[log] IDEA-122300 Show full path in structure filter tooltip

If there are multiple files selected, show them all, but don't let
the tooltip to grow to much, so don't show more than 10 lines.

platform/vcs-log/impl/src/com/intellij/vcs/log/ui/filter/StructureFilterPopupComponent.java

@@ -22,6 +22,7 @@ import com.intellij.openapi.project.DumbAwareAction;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.openapi.vfs.VirtualFile;
+import com.intellij.util.Function;
 import com.intellij.util.containers.ContainerUtil;
 import com.intellij.vcs.log.VcsLogStructureFilter;
 import com.intellij.vcs.log.data.VcsLogStructureFilterImpl;
@@ -32,6 +33,7 @@ import org.jetbrains.annotations.Nullable;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.List;
 
 class StructureFilterPopupComponent extends FilterPopupComponent<VcsLogStructureFilter> {
 
@@ -62,13 +64,31 @@ class StructureFilterPopupComponent extends FilterPopupComponent<VcsLogStructure
     }
     else if (files.size() == 1) {
       VirtualFile file = files.iterator().next();
-      setValue(StringUtil.shortenPathWithEllipsis(file.getPresentableUrl(), FILTER_LABEL_LENGTH));
+      setValue(StringUtil.shortenPathWithEllipsis(file.getPresentableUrl(), FILTER_LABEL_LENGTH), getTooltip(files));
     }
     else {
-      setValue(files.size() + " items");
+      setValue(files.size() + " items", getTooltip(files));
     }
   }
 
+  @NotNull
+  private static String getTooltip(@NotNull Collection<VirtualFile> files) {
+    List<VirtualFile> filesToDisplay = new ArrayList<VirtualFile>(files);
+    if (files.size() > 10) {
+      filesToDisplay = filesToDisplay.subList(0, 10);
+    }
+    String tooltip = StringUtil.join(filesToDisplay, new Function<VirtualFile, String>() {
+      @Override
+      public String fun(VirtualFile file) {
+        return file.getPresentableUrl();
+      }
+    }, "\n");
+    if (files.size() > 10) {
+      tooltip += "\n...";
+    }
+    return tooltip;
+  }
+
   @NotNull
   private static <T> Collection<T> notNullize(@Nullable Collection<T> items) {
     return items != null ? items : Collections.<T>emptyList();