From 4345c5aab6896285fd478f06455a6725e622cd3d Mon Sep 17 00:00:00 2001
From: Aleksey Pivovarov <AMPivovarov@gmail.com>
Date: Wed, 11 Oct 2017 13:48:07 +0300
Subject: [PATCH] diff: try to guess project in DiffApplication

---
 .../applications/ApplicationStarterBase.java  | 28 +++++++++++++++++--
 .../diff/applications/DiffApplication.java    |  3 +-
 .../diff/applications/MergeApplication.java   |  3 +-
 3 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/platform/diff-impl/src/com/intellij/diff/applications/ApplicationStarterBase.java b/platform/diff-impl/src/com/intellij/diff/applications/ApplicationStarterBase.java
index e7acd707d3a5..76c9afa286c7 100644
--- a/platform/diff-impl/src/com/intellij/diff/applications/ApplicationStarterBase.java
+++ b/platform/diff-impl/src/com/intellij/diff/applications/ApplicationStarterBase.java
@@ -20,19 +20,25 @@ import com.intellij.openapi.application.ApplicationStarterEx;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.fileEditor.FileDocumentManager;
 import com.intellij.openapi.project.Project;
+import com.intellij.openapi.project.ProjectLocator;
+import com.intellij.openapi.project.ProjectManager;
 import com.intellij.openapi.ui.Messages;
 import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.openapi.vfs.LocalFileSystem;
 import com.intellij.openapi.vfs.VfsUtil;
 import com.intellij.openapi.vfs.VfsUtilCore;
 import com.intellij.openapi.vfs.VirtualFile;
+import com.intellij.openapi.wm.WindowManager;
+import com.intellij.util.containers.ContainerUtil;
+import com.intellij.util.containers.HashSet;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import javax.swing.*;
 import java.io.File;
-import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Set;
 
 @SuppressWarnings({"UseOfSystemOutOrSystemErr", "CallToPrintStackTrace"})
 public abstract class ApplicationStarterBase extends ApplicationStarterEx {
@@ -151,7 +157,23 @@ public abstract class ApplicationStarterBase extends ApplicationStarterEx {
   }
 
   @Nullable
-  protected Project getProject() {
-    return null; // TODO: try to guess project
+  protected static Project guessProject(@NotNull List<VirtualFile> files) {
+    Set<Project> projects = new HashSet<>();
+    for (VirtualFile file : files) {
+      projects.addAll(ProjectLocator.getInstance().getProjectsForFile(file));
+    }
+
+    if (projects.isEmpty()) {
+      ContainerUtil.addAll(projects, ProjectManager.getInstance().getOpenProjects());
+    }
+    if (projects.isEmpty()) return null;
+
+    Project activeProject = ContainerUtil.find(projects, project -> {
+      JFrame frame = WindowManager.getInstance().getFrame(project);
+      return frame != null && frame.isActive();
+    });
+    if (activeProject != null) return activeProject;
+
+    return projects.iterator().next();
   }
 }
diff --git a/platform/diff-impl/src/com/intellij/diff/applications/DiffApplication.java b/platform/diff-impl/src/com/intellij/diff/applications/DiffApplication.java
index 6be49b7d730d..91ae31ea61f0 100644
--- a/platform/diff-impl/src/com/intellij/diff/applications/DiffApplication.java
+++ b/platform/diff-impl/src/com/intellij/diff/applications/DiffApplication.java
@@ -50,10 +50,9 @@ public class DiffApplication extends ApplicationStarterBase {
 
   @Override
   public void processCommand(@NotNull String[] args, @Nullable String currentDirectory) throws Exception {
-    Project project = getProject();
-
     List<String> filePaths = Arrays.asList(args).subList(1, args.length);
     List<VirtualFile> files = findFiles(filePaths, currentDirectory);
+    Project project = guessProject(files);
 
     DiffRequest request;
     if (files.size() == 3) {
diff --git a/platform/diff-impl/src/com/intellij/diff/applications/MergeApplication.java b/platform/diff-impl/src/com/intellij/diff/applications/MergeApplication.java
index 1605867c3a43..fe5078d87d9d 100644
--- a/platform/diff-impl/src/com/intellij/diff/applications/MergeApplication.java
+++ b/platform/diff-impl/src/com/intellij/diff/applications/MergeApplication.java
@@ -52,10 +52,9 @@ public class MergeApplication extends ApplicationStarterBase {
 
   @Override
   public void processCommand(@NotNull String[] args, @Nullable String currentDirectory) throws Exception {
-    Project project = getProject();
-
     List<String> filePaths = Arrays.asList(args).subList(1, args.length);
     List<VirtualFile> files = findFiles(filePaths, currentDirectory);
+    Project project = guessProject(files);
 
     List<VirtualFile> contents = ContainerUtil.list(files.get(0), files.get(2), files.get(1)); // left, base, right
     VirtualFile outputFile = files.get(files.size() - 1);