IDEA-295565 diff: fix External Diff Tool for files with unknown FileType

Ex: his prevents external tools to work with directory diff.

Fix regression after: b517038a6ec3b99d644623f225980585ebea9d1c

(cherry picked from commit f3a3692b6d4538d022be81434b6636c30aaea8ce)
IJ-CR-25441

GitOrigin-RevId: db2ff42b1b17bb4eb9e52862d4c226c3b3d47a82

3 files changed, 41 insertions, 15 deletions

diff --git a/platform/diff-impl/intellij.platform.diff.impl.iml b/platform/diff-impl/intellij.platform.diff.impl.iml
index afc78f576e8d..5d1b8d7fe421 100644
--- a/platform/diff-impl/intellij.platform.diff.impl.iml
+++ b/platform/diff-impl/intellij.platform.diff.impl.iml
@@ -23,6 +23,5 @@
     <orderEntry type="library" name="fastutil-min" level="project" />
     <orderEntry type="module" module-name="intellij.platform.ide.util.io.impl" />
     <orderEntry type="library" name="kotlinx-coroutines-jdk8" level="project" />
-    <orderEntry type="library" name="StreamEx" level="project" />
   </component>
 </module>
\ No newline at end of file
diff --git a/platform/diff-impl/src/com/intellij/diff/tools/external/ExternalDiffSettings.kt b/platform/diff-impl/src/com/intellij/diff/tools/external/ExternalDiffSettings.kt
index 8dcfcc26d45c..dd3c98dd0d7e 100644
--- a/platform/diff-impl/src/com/intellij/diff/tools/external/ExternalDiffSettings.kt
+++ b/platform/diff-impl/src/com/intellij/diff/tools/external/ExternalDiffSettings.kt
@@ -98,6 +98,16 @@ class ExternalDiffSettings : BaseState(), PersistentStateComponent<ExternalDiffS
       get() = FileTypeManager.getInstance()
 
     @JvmStatic
+    fun findDefaultDiffTool(): ExternalTool? {
+      val diffToolName = instance.defaultToolConfiguration.diffToolName
+
+      if (diffToolName == ExternalToolConfiguration.BUILTIN_TOOL) return null
+      val diffTools = instance.externalTools[ExternalToolGroup.DIFF_TOOL] ?: return null
+
+      return findTool(diffTools, diffToolName)
+    }
+
+    @JvmStatic
     fun findDiffTool(fileType: FileType): ExternalTool? {
       val diffToolName = findToolConfiguration(fileType)?.diffToolName
                          ?: instance.defaultToolConfiguration.diffToolName
diff --git a/platform/diff-impl/src/com/intellij/diff/tools/external/ExternalDiffTool.java b/platform/diff-impl/src/com/intellij/diff/tools/external/ExternalDiffTool.java
index 1c3643482ece..e5f9eb381a85 100644
--- a/platform/diff-impl/src/com/intellij/diff/tools/external/ExternalDiffTool.java
+++ b/platform/diff-impl/src/com/intellij/diff/tools/external/ExternalDiffTool.java
@@ -14,12 +14,14 @@ import com.intellij.openapi.ListSelection;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.diff.DiffBundle;
 import com.intellij.openapi.fileTypes.FileTypeManager;
+import com.intellij.openapi.fileTypes.UnknownFileType;
 import com.intellij.openapi.progress.ProcessCanceledException;
 import com.intellij.openapi.progress.ProgressIndicator;
 import com.intellij.openapi.progress.ProgressManager;
 import com.intellij.openapi.progress.Task;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.ui.Messages;
+import com.intellij.openapi.util.Conditions;
 import com.intellij.openapi.util.NlsContexts;
 import com.intellij.openapi.util.UserDataHolderBase;
 import com.intellij.openapi.util.io.FileUtilRt;
@@ -29,12 +31,13 @@ import com.intellij.util.ThrowableConvertor;
 import com.intellij.util.concurrency.annotations.RequiresBackgroundThread;
 import com.intellij.util.concurrency.annotations.RequiresEdt;
 import com.intellij.util.containers.ContainerUtil;
-import one.util.streamex.StreamEx;
+import com.intellij.util.containers.JBIterable;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Comparator;
 import java.util.List;
 
 public final class ExternalDiffTool {
@@ -52,12 +55,32 @@ public final class ExternalDiffTool {
     if (isDefault()) return true;
 
     FileTypeManager fileTypeManager = FileTypeManager.getInstance();
-    return diffProducers.stream()
-      .map(DiffRequestProducer::getName)
-      .filter(filePath -> !FileUtilRt.getExtension(filePath).equals("tmp"))
-      .map(filePath -> fileTypeManager.getFileTypeByFileName(filePath))
-      .distinct()
-      .anyMatch(fileType -> ExternalDiffSettings.findDiffTool(fileType) != null);
+    return JBIterable.from(diffProducers)
+             .map(DiffRequestProducer::getName)
+             .filter(filePath -> !FileUtilRt.getExtension(filePath).equals("tmp"))
+             .map(filePath -> fileTypeManager.getFileTypeByFileName(filePath))
+             .unique()
+             .map(fileType -> ExternalDiffSettings.findDiffTool(fileType))
+             .filter(Conditions.notNull())
+             .first() != null;
+  }
+
+  @Nullable
+  private static ExternalDiffSettings.ExternalTool getExternalToolFor(@NotNull ContentDiffRequest request) {
+    ExternalDiffSettings.ExternalTool diffTool = JBIterable.from(request.getContents())
+      .map(content -> content.getContentType())
+      .filter(Conditions.notNull())
+      .unique()
+      .sort(Comparator.comparing(fileType -> fileType != UnknownFileType.INSTANCE ? -1 : 1))
+      .map(fileType -> ExternalDiffSettings.findDiffTool(fileType))
+      .filter(Conditions.notNull())
+      .first();
+    if (diffTool != null) return diffTool;
+
+    if (isDefault()) {
+      return ExternalDiffSettings.findDefaultDiffTool();
+    }
+    return null;
   }
 
   public static boolean showIfNeeded(@Nullable Project project,
@@ -120,13 +143,7 @@ public final class ExternalDiffTool {
     throws IOException, ExecutionException {
     if (!canShow(request)) return false;
 
-    List<DiffContent> contents = ((ContentDiffRequest)request).getContents();
-    ExternalDiffSettings.ExternalTool externalTool = StreamEx.of(contents)
-      .map(content -> content.getContentType())
-      .nonNull()
-      .map(fileType -> ExternalDiffSettings.findDiffTool(fileType))
-      .nonNull()
-      .findFirst().orElse(null);
+    ExternalDiffSettings.ExternalTool externalTool = getExternalToolFor(((ContentDiffRequest)request));
     if (externalTool == null) return false;
 
     showRequest(project, request, externalTool);