From dafb022fe56f69b51ec120f437d7caa21b2996c1 Mon Sep 17 00:00:00 2001
From: Christian Rocha <christian@rocha.is>
Date: Tue, 19 May 2020 13:18:32 -0400
Subject: [PATCH] Pager is now called viewport and allows for non-default
 keybindings

---
 pager/pager.go => viewport/viewport.go | 71 ++++++++++++++++++--------
 1 file changed, 50 insertions(+), 21 deletions(-)
 rename pager/pager.go => viewport/viewport.go (64%)

diff --git a/pager/pager.go b/viewport/viewport.go
similarity index 64%
rename from pager/pager.go
rename to viewport/viewport.go
index 664d83d..2301883 100644
--- a/pager/pager.go
+++ b/viewport/viewport.go
@@ -1,4 +1,4 @@
-package pager
+package viewport
 
 import (
 	"strings"
@@ -42,56 +42,85 @@ func NewModel(width, height int) Model {
 	}
 }
 
+// ViewDown moves the view down by the number of lines in the viewport.
+// Basically, "page down."
+func (m *Model) ViewDown() {
+	m.Y = min(len(m.lines)-m.Height, m.Y+m.Height)
+}
+
+// ViewUp moves the view up by one height of the viewport. Basically, "page up."
+func (m *Model) ViewUp() {
+	m.Y = max(0, m.Y-m.Height)
+}
+
+// HalfViewUp moves the view up by half the height of the viewport
+func (m *Model) HalfViewUp() {
+	m.Y = max(0, m.Y-m.Height/2)
+}
+
+// HalfViewDown moves the view down by half the height of the viewport
+func (m *Model) HalfViewDown() {
+	m.Y = min(len(m.lines)-m.Height, m.Y+m.Height/2)
+}
+
+// LineDown moves the view up by the given number of lines.
+func (m *Model) LineDown(n int) {
+	m.Y = min(len(m.lines)-m.Height, m.Y+n)
+}
+
+// LineDown moves the view down by the given number of lines.
+func (m *Model) LineUp(n int) {
+	m.Y = max(0, m.Y-n)
+}
+
 // UPDATE
 
+// Update runs the update loop with default keybindings. To define your own
+// keybindings use the methods on Model.
 func Update(msg boba.Msg, m Model) (Model, boba.Cmd) {
 	switch msg := msg.(type) {
 
 	case boba.KeyMsg:
 		switch msg.String() {
 
-		// Up one page
-		case "pgup":
-			fallthrough
-		case "b":
-			m.Y = max(0, m.Y-m.Height)
-			return m, nil
-
 		// Down one page
 		case "pgdown":
 			fallthrough
 		case "space":
 			fallthrough
 		case "f":
-			m.Y = min(len(m.lines)-m.Height, m.Y+m.Height)
+			m.ViewDown()
 			return m, nil
 
-		// Up half page
-		case "u":
-			m.Y = max(0, m.Y-m.Height/2)
+		// Up one page
+		case "pgup":
+			fallthrough
+		case "b":
+			m.ViewUp()
 			return m, nil
 
 		// Down half page
 		case "d":
-			m.Y = min(len(m.lines)-m.Height, m.Y+m.Height/2)
+			m.HalfViewDown()
 			return m, nil
 
-		// Up one line
-		case "up":
-			fallthrough
-		case "k":
-			m.Y = max(0, m.Y-1)
+		// Up half page
+		case "u":
+			m.HalfViewUp()
 			return m, nil
 
 		// Down one line
 		case "down":
 			fallthrough
 		case "j":
-			m.Y = min(len(m.lines)-m.Height, m.Y+1)
+			m.LineDown(1)
 			return m, nil
 
-		// Re-render
-		case "ctrl+l":
+		// Up one line
+		case "up":
+			fallthrough
+		case "k":
+			m.LineUp(1)
 			return m, nil
 
 		}