package main

import (
	"fmt"
	"math"
	"strconv"
	"strings"
)

const (
	Bold       int = 1
	Faint      int = 2
	Italic     int = 3
	Underline  int = 4
)

type cell struct {
	kind       int      // Enum for the type of cell
	rawVal     string   // A raw string of the value
	num        float64  // A quick reference field for the current value
	expr       []string // Fields representing an expression
	mask       string   // What the user sees
	mods       []int    // Enums of modifiers on the cell
}

func (c cell) String(width int, selected bool) string {
	mods := c.Mods()
	if selected {
		mods += "\033[7m"
	}
	format := "%s %*.*s \033[0m"
	if c.kind == Text {
		format = "%s %-*.*s \033[0m"
	}
	return fmt.Sprintf(format, mods, width-2, width-2, c.mask)
}

func (c cell) Mods() string {
	var o strings.Builder
	for _, mod := range c.mods {
		o.WriteString(fmt.Sprintf("\033[%dm", mod))
	}
	return o.String()
}

func (c *cell) ToggleMod(mod int) {
	if mod > 4 || mod < 1 {
		return
	}
	present := false
	for i, m := range c.mods {
		if m == mod {
			if i != len(c.mods)-1 {
				c.mods[i] = c.mods[len(c.mods)-1]
			}
			c.mods = c.mods[:len(c.mods)-1]
			present = true
			break
		}
	}
	if !present {
		c.mods = append(c.mods, mod)
	}
}

func (c *cell) Edit(row, col, width int, text bool) {
	line := GetEditLine(fmt.Sprintf("%c%d > ", col+64, row), c.rawVal, width)
	if len(line) == 0 {
		return
	}
	fmt.Print("\033[?25l")
	line = strings.TrimSpace(line)
	if text && (!strings.HasPrefix(line, "\"") && !strings.HasSuffix(line, "\"")){
		line = fmt.Sprintf("\"%s\"", line)
	}
	updated := c.Update(line)
	if updated {
		modified = true
	}
}

func (c *cell) Update(val string) bool {
	if val == c.rawVal || len(val) == 0 {
		// If nothing was changed or the change is empty just return
		return false
	}
	c.rawVal = val
	num, err := strconv.ParseFloat(val, 64)
	if err == nil {
		c.kind = Number
		c.num  = num
		c.mask = strconv.FormatFloat(num, 'f', -1, 64)
	} else if strings.HasPrefix(val, "\"") && strings.HasSuffix(val, "\"") {
		c.rawVal = strings.Replace(c.rawVal, " ", "\\_", -1)
		c.kind = Text
		c.mask = strings.Replace(val[1:len(val)-1], "\\_", " ", -1)
	} else {
		c.kind = Expr
		c.expr = strings.Fields(val)
	}
	return true
}

func (c *cell) Calculate() {
	if c.kind != Expr {
		return
	}
	insideString := false
	s := makeStack()

	for _, v := range c.expr {
		var stackError error = nil
		if IsAddr(v) {
			pt, _, _ := Addr2Point(v)
			c, err := GetCell(pt)
			if err != nil {
				c.mask = "#Err: Invalid cell reference " + v
				return
			}
			if c.kind == Text {
				v = c.rawVal
			} else if c.kind == Empty {
				break
			} else {
				v = c.mask
			}
		} else if IsRange(v) {
			stackError = s.Sum(v)
			goto ERRCHECK
		}

		switch true {
		case strings.HasPrefix(v, "\""):
			if !strings.HasSuffix(v, "\"") {
				insideString = true
			}
			s.str.WriteString(strings.Replace(v, "\"", "", -1))
			s.text = true
		case insideString:
			if strings.HasSuffix(v, "\"") {
				insideString = false
				v = strings.Replace(v, "\"", "", -1)
			}
			s.str.WriteRune(' ')
			s.str.WriteString(v)
		case IsFunc(v):
			v = strings.ToUpper(v)
			if v == "SPC" {
				s.str.WriteRune(' ')
				s.text = true
			}
			if v == "+" {
				stackError = s.Add()
			}
			if v == "-" {
				stackError = s.Subtract()
			}
			if v == "/" {
				stackError = s.Divide()
			}
			if v == "*" {
				stackError = s.Multiply()
			}
			if v == "." {
				if s.Len() < 1 {
					stackError = fmt.Errorf("Stack underflow")
				}
				num := s.Pop()
				s.str.WriteString(strconv.FormatFloat(num, 'f', -1, 64))
				s.text = true
			}
			if v == "MIN" {
				stackError = s.Min()
			}
			if v == "MAX" {
				stackError = s.Max()
			}
			if v == "ROUND" {
				stackError = s.Round()
			}
			if v == "SWAP" {
				stackError = s.Swap()
			}
			if v == "DUP" {
				stackError = s.Dup()
			}
			if v == "CLEAR" {
				s.ClearStack()
			}
			if v == "DROP" {
				stackError = s.Drop()
			}
			if v == "OVER" {
				stackError = s.Over()
			}
			if v == "POW" {
				stackError = s.Pow()
			}
			if v == "FLOOR" {
				stackError = s.Floor()
			}
			if v == "CEIL" {
				stackError = s.Ceil()
			}
		default:
			v, err := strconv.ParseFloat(v, 64)
			if err != nil {
				c.mask = "#Err: Cannot parse float"
				return
			}
			s.Push(v)
		}

