From 7c6c2fa3b17f81fddb6189d76fe070eeed871ddd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?St=C9=91rry=20Shiv=C9=91m?= <touka.krs@gmail.com>
Date: Wed, 25 Sep 2024 15:54:25 +0530
Subject: [PATCH] fix: Handle one edge-case in reader & some other improvements
 (#223)

Signed-off-by: starry-shivam <starry@krsh.dev>
---
 .idea/appInsightsSettings.xml                 |   1 +
 .../java/com/starry/myne/di/MainModule.kt     |   8 +-
 .../java/com/starry/myne/epub/EpubCache.kt    |  16 ++
 .../java/com/starry/myne/epub/EpubParser.kt   |  43 ++++-
 .../starry/myne/epub/models/EpubChapter.kt    |   1 +
 .../library/viewmodels/LibraryViewModel.kt    |   1 +
 .../reader/activities/ReaderActivity.kt       |  43 ++---
 .../{ReaderContent.kt => ChaptersContent.kt}  |   6 +-
 .../reader/composables/ReaderScreen.kt        | 162 +++++++++---------
 .../reader/viewmodels/ReaderViewModel.kt      |  33 ++--
 .../java/com/starry/myne/EpubParserTest.kt    |   7 +-
 11 files changed, 186 insertions(+), 135 deletions(-)
 rename app/src/main/java/com/starry/myne/ui/screens/reader/composables/{ReaderContent.kt => ChaptersContent.kt} (98%)

diff --git a/.idea/appInsightsSettings.xml b/.idea/appInsightsSettings.xml
index f9cd1c27..9b2c07c2 100644
--- a/.idea/appInsightsSettings.xml
+++ b/.idea/appInsightsSettings.xml
@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="AppInsightsSettings">
+    <option name="selectedTabId" value="Firebase Crashlytics" />
     <option name="tabSettings">
       <map>
         <entry key="Android Vitals">
diff --git a/app/src/main/java/com/starry/myne/di/MainModule.kt b/app/src/main/java/com/starry/myne/di/MainModule.kt
index c15d3bea..518985e1 100644
--- a/app/src/main/java/com/starry/myne/di/MainModule.kt
+++ b/app/src/main/java/com/starry/myne/di/MainModule.kt
@@ -20,7 +20,6 @@ package com.starry.myne.di
 import android.content.Context
 import com.starry.myne.api.BookAPI
 import com.starry.myne.database.MyneDatabase
-import com.starry.myne.epub.EpubCache
 import com.starry.myne.epub.EpubParser
 import com.starry.myne.helpers.PreferenceUtil
 import com.starry.myne.helpers.book.BookDownloader
@@ -65,12 +64,7 @@ class MainModule {
 
     @Singleton
     @Provides
-    fun provideEpubcahe(@ApplicationContext context: Context) = EpubCache(context)
-
-    @Singleton
-    @Provides
-    fun provideEpubParser(@ApplicationContext context: Context, epubCache: EpubCache) =
-        EpubParser(context, epubCache)
+    fun provideEpubParser(@ApplicationContext context: Context) = EpubParser(context)
 
     @Provides
     @Singleton
diff --git a/app/src/main/java/com/starry/myne/epub/EpubCache.kt b/app/src/main/java/com/starry/myne/epub/EpubCache.kt
index bf660837..076cb4cc 100644
--- a/app/src/main/java/com/starry/myne/epub/EpubCache.kt
+++ b/app/src/main/java/com/starry/myne/epub/EpubCache.kt
@@ -126,6 +126,22 @@ class EpubCache(private val context: Context) {
         }
     }
 
+    /**
+     * Removes a book from the cache.
+     *
+     * @param filepath The path to the book file.
+     */
+    fun remove(filepath: String): Boolean {
+        Log.d(TAG, "Removing book from cache: $filepath")
+        val fileName = File(filepath).nameWithoutExtension
+        val bookFile = File(getPath(), "$fileName.json")
+        return if (bookFile.exists()) {
+            bookFile.delete()
+        } else {
+            false
+        }
+    }
+
     /**
      * Checks if a book is cached.
      *
diff --git a/app/src/main/java/com/starry/myne/epub/EpubParser.kt b/app/src/main/java/com/starry/myne/epub/EpubParser.kt
index 04486b6e..1e741b80 100644
--- a/app/src/main/java/com/starry/myne/epub/EpubParser.kt
+++ b/app/src/main/java/com/starry/myne/epub/EpubParser.kt
@@ -31,6 +31,7 @@ import org.w3c.dom.Node
 import java.io.File
 import java.io.FileInputStream
 import java.io.InputStream
+import java.util.concurrent.ThreadLocalRandom
 import java.util.zip.ZipFile
 import java.util.zip.ZipInputStream
 
