fileName == null) {
-                fileName = "Untitled.md"
-            }
-            loadMarkdown(fileName, `in`!!, null, true)
+            val inputStream = context.contentResolver.openInputStream(fileUri) ?: return null
+            loadMarkdown(fileName ?: "Untitled.md", inputStream, true)
         } catch (e: Exception) {
             errorHandler.reportException(e)
-            val currentEditView = editView
-            currentEditView?.onFileLoaded(false)
+            editView?.onFileLoaded(false)
+            null
         }
+    }
 
+    companion object {
+        const val HOEDOWN_FLAGS = AndDown.HOEDOWN_EXT_STRIKETHROUGH or AndDown.HOEDOWN_EXT_TABLES or
+                AndDown.HOEDOWN_EXT_UNDERLINE or AndDown.HOEDOWN_EXT_SUPERSCRIPT or
+                AndDown.HOEDOWN_EXT_FENCED_CODE
     }
 }

app/src/main/java/com/wbrawner/simplemarkdown/utility/MarkdownObserver.java

@@ -1,40 +0,0 @@
-package com.wbrawner.simplemarkdown.utility;
-
-import com.wbrawner.simplemarkdown.presentation.MarkdownPresenter;
-
-import io.reactivex.Observable;
-import io.reactivex.Observer;
-import io.reactivex.disposables.Disposable;
-
-public class MarkdownObserver implements Observer<String> {
-    private MarkdownPresenter presenter;
-    private Observable<String> obs;
-
-    public MarkdownObserver(MarkdownPresenter presenter, Observable<String> obs) {
-        this.presenter = presenter;
-        this.obs = obs;
-    }
-
-    @Override
-    public void onSubscribe(Disposable d) {
-
-    }
-
-    @Override
-    public void onNext(String markdown) {
-        presenter.onMarkdownEdited(markdown);
-    }
-
-    @Override
-    public void onError(Throwable e) {
-        System.err.println("An error occurred while handling the markdown");
-        e.printStackTrace();
-        // TODO: report this?
-        obs.subscribe(this);
-    }
-
-    @Override
-    public void onComplete() {
-
-    }
-}

app/src/main/java/com/wbrawner/simplemarkdown/utility/ReadabilityObserver.java

@@ -1,59 +0,0 @@
-package com.wbrawner.simplemarkdown.utility;
-
-import android.graphics.Color;
-import android.text.SpannableString;
-import android.text.style.BackgroundColorSpan;
-import android.util.Log;
-import android.widget.EditText;
-import android.widget.TextView;
-
-import com.wbrawner.simplemarkdown.model.Readability;
-import com.wbrawner.simplemarkdown.model.Sentence;
-
-import io.reactivex.Observer;
-import io.reactivex.disposables.Disposable;
-
-public class ReadabilityObserver implements Observer<String> {
-    private EditText text;
-    private String previousValue = "";
-
-    public ReadabilityObserver(EditText text) {
-        this.text = text;
-    }
-
-    @Override
-    public void onSubscribe(Disposable d) {
-
-    }
-
-    @Override
-    public void onNext(String markdown) {
-        long start = System.currentTimeMillis();
-        if (markdown.length() < 1) return;
-        if (previousValue.equals(markdown)) return;
-        Readability readability = new Readability(markdown);
-        SpannableString span = new SpannableString(markdown);
-        for (Sentence sentence : readability.sentences()) {
-            int color = Color.TRANSPARENT;
-            if (sentence.syllableCount() > 25) color = Color.argb(100, 229, 232, 42);
-            if (sentence.syllableCount() > 35) color = Color.argb(100, 193, 66, 66);
-            span.setSpan(new BackgroundColorSpan(color), sentence.start(), sentence.end(), 0);
-        }
-        text.setTextKeepState(span, TextView.BufferType.SPANNABLE);
-        previousValue = markdown;
-        long timeTakenMs = System.currentTimeMillis() - start;
-        Log.d("SimpleMarkdown", "Handled markdown in " + timeTakenMs + "ms");
-    }
-
-    @Override
-    public void onError(Throwable e) {
-        System.err.println("An error occurred while handling the markdown");
-        e.printStackTrace();
-        // TODO: report this?
-    }
-
-    @Override
-    public void onComplete() {
-
-    }
-}

