fix(gettext): coalesce duplicate file changes in incremental msg* tasks

plugins/gettext-plugin/src/main/kotlin/com/github/vlsi/gradle/gettext/FileChangeCoalescing.kt

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2019 Vladimir Sitnikov <sitnikov.vladimir@gmail.com>
+ *
+ * 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 com.github.vlsi.gradle.gettext
+
+import org.gradle.api.file.FileType
+import org.gradle.work.ChangeType
+import org.gradle.work.FileChange
+import java.io.File
+
+/**
+ * Collapses duplicate [FileChange] events for the same physical file into a single event.
+ *
+ * Gradle may report the same file as both ADDED and REMOVED in one invocation when the
+ * incremental input collection contains multiple entries that resolve to the same path
+ * (e.g. overlapping providers from feature variants reusing the main source set).
+ * Acting on both events deletes the freshly produced output. See
+ * https://github.com/vlsi/vlsi-release-plugins for the original report.
+ *
+ * Rules applied per `file.absolutePath`:
+ *  - non-FILE entries (directories, missing) are dropped;
+ *  - any non-REMOVED event (ADDED/MODIFIED) wins over a REMOVED event;
+ *  - a pure-REMOVED event is suppressed when the file is still present in
+ *    [currentSourceFiles], i.e. the snapshot still contains it.
+ *
+ * Insertion order is preserved so processing matches the original iteration order.
+ */
+internal fun coalesceFileChanges(
+    changes: Iterable<FileChange>,
+    currentSourceFiles: Set<File>,
+): List<FileChange> {
+    val byPath = LinkedHashMap<String, FileChange>()
+    for (change in changes) {
+        if (change.fileType != FileType.FILE) {
+            continue
+        }
+        val key = change.file.absolutePath
+        val existing = byPath[key]
+        if (existing == null ||
+            existing.changeType == ChangeType.REMOVED && change.changeType != ChangeType.REMOVED
+        ) {
+            byPath[key] = change
+        }
+    }
+    return byPath.values.filter { change ->
+        change.changeType != ChangeType.REMOVED || change.file !in currentSourceFiles
+    }
+}

plugins/gettext-plugin/src/main/kotlin/com/github/vlsi/gradle/gettext/MsgAttribTask.kt

@@ -17,7 +17,6 @@
 package com.github.vlsi.gradle.gettext
 
 import org.gradle.api.file.FileSystemOperations
-import org.gradle.api.file.FileType
 import org.gradle.api.model.ObjectFactory
 import org.gradle.api.tasks.Input
 import org.gradle.api.tasks.InputFiles
@@ -57,10 +56,8 @@ abstract class MsgAttribTask @Inject constructor(
         val outDir = outputDir.get().asFile
         val cmd = executable.get()
         val arg = args.get()
-        for (po in inputChanges.getFileChanges(poFiles)) {
-            if (po.fileType != FileType.FILE) {
-                continue
-            }
+        val currentPoFiles = poFiles.files
+        for (po in coalesceFileChanges(inputChanges.getFileChanges(poFiles), currentPoFiles)) {
             val outFile = File(outDir, po.file.name)
             if (po.changeType == ChangeType.REMOVED) {
                 logger.debug("Removing output {}", outFile)

plugins/gettext-plugin/src/main/kotlin/com/github/vlsi/gradle/gettext/MsgFmtTask.kt

@@ -17,7 +17,6 @@
 package com.github.vlsi.gradle.gettext
 
 import org.gradle.api.GradleException
-import org.gradle.api.file.FileType
 import org.gradle.api.model.ObjectFactory
 import org.gradle.api.tasks.Input
 import org.gradle.api.tasks.InputFiles
@@ -82,11 +81,8 @@ abstract class MsgFmtTask @Inject constructor(
         val cmd = executable.get()
         val arg = args.get()
         val targetBundle = targetBundle.get()
-        for (po in inputChanges.getFileChanges(poFiles)) {
-            if (po.fileType != FileType.FILE) {
-                continue
-            }
-
+        val currentPoFiles = poFiles.files
+        for (po in coalesceFileChanges(inputChanges.getFileChanges(poFiles), currentPoFiles)) {
             val locale = po.file.nameWithoutExtension.toJavaLocale()
 
             val outputName = when (format.get()) {

plugins/gettext-plugin/src/main/kotlin/com/github/vlsi/gradle/gettext/MsgMergeTask.kt

@@ -16,7 +16,6 @@
  */
 package com.github.vlsi.gradle.gettext
 
-import org.gradle.api.file.FileType
 import org.gradle.api.model.ObjectFactory
 import org.gradle.api.tasks.Input
 import org.gradle.api.tasks.InputFile
@@ -61,10 +60,8 @@ abstract class MsgMergeTask @Inject constructor(
         val cmd = executable.get()
         val arg = args.get()
         val pot = potFile.get().asFile.absolutePath
-        for (po in inputChanges.getFileChanges(poFiles)) {
-            if (po.fileType != FileType.FILE) {
-                continue
-            }
+        val currentPoFiles = poFiles.files
+        for (po in coalesceFileChanges(inputChanges.getFileChanges(poFiles), currentPoFiles)) {
             val outFile = File(outDir, po.file.name)
             if (po.changeType == ChangeType.REMOVED) {
                 logger.debug("Removing output {}", outFile)

plugins/gettext-plugin/src/test/kotlin/com/github/vlsi/gradle/gettext/FileChangeCoalescingTest.kt

