quotes for the plain text version + refactoring for #2957

FlowCrypt/src/main/java/com/flowcrypt/email/extensions/com/google/api/services/gmail/model/ThreadExt.kt

@@ -20,9 +20,10 @@ import jakarta.mail.internet.InternetAddress
  */
 fun Thread.getUniqueRecipients(account: String): List<InternetAddress> {
   return mutableListOf<InternetAddress>().apply {
-    if (messages == null || messages.isEmpty()) {
+    if (messages.isNullOrEmpty()) {
       return@apply
     }
+
     val fromHeaderName = "From"
 
     val filteredHeaders = if (messages.size > 1) {
@@ -42,7 +43,7 @@ fun Thread.getUniqueRecipients(account: String): List<InternetAddress> {
         } else emptyList()
       }.ifEmpty {
         //otherwise we will use all recipients
-        messages.flatMap { message -> message.filterHeadersWithName(fromHeaderName) }
+        messages.flatMap { it.filterHeadersWithName(fromHeaderName) }
       }
     } else {
       messages.first().filterHeadersWithName(fromHeaderName)

FlowCrypt/src/main/java/com/flowcrypt/email/security/pgp/PgpMsg.kt

@@ -59,6 +59,7 @@ import org.json.JSONObject
 import org.jsoup.Jsoup
 import org.jsoup.nodes.Document
 import org.jsoup.nodes.Element
+import org.jsoup.nodes.Entities
 import org.jsoup.nodes.TextNode
 import org.jsoup.parser.Parser
 import org.owasp.html.HtmlPolicyBuilder
@@ -530,7 +531,7 @@ object PgpMsg {
     if (dirtyHtml == null) return null
 
     val originalDocument = Jsoup.parse(dirtyHtml, "", Parser.xmlParser())
-    originalDocument.select("div.gmail_quote").firstOrNull()?.let { element ->
+    originalDocument.select("div.gmail_quote,div.flowcrypt_quote").firstOrNull()?.let { element ->
       //we wrap Gmail quote with 'details' tag
       val generation = Element("details").apply {
         appendChild(Element("summary"))
@@ -1214,7 +1215,7 @@ object PgpMsg {
 
           MsgBlock.Type.PLAIN_TEXT -> {
             val html = fmtMsgContentBlockAsHtml(
-              content.toEscapedHtml(),
+              checkAndReturnQuotesFormatIfFound(content) ?: content.toEscapedHtml(),
               if (block.isOpenPGPMimeSigned) FrameColor.GRAY else FrameColor.PLAIN
             )
             msgContentAsHtml.append(html)
@@ -1304,6 +1305,92 @@ object PgpMsg {
     )
   }
 
