Fix invalid selection/span ranges causing editor crashes #1112

Author: Twinsen81

aztec/src/main/kotlin/org/wordpress/aztec/AztecText.kt

@@ -1588,6 +1588,31 @@ open class AztecText : AppCompatEditText, TextWatcher, UnknownHtmlSpan.OnUnknown
 
     // Helper ======================================================================================
 
+    /**
+     * Some Android versions/framework builds are very strict about selection offsets and will crash
+     * when selection handles try to position at an invalid cursor offset (e.g. -1 or > text length).
+     *
+     * Aztec can temporarily compute such offsets while mutating text (indent/outdent, span re-application, etc),
+     * so we clamp selection to a valid range here to avoid framework crashes.
+     *
+     * NOTE: We clamp to [0, safeLength] to avoid placing selection on the end-of-buffer marker.
+     */
+    override fun setSelection(index: Int) {
+        val max = EndOfBufferMarkerAdder.safeLength(this)
+        super.setSelection(index.coerceIn(0, max))
+    }
+
+    override fun setSelection(start: Int, stop: Int) {
+        val max = EndOfBufferMarkerAdder.safeLength(this)
+        val s = start.coerceIn(0, max)
+        val e = stop.coerceIn(0, max)
+        if (s <= e) {
+            super.setSelection(s, e)
+        } else {
+            super.setSelection(e, s)
+        }
+    }
+
     fun consumeCursorPosition(text: SpannableStringBuilder): Int {
         var cursorPosition = Math.min(selectionStart, text.length)
 

aztec/src/main/kotlin/org/wordpress/aztec/formatting/LineBlockFormatter.kt

@@ -219,7 +219,22 @@ class LineBlockFormatter(editor: AztecText) : AztecFormatter(editor) {
         this.onEach { editableText.removeSpan(it.span) }
         action()
         this.onEach {
-            editableText.setSpan(it.span, it.spanStart, it.spanEnd, it.spanFlags)
+            val len = editableText.length
+            if (len <= 0) return@onEach
+
+            val start = it.spanStart.coerceIn(0, len)
+            val end = it.spanEnd.coerceIn(0, len)
+            if (start >= end) return@onEach
+
+            try {
+                editableText.setSpan(it.span, start, end, it.spanFlags)
+            } catch (_: IndexOutOfBoundsException) {
+                // Defensive: text may have been modified by other watchers by the time we restore spans.
+            } catch (_: IllegalArgumentException) {
+                // Defensive: some framework builds throw IllegalArgumentException on invalid ranges.
+            } catch (_: RuntimeException) {
+                // Defensive: SpannableStringBuilder.setSpan can throw RuntimeException for invalid ranges.
+            }
         }
     }
 

aztec/src/main/kotlin/org/wordpress/aztec/watchers/SuggestionWatcher.kt

@@ -142,19 +142,26 @@ class SuggestionWatcher(aztecText: AztecText) : TextWatcher {
 
     private fun reapplyCarriedOverInlineSpans(editableText: Spannable) {
         carryOverSpans.forEach {
-            if (it.start >= 0 && it.end <= editableText.length && it.start < it.end) {
-                try {
-                    editableText.setSpan(
-                        it.span,
-                        it.start,
-                        it.end,
-                        Spanned.SPAN_EXCLUSIVE_EXCLUSIVE
-                    )
-                } catch (e: IndexOutOfBoundsException) {
-                    // This is a workaround for a possible bug in the Android framework
-                    // https://github.com/wordpress-mobile/WordPress-Android/issues/20481
-                    e.printStackTrace()
-                }
+            val len = editableText.length
+            if (len <= 0) return@forEach
+
+            val start = it.start.coerceIn(0, len)
+            val end = it.end.coerceIn(0, len)
+            if (start >= end) return@forEach
+
+            try {
+                editableText.setSpan(
+                    it.span,
+                    start,
+                    end,
+                    Spanned.SPAN_EXCLUSIVE_EXCLUSIVE
+                )
+            } catch (_: IndexOutOfBoundsException) {
+                // Defensive: spans can become invalid if the framework modifies text concurrently.
+            } catch (_: IllegalArgumentException) {
+                // Defensive: newer framework builds can throw on edge-case span/selection interactions.
+            } catch (_: RuntimeException) {
+                // Defensive: SpannableStringBuilder.setSpan can throw RuntimeException for invalid ranges.
             }
         }
     }

aztec/src/test/kotlin/org/wordpress/aztec/IndentTest.kt

@@ -248,6 +248,27 @@ class IndentTest {
         Assert.assertEquals("123<br>456", editText.toHtml())
     }
 
+    @Test
+    @Throws(Exception::class)
+    fun testOutdentAtStartOfDocumentDoesNotCrashAndClampsSelection() {
+        // Regression test:
+        // Outdenting when the caret is at position 0 and the first character is a tab used to compute
+        // selection = -1 and crash inside EditText.setSelection (setSpan(-1...-1)).
+        editText.fromHtml("\t123")
+
+        // Place caret at the very beginning (this matches the crash repro from the app).
+        editText.setSelection(0)
+        Assert.assertTrue(editText.isOutdentAvailable())
+
+        // Should not throw.
+        editText.outdent()
+
+        // Verify text was outdented and selection remained valid.
+        Assert.assertEquals("123", editText.toHtml())
+        Assert.assertEquals(0, editText.selectionStart)
+        Assert.assertEquals(0, editText.selectionEnd)
+    }
+
     @Test
     @Throws(Exception::class)
     fun doesNotIndentMedia() {