@@ -38,7 +39,7 @@ import java.util.zip.ZipInputStream
 /**
  * Parses an EPUB file and creates an [EpubBook] object.
  */
-class EpubParser(private val context: Context, private val epubCache: EpubCache) {
+class EpubParser(private val context: Context) {
 
     /**
      * Represents an EPUB document.
@@ -104,6 +105,8 @@ class EpubParser(private val context: Context, private val epubCache: EpubCache)
         const val TAG = "EpubParser"
     }
 
+    private val epubCache = EpubCache(context)
+
     /**
      * Creates an [EpubBook] object from an EPUB file.
      *
@@ -154,6 +157,15 @@ class EpubParser(private val context: Context, private val epubCache: EpubCache)
         return epubCache.isCached(filePath)
     }
 
+    /**
+     * Removes an EPUB book from the cache.
+     *
+     * @param filePath The file path of the EPUB file.
+     */
+    fun removeBookFromCache(filePath: String): Boolean {
+        return epubCache.remove(filePath)
+    }
+
     /**
      * Parses and creates an [EpubBook] object from the EPUB files and document.
      * This function is called from [createEpubBook] and [createEpubBook].
@@ -191,9 +203,9 @@ class EpubParser(private val context: Context, private val epubCache: EpubCache)
         }
 
         // Determine the method of parsing chapters based on the presence of ToC and
-        // the shouldUseToc flag. If tocNavPoints is not null or empty and shouldUseToc
-        // is true, use the ToC file for parsing. Otherwise, parse using the spine.
-        val chapters = if (!tocNavPoints.isNullOrEmpty() && shouldUseToc) {
+        // the shouldUseToc flag. We also check if the ToC file has more than one navPoint
+        // to ensure that it is a valid ToC file.
+        val chapters = if (shouldUseToc && !tocNavPoints.isNullOrEmpty() && tocNavPoints.size > 1) {
             Log.d(TAG, "Parsing based on ToC file")
             parseUsingTocFile(tocNavPoints, files, hrefRootPath, document, manifestItems)
         } else {
@@ -231,17 +243,17 @@ class EpubParser(private val context: Context, private val epubCache: EpubCache)
         val epubDocument = try {
             createEpubDocument(files)
         } catch (exc: EpubParserException) {
-            // In some rare cases, the ZipInputStream does not contains / fails to read all of the files
+            // In some rare cases, the ZipInputStream does not contain or fails to read all of the files
             // required to parse the EPUB archive, even though the zip file itself contains them.
             // In such cases, retry parsing the EPUB file by directly using the ZipFile API.
             // Since ZipFile requires a file path, we need to create a temporary file from the input stream.
             //
-            // Reasons for this issue are unknown and may be related to how the EPUB file is compressed
-            // i.e. weather it is missing some metadata or file/folder entry in it's header or how the
+            // The reasons for this issue are unknown and may be related to how the EPUB file is compressed,
+            // i.e., whether it is missing some metadata or file/folder entry in its header, or how the
             // ZipInputStream reads the file.
             //
-            // If someone knows the exact reason for this issue, or have dealt with it before, please
-            // let me know or feel free to create a PR with a better solution.
+            // If anyone knows the exact reason for this issue or has dealt with it before, please
+            // let me know, or feel free to create a PR with a better solution.
             if (exc.message == "META-INF/container.xml file missing"
                 || exc.message == ".opf file missing"
             ) {
@@ -413,6 +425,17 @@ class EpubParser(private val context: Context, private val epubCache: EpubCache)
         return navPoints
     }
 
