package main

import "bytes"
import "image"
import _ "embed"
import _ "image/png"
import "git.tebibyte.media/sashakoshka/stone"
import _ "git.tebibyte.media/sashakoshka/stone/backends/x"
	
//go:embed icon/icon64.png
var iconBytes []byte

var application = &stone.Application { }

var expressionRoot Expression
var inputBuffer stone.DamageBuffer
var showLeftColumn bool
var showEndResult  bool = true
var showSigned     bool = true
var showFloat      bool

func main () {
	application.SetTitle("MathPan")
	application.SetSize(64, 12)

	icon, _, err := image.Decode(bytes.NewReader(iconBytes))
	if err != nil { panic(err) }
	application.SetIcon([]image.Image { icon })
	
	application.OnStart(onStart)
	application.OnResize(redraw)
	application.OnPress(onPress)
	
	err = application.Run()
	if err != nil { panic(err) }
}

func onPress (button stone.Button, modifiers stone.Modifiers) {
	switch button {
	case ',':
		if selectedExpression == nil { break }
		
		newSelection := selectedExpression.Parent()
		if newSelection != nil {
			selectedExpression = newSelection
		}
		
		redraw()
		application.Draw()
		
	case stone.KeyLeft:
		if selectedExpression == nil { break }
		
		newSelection := selectedExpression.Previous()
		if newSelection != nil {
			selectedExpression = newSelection
		}
		
		redraw()
		application.Draw()
		
	case stone.KeyRight:
		if selectedExpression == nil { break }
		
		newSelection := selectedExpression.Next()
		if newSelection != nil {
			selectedExpression = newSelection
		}
		
		redraw()
		application.Draw()

	case '[':
		insertGeneric (&Operation {
			floating: showFloat,
		}, modifiers.Alt, true, false)
		redraw()
		application.Draw()

	case ']':
		insertGeneric (&Operation {
			floating: showFloat,
		}, modifiers.Alt, false, false)
		redraw()
		application.Draw()

	case '\\':
		insertOperation('?', false, true)
		redraw()
		application.Draw()
		
	case
		'+', '-', '*', '/', 'p', 'P', '%', '|', '~', '&', '^', 'm',
		'l', 'r':
		
		insertOperation(rune(button), modifiers.Alt, false)
		redraw()
		application.Draw()

	case stone.KeyDelete:
		if selectedExpression == nil { break }
		parent := selectedExpression.Parent()
		
		if parent == nil {
			expressionRoot = nil
			selectedExpression = nil
		} else {
			previous := selectedExpression.Parent().Previous()
			next     := selectedExpression.Parent().Next()
			
			selectedExpression.Parent().Disown(selectedExpression)

			if next == nil {
				selectedExpression = previous
			} else {
				selectedExpression = next
			}
		}
		
		redraw()
		application.Draw()

	case stone.KeyBackspace:
		if selectedExpression == nil { break }
		
		parent := selectedExpression.Parent()

		switch selectedExpression.(type) {	
		case *IntegerLiteral:
			integer := selectedExpression.(*IntegerLiteral)
			if integer.value == 0 { break }
			integer.value /= int64(integer.displayRadix)
			goto stopBackspacing
		}
		
		if parent == nil {
			expressionRoot = nil
			selectedExpression = nil
		} else {
			previous := selectedExpression.Parent().Previous()
			
			selectedExpression.Parent().Disown(selectedExpression)

			if previous != nil {
				selectedExpression = previous
			}
		}
		
		stopBackspacing:
		redraw()
		application.Draw()

	case ' ':
		insertNumber(0, modifiers.Alt, modifiers.Shift)
		redraw()
		application.Draw()

	case
		'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
		'a', 'b', 'c', 'd', 'e', 'f':

		value := rune(button)
		if value >= 'a' {
			value -= 'a'
			value += 10
		} else {
			value -= '0'
		}

		switch selectedExpression.(type) {
		case *Operation, nil:
			insertNumber(int64(value), modifiers.Alt, false)
			