+  private fun checkAndReturnQuotesFormatIfFound(content: String): String? {
+    return buildQuotes(originalContent = content, unwrapContent = false)?.outerHtml()
+  }
+
+  private fun buildQuotes(originalContent: String, unwrapContent: Boolean = true): Element? {
+    val content = if (unwrapContent) {
+      //remove > at the beginning of all lines to define next quotes level
+      val patternQuotesSign = "^>([^\\S\\r\\n])?".toRegex(RegexOption.MULTILINE)
+      originalContent.replace(patternQuotesSign, "")
+    } else {
+      originalContent
+    }
+
+    val newLineStringPattern = "\\r\\n|\\r|\\n"
+    val beforeQuotesHeaderStringPattern = "^.*:($newLineStringPattern){1,2}"
+    val patternQuotes = (if (unwrapContent) {
+      "(^>.*\$($newLineStringPattern))+"
+    } else {
+      "($beforeQuotesHeaderStringPattern)(^>.*\$($newLineStringPattern))+"
+    }).toRegex(RegexOption.MULTILINE)
+    val tagDiv = "div"
+    val tagBlockquote = "blockquote"
+
+    val matchingResult = patternQuotes.find(content)?.groups?.firstOrNull()
+      ?: return Element(tagDiv).apply {
+        append(prepareHtmlFromGivenText(content))
+      }.takeIf { unwrapContent }
+    val quotes = matchingResult.value
+
+    return Element(tagDiv).apply {
+      //prepend text before quotes
+      if (matchingResult.range.first > 0) {
+        prepend(prepareHtmlFromGivenText(content.substring(0, matchingResult.range.first)))
+      }
+
+      //append quotes
+      if (unwrapContent) {
+        appendChild(
+          Element(tagBlockquote).apply {
+            buildQuotes(quotes)?.let { appendChild(it) }
+          }
+        )
+      } else {
+        appendChild(
+          Element(tagDiv).apply {
+            attr("class", "flowcrypt_quote")
+            //for better UI experience we need to extract the quote header of the first quote
+            //and add it separately
+            val quotesHeader =
+              quotes.replace("(^>.*\$($newLineStringPattern))+".toRegex(RegexOption.MULTILINE), "")
+            append(prepareHtmlFromGivenText(quotesHeader))
+
+            appendChild(
+              Element(tagBlockquote).apply {
+                //here we should pass clear quotes and drop the first quote header
+                buildQuotes(quotes.replaceFirst(quotesHeader, ""))?.let { appendChild(it) }
+              }
+            )
+          }
+        )
+      }
+
+      //append text after quotes
+      if (matchingResult.range.last < content.length) {
+        append(
+          prepareHtmlFromGivenText(content.substring(matchingResult.range.last + 1, content.length))
+        )
+      }
+    }
+  }
+
+  private fun prepareHtmlFromGivenText(content: String): String {
+    val newLineStringPattern = "\\r\\n|\\r|\\n"
+    val patternNewLine = "($newLineStringPattern)".toRegex()
+    val patternEscapedEmailAddress = "&lt;(\\S+@\\S+)&gt;".toRegex()
+    val emailAddressReplacement = "<a href=mailto:\$1>\$1</a>"
+    val br = "<br>"
+    return Entities
+      //escape given text to fit HTML standard
+      .escape(content)
+      //Prepare <a href> for email addresses.
+      .replace(patternEscapedEmailAddress, emailAddressReplacement)
+      //Replace CRLF with <br> to transform to HTML.
+      .replace(patternNewLine, br)
+  }
+
   /**
    * replace content of images: <img src="cid:16c7a8c3c6a8d4ab1e01">
    */

FlowCrypt/src/test/java/com/flowcrypt/email/security/pgp/PgpMsgTest.kt

@@ -615,6 +615,133 @@ class PgpMsgTest {
     assertEquals(1, document.select("summary").size)
   }
 