+    /**
+     * Generate a unique ID for a chapter.
+     *
+     * @return The generated ID.
+     */
+    private fun generateId(): String {
+        val timestamp = System.currentTimeMillis()
+        val randomSuffix = ThreadLocalRandom.current().nextInt(1000, 9999)
+        return "$timestamp-$randomSuffix"
+    }
+
     /**
      * Parse the EPUB file using the table of contents (ToC) file.
      * This method is called from [parseAndCreateEbook].
@@ -468,6 +491,7 @@ class EpubParser(private val context: Context, private val epubCache: EpubCache)
                 if (res != null) {
                     listOf(
                         EpubChapter(
+                            chapterId = generateId(),
                             absPath = chapterSrc,
                             title = title?.takeIf { it.isNotEmpty() } ?: "Chapter $index",
                             body = res.body
@@ -548,6 +572,7 @@ class EpubParser(private val context: Context, private val epubCache: EpubCache)
                 it.chapterIndex
             }.map { (index, list) ->
                 EpubChapter(
+                    chapterId = generateId(),
                     absPath = list.first().url,
                     title = list.first().title?.takeIf { it.isNotBlank() } ?: "Chapter $index",
                     body = list.joinToString("\n\n") { it.body }
diff --git a/app/src/main/java/com/starry/myne/epub/models/EpubChapter.kt b/app/src/main/java/com/starry/myne/epub/models/EpubChapter.kt
index de4d6226..579a9418 100644
--- a/app/src/main/java/com/starry/myne/epub/models/EpubChapter.kt
+++ b/app/src/main/java/com/starry/myne/epub/models/EpubChapter.kt
@@ -28,6 +28,7 @@ import kotlinx.serialization.Serializable
  */
 @Serializable
 data class EpubChapter(
+    val chapterId: String,
     val absPath: String,
     val title: String,
     val body: String
diff --git a/app/src/main/java/com/starry/myne/ui/screens/library/viewmodels/LibraryViewModel.kt b/app/src/main/java/com/starry/myne/ui/screens/library/viewmodels/LibraryViewModel.kt
index 17b3fd2a..b8e5e81f 100644
--- a/app/src/main/java/com/starry/myne/ui/screens/library/viewmodels/LibraryViewModel.kt
+++ b/app/src/main/java/com/starry/myne/ui/screens/library/viewmodels/LibraryViewModel.kt
@@ -55,6 +55,7 @@ class LibraryViewModel @Inject constructor(
     val showOnboardingTapTargets: State<Boolean> = _showOnboardingTapTargets
 
     fun deleteItemFromDB(item: LibraryItem) {
+        epubParser.removeBookFromCache(item.filePath)
         viewModelScope.launch(Dispatchers.IO) { libraryDao.delete(item) }
     }
 
diff --git a/app/src/main/java/com/starry/myne/ui/screens/reader/activities/ReaderActivity.kt b/app/src/main/java/com/starry/myne/ui/screens/reader/activities/ReaderActivity.kt
index 0e1a2b3c..cb882f55 100644
--- a/app/src/main/java/com/starry/myne/ui/screens/reader/activities/ReaderActivity.kt
+++ b/app/src/main/java/com/starry/myne/ui/screens/reader/activities/ReaderActivity.kt
@@ -27,6 +27,7 @@ import androidx.appcompat.app.AppCompatActivity
 import androidx.compose.foundation.lazy.LazyListState
 import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.snapshotFlow
 import androidx.core.view.WindowCompat
@@ -36,7 +37,7 @@ import androidx.lifecycle.ViewModelProvider
 import com.starry.myne.R
 import com.starry.myne.helpers.Constants
 import com.starry.myne.helpers.toToast
-import com.starry.myne.ui.screens.reader.composables.ReaderContent
+import com.starry.myne.ui.screens.reader.composables.ChaptersContent
 import com.starry.myne.ui.screens.reader.composables.ReaderScreen
 import com.starry.myne.ui.screens.reader.viewmodels.ReaderViewModel
 import com.starry.myne.ui.screens.settings.viewmodels.SettingsViewModel
@@ -80,40 +81,39 @@ class ReaderActivity : AppCompatActivity() {
         // Set UI contents.
         setContent {
             MyneTheme(settingsViewModel = settingsViewModel) {
-
                 val lazyListState = rememberLazyListState()
                 val coroutineScope = rememberCoroutineScope()
-
                 // Handle intent and load epub book.
-                val intentData = handleIntent(intent = intent,
-                    viewModel = viewModel,
-                    contentResolver = contentResolver,
-                    scrollToPosition = { index, offset ->
-                        coroutineScope.launch {
-                            lazyListState.scrollToItem(index, offset)
-                        }
-                    },
-                    onError = {
-                        getString(R.string.error).toToast(this)
-                        finish()
-                    })
+                val intentData = remember {
+                    handleIntent(intent = intent,
+                        viewModel = viewModel,
+                        contentResolver = contentResolver,
+                        scrollToPosition = { index, offset ->
+                            coroutineScope.launch {
+                                lazyListState.scrollToItem(index, offset)
+                            }
+                        },
+                        onError = {
+                            getString(R.string.error).toToast(this)
+                            finish()
+                        })
+                }
 
