From 0d9399a1a45da32b86c043fa5323866bcd040b18 Mon Sep 17 00:00:00 2001
From: Vitor Pamplona <vitor@vitorpamplona.com>
Date: Thu, 13 Jul 2023 19:23:26 -0400
Subject: [PATCH] Fixing Right To Left Text

---
 .../amethyst/service/CachedRichTextParser.kt  | 18 +++---
 .../amethyst/ui/components/RichTextViewer.kt  | 64 ++++++++++++-------
 2 files changed, 51 insertions(+), 31 deletions(-)

diff --git a/app/src/main/java/com/vitorpamplona/amethyst/service/CachedRichTextParser.kt b/app/src/main/java/com/vitorpamplona/amethyst/service/CachedRichTextParser.kt
index 1c18c56c3..163ffc0ea 100644
--- a/app/src/main/java/com/vitorpamplona/amethyst/service/CachedRichTextParser.kt
+++ b/app/src/main/java/com/vitorpamplona/amethyst/service/CachedRichTextParser.kt
@@ -30,9 +30,11 @@ data class RichTextViewerState(
     val imagesForPager: ImmutableMap<String, ZoomableUrlContent>,
     val imageList: ImmutableList<ZoomableUrlContent>,
     val customEmoji: ImmutableMap<String, String>,
-    val paragraphs: ImmutableList<ImmutableList<Segment>>
+    val paragraphs: ImmutableList<ParagraphState>
 )
 
+data class ParagraphState(val words: ImmutableList<Segment>, val isRTL: Boolean)
+
 object CachedRichTextParser {
     val richTextCache = LruCache<String, RichTextViewerState>(200)
 
@@ -108,13 +110,15 @@ class RichTextParser() {
         )
     }
 
-    private fun findTextSegments(content: String, images: Set<String>, urls: Set<String>, emojis: Map<String, String>, tags: ImmutableListOfLists<String>): ImmutableList<ImmutableList<Segment>> {
-        var paragraphSegments = persistentListOf<ImmutableList<Segment>>()
+    private fun findTextSegments(content: String, images: Set<String>, urls: Set<String>, emojis: Map<String, String>, tags: ImmutableListOfLists<String>): ImmutableList<ParagraphState> {
+        var paragraphSegments = persistentListOf<ParagraphState>()
 
         content.split('\n').forEach { paragraph ->
             var segments = persistentListOf<Segment>()
             var isDirty = false
 
+            val isRTL = isArabic(paragraph)
+
             val wordList = paragraph.split(' ')
             wordList.forEach { word ->
                 val wordSegment = wordIdentifier(word, images, urls, emojis, tags)
@@ -125,13 +129,9 @@ class RichTextParser() {
             }
 
             val newSegments = if (isDirty) {
-                if (isArabic(paragraph)) {
-                    segments.asReversed().toImmutableList()
-                } else {
-                    segments
-                }
+                ParagraphState(segments, isRTL)
             } else {
-                persistentListOf<Segment>(RegularTextSegment(paragraph))
+                ParagraphState(persistentListOf<Segment>(RegularTextSegment(paragraph)), isRTL)
             }
 
             paragraphSegments = paragraphSegments.add(newSegments)
diff --git a/app/src/main/java/com/vitorpamplona/amethyst/ui/components/RichTextViewer.kt b/app/src/main/java/com/vitorpamplona/amethyst/ui/components/RichTextViewer.kt
index 953bc2deb..c366bdfb3 100644
--- a/app/src/main/java/com/vitorpamplona/amethyst/ui/components/RichTextViewer.kt
+++ b/app/src/main/java/com/vitorpamplona/amethyst/ui/components/RichTextViewer.kt
@@ -17,16 +17,19 @@ import androidx.compose.material.ProvideTextStyle
 import androidx.compose.material.Text
 import androidx.compose.runtime.*
 import androidx.compose.runtime.livedata.observeAsState
+import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.takeOrElse
 import androidx.compose.ui.layout.SubcomposeLayout
+import androidx.compose.ui.platform.LocalLayoutDirection
 import androidx.compose.ui.platform.LocalUriHandler
 import androidx.compose.ui.res.painterResource
 import androidx.compose.ui.text.*
 import androidx.compose.ui.text.style.TextDirection
 import androidx.compose.ui.unit.Constraints
 import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.LayoutDirection
 import androidx.compose.ui.unit.em
 import androidx.lifecycle.distinctUntilChanged
 import androidx.lifecycle.map
@@ -136,7 +139,6 @@ private fun RenderRegular(
     val currentTextStyle = LocalTextStyle.current
 
     val textStyle = currentTextStyle.copy(
-        textDirection = TextDirection.Content,
         lineHeight = 1.4.em,
         color = currentTextStyle.color.takeOrElse {
             LocalContentColor.current.copy(alpha = LocalContentAlpha.current)
@@ -144,36 +146,54 @@ private fun RenderRegular(
     )
 
     MeasureSpaceWidth() { spaceWidth ->
-        Column {
+        Column() {
             if (canPreview) {
                 // FlowRow doesn't work well with paragraphs. So we need to split them
                 state.paragraphs.forEach { paragraph ->
-                    FlowRow(horizontalArrangement = Arrangement.spacedBy(spaceWidth)) {
-                        paragraph.forEach { word ->
-                            RenderWordWithPreview(
-                                word,
-                                state,
-                                backgroundColor,
-                                textStyle,
-                                accountViewModel,
-                                nav
-                            )
+                    val direction = if (paragraph.isRTL) {
+                        LayoutDirection.Rtl
+                    } else LayoutDirection.Ltr
+
+                    CompositionLocalProvider(LocalLayoutDirection provides direction) {
+                        FlowRow(
+                            modifier = Modifier.align(if (paragraph.isRTL) Alignment.End else Alignment.Start),
+                            horizontalArrangement = Arrangement.spacedBy(spaceWidth)
+                        ) {
+                            paragraph.words.forEach { word ->
+                                RenderWordWithPreview(
+                                    word,
+                                    state,
+                                    backgroundColor,
+                                    textStyle,
+                                    accountViewModel,
+                                    nav
+                                )
+                            }
                         }
                     }
                 }
             } else {
                 // FlowRow doesn't work well with paragraphs. So we need to split them
                 state.paragraphs.forEach { paragraph ->
-                    FlowRow(horizontalArrangement = Arrangement.spacedBy(spaceWidth)) {
-                        paragraph.forEach { word ->
-                            RenderWordWithoutPreview(
-                                word,
-                                state,
-                                backgroundColor,
-                                textStyle,
-                                accountViewModel,
-                                nav
-                            )
+                    val direction = if (paragraph.isRTL) {
+                        LayoutDirection.Rtl
+                    } else LayoutDirection.Ltr
+
+                    CompositionLocalProvider(LocalLayoutDirection provides direction) {
+                        FlowRow(
+                            horizontalArrangement = Arrangement.spacedBy(spaceWidth),
+                            modifier = Modifier.align(if (paragraph.isRTL) Alignment.End else Alignment.Start),
+                        ) {
+                            paragraph.words.forEach { word ->
+                                RenderWordWithoutPreview(
+                                    word,
+                                    state,
+                                    backgroundColor,
+                                    textStyle,
+                                    accountViewModel,
+                                    nav
+                                )
+                            }
                         }
                     }
                 }