app/src/main/java/com/wbrawner/simplemarkdown/view/MarkdownEditView.kt

@@ -1,10 +0,0 @@
-package com.wbrawner.simplemarkdown.view
-
-interface MarkdownEditView {
-    var markdown: String
-    fun setTitle(title: String)
-
-    fun onFileSaved(success: Boolean)
-
-    fun onFileLoaded(success: Boolean)
-}

app/src/main/java/com/wbrawner/simplemarkdown/view/MarkdownPreviewView.kt

@@ -1,5 +0,0 @@
-package com.wbrawner.simplemarkdown.view
-
-interface MarkdownPreviewView {
-    fun updatePreview(html: String)
-}

app/src/main/java/com/wbrawner/simplemarkdown/view/activity/MainActivity.kt

@@ -24,19 +24,20 @@ import com.wbrawner.simplemarkdown.utility.ErrorHandler
 import com.wbrawner.simplemarkdown.utility.Utils
 import com.wbrawner.simplemarkdown.view.adapter.EditPagerAdapter
 import kotlinx.android.synthetic.main.activity_main.*
+import kotlinx.coroutines.*
 import java.io.File
 import java.io.FileInputStream
-import java.io.InputStream
 import javax.inject.Inject
+import kotlin.coroutines.CoroutineContext
 
-class MainActivity : AppCompatActivity(), ActivityCompat.OnRequestPermissionsResultCallback {
+class MainActivity : AppCompatActivity(), ActivityCompat.OnRequestPermissionsResultCallback, CoroutineScope {
 
     @Inject
     lateinit var presenter: MarkdownPresenter
     @Inject
     lateinit var errorHandler: ErrorHandler
     private var shouldAutoSave = true
-    private var newFileHandler: NewFileHandler? = null
+    override val coroutineContext: CoroutineContext = Dispatchers.Main
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -65,7 +66,9 @@ class MainActivity : AppCompatActivity(), ActivityCompat.OnRequestPermissionsRes
         super.onUserLeaveHint()
         if (shouldAutoSave && presenter.markdown.isNotEmpty() && Utils.isAutosaveEnabled(this)) {
 
-            presenter.saveMarkdown(null, "autosave.md", File(filesDir, "autosave.md").outputStream())
+            launch {
+                presenter.saveMarkdown("autosave.md", File(filesDir, "autosave.md").outputStream())
+            }
         }
     }
 
@@ -130,28 +133,18 @@ class MainActivity : AppCompatActivity(), ActivityCompat.OnRequestPermissionsRes
             }
         }
         infoIntent.putExtra("title", title)
-        var `in`: InputStream? = null
-        try {
-            val assetManager = assets
-            if (assetManager != null) {
-                `in` = assetManager.open(fileName)
+        launch {
+            try {
+                val inputStream = assets?.open(fileName)
+                        ?: throw RuntimeException("Unable to open stream to $fileName")
+                val html = presenter.loadMarkdown(fileName, inputStream, false)
+                infoIntent.putExtra("html", html)
+                startActivity(infoIntent)
+            } catch (e: Exception) {
+                errorHandler.reportException(e)
+                Toast.makeText(this@MainActivity, R.string.file_load_error, Toast.LENGTH_SHORT).show()
             }
-            presenter.loadMarkdown(fileName, `in`, object : MarkdownPresenter.FileLoadedListener {
-                override fun onSuccess(html: String) {
-                    infoIntent.putExtra("html", html)
-                    startActivity(infoIntent)
-                }
-
-                override fun onError() {
-                    Toast.makeText(this@MainActivity, R.string.file_load_error, Toast.LENGTH_SHORT)
-                            .show()
-                }
-            }, false)
-        } catch (e: Exception) {
-            errorHandler.reportException(e)
-            Toast.makeText(this@MainActivity, R.string.file_load_error, Toast.LENGTH_SHORT).show()
         }
-
     }
 