		case *IntegerLiteral:
			integer := selectedExpression.(*IntegerLiteral)
			integer.value *= int64(integer.displayRadix)
			if integer.value < 0 {
				integer.value -= int64(value)
			} else {
				integer.value += int64(value)
			}
		}
		
		redraw()
		application.Draw()

	case 'x':
		switch selectedExpression.(type) {
		case *IntegerLiteral:
			integer := selectedExpression.(*IntegerLiteral)
			switch integer.displayRadix {
			case 2:
				integer.displayRadix = 8
			case 8:
				integer.displayRadix = 10
			case 10:
				integer.displayRadix = 16
			case 16:
				integer.displayRadix = 2
			}
		}
		
		redraw()
		application.Draw()
	
	case 'X':
		switch selectedExpression.(type) {
		case *IntegerLiteral:
			integer := selectedExpression.(*IntegerLiteral)
			switch integer.displayRadix {
			case 2:
				integer.displayRadix = 16
			case 8:
				integer.displayRadix = 2
			case 10:
				integer.displayRadix = 8
			case 16:
				integer.displayRadix = 10
			}
		}
		
		redraw()
		application.Draw()

	case 's':
		switch selectedExpression.(type) {
		case *IntegerLiteral:
			integer := selectedExpression.(*IntegerLiteral)
			integer.value *= -1
		}
		
		redraw()
		application.Draw()

	case 'S':
		showSigned = !showSigned
		redraw()
		application.Draw()

	case 'q':
		showEndResult = !showEndResult
		redraw()
		application.Draw()

	case 'z':
		switch selectedExpression.(type) {
		case *Operation:
			operation := selectedExpression.(*Operation)
			operation.floating = !operation.floating
		}
		redraw()
		application.Draw()

	case 'Z':
		showFloat = !showFloat
		redraw()
		application.Draw()
	}
}

func insertOperation (symbol rune, swap, encompass bool) {
	var opcode Opcode
	switch (symbol) {
	case '?': opcode = OpcodeUnknown
	case '+': opcode = OpcodeAdd
	case '-': opcode = OpcodeSubtract
	case '*': opcode = OpcodeMultiply
	case '/': opcode = OpcodeDivide
	case 'p': opcode = OpcodePower
	case 'P': opcode = OpcodeRoot
	case '%': opcode = OpcodeModulo
	case '|': opcode = OpcodeOr
	case '~': opcode = OpcodeNot
	case '&': opcode = OpcodeAnd
	case '^': opcode = OpcodeXor
	case 'l': opcode = OpcodeLeftShift
	case 'r': opcode = OpcodeRightShift
	case 'm': opcode = OpcodeMean
	}

	newExpression := Operation { opcode: opcode, floating: showFloat }

	if encompass {
		if selectedExpression == nil { return }
		parent := selectedExpression.Parent()

		newExpression.Adopt(selectedExpression)
		if parent == nil {
			expressionRoot = &newExpression
		} else {
			parent.Swap(selectedExpression, &newExpression)
		}

		selectedExpression = &newExpression
		return
	}

	operation, isOperation := selectedExpression.(*Operation)
	if isOperation {
		if operation.opcode == OpcodeUnknown || swap {
			operation.opcode = opcode
			return
		}
	}
	
	insertGeneric(&newExpression, swap, false, true)
}

func insertNumber (value int64, swap, before bool) {
	insertGeneric (&IntegerLiteral {
		displayRadix: 10,
		value: value,
	}, swap, before, true)
}

func insertGeneric (expression Expression, swap, before, fillIn bool) {
	// if there are no expressions, place this at root
	if selectedExpression == nil || expressionRoot == nil {
		expressionRoot = expression
		selectedExpression = expression
		return
	}

	// prefer filling an empty operation
	operation, isOperation := selectedExpression.(*Operation)
	if fillIn && isOperation && len(operation.operands) == 0 {
		operation.Adopt(expression)
		selectedExpression = expression
		return
	}

	// insert expression into the parent operation
	parent := selectedExpression.Parent()
	if parent == nil { return }
	if swap {
		parent.Swap(selectedExpression, expression)
	} else {
		parent.Insert(selectedExpression, expression, !before)
	}
	selectedExpression = expression
}

func onStart () {
	redraw()
}