From 462336ed495b653e96c568acb66c638c47b0358e Mon Sep 17 00:00:00 2001
From: Andreas Kling <awesomekling@gmail.com>
Date: Mon, 19 Aug 2019 19:07:52 +0200
Subject: [PATCH] LibVT: Add scrollback history to VT::Terminal

The default (hard-coded) history size is 500 lines. When the history is
altered, the TerminalClient is notified via terminal_history_changed().
---
 Libraries/LibVT/Terminal.cpp | 7 +++++++
 Libraries/LibVT/Terminal.h   | 5 +++++
 2 files changed, 12 insertions(+)

diff --git a/Libraries/LibVT/Terminal.cpp b/Libraries/LibVT/Terminal.cpp
index 4b2cd501f8d..afbe8d4ab6e 100644
--- a/Libraries/LibVT/Terminal.cpp
+++ b/Libraries/LibVT/Terminal.cpp
@@ -666,6 +666,13 @@ void Terminal::scroll_up()
 {
     // NOTE: We have to invalidate the cursor first.
     invalidate_cursor();
+    if (m_scroll_region_top == 0) {
+        auto line = move(m_lines.ptr_at(m_scroll_region_top));
+        m_history.append(move(line));
+        while (m_history.size() > max_history_size())
+            m_history.take_first();
+        m_client.terminal_history_changed();
+    }
     m_lines.remove(m_scroll_region_top);
     m_lines.insert(m_scroll_region_bottom, make<Line>(m_columns));
     m_need_full_flush = true;
diff --git a/Libraries/LibVT/Terminal.h b/Libraries/LibVT/Terminal.h
index f52eda5e2a4..d6bf5e736b9 100644
--- a/Libraries/LibVT/Terminal.h
+++ b/Libraries/LibVT/Terminal.h
@@ -14,6 +14,7 @@ public:
     virtual void beep() = 0;
     virtual void set_window_title(const StringView&) = 0;
     virtual void terminal_did_resize(u16 columns, u16 rows) = 0;
+    virtual void terminal_history_changed() = 0;
 };
 
 struct Attribute {
@@ -98,6 +99,9 @@ public:
         return m_lines[index];
     }
 
+    int max_history_size() const { return 500; }
+    const NonnullOwnPtrVector<Line>& history() const { return m_history; }
+
 private:
     typedef Vector<unsigned, 4> ParamVector;
 
@@ -137,6 +141,7 @@ private:
 
     TerminalClient& m_client;
 
+    NonnullOwnPtrVector<Line> m_history;
     NonnullOwnPtrVector<Line> m_lines;
 
     int m_scroll_region_top { 0 };