From ec42140241ed3d11a2f91a8a658a1dd30cf39fb5 Mon Sep 17 00:00:00 2001
From: Zachary Yedidia <zyedidia@gmail.com>
Date: Sun, 27 Mar 2016 17:53:00 -0400
Subject: [PATCH] Add help text

---
 src/help.go       | 86 +++++++++++++++++++++++++++++++++++++++++++++++
 src/micro.go      |  4 +++
 src/statusline.go |  4 +++
 src/view.go       |  4 ++-
 4 files changed, 97 insertions(+), 1 deletion(-)
 create mode 100644 src/help.go

diff --git a/src/help.go b/src/help.go
new file mode 100644
index 00000000..a46360ad
--- /dev/null
+++ b/src/help.go
@@ -0,0 +1,86 @@
+package main
+
+import (
+	"github.com/gdamore/tcell"
+	"strings"
+)
+
+const helpTxt = `Press Ctrl-q to quit help
+
+Micro keybindings:
+
+Ctrl-q:   Quit
+Ctrl-s:   Save
+Ctrl-o:   Open file
+
+Ctrl-z:   Undo
+Ctrl-y:   Redo
+
+Ctrl-a:   Select all
+
+Ctrl-c:   Copy
+Ctrl-x:   Cut
+Ctrl-v:   Paste
+
+Ctrl-h:   Open help
+
+Ctrl-u:   Half page up
+Ctrl-d:   Half page down
+PageUp:   Page up
+PageDown: Page down
+
+Ctrl-e:   Set option
+
+Micro options:
+
+colorscheme: loads the colorscheme stored in ~/.micro/colorschemes/'option'.micro
+	default value: 'default'
+
+tabsize: sets the tab size to 'option'
+	default value: '4'
+`
+
+// DisplayHelp displays the help txt
+// It blocks the main loop
+func DisplayHelp() {
+	topline := 0
+	_, height := screen.Size()
+	screen.HideCursor()
+	totalLines := strings.Split(helpTxt, "\n")
+	for {
+		screen.Clear()
+
+		lineEnd := topline + height
+		if lineEnd > len(totalLines) {
+			lineEnd = len(totalLines)
+		}
+		lines := totalLines[topline:lineEnd]
+		for y, line := range lines {
+			for x, ch := range line {
+				st := tcell.StyleDefault
+				screen.SetContent(x, y, ch, nil, st)
+			}
+		}
+
+		screen.Show()
+
+		event := screen.PollEvent()
+		switch e := event.(type) {
+		case *tcell.EventResize:
+			_, height = e.Size()
+		case *tcell.EventKey:
+			switch e.Key() {
+			case tcell.KeyUp:
+				if topline > 0 {
+					topline--
+				}
+			case tcell.KeyDown:
+				if topline < len(totalLines)-height {
+					topline++
+				}
+			case tcell.KeyCtrlQ, tcell.KeyCtrlW, tcell.KeyEscape, tcell.KeyCtrlC:
+				return
+			}
+		}
+	}
+}
diff --git a/src/micro.go b/src/micro.go
index e3df3c7a..884272d1 100644
--- a/src/micro.go
+++ b/src/micro.go
@@ -147,6 +147,10 @@ func main() {
 				}
 			case tcell.KeyCtrlE:
 				SetOption(view)
+			case tcell.KeyCtrlH:
+				DisplayHelp()
+				// Make sure to resize the view if the user resized the terminal while looking at the help text
+				view.Resize(screen.Size())
 			}
 		}
 
diff --git a/src/statusline.go b/src/statusline.go
index e3b1d87e..a62b046a 100644
--- a/src/statusline.go
+++ b/src/statusline.go
@@ -41,6 +41,8 @@ func (sline *Statusline) Display() {
 	// Add the filetype
 	file += " " + sline.view.buf.filetype
 
+	centerText := "Press Ctrl-h for help"
+
 	statusLineStyle := tcell.StyleDefault.Reverse(true)
 	if style, ok := colorscheme["statusline"]; ok {
 		statusLineStyle = style
@@ -51,6 +53,8 @@ func (sline *Statusline) Display() {
 	for x := 0; x < sline.view.width; x++ {
 		if x < len(fileRunes) {
 			screen.SetContent(x, y, fileRunes[x], nil, statusLineStyle)
+		} else if x >= sline.view.width/2-len(centerText)/2 && x < len(centerText)+sline.view.width/2-len(centerText)/2 {
+			screen.SetContent(x, y, []rune(centerText)[x-sline.view.width/2+len(centerText)/2], nil, statusLineStyle)
 		} else {
 			screen.SetContent(x, y, ' ', nil, statusLineStyle)
 		}
diff --git a/src/view.go b/src/view.go
index 0263d45d..58fe28ba 100644
--- a/src/view.go
+++ b/src/view.go
@@ -159,7 +159,9 @@ func (v *View) PageDown() {
 	if len(v.buf.lines)-(v.topline+v.height) > v.height {
 		v.ScrollDown(v.height)
 	} else {
-		v.topline = len(v.buf.lines) - v.height
+		if len(v.buf.lines) >= v.height {
+			v.topline = len(v.buf.lines) - v.height
+		}
 	}
 }