feat: support links in markdown

Signed-off-by: Infi <infi@infi.sh>

app/src/main/java/chat/revolt/api/internals/Members.kt

@@ -29,4 +29,13 @@ class Members {
     fun clear() {
         memberCache.clear()
     }
+
+    /**
+     * Returns a Map of userId to server-nickname for the given serverId.
+     */
+    fun markdownMemberMapFor(serverId: String): Map<String, String> {
+        return memberCache[serverId]?.mapNotNull { (userId, member) ->
+            member.nickname?.let { userId to member.nickname }
+        }?.toMap() ?: emptyMap()
+    }
 }

app/src/main/java/chat/revolt/components/chat/Message.kt

@@ -6,6 +6,7 @@ import android.net.Uri
 import android.text.SpannableStringBuilder
 import android.text.TextUtils
 import android.text.format.DateUtils
+import android.text.method.LinkMovementMethod
 import android.widget.Toast
 import androidx.activity.compose.rememberLauncherForActivityResult
 import androidx.activity.result.contract.ActivityResultContracts
@@ -293,6 +294,8 @@ fun Message(
                                     textSize = 16f
                                     typeface = ResourcesCompat.getFont(ctx, R.font.inter)
 
+                                    movementMethod = LinkMovementMethod.getInstance()
+
                                     setTextColor(contentColor.toArgb())
                                 }
                             },

app/src/main/java/chat/revolt/components/generic/Markdown.kt

@@ -2,6 +2,7 @@ package chat.revolt.components.generic
 
 import android.text.SpannableStringBuilder
 import android.text.TextUtils
+import android.text.method.LinkMovementMethod
 import android.util.Log
 import android.util.TypedValue
 import android.view.ViewGroup
@@ -24,13 +25,10 @@ import androidx.compose.ui.viewinterop.AndroidView
 import androidx.core.content.res.ResourcesCompat
 import chat.revolt.R
 import chat.revolt.api.RevoltAPI
-import chat.revolt.internals.markdown.ChannelMentionRule
-import chat.revolt.internals.markdown.CustomEmoteRule
 import chat.revolt.internals.markdown.MarkdownContext
 import chat.revolt.internals.markdown.MarkdownParser
 import chat.revolt.internals.markdown.MarkdownState
-import chat.revolt.internals.markdown.TimestampRule
+import chat.revolt.internals.markdown.addRevoltRules
-import chat.revolt.internals.markdown.UserMentionRule
 import chat.revolt.internals.markdown.createCodeRule
 import chat.revolt.internals.markdown.createInlineCodeRule
 import com.discord.simpleast.core.simple.SimpleMarkdownRules
@@ -58,12 +56,9 @@ fun UIMarkdown(
     LaunchedEffect(text) {
         val parser = MarkdownParser()
             .addRules(
-                SimpleMarkdownRules.createEscapeRule(),
+                SimpleMarkdownRules.createEscapeRule()
-                UserMentionRule(),
-                ChannelMentionRule(),
-                CustomEmoteRule(),
-                TimestampRule(),
             )
+            .addRevoltRules()
             .addRules(
                 createCodeRule(context, codeBlockColor.toArgb()),
                 createInlineCodeRule(context, codeBlockColor.toArgb()),
@@ -102,6 +97,8 @@ fun UIMarkdown(
                 setMaxLines(maxLines)
                 setTextSize(TypedValue.COMPLEX_UNIT_SP, fontSize.value)
 
+                movementMethod = LinkMovementMethod.getInstance()
+
                 layoutParams = ViewGroup.LayoutParams(
                     ViewGroup.LayoutParams.WRAP_CONTENT,
                     ViewGroup.LayoutParams.WRAP_CONTENT

app/src/main/java/chat/revolt/internals/markdown/LinkSpan.kt

@@ -0,0 +1,22 @@
+package chat.revolt.internals.markdown
+
+import android.net.Uri
+import android.text.TextPaint
+import android.text.style.ClickableSpan
+import android.view.View
+import androidx.browser.customtabs.CustomTabsIntent
+
+class LinkSpan(private val url: String) : ClickableSpan() {
+    override fun onClick(widget: View) {
+        val customTab = CustomTabsIntent.Builder()
+            .setShowTitle(true)
+            .build()
+
+        customTab.launchUrl(widget.context, Uri.parse(url))
+    }
+
+    override fun updateDrawState(ds: TextPaint) {
+        ds.color = ds.linkColor
+        ds.isUnderlineText = false
+    }
+}

app/src/main/java/chat/revolt/internals/markdown/MarkdownNodes.kt

@@ -1,6 +1,7 @@
 package chat.revolt.internals.markdown
 
 import android.text.SpannableStringBuilder
+import android.text.Spanned
 import android.text.format.DateUtils
 import android.util.Log
 import com.discord.simpleast.core.node.Node
@@ -101,4 +102,16 @@ class TimestampNode(private val timestamp: Long, private val modifier: String? =
             builder.append("<invalid timestamp>")
         }
     }
+}
+
+class LinkNode(val content: String, val url: String = content) : Node<MarkdownContext>() {
+    override fun render(builder: SpannableStringBuilder, renderContext: MarkdownContext) {
+        builder.append(content)
+        builder.setSpan(
+            LinkSpan(url),
+            builder.length - content.length,
+            builder.length,
+            Spanned.SPAN_EXCLUSIVE_EXCLUSIVE
+        )
+    }
 }

