From cda83e8ae1389b03c1b431103200843bcc1778c3 Mon Sep 17 00:00:00 2001
From: Luke Dashjr <luke-jr+git@utopios.org>
Date: Thu, 10 Dec 2020 22:26:17 +0000
Subject: [PATCH 1/2] GUI: Intro: Output a std::unique_ptr<Intro> from
 Intro::showIfNeeded

---
 src/qt/bitcoin.cpp | 10 +++++-----
 src/qt/intro.cpp   | 18 +++++++-----------
 src/qt/intro.h     |  4 +++-
 3 files changed, 15 insertions(+), 17 deletions(-)

diff --git a/src/qt/bitcoin.cpp b/src/qt/bitcoin.cpp
index bad4e72794..2cae57205f 100644
--- a/src/qt/bitcoin.cpp
+++ b/src/qt/bitcoin.cpp
@@ -575,10 +575,9 @@ int GuiMain(int argc, char* argv[])
 
     /// 5. Now that settings and translations are available, ask user for data directory
     // User language is set up: pick a data directory
-    bool did_show_intro = false;
-    int64_t prune_MiB = 0;  // Intro dialog prune configuration
+    std::unique_ptr<Intro> intro;
     // Gracefully exit if the user cancels
-    if (!Intro::showIfNeeded(did_show_intro, prune_MiB)) return EXIT_SUCCESS;
+    if (!Intro::showIfNeeded(intro)) return EXIT_SUCCESS;
 
     /// 6-7. Parse bitcoin.conf, determine network, switch to network specific
     /// options, and create datadir and settings.json.
@@ -651,9 +650,10 @@ int GuiMain(int argc, char* argv[])
         return EXIT_FAILURE;
     }
 
-    if (did_show_intro) {
+    if (intro) {
         // Store intro dialog settings other than datadir (network specific)
-        app.InitPruneSetting(prune_MiB);
+        app.InitPruneSetting(intro->getPruneMiB());
+        intro.reset();
     }
 
     try
diff --git a/src/qt/intro.cpp b/src/qt/intro.cpp
index f86b167076..37d7a3e6e0 100644
--- a/src/qt/intro.cpp
+++ b/src/qt/intro.cpp
@@ -202,9 +202,9 @@ int64_t Intro::getPruneMiB() const
     }
 }
 
-bool Intro::showIfNeeded(bool& did_show_intro, int64_t& prune_MiB)
+bool Intro::showIfNeeded(std::unique_ptr<Intro>& intro)
 {
-    did_show_intro = false;
+    intro.reset();
 
     QSettings settings;
     /* If data directory provided on command line, no need to look at settings
@@ -226,19 +226,18 @@ bool Intro::showIfNeeded(bool& did_show_intro, int64_t& prune_MiB)
         }
 
         /* If current default data directory does not exist, let the user choose one */
-        Intro intro(nullptr, Params().AssumedBlockchainSize(), Params().AssumedChainStateSize());
-        intro.setDataDirectory(dataDir);
-        intro.setWindowIcon(QIcon(":icons/bitcoin"));
-        did_show_intro = true;
+        intro = std::make_unique<Intro>(nullptr, Params().AssumedBlockchainSize(), Params().AssumedChainStateSize());
+        intro->setDataDirectory(dataDir);
+        intro->setWindowIcon(QIcon(QStringLiteral(":icons/bitcoin")));
 
         while(true)
         {
-            if(!intro.exec())
+            if(!intro->exec())
             {
                 /* Cancel clicked */
                 return false;
             }
-            dataDir = intro.getDataDirectory();
+            dataDir = intro->getDataDirectory();
             try {
                 if (TryCreateDirectories(GUIUtil::QStringToPath(dataDir))) {
                     // If a new data directory has been created, make wallets subdirectory too
@@ -252,9 +251,6 @@ bool Intro::showIfNeeded(bool& did_show_intro, int64_t& prune_MiB)
             }
         }
 
-        // Additional preferences:
-        prune_MiB = intro.getPruneMiB();
-
         settings.setValue("strDataDir", dataDir);
         settings.setValue("fReset", false);
     }
diff --git a/src/qt/intro.h b/src/qt/intro.h
index 900c657b27..063b0cf43d 100644
--- a/src/qt/intro.h
+++ b/src/qt/intro.h
@@ -9,6 +9,8 @@
 #include <QMutex>
 #include <QThread>
 
