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
}