From df470b91539905d7257c737ba3c7cbd989761fc6 Mon Sep 17 00:00:00 2001
From: Brian Buller <brbuller@gmail.com>
Date: Mon, 30 Nov 2015 08:23:49 -0600
Subject: [PATCH] Initial Commit

Started dev on a calculator module
---
 termbox_calculator.go | 83 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 83 insertions(+)
 create mode 100644 termbox_calculator.go

diff --git a/termbox_calculator.go b/termbox_calculator.go
new file mode 100644
index 0000000..6febb15
--- /dev/null
+++ b/termbox_calculator.go
@@ -0,0 +1,83 @@
+package termboxModules
+
+import "github.com/nsf/termbox-go"
+
+// Calculator An input field that allows simple maths
+type Calculator struct {
+	text                string
+	input               *InputField
+	x, y, width, height int
+	cursor              int
+	bg, fg              termbox.Attribute
+	history             []string
+	opStack             []string
+	showHistoryLines    int
+}
+
+// CreateCalculator Create a calculator module
+func CreateCalculator(x, y, width, height int, fg, bg termbox.Attribute) *Calculator {
+	i := Calculator{x: x, y: y, width: width, height: height, fg: fg, bg: bg, showHistoryLines: 0}
+	i.input = CreateInputField(i.x, i.y, i.width, 2, i.fg, i.bg)
+	i.input.bordered = true
+	return &i
+}
+
+// PushOpStack Pushes a value onto the opStack
+func (calc *Calculator) PushOpStack(v string) {
+	calc.opStack = append(calc.opStack, v)
+}
+
+// PopOpStack Pops the last value off of the opStack
+func (calc *Calculator) PopOpStack() string {
+	prevEntry := opStack[len(opStack)-1]
+	calc.opStack = opStack[:len(opStack)-1]
+	return prevEntry
+}
+
+// HandleKeyPress Handle the termbox event, return true if it was consumed
+func (calc *Calculator) HandleKeyPress(event termbox.Event) bool {
+	if event.Ch == '+' || event.Ch == '-' || event.Ch == '*' || event.Ch == '/' {
+		// Save the value of input to opStack
+		calc.PushOpStack(i.input.GetValue())
+		calc.PushOpStack(string(event.Ch))
+		i.input.SetValue("")
+		return true
+	} else if event.Ch == '=' {
+		// Perform the operation
+		var total int
+		// Go ltr through stack doing all multiplication & division
+		/*
+			for len(opStack) > 0 {
+				prevEntry := calc.PopStack()
+				if prevEntry == "+" {
+					prevEntry = calc.PopStack()
+					if addVal, err := strconv.Atoi(prevEntry); err == nil {
+						total = total + addVal
+					}
+				} else if prevEntry == "-" {
+					prevEntry = calc.PopStack()
+					if subVal, err := strconv.Atoi(prevEntry); err == nil {
+						total = total - subVal
+					}
+				} else if prevEntry == "*" {
+					prevEntry = calc.PopStack()
+					if multVal, err := strconv.Atoi(prevEntry); err == nil {
+						total = total * multVal
+					}
+				} else if prevEntry == "/" {
+					prevEntry = calc.PopStack()
+					if divVal, err := strconv.Atoi(prevEntry); err == nil {
+						total = total / divVal
+					}
+				}
+			}
+		*/
+	} else if event.Ch == '0' || event.Ch == '1' ||
+		event.Ch == '2' || event.Ch == '3' ||
+		event.Ch == '4' || event.Ch == '5' ||
+		event.Ch == '6' || event.Ch == '7' ||
+		event.Ch == '8' || event.Ch == '9' {
+		return i.input.HandleKeyPress(event)
+	}
+	return false
+}