+#include <memory>
+
 static const bool DEFAULT_CHOOSE_DATADIR = false;
 
 class FreespaceChecker;
@@ -48,7 +50,7 @@ public:
      * @note do NOT call global gArgs.GetDataDirNet() before calling this function, this
      * will cause the wrong path to be cached.
      */
-    static bool showIfNeeded(bool& did_show_intro, int64_t& prune_MiB);
+    static bool showIfNeeded(std::unique_ptr<Intro>& intro);
 
 Q_SIGNALS:
     void requestCheck();

From 2da00fd2bd6941352057e15c0987d808fcacf079 Mon Sep 17 00:00:00 2001
From: Luke Dashjr <luke-jr+git@utopios.org>
Date: Thu, 10 Dec 2020 23:26:03 +0000
Subject: [PATCH 2/2] GUI: Intro: Have user choose assumevalid

---
 src/qt/bitcoin.cpp    | 10 +++++++-
 src/qt/bitcoin.h      |  1 +
 src/qt/forms/intro.ui | 58 +++++++++++++++++++++++++++++++++++++++++++
 src/qt/intro.cpp      | 39 +++++++++++++++++++++++++++++
 src/qt/intro.h        |  1 +
 5 files changed, 108 insertions(+), 1 deletion(-)

diff --git a/src/qt/bitcoin.cpp b/src/qt/bitcoin.cpp
index 2cae57205f..eb3e13693b 100644
--- a/src/qt/bitcoin.cpp
+++ b/src/qt/bitcoin.cpp
@@ -37,6 +37,7 @@
 #include <util/string.h>
 #include <util/threadnames.h>
 #include <util/translation.h>
+#include <univalue.h>
 #include <validation.h>
 
 #ifdef ENABLE_WALLET
@@ -653,7 +654,7 @@ int GuiMain(int argc, char* argv[])
     if (intro) {
         // Store intro dialog settings other than datadir (network specific)
         app.InitPruneSetting(intro->getPruneMiB());
-        intro.reset();
+        gArgs.ForceSetArg("-assumevalid", intro->getAssumeValid().toStdString());
     }
 
     try
@@ -663,6 +664,13 @@ int GuiMain(int argc, char* argv[])
         // This is acceptable because this function only contains steps that are quick to execute,
         // so the GUI thread won't be held up.
         if (app.baseInitialize()) {
+            if (intro) {
+                // Store intro dialog settings other than datadir (network specific)
+                common::SettingsValue intro_assumevalid = intro->getAssumeValid().toStdString();
+                app.node().context()->chain->overwriteRwSetting("assumevalid", intro_assumevalid);
+                // We can release the Intro widget now
+                intro.reset();
+            }
             app.requestInitialize();
 #if defined(Q_OS_WIN)
             WinShutdownMonitor::registerShutdownBlockReason(QObject::tr("%1 didn't yet exit safely…").arg(PACKAGE_NAME), (HWND)app.getMainWinId());
diff --git a/src/qt/bitcoin.h b/src/qt/bitcoin.h
index 9622c9d57d..5ce499f749 100644
--- a/src/qt/bitcoin.h
+++ b/src/qt/bitcoin.h
@@ -9,6 +9,7 @@
 #include <config/bitcoin-config.h>
 #endif
 
+#include <interfaces/chain.h>
 #include <interfaces/node.h>
 #include <qt/initexecutor.h>
 