+  @Test
+  fun testQuotesParsingAndHtmlManipulationForPlainMode() {
+    val mimeMessageRaw = """
+    MIME-Version: 1.0
+    Date: Mon, 24 Feb 2025 17:02:47 +0200
+    Message-ID: <messageid@flowcrypt.test>
+    Subject: Re: Quotes for plain text
+    From: Den at FlowCrypt <den@flowcrypt.test>
+    To: DenBond7 <denbond7@flowcrypt.test>
+    Content-Type: text/plain; charset="UTF-8"
+    Content-Transfer-Encoding: quoted-printable
+
+    reply 2
+
+    The top-level build.gradle.kts file (for the Kotlin DSL) or
+    build.gradle file (for the Groovy DSL) is located in the root project
+    directory. It typically defines the common versions of plugins used by
+    modules in your project.
+
+    The following code sample describes the default settings and DSL
+    elements in the top-level build script after creating a new project
+
+    On Mon, Feb 24, 2025 at 5:02=E2=80=AFPM DenBond7 <denbond7@flowcrypt.tes=
+    t> wrote:
+    >
+    > 2
+    >
+    > Creating custom build configurations requires you to make changes to
+    > one or more build configuration files. These plain-text files use a
+    > domain-specific language (DSL) to describe and manipulate the build
+    > logic using Kotlin script, which is a flavor of the Kotlin language.
+    > You can also use Groovy, which is a dynamic language for the Java
+    > Virtual Machine (JVM), to configure your builds.
+    >
+    > You don't need to know Kotlin script or Groovy to start configuring
+    > your build because the Android Gradle plugin introduces most of the
+    > DSL elements you need. To learn more about the Android Gradle plugin
+    > DSL, read the DSL reference documentation. Kotlin script also relies
+    > on the underlying Gradle Kotlin DSL
+    >
+    > When starting a new project, Android Studio automatically creates some
+    > of these files for you and populates them based on sensible defaults.
+    > For an overview of the created files, see Android build structure.
+    >
+    > =D0=BF=D0=BD, 24 =D0=BB=D1=8E=D1=82. 2025=E2=80=AF=D1=80. =D0=BE 17:01 De=
+    n at FlowCrypt <den@flowcrypt.test> =D0=BF=D0=B8=D1=88=D0=B5:
+    > >
+    > > reply 1
+    > >
+    > > Build types define certain properties that Gradle uses when building
+    > > and packaging your app. Build types are typically configured for
+    > > different stages of your development lifecycle.
+    > >
+    > > For example, the debug build type enables debug options and signs the
+    > > app with the debug key, while the release build type may shrink,
+    > > obfuscate, and sign your app with a release key for distribution.
+    > >
+    > > You must define at least one build type to build your app. Android
+    > > Studio creates the debug and release build types by default. To start
+    > > customizing packaging settings for your app, learn how to configure
+    > > build types.
+    > >
+    > >
+    > > On Mon, Feb 24, 2025 at 5:00=E2=80=AFPM DenBond7 <denbond7@flowcrypt.tes=
+    t> wrote:
+    > > >
+    > > > 1
+    > > >
+    > > > The Android build system compiles app resources and source code and
+    > > > packages them into APKs or Android App Bundles that you can test,
+    > > > deploy, sign, and distribute.
+    > > >
+    > > > In Gradle build overview and Android build structure, we discussed
+    > > > build concepts and the structure of an Android app. Now it's time to
+    > > > configure the build.
+    > > >
+    > > >
+    > > > --
+    > > > Regards,
+    > > > Denys Bondarenko
+    > >
+    > >
+    > >
+    > > --
+    > > Regards,
+    > > Den at FlowCrypt
+    >
+    >
+    >
+    > --
+    > Regards,
+    > Denys Bondarenko
+
+
+
+    --=20
+    Regards,
+    Den at FlowCrypt""".trimIndent()
+
+    val processedMimeMessageResult = runBlocking {
+      PgpMsg.processMimeMessage(
+        MimeMessage(Session.getInstance(Properties()), mimeMessageRaw.toInputStream()),
+        PGPPublicKeyRingCollection(listOf()),
+        PGPSecretKeyRingCollection(listOf()),
+        SecretKeyRingProtector.unprotectedKeys(),
+      )
+    }
+
+    assertEquals(1, processedMimeMessageResult.blocks.size)
+
+    val plainHtmlBlock = processedMimeMessageResult.blocks.first {
+      it.type == MsgBlock.Type.PLAIN_HTML
+    }
+
+    val document = Jsoup.parse(requireNotNull(plainHtmlBlock.content), "", Parser.xmlParser())
+    assertNotNull(document.select("details").first())
+    assertEquals(1, document.select("details").size)
+    assertNotNull(document.select("summary").first())
+    assertEquals(1, document.select("summary").size)
+
+    val quotes = document.select("blockquote")
+    assertEquals(3, quotes.size)
+    assertTrue(quotes[0].text().startsWith("2 Creating custom build configurations requires"))
+    assertTrue(quotes[1].text().startsWith("reply 1"))
+    assertTrue(quotes[2].text().startsWith("1 The Android build system"))
+  }
+
   private data class RenderedBlock(
     val rendered: Boolean,
     val frameColor: String?,