                 ReaderScreen(
                     viewModel = viewModel,
-                    lazyListState = lazyListState,
-                    readerContent = {
+                    onScrollToChapter = { lazyListState.scrollToItem(it) },
+                    chaptersContent = {
                         LaunchedEffect(lazyListState) {
                             snapshotFlow {
                                 lazyListState.firstVisibleItemScrollOffset
                             }.collect { visibleChapterOffset ->
-                                // fetch last visible chapter position and offset.
+                                // Get the currently visible chapter index.
                                 val visibleChapterIdx = lazyListState.firstVisibleItemIndex
                                 // Set currently visible chapter & index.
                                 viewModel.setVisibleChapterIndex(visibleChapterIdx)
                                 viewModel.setChapterScrollPercent(
                                     calculateChapterPercentage(lazyListState)
                                 )
-
                                 // If book was not opened from external epub file, update the
                                 // reading progress into the database.
                                 if (!intentData.isExternalFile) {
@@ -129,13 +129,14 @@ class ReaderActivity : AppCompatActivity() {
                         }
 
                         // Reader content lazy column.
-                        ReaderContent(
+                        ChaptersContent(
                             state = viewModel.state,
                             lazyListState = lazyListState,
                             onToggleReaderMenu = {
                                 viewModel.toggleReaderMenu()
                                 toggleSystemBars(viewModel.state.showReaderMenu)
-                            })
+                            }
+                        )
                     })
             }
         }
diff --git a/app/src/main/java/com/starry/myne/ui/screens/reader/composables/ReaderContent.kt b/app/src/main/java/com/starry/myne/ui/screens/reader/composables/ChaptersContent.kt
similarity index 98%
rename from app/src/main/java/com/starry/myne/ui/screens/reader/composables/ReaderContent.kt
rename to app/src/main/java/com/starry/myne/ui/screens/reader/composables/ChaptersContent.kt
index 5855feb0..710df248 100644
--- a/app/src/main/java/com/starry/myne/ui/screens/reader/composables/ReaderContent.kt
+++ b/app/src/main/java/com/starry/myne/ui/screens/reader/composables/ChaptersContent.kt
@@ -61,7 +61,7 @@ import com.starry.myne.ui.theme.pacificoFont
 
 
 @Composable
-fun ReaderContent(
+fun ChaptersContent(
     state: ReaderScreenState,
     lazyListState: LazyListState,
     onToggleReaderMenu: () -> Unit
@@ -72,7 +72,7 @@ fun ReaderContent(
     ) {
         items(
             count = state.epubBook!!.chapters.size,
-            key = { index -> state.epubBook.chapters[index].hashCode() }
+            key = { index -> state.epubBook.chapters[index].chapterId }
         ) { index ->
             val chapter = state.epubBook.chapters[index]
             ChapterLazyItemItem(
@@ -194,9 +194,7 @@ private fun ChapterLazyItemItem(
                             onClick()
                         }
                     }
-
                 }
-            //  .noRippleClickable { onClick() }
         ) {
             Text(
                 modifier = Modifier.padding(start = 12.dp, end = 4.dp, top = 10.dp),
diff --git a/app/src/main/java/com/starry/myne/ui/screens/reader/composables/ReaderScreen.kt b/app/src/main/java/com/starry/myne/ui/screens/reader/composables/ReaderScreen.kt
index 15381cf4..82edc7e6 100644
--- a/app/src/main/java/com/starry/myne/ui/screens/reader/composables/ReaderScreen.kt
+++ b/app/src/main/java/com/starry/myne/ui/screens/reader/composables/ReaderScreen.kt
@@ -42,7 +42,6 @@ import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.layout.systemBarsPadding
 import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.lazy.LazyColumn
-import androidx.compose.foundation.lazy.LazyListState
 import androidx.compose.foundation.selection.selectable
 import androidx.compose.foundation.selection.selectableGroup
 import androidx.compose.foundation.shape.RoundedCornerShape
@@ -76,6 +75,7 @@ import androidx.compose.material3.rememberDrawerState
 import androidx.compose.material3.surfaceColorAtElevation
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.MutableState
+import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
@@ -101,12 +101,11 @@ import kotlinx.coroutines.launch
 