diff --git a/src/qt/forms/intro.ui b/src/qt/forms/intro.ui
index 9ab91f6aa9..33703e0124 100644
--- a/src/qt/forms/intro.ui
+++ b/src/qt/forms/intro.ui
@@ -271,6 +271,64 @@
      </item>
     </layout>
    </item>
+   <item>
+    <widget class="QWidget" name="groupAssumeValid">
+     <layout class="QVBoxLayout">
+      <item>
+       <widget class="QLabel" name="lblExplanationAssumeValid">
+        <property name="text">
+         <string>The initial synchronisation process can go faster if you skip verification of older transactions. This does, however, require trusting that the &quot;assumed valid&quot; blockchain below is in fact valid. Uncheck this if you want to fully validate the entire blockchain history.</string>
+        </property>
+        <property name="wordWrap">
+         <bool>true</bool>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <layout class="QHBoxLayout" name="layoutAssumeValid">
+        <item>
+         <widget class="QCheckBox" name="assumevalid">
+          <property name="toolTip">
+           <string>Reverting this setting will slow down initial synchronisation due to validating old transactions</string>
+          </property>
+          <property name="text">
+           <string>Skip validation of the transactions until after block:</string>
+          </property>
+          <property name="checked">
+           <bool>true</bool>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <spacer>
+          <property name="orientation">
+           <enum>Qt::Horizontal</enum>
+          </property>
+         </spacer>
+        </item>
+       </layout>
+      </item>
+      <item>
+       <layout class="QHBoxLayout" name="layoutAssumeValidBlock">
+        <item>
+         <spacer>
+          <property name="orientation">
+           <enum>Qt::Horizontal</enum>
+          </property>
+         </spacer>
+        </item>
+        <item>
+         <widget class="QLineEdit" name="assumevalidBlock">
+          <property name="maxLength">
+           <number>64</number>
+          </property>
+         </widget>
+        </item>
+       </layout>
+      </item>
+     </layout>
+    </widget>
+   </item>
    <item>
     <spacer name="verticalSpacer">
      <property name="orientation">
diff --git a/src/qt/intro.cpp b/src/qt/intro.cpp
index 37d7a3e6e0..eb3f6c9a20 100644
--- a/src/qt/intro.cpp
+++ b/src/qt/intro.cpp
@@ -161,6 +161,37 @@ Intro::Intro(QWidget *parent, int64_t blockchain_size_gb, int64_t chain_state_si
         UpdateFreeSpaceLabel();
     });
 
+    bool have_user_assumevalid = false;
+    if (gArgs.IsArgSet("-assumevalid")) {
+        const auto user_assumevalid = gArgs.GetArg("-assumevalid", /* ignored default; determines return type */ "");
+        if (uint256S(user_assumevalid).IsNull()) {
+            // -assumevalid=0: default checkbox to off, and initialise with chainparams later
+            ui->assumevalid->setChecked(false);
+        } else {
+            // -assumevalid=blockhash: initialise with the user-specified value, enabled
+            ui->assumevalid->setChecked(true);
+            ui->assumevalidBlock->setText(QString::fromStdString(user_assumevalid));
+            have_user_assumevalid = true;
+        }
+    }
+    if (!have_user_assumevalid) {
+        const auto chainparams = CreateChainParams(gArgs, gArgs.GetChainType());
+        const uint256 default_assumevalid = chainparams ? chainparams->GetConsensus().defaultAssumeValid : uint256();
+        if (default_assumevalid.IsNull()) {
+            // no chainparams assumevalid (nor user-provided), so hide the options entirely
+            ui->groupAssumeValid->setVisible(false);
+        } else {
+            // assumevalid from chainparams only (normal case): disable editing of blockhash
+            ui->assumevalidBlock->setText(QString::fromStdString(default_assumevalid.GetHex()));
+            ui->assumevalidBlock->setReadOnly(true);
+        }
+    }
+    {
+        // TODO: Ideally, we would include actual margins here (instead of extra digits), but this seems non-trivial
+        const int text_width = ui->assumevalidBlock->fontMetrics().horizontalAdvance(QStringLiteral("4")) * (64 + 4);
+        ui->assumevalidBlock->setFixedWidth(text_width);
+    }
+
     startThread();
 }
 
@@ -202,6 +233,14 @@ int64_t Intro::getPruneMiB() const
     }
 }
 
+QString Intro::getAssumeValid() const
+{
+    if (!ui->assumevalid->isChecked()) {
+        return QStringLiteral("0");
+    }
+    return ui->assumevalidBlock->text();
+}
+
 bool Intro::showIfNeeded(std::unique_ptr<Intro>& intro)
 {
     intro.reset();
diff --git a/src/qt/intro.h b/src/qt/intro.h
index 063b0cf43d..1e3eb5c629 100644
--- a/src/qt/intro.h
+++ b/src/qt/intro.h
@@ -39,6 +39,7 @@ public:
     QString getDataDirectory();
     void setDataDirectory(const QString &dataDir);
     int64_t getPruneMiB() const;
+    QString getAssumeValid() const;
 
     /**
      * Determine data directory. Let the user choose if the current one doesn't exist.