app/src/main/java/chat/revolt/internals/markdown/MarkdownRules.kt

@@ -67,6 +67,42 @@ class TimestampRule<S> :
     }
 }
 
+const val RE_LINK =
+    "<?https?://(www\\.)?[-a-zA-Z0-9@:%._+~#=]{2,256}\\.[a-z]{2,4}\\b([-a-zA-Z0-9@:%_+.~#?&/=]*)>?"
+
+class LinkRule<S> : Rule<MarkdownContext, Node<MarkdownContext>, S>(
+    Pattern.compile("^$RE_LINK")
+) {
+    override fun parse(
+        matcher: Matcher,
+        parser: Parser<MarkdownContext, in Node<MarkdownContext>, S>,
+        state: S
+    ): ParseSpec<MarkdownContext, S> {
+        val url = matcher.group(0)!!.trimStart('<').trimEnd('>')
+        return ParseSpec.createTerminal(
+            LinkNode(url),
+            state
+        )
+    }
+}
+
+class NamedLinkRule<S> : Rule<MarkdownContext, Node<MarkdownContext>, S>(
+    Pattern.compile("^\\[([^]]+)]\\(($RE_LINK)\\)")
+) {
+    override fun parse(
+        matcher: Matcher,
+        parser: Parser<MarkdownContext, in Node<MarkdownContext>, S>,
+        state: S
+    ): ParseSpec<MarkdownContext, S> {
+        val content = matcher.group(1)!!
+        val url = matcher.group(2)!!.trimStart('<').trimEnd('>')
+        return ParseSpec.createTerminal(
+            LinkNode(content, url),
+            state
+        )
+    }
+}
+
 fun <RC, S> createInlineCodeRule(context: Context, backgroundColor: Int): Rule<RC, Node<RC>, S> {
     return CodeRules.createInlineCodeRule(
         { listOf(TextAppearanceSpan(context, R.style.Code_TextAppearance)) },
@@ -155,4 +191,15 @@ fun <RC> createCodeRule(
             )
         }
     }
-}
+}
+
+fun MarkdownParser.addRevoltRules(): MarkdownParser {
+    return addRules(
+        UserMentionRule(),
+        ChannelMentionRule(),
+        CustomEmoteRule(),
+        TimestampRule(),
+        NamedLinkRule(),
+        LinkRule(),
+    )
+}

app/src/main/java/chat/revolt/screens/chat/views/channel/ChannelScreen.kt

@@ -77,13 +77,10 @@ import chat.revolt.components.screens.chat.AttachmentManager
 import chat.revolt.components.screens.chat.ChannelHeader
 import chat.revolt.components.screens.chat.ReplyManager
 import chat.revolt.components.screens.chat.TypingIndicator
-import chat.revolt.internals.markdown.ChannelMentionRule
-import chat.revolt.internals.markdown.CustomEmoteRule
 import chat.revolt.internals.markdown.MarkdownContext
 import chat.revolt.internals.markdown.MarkdownParser
 import chat.revolt.internals.markdown.MarkdownState
-import chat.revolt.internals.markdown.TimestampRule
+import chat.revolt.internals.markdown.addRevoltRules
-import chat.revolt.internals.markdown.UserMentionRule
 import chat.revolt.internals.markdown.createCodeRule
 import chat.revolt.internals.markdown.createInlineCodeRule
 import chat.revolt.sheets.ChannelInfoSheet
@@ -300,11 +297,8 @@ fun ChannelScreen(
                                 val parser = MarkdownParser()
                                     .addRules(
                                         SimpleMarkdownRules.createEscapeRule(),
-                                        UserMentionRule(),
-                                        ChannelMentionRule(),
-                                        CustomEmoteRule(),
-                                        TimestampRule(),
                                     )
+                                    .addRevoltRules()
                                     .addRules(
                                         createCodeRule(context, codeBlockColor.toArgb()),
                                         createInlineCodeRule(context, codeBlockColor.toArgb()),
@@ -320,7 +314,11 @@ fun ChannelScreen(
                                     parser = parser,
                                     initialState = MarkdownState(0),
                                     renderContext = MarkdownContext(
-                                        memberMap = mapOf(),
+                                        memberMap = viewModel.activeChannel?.server?.let { serverId ->
+                                            RevoltAPI.members.markdownMemberMapFor(
+                                                serverId
+                                            )
+                                        } ?: mapOf(),
                                         userMap = RevoltAPI.userCache.toMap(),
                                         channelMap = RevoltAPI.channelCache.mapValues { ch ->
                                             ch.value.name ?: ch.value.id ?: "#DeletedChannel"