     override fun onRequestPermissionsResult(
@@ -197,12 +190,13 @@ class MainActivity : AppCompatActivity(), ActivityCompat.OnRequestPermissionsRes
 
                 contentResolver.openFileDescriptor(data.data!!, "r")?.let {
                     val fileInput = FileInputStream(it.fileDescriptor)
-                    presenter.loadMarkdown(fileName, fileInput)
+                    launch {
+                        presenter.loadMarkdown(fileName, fileInput)
+                    }
                 }
             }
             REQUEST_SAVE_FILE -> {
-                if (resultCode != Activity.RESULT_OK
-                        || data?.data == null) {
+                if (resultCode != Activity.RESULT_OK || data?.data == null) {
                     return
                 }
 
@@ -213,11 +207,14 @@ class MainActivity : AppCompatActivity(), ActivityCompat.OnRequestPermissionsRes
                             cursor.getString(nameIndex)
                         } ?: "Untitled.md"
 
-                presenter.saveMarkdown(
-                        newFileHandler,
-                        fileName,
-                        contentResolver.openOutputStream(data.data!!)
-                )
+                launch {
+                    val outputStream = contentResolver.openOutputStream(data.data!!)
+                            ?: throw RuntimeException("Unable to open output stream to save file")
+                    presenter.saveMarkdown(
+                            fileName,
+                            outputStream
+                    )
+                }
             }
             REQUEST_DARK_MODE -> recreate()
         }
@@ -228,11 +225,10 @@ class MainActivity : AppCompatActivity(), ActivityCompat.OnRequestPermissionsRes
         AlertDialog.Builder(this)
                 .setTitle(R.string.save_changes)
                 .setMessage(R.string.prompt_save_changes)
-                .setNegativeButton(R.string.action_discard) { d, _ ->
+                .setNegativeButton(R.string.action_discard) { _, _ ->
                     presenter.newFile("Untitled.md")
                 }
-                .setPositiveButton(R.string.action_save) { d, _ ->
-                    newFileHandler = NewFileHandler()
+                .setPositiveButton(R.string.action_save) { _, _ ->
                     requestFileOp(REQUEST_SAVE_FILE)
                 }
                 .create()
@@ -283,17 +279,11 @@ class MainActivity : AppCompatActivity(), ActivityCompat.OnRequestPermissionsRes
         shouldAutoSave = true
     }
 
-    private inner class NewFileHandler : MarkdownPresenter.MarkdownSavedListener {
-        override fun saveComplete(success: Boolean) {
-            if (success) {
-                presenter.newFile("Untitled.md")
-            } else {
-                Toast.makeText(
-                        this@MainActivity,
-                        R.string.file_save_error,
-                        Toast.LENGTH_SHORT
-                ).show()
-            }
+
+    override fun onDestroy() {
+        super.onDestroy()
+        coroutineContext[Job]?.let {
+            cancel()
         }
     }
 }

app/src/main/java/com/wbrawner/simplemarkdown/view/activity/SplashActivity.kt

@@ -10,25 +10,28 @@ import com.wbrawner.simplemarkdown.MarkdownApplication
 import com.wbrawner.simplemarkdown.R
 import com.wbrawner.simplemarkdown.presentation.MarkdownPresenter
 import com.wbrawner.simplemarkdown.utility.ErrorHandler
+import kotlinx.coroutines.*
 import java.io.File
-import java.io.FileInputStream
 import java.io.FileNotFoundException
 import javax.inject.Inject
+import kotlin.coroutines.CoroutineContext
 
-class SplashActivity : AppCompatActivity() {
+class SplashActivity : AppCompatActivity(), CoroutineScope {
+
+    override val coroutineContext: CoroutineContext = Dispatchers.Main
 
     @Inject
-    internal var presenter: MarkdownPresenter? = null
+    lateinit var presenter: MarkdownPresenter
 
