[vcs-log] display commit signature description in tooltip

GitOrigin-RevId: c0a1bf7cbb888cb48df10a095b5fd3990f667a66

platform/util/ui/src/com/intellij/util/ui/ExtendableHTMLViewFactory.kt

@@ -4,6 +4,7 @@ package com.intellij.util.ui
 import com.intellij.openapi.diagnostic.thisLogger
 import com.intellij.openapi.util.IconLoader
 import com.intellij.ui.scale.JBUIScale
+import com.intellij.util.text.nullize
 import java.awt.*
 import java.awt.image.BufferedImage
 import java.io.ByteArrayInputStream
@@ -137,7 +138,7 @@ internal constructor(private val extensions: List<(Element, View) -> View?>,
         }
 
         override fun getToolTipText(x: Float, y: Float, allocation: Shape): String? {
-          return element.attributes.getAttribute(HTML.Attribute.ALT) as? String
+          return (element.attributes.getAttribute(HTML.Attribute.ALT) as? String)?.nullize(true)
         }
 
         override fun paint(g: Graphics, allocation: Shape) {

platform/vcs-log/impl/src/com/intellij/vcs/log/ui/details/commit/CommitDetailsPanel.kt

@@ -277,7 +277,12 @@ private class HashAndAuthorPanel : HtmlPanel() {
     @Suppress("HardCodedStringLiteral")
     return presentation.hashAndAuthor.let {
       if (signature != null) {
-        it + """<span class='signature'>&nbsp;&nbsp;&nbsp; <icon src='sig'/>&nbsp;${signature.text}</span>"""
+        val tooltip = signature.description?.toString()
+        //language=html
+        it + """<span class='signature'>&nbsp;&nbsp;&nbsp; 
+          |<icon src='sig' alt='${tooltip.orEmpty()}'/>
+          |&nbsp;${signature.text}
+          |</span>""".trimMargin()
       }
       else it
     }

plugins/git4idea/src/git4idea/log/GitCommitSignatureStatusProvider.kt

@@ -5,10 +5,10 @@ import com.intellij.openapi.components.Service
 import com.intellij.openapi.components.service
 import com.intellij.openapi.project.Project
 import com.intellij.openapi.util.SystemInfo
-import com.intellij.vcs.log.data.util.VcsCommitsDataLoader
 import com.intellij.openapi.util.text.HtmlBuilder
 import com.intellij.openapi.util.text.HtmlChunk
 import com.intellij.util.ui.EmptyIcon
+import com.intellij.vcs.log.data.util.VcsCommitsDataLoader
 import com.intellij.vcs.log.ui.frame.VcsCommitExternalStatusPresentation
 import com.intellij.vcs.log.ui.frame.VcsCommitExternalStatusProvider
 import com.intellij.vcs.log.ui.table.column.util.VcsLogExternalStatusColumnService
@@ -52,17 +52,19 @@ internal class GitCommitSignatureStatusProvider : VcsCommitExternalStatusProvide
 
       override val text: String
         get() = when (signature) {
-          is GitCommitSignature.Verified ->
-            HtmlBuilder()
-              .append(GitBundle.message("tooltip.commit.signature.verify.success"))
-              .append(HtmlChunk.br())
-              .append(signature.user)
-              .append(HtmlChunk.br())
-              .append(signature.fingerprint)
-              .toFragment().toString()
+          is GitCommitSignature.Verified -> GitBundle.message("tooltip.commit.signature.verify.success")
           GitCommitSignature.NotVerified -> GitBundle.message("tooltip.commit.signature.verify.failure")
           GitCommitSignature.NoSignature -> GitBundle.message("tooltip.no.commit.signature")
         }
+
+      override val description: HtmlChunk?
+        get() = if (signature is GitCommitSignature.Verified)
+          HtmlBuilder()
+            .append(signature.user)
+            .append(HtmlChunk.br())
+            .append(signature.fingerprint)
+            .toFragment()
+        else null
     }
   }
 }