Adding spoiler tag support

app/src/main/java/com/jerboa/ui/components/common/MarkdownHelper.kt

@@ -2,10 +2,7 @@ package com.jerboa.ui.components.common
 
 import android.content.Context
 import android.os.Build
-import android.text.Spannable
-import android.text.SpannableStringBuilder
 import android.text.TextUtils
-import android.text.style.URLSpan
 import android.text.util.Linkify
 import android.util.TypedValue
 import android.view.View
@@ -36,15 +33,11 @@ import coil.ImageLoader
 import com.jerboa.R
 import com.jerboa.convertSpToPx
 import com.jerboa.openLink
+import com.jerboa.util.MarkwonLemmyLinkPlugin
+import com.jerboa.util.MarkwonSpoilerPlugin
 import io.noties.markwon.AbstractMarkwonPlugin
 import io.noties.markwon.Markwon
 import io.noties.markwon.MarkwonConfiguration
-import io.noties.markwon.MarkwonPlugin
-import io.noties.markwon.MarkwonVisitor
-import io.noties.markwon.SpannableBuilder
-import io.noties.markwon.core.CorePlugin
-import io.noties.markwon.core.CorePlugin.OnTextAddedListener
-import io.noties.markwon.core.CoreProps
 import io.noties.markwon.ext.strikethrough.StrikethroughPlugin
 import io.noties.markwon.ext.tables.TableAwareMovementMethod
 import io.noties.markwon.ext.tables.TablePlugin
@@ -54,7 +47,6 @@ import io.noties.markwon.image.AsyncDrawableSpan
 import io.noties.markwon.image.coil.CoilImagesPlugin
 import io.noties.markwon.linkify.LinkifyPlugin
 import io.noties.markwon.movement.MovementMethodPlugin
-import org.commonmark.node.Link
 import java.util.regex.Pattern
 
 /**
@@ -85,52 +77,6 @@ val lemmyCommunityPattern: Pattern =
 val lemmyUserPattern: Pattern =
     Pattern.compile("(?<!\\S)@($userPatternFragment)(?:@($instancePatternFragment))?\\b")
 
-/**
- * Plugin to turn Lemmy-specific URIs into clickable links.
- */
-class LemmyLinkPlugin : AbstractMarkwonPlugin() {
-    override fun configure(registry: MarkwonPlugin.Registry) {
-        registry.require(CorePlugin::class.java) { it.addOnTextAddedListener(LemmyTextAddedListener()) }
-    }
-
-    private class LemmyTextAddedListener : OnTextAddedListener {
-        override fun onTextAdded(visitor: MarkwonVisitor, text: String, start: Int) {
-            // we will be using the link that is used by markdown (instead of directly applying URLSpan)
-            val spanFactory = visitor.configuration().spansFactory().get(
-                Link::class.java,
-            ) ?: return
-
-            // don't re-use builder (thread safety achieved for
-            // render calls from different threads and ... better performance)
-            val builder = SpannableStringBuilder(text)
-            if (addLinks(builder)) {
-                // target URL span specifically
-                val spans = builder.getSpans(0, builder.length, URLSpan::class.java)
-                if (!spans.isNullOrEmpty()) {
-                    val renderProps = visitor.renderProps()
-                    val spannableBuilder = visitor.builder()
-                    for (span in spans) {
-                        CoreProps.LINK_DESTINATION[renderProps] = span.url
-                        SpannableBuilder.setSpans(
-                            spannableBuilder,
-                            spanFactory.getSpans(visitor.configuration(), renderProps),
-                            start + builder.getSpanStart(span),
-                            start + builder.getSpanEnd(span),
-                        )
-                    }
-                }
-            }
-        }
-
-        fun addLinks(text: Spannable): Boolean {
-            val communityLinkAdded = Linkify.addLinks(text, lemmyCommunityPattern, null)
-            val userLinkAdded = Linkify.addLinks(text, lemmyUserPattern, null)
-
-            return communityLinkAdded || userLinkAdded
-        }
-    }
-}
-
 object MarkdownHelper {
     private var markwon: Markwon? = null
     private var previewMarkwon: Markwon? = null
@@ -146,14 +92,15 @@ object MarkdownHelper {
         markwon = Markwon.builder(context)
             // email urls interfere with lemmy links
             .usePlugin(LinkifyPlugin.create(Linkify.WEB_URLS))
-            .usePlugin(LemmyLinkPlugin())
+            .usePlugin(MarkwonLemmyLinkPlugin())
             .usePlugin(StrikethroughPlugin.create())
             .usePlugin(TablePlugin.create(context))
             .usePlugin(CoilImagesPlugin.create(context, loader))
             .usePlugin(HtmlPlugin.create())
             // use TableAwareLinkMovementMethod to handle clicks inside tables,
             // wraps LinkMovementMethod internally
             .usePlugin(MovementMethodPlugin.create(TableAwareMovementMethod.create()))
+            .usePlugin(MarkwonSpoilerPlugin(false))
             .usePlugin(object : AbstractMarkwonPlugin() {
                 override fun configureConfiguration(builder: MarkwonConfiguration.Builder) {
                     builder.linkResolver { _, link ->
@@ -167,7 +114,7 @@ object MarkdownHelper {
         previewMarkwon = Markwon.builder(context)
             // email urls interfere with lemmy links
             .usePlugin(LinkifyPlugin.create(Linkify.WEB_URLS))
-            .usePlugin(LemmyLinkPlugin())
+            .usePlugin(MarkwonLemmyLinkPlugin())
             .usePlugin(StrikethroughPlugin.create())
             .usePlugin(TablePlugin.create(context))
             .usePlugin(HtmlPlugin.create { plugin -> plugin.addHandler(TagHandlerNoOp.create("img")) })
@@ -176,6 +123,7 @@ object MarkdownHelper {
                     builder.linkResolver { _, _ -> }
                 }
             })
+            .usePlugin(MarkwonSpoilerPlugin(true))
             .build()
     }
 