     @Inject
-    internal var errorHandler: ErrorHandler? = null
+    lateinit var errorHandler: ErrorHandler
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         val sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this)
         (application as MarkdownApplication).component.inject(this)
         if (sharedPreferences.getBoolean(getString(R.string.error_reports_enabled), true)) {
-            errorHandler!!.init(this)
+            errorHandler.init(this)
         }
 
         val darkModeValue = sharedPreferences.getString(
@@ -36,11 +39,10 @@ class SplashActivity : AppCompatActivity() {
                 getString(R.string.pref_value_auto)
         )
 
-        var darkMode: Int
-        if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.P) {
-            darkMode = AppCompatDelegate.MODE_NIGHT_AUTO
+        var darkMode = if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.P) {
+            AppCompatDelegate.MODE_NIGHT_AUTO
         } else {
-            darkMode = AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM
+            AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM
         }
 
         if (darkModeValue != null && !darkModeValue.isEmpty()) {
@@ -52,33 +54,26 @@ class SplashActivity : AppCompatActivity() {
         }
         AppCompatDelegate.setDefaultNightMode(darkMode)
 
-        val intent = intent
-        if (intent != null && intent.data != null) {
-            presenter!!.loadFromUri(applicationContext, intent.data)
+        if (intent?.data != null) {
+            launch {
+                presenter.loadFromUri(applicationContext, intent.data!!)
+            }
         } else {
-            presenter!!.fileName = "Untitled.md"
+            presenter.fileName = "Untitled.md"
             val autosave = File(filesDir, "autosave.md")
             if (autosave.exists()) {
                 try {
-                    val fileInputStream = FileInputStream(autosave)
-                    presenter!!.loadMarkdown(
-                            "Untitled.md",
-                            fileInputStream,
-                            object : MarkdownPresenter.FileLoadedListener {
-                                override fun onSuccess(markdown: String) {
-                                    autosave.delete()
-                                }
-
-                                override fun onError() {
-                                    autosave.delete()
-                                }
-                            },
-                            true
-                    )
+                    launch {
+                        presenter.loadMarkdown(
+                                "Untitled.md",
+                                autosave.inputStream(),
+                                true
+                        )
+                        autosave.delete()
+                    }
                 } catch (ignored: FileNotFoundException) {
                     return
                 }
-
             }
         }
 
@@ -86,4 +81,11 @@ class SplashActivity : AppCompatActivity() {
         startActivity(startIntent)
         finish()
     }
+
+    override fun onDestroy() {
+        super.onDestroy()
+        coroutineContext[Job]?.let {
+            cancel()
+        }
+    }
 }

app/src/main/java/com/wbrawner/simplemarkdown/view/fragment/EditFragment.kt

@@ -1,72 +1,126 @@
 package com.wbrawner.simplemarkdown.view.fragment
 
 import android.annotation.SuppressLint
+import android.graphics.Color
 import android.os.Bundle
 import android.preference.PreferenceManager
+import android.text.Editable
+import android.text.SpannableString
+import android.text.TextWatcher
+import android.text.style.BackgroundColorSpan
+import android.util.Log
 import android.view.LayoutInflater
 import android.view.MotionEvent
 import android.view.View
 import android.view.ViewGroup
 import android.widget.EditText
 import android.widget.ScrollView
+import android.widget.TextView
 import android.widget.Toast
 import androidx.fragment.app.Fragment
-import com.jakewharton.rxbinding2.widget.RxTextView
 import com.wbrawner.simplemarkdown.MarkdownApplication
 import com.wbrawner.simplemarkdown.R
+import com.wbrawner.simplemarkdown.model.Readability
+import com.wbrawner.simplemarkdown.presentation.MarkdownEditView
 import com.wbrawner.simplemarkdown.presentation.MarkdownPresenter
-import com.wbrawner.simplemarkdown.utility.MarkdownObserver
-import com.wbrawner.simplemarkdown.utility.ReadabilityObserver
 import com.wbrawner.simplemarkdown.utility.hideKeyboard
 import com.wbrawner.simplemarkdown.utility.showKeyboard
-import com.wbrawner.simplemarkdown.view.MarkdownEditView
 import com.wbrawner.simplemarkdown.view.ViewPagerPage
-import io.reactivex.android.schedulers.AndroidSchedulers
-import io.reactivex.schedulers.Schedulers
-import java.util.concurrent.TimeUnit
+import kotlinx.coroutines.*
 import javax.inject.Inject
+import kotlin.coroutines.CoroutineContext
 import kotlin.math.abs
 
