From 38763d057559033cddc21a7d2e5617bdc7328dcc Mon Sep 17 00:00:00 2001
From: Adam Brown <adampsbrown@gmail.com>
Date: Wed, 13 Jul 2022 12:04:19 +0100
Subject: [PATCH] adding function to extract usernames from full matrix ids

---
 .../matrix/android/sdk/api/MatrixPatterns.kt    | 14 ++++++++++++++
 .../android/sdk/api/MatrixPatternsTest.kt       | 17 +++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/MatrixPatterns.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/MatrixPatterns.kt
index 82f39806c0..bae4b06a05 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/MatrixPatterns.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/MatrixPatterns.kt
@@ -156,6 +156,20 @@ object MatrixPatterns {
         return matrixId?.substringAfter(":", missingDelimiterValue = "")?.takeIf { it.isNotEmpty() }
     }
 
+    /**
+     * Extract user name from a matrix id.
+     *
+     * @param matrixId
+     * @return null if the input is not a valid matrixId
+     */
+    fun extractUserNameFromId(matrixId: String): String? {
+        return if (isUserId(matrixId)) {
+            matrixId.removePrefix("@").substringBefore(":", missingDelimiterValue = "")
+        } else {
+            null
+        }
+    }
+
     /**
      * Orders which are not strings, or do not consist solely of ascii characters in the range \x20 (space) to \x7E (~),
      * or consist of more than 50 characters, are forbidden and the field should be ignored if received.
diff --git a/matrix-sdk-android/src/test/java/org/matrix/android/sdk/api/MatrixPatternsTest.kt b/matrix-sdk-android/src/test/java/org/matrix/android/sdk/api/MatrixPatternsTest.kt
index 0d0450adc2..ec587e0536 100644
--- a/matrix-sdk-android/src/test/java/org/matrix/android/sdk/api/MatrixPatternsTest.kt
+++ b/matrix-sdk-android/src/test/java/org/matrix/android/sdk/api/MatrixPatternsTest.kt
@@ -35,6 +35,23 @@ class MatrixPatternsTest {
             MatrixPatterns.isUserId(input) shouldBeEqualTo expected
         }
     }
+
+    @Test
+    fun `given matrix id cases, when extracting userName, then returns expected`() {
+        val cases = listOf(
+                MatrixIdCase("foobar", userName = null),
+                MatrixIdCase("@foobar", userName = null),
+                MatrixIdCase("foobar@matrix.org", userName = null),
+                MatrixIdCase("@foobar: matrix.org", userName = null),
+                MatrixIdCase("foobar:matrix.org", userName = null),
+                MatrixIdCase("@foobar:matrix.org", userName = "foobar"),
+        )
+
+        cases.forEach { (input, expected) ->
+            MatrixPatterns.extractUserNameFromId(input) shouldBeEqualTo expected
+        }
+    }
 }
 
 private data class UserIdCase(val input: String, val isUserId: Boolean)
+private data class MatrixIdCase(val input: String, val userName: String?)