@@ -0,0 +1,155 @@
+/*
+ * Copyright 2019 Vladimir Sitnikov <sitnikov.vladimir@gmail.com>
+ *
+ * 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 com.github.vlsi.gradle.gettext
+
+import org.gradle.api.file.FileType
+import org.gradle.work.ChangeType
+import org.gradle.work.FileChange
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
+import java.io.File
+
+class FileChangeCoalescingTest {
+    private data class FakeFileChange(
+        private val file: File,
+        private val changeType: ChangeType,
+        private val fileType: FileType = FileType.FILE,
+        private val normalizedPath: String = file.name,
+    ) : FileChange {
+        override fun getFile(): File = file
+        override fun getChangeType(): ChangeType = changeType
+        override fun getFileType(): FileType = fileType
+        override fun getNormalizedPath(): String = normalizedPath
+    }
+
+    private fun key(change: FileChange) = change.file.absolutePath to change.changeType
+
+    @Test
+    fun `ADDED followed by REMOVED for same file collapses to ADDED`() {
+        val po = File("/src/ru.po")
+        val changes = listOf(
+            FakeFileChange(po, ChangeType.ADDED),
+            FakeFileChange(po, ChangeType.REMOVED),
+        )
+
+        val result = coalesceFileChanges(changes, setOf(po))
+
+        assertEquals(listOf(po.absolutePath to ChangeType.ADDED), result.map(::key))
+    }
+
+    @Test
+    fun `REMOVED followed by ADDED for same file collapses to ADDED`() {
+        val po = File("/src/ru.po")
+        val changes = listOf(
+            FakeFileChange(po, ChangeType.REMOVED),
+            FakeFileChange(po, ChangeType.ADDED),
+        )
+
+        val result = coalesceFileChanges(changes, setOf(po))
+
+        assertEquals(listOf(po.absolutePath to ChangeType.ADDED), result.map(::key))
+    }
+
+    @Test
+    fun `MODIFIED wins over REMOVED for same file`() {
+        val po = File("/src/ru.po")
+        val changes = listOf(
+            FakeFileChange(po, ChangeType.MODIFIED),
+            FakeFileChange(po, ChangeType.REMOVED),
+        )
+
+        val result = coalesceFileChanges(changes, setOf(po))
+
+        assertEquals(listOf(po.absolutePath to ChangeType.MODIFIED), result.map(::key))
+    }
+
+    @Test
+    fun `pure REMOVED is suppressed when file still present in snapshot`() {
+        val po = File("/src/ru.po")
+        val changes = listOf(FakeFileChange(po, ChangeType.REMOVED))
+
+        val result = coalesceFileChanges(changes, setOf(po))
+
+        assertEquals(emptyList<Pair<String, ChangeType>>(), result.map(::key))
+    }
+
+    @Test
+    fun `pure REMOVED is kept when file absent from snapshot`() {
+        val po = File("/src/ru.po")
+        val changes = listOf(FakeFileChange(po, ChangeType.REMOVED))
+
+        val result = coalesceFileChanges(changes, emptySet())
+
+        assertEquals(listOf(po.absolutePath to ChangeType.REMOVED), result.map(::key))
+    }
+
+    @Test
+    fun `non-FILE entries are dropped`() {
+        val dir = File("/src/locales")
+        val po = File("/src/locales/ru.po")
+        val changes = listOf(
+            FakeFileChange(dir, ChangeType.ADDED, fileType = FileType.DIRECTORY),
+            FakeFileChange(po, ChangeType.ADDED),
+        )
+
+        val result = coalesceFileChanges(changes, setOf(po))
+
+        assertEquals(listOf(po.absolutePath to ChangeType.ADDED), result.map(::key))
+    }
+
+    @Test
+    fun `distinct files are reported independently`() {
+        val ru = File("/src/ru.po")
+        val de = File("/src/de.po")
+        val es = File("/src/es.po")
+        val changes = listOf(
+            FakeFileChange(ru, ChangeType.ADDED),
+            FakeFileChange(de, ChangeType.MODIFIED),
+            FakeFileChange(es, ChangeType.REMOVED),
+        )
+
+        val result = coalesceFileChanges(changes, setOf(ru, de))
+
+        assertEquals(
+            listOf(
+                ru.absolutePath to ChangeType.ADDED,
+                de.absolutePath to ChangeType.MODIFIED,
+                es.absolutePath to ChangeType.REMOVED,
+            ),
+            result.map(::key),
+        )
+    }
+
+    @Test
+    fun `insertion order is preserved across distinct files`() {
+        val a = File("/src/a.po")
+        val b = File("/src/b.po")
+        val c = File("/src/c.po")
+        val changes = listOf(
+            FakeFileChange(b, ChangeType.ADDED),
+            FakeFileChange(a, ChangeType.ADDED),
+            FakeFileChange(c, ChangeType.ADDED),
+        )
+
+        val result = coalesceFileChanges(changes, setOf(a, b, c))
+
+        assertEquals(
+            listOf(b.absolutePath, a.absolutePath, c.absolutePath),
+            result.map { it.file.absolutePath },
+        )
+    }
+}