-class EditFragment : Fragment(), MarkdownEditView, ViewPagerPage {
+class EditFragment : Fragment(), MarkdownEditView, ViewPagerPage, CoroutineScope {
     @Inject
     lateinit var presenter: MarkdownPresenter
     private var markdownEditor: EditText? = null
     private var markdownEditorScroller: ScrollView? = null
+    override var markdown: String
+        get() = markdownEditor?.text?.toString() ?: ""
+        set(value) {
+            markdownEditor?.setText(value)
+        }
+    override val coroutineContext: CoroutineContext = Dispatchers.Main
 
     @SuppressLint("ClickableViewAccessibility")
     override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
-                              savedInstanceState: Bundle?): View? {
-        // Inflate the layout for this fragment
-        val view = inflater.inflate(R.layout.fragment_edit, container, false)
-        markdownEditor = view.findViewById(R.id.markdown_edit)
-        markdownEditorScroller = view.findViewById(R.id.markdown_edit_container)
-        val activity = activity
-        if (activity != null) {
-            (activity.application as MarkdownApplication).component.inject(this)
-        }
-        val obs = RxTextView.textChanges(markdownEditor!!)
-                .debounce(50, TimeUnit.MILLISECONDS)
-                .map { it.toString() }
-                .subscribeOn(Schedulers.io())
-                .observeOn(AndroidSchedulers.mainThread())
-        obs.subscribe(MarkdownObserver(presenter, obs))
-        val sharedPrefs = PreferenceManager.getDefaultSharedPreferences(requireContext())
-        val enableReadability = sharedPrefs.getBoolean(getString(R.string.readability_enabled), false)
-        if (enableReadability) {
-            val readabilityObserver = RxTextView.textChanges(markdownEditor!!)
-                    .debounce(250, TimeUnit.MILLISECONDS)
-                    .map { it.toString() }
-                    .subscribeOn(Schedulers.io())
-                    .observeOn(AndroidSchedulers.mainThread())
-            readabilityObserver.subscribe(ReadabilityObserver(markdownEditor))
-        }
-        return view
-    }
+                              savedInstanceState: Bundle?): View? =
+            inflater.inflate(R.layout.fragment_edit, container, false)
 
     @SuppressLint("ClickableViewAccessibility")
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
-        presenter.setEditView(this@EditFragment)
+        markdownEditor = view.findViewById(R.id.markdown_edit)
+        markdownEditorScroller = view.findViewById(R.id.markdown_edit_container)
+        markdownEditor?.addTextChangedListener(object : TextWatcher {
+            private var searchFor = ""
+
+            override fun afterTextChanged(s: Editable?) {
+                val searchText = s.toString().trim()
+                if (searchText == searchFor)
+                    return
+
+                searchFor = searchText
+
+                launch {
+                    delay(50)
+                    if (searchText != searchFor)
+                        return@launch
+                    presenter.onMarkdownEdited(searchText)
+                }
+            }
+
+            override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {
+            }
+
+            override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
+            }
+
+        })
+        val sharedPrefs = PreferenceManager.getDefaultSharedPreferences(requireContext())
+        val enableReadability = sharedPrefs.getBoolean(getString(R.string.readability_enabled), false)
+        if (enableReadability) {
+            markdownEditor?.addTextChangedListener(object : TextWatcher {
+                private var previousValue = ""
+                private var searchFor = ""
+
+                override fun afterTextChanged(s: Editable?) {
+                    val searchText = s.toString().trim()
+                    if (searchText == searchFor)
+                        return
+
+                    searchFor = searchText
+
+                    launch {
+                        delay(250)
+                        if (searchText != searchFor)
+                            return@launch
+                        val start = System.currentTimeMillis()
+                        if (markdown.isEmpty()) return@launch
+                        if (previousValue == markdown) return@launch
+                        val readability = Readability(markdown)
+                        val span = SpannableString(markdown)
+                        for (sentence in readability.sentences()) {
+                            var color = Color.TRANSPARENT
+                            if (sentence.syllableCount() > 25) color = Color.argb(100, 229, 232, 42)
+                            if (sentence.syllableCount() > 35) color = Color.argb(100, 193, 66, 66)
+                            span.setSpan(BackgroundColorSpan(color), sentence.start(), sentence.end(), 0)
+                        }
+                        markdownEditor?.setTextKeepState(span, TextView.BufferType.SPANNABLE)
+                        previousValue = markdown
+                        val timeTakenMs = System.currentTimeMillis() - start
+                        Log.d("SimpleMarkdown", "Handled markdown in " + timeTakenMs + "ms")
+                    }
+                }
+
+                override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {
+                }
+
+                override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
+                }
+            })
+        }
 