@@ -254,7 +202,7 @@ object MarkdownHelper {
             setTextColor(textColor.toArgb())
             setTextSize(TypedValue.COMPLEX_UNIT_SP, mergedStyle.fontSize.value)
             if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
-                setLineHeight(convertSpToPx(mergedStyle.lineHeight, context))
+                lineHeight = convertSpToPx(mergedStyle.lineHeight, context)
             }
             width = maxWidth
 

app/src/main/java/com/jerboa/util/MarkwonLemmyLinkPlugin.kt

@@ -0,0 +1,58 @@
+package com.jerboa.util
+
+import android.text.Spannable
+import android.text.SpannableStringBuilder
+import android.text.style.URLSpan
+import android.text.util.Linkify
+import com.jerboa.ui.components.common.lemmyCommunityPattern
+import com.jerboa.ui.components.common.lemmyUserPattern
+import io.noties.markwon.*
+import io.noties.markwon.core.CorePlugin
+import io.noties.markwon.core.CoreProps
+import org.commonmark.node.Link
+
+/**
+ * Plugin to turn Lemmy-specific URIs into clickable links.
+ */
+class MarkwonLemmyLinkPlugin : AbstractMarkwonPlugin() {
+    override fun configure(registry: MarkwonPlugin.Registry) {
+        registry.require(CorePlugin::class.java) { it.addOnTextAddedListener(LemmyTextAddedListener()) }
+    }
+
+    private class LemmyTextAddedListener : CorePlugin.OnTextAddedListener {
+        override fun onTextAdded(visitor: MarkwonVisitor, text: String, start: Int) {
+            // we will be using the link that is used by markdown (instead of directly applying URLSpan)
+            val spanFactory = visitor.configuration().spansFactory().get(
+                Link::class.java,
+            ) ?: return
+
+            // don't re-use builder (thread safety achieved for
+            // render calls from different threads and ... better performance)
+            val builder = SpannableStringBuilder(text)
+            if (addLinks(builder)) {
+                // target URL span specifically
+                val spans = builder.getSpans(0, builder.length, URLSpan::class.java)
+                if (!spans.isNullOrEmpty()) {
+                    val renderProps = visitor.renderProps()
+                    val spannableBuilder = visitor.builder()
+                    for (span in spans) {
+                        CoreProps.LINK_DESTINATION[renderProps] = span.url
+                        SpannableBuilder.setSpans(
+                            spannableBuilder,
+                            spanFactory.getSpans(visitor.configuration(), renderProps),
+                            start + builder.getSpanStart(span),
+                            start + builder.getSpanEnd(span),
+                        )
+                    }
+                }
+            }
+        }
+
+        fun addLinks(text: Spannable): Boolean {
+            val communityLinkAdded = Linkify.addLinks(text, lemmyCommunityPattern, null)
+            val userLinkAdded = Linkify.addLinks(text, lemmyUserPattern, null)
+
+            return communityLinkAdded || userLinkAdded
+        }
+    }
+}

