Truncate and ellipsize long reactions (#821)

* Truncate and ellipsize long reactions

* Update screenshots

---------

Co-authored-by: ElementBot <benoitm+elementbot@element.io>

libraries/core/src/main/kotlin/io/element/android/libraries/core/extensions/BasicExtensions.kt

@@ -58,6 +58,21 @@ fun String?.insertBeforeLast(insert: String, delimiter: String = "."): String {
     }
 }
 
+/**
+ * Truncate and ellipsize text if it exceeds the given length.
+ *
+ * Throws if length is < 1.
+ */
+fun String.ellipsize(length: Int): String {
+    require(length > 1)
+
+    if (this.length <= length) {
+        return this
+    }
+
+    return "${this.take(length)}…"
+}
+
 inline fun <reified R> Any?.takeAs(): R? {
     return takeIf { it is R } as R?
 }

libraries/core/src/test/kotlin/io/element/android/libraries/core/extensions/BasicExtensionsTest.kt

@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2023 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.core.extensions
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class BasicExtensionsTest {
+
+    @Test(expected = IllegalArgumentException::class)
+    fun `test ellipsize at 0`() {
+        "1234567890".ellipsize(0)
+    }
+
+    @Test
+    fun `test ellipsize at 1`() {
+        assertEquals(
+            "1…",
+            "1234567890".ellipsize(1)
+        )
+    }
+
+    @Test
+    fun `test ellipsize at 5`() {
+        val output = "1234567890".ellipsize(5)
+        assertEquals("12345…", output)
+    }
+
+    @Test
+    fun `test ellipsize noop 1`() {
+        val input = "12345"
+        val output = input.ellipsize(5)
+        assertEquals(input, output)
+    }
+
+    @Test
+    fun `test ellipsize noop 2`() {
+        val input = "123"
+        val output = input.ellipsize(5)
+        assertEquals(input, output)
+    }
+}