         var touchDown = 0L
         var oldX = 0f
@@ -92,18 +146,32 @@ class EditFragment : Fragment(), MarkdownEditView, ViewPagerPage {
         }
     }
 
+    override fun onActivityCreated(savedInstanceState: Bundle?) {
+        super.onActivityCreated(savedInstanceState)
+        @Suppress("CAST_NEVER_SUCCEEDS")
+        (activity?.application as? MarkdownApplication)?.component?.inject(this)
+        presenter.editView = this@EditFragment
+    }
+
     override fun onResume() {
         super.onResume()
-        presenter.setEditView(this)
+        presenter.editView = this
         markdown = presenter.markdown
     }
 
     override fun onPause() {
         super.onPause()
-        presenter.setEditView(null)
+        presenter.editView = null
         markdownEditor?.hideKeyboard()
     }
 
+    override fun onDestroy() {
+        coroutineContext[Job]?.let {
+            cancel()
+        }
+        super.onDestroy()
+    }
+
     override fun onSelected() {
         markdownEditor?.showKeyboard()
     }
@@ -112,14 +180,6 @@ class EditFragment : Fragment(), MarkdownEditView, ViewPagerPage {
         markdownEditor?.hideKeyboard()
     }
 
-    override fun getMarkdown(): String {
-        return markdownEditor!!.text.toString()
-    }
-
-    override fun setMarkdown(markdown: String) {
-        markdownEditor?.setText(markdown)
-    }
-
     override fun setTitle(title: String) {
         val activity = activity
         if (activity != null) {

app/src/main/java/com/wbrawner/simplemarkdown/view/fragment/PreviewFragment.kt

@@ -15,7 +15,7 @@ import com.wbrawner.simplemarkdown.BuildConfig
 import com.wbrawner.simplemarkdown.MarkdownApplication
 import com.wbrawner.simplemarkdown.R
 import com.wbrawner.simplemarkdown.presentation.MarkdownPresenter
-import com.wbrawner.simplemarkdown.view.MarkdownPreviewView
+import com.wbrawner.simplemarkdown.presentation.MarkdownPreviewView
 import javax.inject.Inject
 
 
@@ -50,7 +50,7 @@ class PreviewFragment : Fragment(), MarkdownPreviewView {
             }
             @Suppress("ConstantConditionIf")
             val css: String? = if (!BuildConfig.ENABLE_CUSTOM_CSS) {
-                getString(defaultCssId)
+                context?.getString(defaultCssId)
             } else {
                 sharedPreferences!!.getString(
                         getString(R.string.pref_custom_css),
@@ -70,7 +70,7 @@ class PreviewFragment : Fragment(), MarkdownPreviewView {
 
     override fun onResume() {
         super.onResume()
-        presenter.setPreviewView(this)
+        presenter.previewView = this
         presenter.onMarkdownEdited()
     }
 
@@ -78,13 +78,14 @@ class PreviewFragment : Fragment(), MarkdownPreviewView {
         markdownPreview?.let {
             (it.parent as ViewGroup).removeView(it)
             it.destroy()
+            markdownPreview = null
         }
         super.onDestroyView()
     }
 
     override fun onDestroy() {
         super.onDestroy()
-        presenter.setPreviewView(null)
+        presenter.previewView = null
     }
 
     companion object {