 enum class TextScaleButtonType { INCREASE, DECREASE }
 
-@OptIn(ExperimentalMaterial3Api::class)
 @Composable
 fun ReaderScreen(
     viewModel: ReaderViewModel,
-    lazyListState: LazyListState,
-    readerContent: @Composable (paddingValues: PaddingValues) -> Unit
+    onScrollToChapter: suspend (Int) -> Unit,
+    chaptersContent: @Composable (paddingValues: PaddingValues) -> Unit
 ) {
     // Hide reader menu on back press.
     BackHandler(viewModel.state.showReaderMenu) {
@@ -118,9 +117,6 @@ fun ReaderScreen(
     FontChooserDialog(showFontDialog, viewModel)
 
     val snackBarHostState = remember { SnackbarHostState() }
-    val currentChapter =
-        viewModel.state.epubBook?.chapters?.getOrNull(viewModel.visibleChapterIndex.value)
-
     val drawerState = rememberDrawerState(DrawerValue.Closed)
     val chapters = viewModel.state.epubBook?.chapters
     val coroutineScope = rememberCoroutineScope()
@@ -167,11 +163,11 @@ fun ReaderScreen(
                                         overflow = TextOverflow.Ellipsis
                                     )
                                 },
-                                selected = idx == viewModel.visibleChapterIndex.value,
+                                selected = idx == viewModel.visibleChapterIndex.collectAsState().value,
                                 onClick = {
                                     coroutineScope.launch {
                                         drawerState.close()
-                                        lazyListState.scrollToItem(idx)
+                                        onScrollToChapter(idx)
                                     }
                                 }
                             )
@@ -180,77 +176,13 @@ fun ReaderScreen(
                 }
             }
         }) {
-
         Scaffold(
             snackbarHost = { SnackbarHost(snackBarHostState) },
             topBar = {
-                AnimatedVisibility(
-                    visible = viewModel.state.showReaderMenu,
-                    enter = expandVertically(initialHeight = { 0 }, expandFrom = Alignment.Top)
-                            + fadeIn(),
-                    exit = shrinkVertically(targetHeight = { 0 }, shrinkTowards = Alignment.Top)
-                            + fadeOut(),
-                ) {
-                    Surface(color = MaterialTheme.colorScheme.surfaceColorAtElevation(2.dp)) {
-                        Column(modifier = Modifier.displayCutoutPadding()) {
-                            TopAppBar(
-                                colors = TopAppBarDefaults.topAppBarColors(
-                                    containerColor = MaterialTheme.colorScheme.surfaceColorAtElevation(
-                                        2.dp
-                                    ),
-                                    scrolledContainerColor = MaterialTheme.colorScheme.surfaceColorAtElevation(
-                                        2.dp
-                                    ),
-                                ),
-                                title = {
-                                    viewModel.state.epubBook?.let {
-                                        Text(
-                                            text = it.title,
-                                            maxLines = 1,
-                                            overflow = TextOverflow.Ellipsis,
-                                            modifier = Modifier.animateContentSize(),
-                                            color = MaterialTheme.colorScheme.onSurface,
-                                            fontFamily = poppinsFont
-                                        )
-                                    }
-                                },
-                                actions = {
-                                    IconButton(onClick = { coroutineScope.launch { drawerState.open() } }) {
-                                        Icon(
-                                            Icons.Filled.Menu, null,
-                                            tint = MaterialTheme.colorScheme.onSurface
-                                        )
-                                    }
-                                }
-                            )
-                            Column(
-                                modifier = Modifier
-                                    .padding(bottom = 8.dp)
-                                    .padding(horizontal = 16.dp),
-                            ) {
-                                currentChapter?.title?.let {
-                                    Text(
-                                        text = it,
-                                        maxLines = 2,
-                                        overflow = TextOverflow.Ellipsis,
-                                        color = MaterialTheme.colorScheme.onSurface,
-                                        fontFamily = poppinsFont,
-                                        fontWeight = FontWeight.Medium
-                                    )
-                                }
-                            }
-                            val chapterProgressbarState = animateFloatAsState(
-                                targetValue = viewModel.chapterScrolledPercent.value,
-                                label = "chapter progress bar state animation"
-                            )
-                            LinearProgressIndicator(
-                                progress = { chapterProgressbarState.value },
-                                modifier = Modifier.fillMaxWidth(),
-                                color = MaterialTheme.colorScheme.primary,
-                            )
-                        }
-                    }
-                }
+                ReaderTopAppBar(
+                    viewModel = viewModel,
+                    onChapterListClicked = { coroutineScope.launch { drawerState.open() } }
+                )
             },
             bottomBar = {
                 AnimatedVisibility(
@@ -282,7 +214,7 @@ fun ReaderScreen(
                             }
                         }
                     } else {
-                        readerContent(paddingValues)
+                        chaptersContent(paddingValues)
                     }
                 }
             }
@@ -366,6 +298,80 @@ private fun FontChooserDialog(
     }
 }
 