app/src/main/java/com/jerboa/util/MarkwonSpoilerPlugin.kt

@@ -0,0 +1,140 @@
+package com.jerboa.util
+
+import android.text.SpannableStringBuilder
+import android.text.Spanned
+import android.text.TextPaint
+import android.text.style.ClickableSpan
+import android.util.Log
+import android.view.View
+import android.widget.TextView
+import io.noties.markwon.AbstractMarkwonPlugin
+import io.noties.markwon.MarkwonPlugin
+import io.noties.markwon.MarkwonVisitor
+import io.noties.markwon.core.CorePlugin
+import io.noties.markwon.image.AsyncDrawableScheduler
+
+data class SpoilerTitleSpan(val title: CharSequence)
+class SpoilerCloseSpan
+
+class MarkwonSpoilerPlugin(val preview: Boolean) : AbstractMarkwonPlugin() {
+    override fun configure(registry: MarkwonPlugin.Registry) {
+        registry.require(CorePlugin::class.java) {
+            it.addOnTextAddedListener(
+                SpoilerTextAddedListener(),
+            )
+        }
+    }
+
+    private class SpoilerTextAddedListener : CorePlugin.OnTextAddedListener {
+        override fun onTextAdded(visitor: MarkwonVisitor, text: String, start: Int) {
+            val spoilerTitleRegex = Regex("(:::\\s*spoiler\\s*)(.*)")
+            // Find all spoiler "start" lines
+            val spoilerTitles = spoilerTitleRegex.findAll(text)
+
+            for (match in spoilerTitles) {
+                val spoilerTitle = match.groups[2]!!.value
+                visitor.builder().setSpan(
+                    SpoilerTitleSpan(spoilerTitle),
+                    start,
+                    start + match.groups[2]!!.range.last,
+                    Spanned.SPAN_EXCLUSIVE_EXCLUSIVE,
+                )
+            }
+
+            val spoilerCloseRegex = Regex("^(?!.*spoiler).*:::")
+            // Find all spoiler "end" lines
+            val spoilerCloses = spoilerCloseRegex.findAll(text)
+            for (match in spoilerCloses) {
+                visitor.builder()
+                    .setSpan(SpoilerCloseSpan(), start, start + 3, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE)
+            }
+        }
+    }
+
+    override fun afterSetText(textView: TextView) {
+        try {
+            val spanned = SpannableStringBuilder(textView.text)
+            val spoilerTitleSpans =
+                spanned.getSpans(0, spanned.length, SpoilerTitleSpan::class.java)
+            val spoilerCloseSpans =
+                spanned.getSpans(0, spanned.length, SpoilerCloseSpan::class.java)
+
+            spoilerTitleSpans.sortBy { spanned.getSpanStart(it) }
+            spoilerCloseSpans.sortBy { spanned.getSpanStart(it) }
+
+            spoilerTitleSpans.forEachIndexed { index, spoilerTitleSpan ->
+                val spoilerStart = spanned.getSpanStart(spoilerTitleSpan)
+
+                var spoilerEnd = spanned.length
+                if (index < spoilerCloseSpans.size) {
+                    val spoilerCloseSpan = spoilerCloseSpans[index]
+                    spoilerEnd = spanned.getSpanEnd(spoilerCloseSpan)
+                }
+
+                var open = false
+                val getSpoilerTitle = { openParam: Boolean ->
+                    if (openParam) "▼ ${spoilerTitleSpan.title}" else "▶ ${spoilerTitleSpan.title}"
+                }
+
+                val spoilerTitle = getSpoilerTitle(false)
+
+                val spoilerContent = spanned.subSequence(
+                    spanned.getSpanEnd(spoilerTitleSpan) + 1,
+                    spoilerEnd - 3,
+                ) as SpannableStringBuilder
+
+                // Remove spoiler content from span
+                spanned.replace(spoilerStart, spoilerEnd, spoilerTitle)
+                // Set span block title
+                spanned.setSpan(
+                    spoilerTitle,
+                    spoilerStart,
+                    spoilerStart + spoilerTitle.length,
+                    Spanned.SPAN_EXCLUSIVE_EXCLUSIVE,
+                )
+
+                val wrapper = object : ClickableSpan() {
+                    override fun onClick(p0: View) {
+                        if (!preview) {
+                            textView.cancelPendingInputEvents()
+                            open = !open
+
+                            spanned.replace(
+                                spoilerStart,
+                                spoilerStart + spoilerTitle.length,
+                                getSpoilerTitle(open),
+                            )
+                            if (open) {
+                                spanned.insert(spoilerStart + spoilerTitle.length, spoilerContent)
+                            } else {
+                                spanned.replace(
+                                    spoilerStart + spoilerTitle.length,
+                                    spoilerStart + spoilerTitle.length + spoilerContent.length,
+                                    "",
+                                )
+                            }
+
+                            textView.text = spanned
+                            AsyncDrawableScheduler.schedule(textView)
+                        }
+                    }
+
+                    override fun updateDrawState(ds: TextPaint) {
+                    }
+                }
+
+                // Set spoiler block type as ClickableSpan
+                spanned.setSpan(
+                    wrapper,
+                    spoilerStart,
+                    spoilerStart + spoilerTitle.length,
+                    Spanned.SPAN_EXCLUSIVE_EXCLUSIVE,
+                )
+
+                textView.text = spanned
+            }
+        } catch (e: Exception) {
+            Log.w("jerboa", "Failed to parse spoiler tag. Format incorrect")
+        }
+    }
+}