From 2c0fbfccc6907261f77755f13698932a6b21dc2b Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Tue, 10 May 2022 19:42:00 -0700
Subject: [PATCH] implement CUD, CUU

---
 src/Window.zig            |  8 ++++++++
 src/terminal/Terminal.zig | 29 +++++++++++++++++++++++++++--
 src/terminal/stream.zig   | 24 ++++++++++++++++++++++++
 3 files changed, 59 insertions(+), 2 deletions(-)

diff --git a/src/Window.zig b/src/Window.zig
index 60bacd566..0b21f5090 100644
--- a/src/Window.zig
+++ b/src/Window.zig
@@ -525,6 +525,14 @@ pub fn setCursorRight(self: *Window, amount: u16) !void {
     self.terminal.cursorRight(amount);
 }
 
+pub fn setCursorDown(self: *Window, amount: u16) !void {
+    self.terminal.cursorDown(amount);
+}
+
+pub fn setCursorUp(self: *Window, amount: u16) !void {
+    self.terminal.cursorUp(amount);
+}
+
 pub fn setCursorCol(self: *Window, col: u16) !void {
     try self.terminal.setCursorPos(self.terminal.cursor.y + 1, col);
 }
diff --git a/src/terminal/Terminal.zig b/src/terminal/Terminal.zig
index 4fde7762b..89b6836fb 100644
--- a/src/terminal/Terminal.zig
+++ b/src/terminal/Terminal.zig
@@ -295,11 +295,36 @@ pub fn cursorRight(self: *Terminal, count: usize) void {
     defer tracy.end();
 
     self.cursor.x += count;
-    if (self.cursor.x == self.cols) {
-        self.cursor.x -= 1;
+    if (self.cursor.x >= self.cols) {
+        self.cursor.x = self.cols - 1;
     }
 }
 
+/// Move the cursor down amount lines. If amount is greater than the maximum
+/// move distance then it is internally adjusted to the maximum. This sequence
+/// will not scroll the screen or scroll region. If amount is 0, adjust it to 1.
+// TODO: test
+pub fn cursorDown(self: *Terminal, count: usize) void {
+    const tracy = trace(@src());
+    defer tracy.end();
+
+    self.cursor.y += count;
+    if (self.cursor.y >= self.rows) {
+        self.cursor.y = self.rows - 1;
+    }
+}
+
+/// Move the cursor up amount lines. If amount is greater than the maximum
+/// move distance then it is internally adjusted to the maximum. If amount is
+/// 0, adjust it to 1.
+// TODO: test
+pub fn cursorUp(self: *Terminal, count: usize) void {
+    const tracy = trace(@src());
+    defer tracy.end();
+
+    self.cursor.y -|= count;
+}
+
 /// Backspace moves the cursor back a column (but not less than 0).
 pub fn backspace(self: *Terminal) void {
     const tracy = trace(@src());
diff --git a/src/terminal/stream.zig b/src/terminal/stream.zig
index e2da79c0d..f9f6d7c3d 100644
--- a/src/terminal/stream.zig
+++ b/src/terminal/stream.zig
@@ -94,6 +94,30 @@ pub fn Stream(comptime Handler: type) type {
 
         fn csiDispatch(self: *Self, action: Parser.Action.CSI) !void {
             switch (action.final) {
+                // CUU - Cursor Up
+                'A' => if (@hasDecl(T, "setCursorUp")) try self.handler.setCursorUp(
+                    switch (action.params.len) {
+                        0 => 1,
+                        1 => action.params[0],
+                        else => {
+                            log.warn("invalid cursor up command: {}", .{action});
+                            return;
+                        },
+                    },
+                ) else log.warn("unimplemented CSI callback: {}", .{action}),
+
+                // CUD - Cursor Down
+                'B' => if (@hasDecl(T, "setCursorDown")) try self.handler.setCursorDown(
+                    switch (action.params.len) {
+                        0 => 1,
+                        1 => action.params[0],
+                        else => {
+                            log.warn("invalid cursor down command: {}", .{action});
+                            return;
+                        },
+                    },
+                ) else log.warn("unimplemented CSI callback: {}", .{action}),
+
                 // CUF - Cursor Right
                 'C' => if (@hasDecl(T, "setCursorRight")) try self.handler.setCursorRight(
                     switch (action.params.len) {