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+private fun ReaderTopAppBar(
+    viewModel: ReaderViewModel,
+    onChapterListClicked: () -> Unit,
+) {
+    AnimatedVisibility(
+        visible = viewModel.state.showReaderMenu,
+        enter = expandVertically(initialHeight = { 0 }, expandFrom = Alignment.Top)
+                + fadeIn(),
+        exit = shrinkVertically(targetHeight = { 0 }, shrinkTowards = Alignment.Top)
+                + fadeOut(),
+    ) {
+        Surface(color = MaterialTheme.colorScheme.surfaceColorAtElevation(2.dp)) {
+            Column(modifier = Modifier.displayCutoutPadding()) {
+                TopAppBar(
+                    colors = TopAppBarDefaults.topAppBarColors(
+                        containerColor = MaterialTheme.colorScheme.surfaceColorAtElevation(
+                            2.dp
+                        ),
+                        scrolledContainerColor = MaterialTheme.colorScheme.surfaceColorAtElevation(
+                            2.dp
+                        ),
+                    ),
+                    title = {
+                        viewModel.state.epubBook?.let {
+                            Text(
+                                text = it.title,
+                                maxLines = 1,
+                                overflow = TextOverflow.Ellipsis,
+                                modifier = Modifier.animateContentSize(),
+                                color = MaterialTheme.colorScheme.onSurface,
+                                fontFamily = poppinsFont
+                            )
+                        }
+                    },
+                    actions = {
+                        IconButton(onClick = onChapterListClicked) {
+                            Icon(
+                                Icons.Filled.Menu, null,
+                                tint = MaterialTheme.colorScheme.onSurface
+                            )
+                        }
+                    }
+                )
+                Column(
+                    modifier = Modifier
+                        .padding(bottom = 8.dp)
+                        .padding(horizontal = 16.dp),
+                ) {
+                    viewModel.currentChapter.collectAsState().value?.let { chapter ->
+                        Text(
+                            text = chapter.title,
+                            maxLines = 2,
+                            overflow = TextOverflow.Ellipsis,
+                            color = MaterialTheme.colorScheme.onSurface,
+                            fontFamily = poppinsFont,
+                            fontWeight = FontWeight.Medium
+                        )
+                    }
+                }
+                val chapterProgressbarState = animateFloatAsState(
+                    targetValue = viewModel.chapterScrolledPercent.collectAsState().value,
+                    label = "chapter progress bar state animation"
+                )
+                LinearProgressIndicator(
+                    progress = { chapterProgressbarState.value },
+                    modifier = Modifier.fillMaxWidth(),
+                    color = MaterialTheme.colorScheme.primary,
+                )
+            }
+        }
+    }
+}
 
 @Composable
 private fun BottomSheetContents(
diff --git a/app/src/main/java/com/starry/myne/ui/screens/reader/viewmodels/ReaderViewModel.kt b/app/src/main/java/com/starry/myne/ui/screens/reader/viewmodels/ReaderViewModel.kt
index f515468b..a69d4229 100644
--- a/app/src/main/java/com/starry/myne/ui/screens/reader/viewmodels/ReaderViewModel.kt
+++ b/app/src/main/java/com/starry/myne/ui/screens/reader/viewmodels/ReaderViewModel.kt
@@ -17,10 +17,7 @@
 
 package com.starry.myne.ui.screens.reader.viewmodels
 
-import androidx.compose.runtime.State
 import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableFloatStateOf
-import androidx.compose.runtime.mutableIntStateOf
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.setValue
 import androidx.lifecycle.ViewModel
@@ -30,11 +27,14 @@ import com.starry.myne.database.reader.ReaderDao
 import com.starry.myne.database.reader.ReaderData
 import com.starry.myne.epub.EpubParser
 import com.starry.myne.epub.models.EpubBook
+import com.starry.myne.epub.models.EpubChapter
 import com.starry.myne.helpers.PreferenceUtil
 import com.starry.myne.ui.screens.reader.others.ReaderFont
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.launch
 import java.io.FileInputStream
 import javax.inject.Inject
@@ -65,11 +65,24 @@ class ReaderViewModel @Inject constructor(
         )
     )
 
-    private val _chapterScrolledPercent = mutableFloatStateOf(0f)
-    val chapterScrolledPercent: State<Float> = _chapterScrolledPercent
+    private val _chapterScrolledPercent = MutableStateFlow(0f)
+    val chapterScrolledPercent: StateFlow<Float> = _chapterScrolledPercent
 
-    private val _visibleChapterIndex = mutableIntStateOf(0)
-    val visibleChapterIndex: State<Int> = _visibleChapterIndex
+    private val _visibleChapterIndex = MutableStateFlow(0)
+    val visibleChapterIndex: StateFlow<Int> = _visibleChapterIndex
+
+    private val _currentChapter = MutableStateFlow(
+        state.epubBook?.chapters?.getOrNull(_visibleChapterIndex.value)
+    )
+    val currentChapter: StateFlow<EpubChapter?> = _currentChapter
+
+    init {
+        viewModelScope.launch {
+            _visibleChapterIndex.collect { index ->
+                _currentChapter.value = state.epubBook?.chapters?.getOrNull(index)
+            }
+        }
+    }
 
     fun loadEpubBook(libraryItemId: Int, onLoaded: (ReaderScreenState) -> Unit) {
         viewModelScope.launch(Dispatchers.IO) {
@@ -77,7 +90,7 @@ class ReaderViewModel @Inject constructor(
             state = state.copy(shouldShowLoader = !epubParser.isBookCached(libraryItem!!.filePath))
             val readerData = readerDao.getReaderData(libraryItemId)
             // parse and create epub book
-            var epubBook = epubParser.createEpubBook(libraryItem!!.filePath)
+            var epubBook = epubParser.createEpubBook(libraryItem.filePath)
             // Gutenberg for some reason don't include proper navMap in chinese books
             // in toc, so we need to parse the book based on spine, instead of toc.
             // This is a workaround for internal chinese books.
@@ -137,11 +150,11 @@ class ReaderViewModel @Inject constructor(
     }
 
     fun setChapterScrollPercent(percent: Float) {
-        _chapterScrolledPercent.floatValue = percent
+        _chapterScrolledPercent.value = percent
     }
 
     fun setVisibleChapterIndex(index: Int) {
-        _visibleChapterIndex.intValue = index
+        _visibleChapterIndex.value = index
     }
 
     fun toggleReaderMenu() {
diff --git a/app/src/test/java/com/starry/myne/EpubParserTest.kt b/app/src/test/java/com/starry/myne/EpubParserTest.kt
index b7a64d53..d9d95f10 100644
--- a/app/src/test/java/com/starry/myne/EpubParserTest.kt
+++ b/app/src/test/java/com/starry/myne/EpubParserTest.kt
@@ -18,7 +18,6 @@ package com.starry.myne
 
 import android.graphics.Bitmap
 import com.google.common.truth.Truth.assertThat
-import com.starry.myne.epub.EpubCache
 import com.starry.myne.epub.EpubParser
 import kotlinx.coroutines.runBlocking
 import org.junit.Before
@@ -44,11 +43,7 @@ class EpubParserTest {
 
     @Before
     fun setup() {
-        epubParser = EpubParser(
-            RuntimeEnvironment.getApplication(),
-            EpubCache(RuntimeEnvironment.getApplication())
-        )
-
+        epubParser = EpubParser(RuntimeEnvironment.getApplication())
         // Create a sample EPUB file for testing
         testEpubFile = createSampleEpubFile(hasToc = false)
         testEpubWithTocFile = createSampleEpubFile(hasToc = true)