		ERRCHECK: if stackError != nil {
			c.mask = fmt.Sprintf("#ERR: %s", stackError.Error())
			return
		}
	}

	if s.text {
		if s.ptr != -1 {
			for s.Len() > 0 {
				num := s.Pop()
				s.str.WriteString(strconv.FormatFloat(num, 'f', -1, 64))
			}
		}
		c.mask = strings.Replace(s.str.String(), "\\_", " ", -1)
	} else if s.ptr == 0 {
		c.mask = strconv.FormatFloat(s.data[0], 'f', -1, 64)
	} else if s.ptr == -1 {
		c.mask = ""
	} else {
		c.mask = "#Err: Invalid Formula"
	}
}

type stack struct {
	data  [100]float64
	ptr   int
	text  bool
	str   strings.Builder
}

func makeStack() stack {
	return stack{data: [100]float64{}, ptr: -1, text: false}
}

func (s *stack) Push(v float64) {
	if s.ptr >= 99 {
		panic("Stack overflow")
	}
	s.ptr++
	s.data[s.ptr] = v
}

func (s *stack) Pop() float64 {
	if s.ptr < 0 {
		panic("Stack underflow")
	}
	s.ptr--
	return s.data[s.ptr+1]
}

func (s stack) Len() int {
	return s.ptr + 1
}

func (s *stack) Dup() error {
	if s.Len() < 1 {
		return fmt.Errorf("Stack underflow")
	}
	val := s.Pop()
	s.Push(val)
	s.Push(val)
	return nil
}

func (s *stack) Drop() error {
	if s.Len() < 1 {
		return fmt.Errorf("Stack underflow")
	}
	s.Pop()
	return nil
}

func (s *stack) ClearStack() {
	s.ptr = -1
}

func (s *stack) Add() error {
	if s.Len() < 2 {
		return fmt.Errorf("Stack underflow")
	}
	if s.text {
		val := strconv.FormatFloat(s.Pop(), 'f', -1, 64)
		s.str.WriteString(val)
	} else {
		s.Push(s.Pop() + s.Pop())
	}
	return nil
}

func (s *stack) Subtract() error {
	if s.Len() < 2 {
		return fmt.Errorf("Stack underflow")
	}
	second := s.Pop()
	s.Push(s.Pop() - second)
	return nil
}

func (s *stack) Multiply() error {
	if s.Len() < 2 {
		return fmt.Errorf("Stack underflow")
	}
	s.Push(s.Pop() * s.Pop())
	return nil
}

func (s *stack) Divide() error {
	if s.Len() < 2 {
		return fmt.Errorf("Stack underflow")
	}
	second := s.Pop()
	s.Push(s.Pop() / second)
	return nil
}

func (s *stack) Min() error {
	if s.Len() < 2 {
		return fmt.Errorf("Stack underflow")
	}
	one := s.Pop()
	two := s.Pop()
	if one < two {
		s.Push(one)
	} else {
		s.Push(two)
	}
	return nil
}

func (s *stack) Max() error {
	if s.Len() < 2 {
		return fmt.Errorf("Stack underflow")
	}
	one := s.Pop()
	two := s.Pop()
	if one > two {
		s.Push(one)
	} else {
		s.Push(two)
	}
	return nil
}

func (s *stack) Round() error {
	if s.Len() < 2 {
		return fmt.Errorf("Stack underflow")
	}
	decimals := s.Pop()
	num := s.Pop()
	s.Push(math.Round(num*math.Pow(10, decimals)) / math.Pow(10, decimals))
	return nil
}

func (s *stack) Over() error {
	if s.Len() < 2 {
		return fmt.Errorf("Stack underflow")
	}
	tos := s.Pop()
	cpy := s.Pop()
	s.Push(cpy)
	s.Push(tos)
	s.Push(cpy)
	return nil
}

func (s *stack) Swap() error {
	if s.Len() < 2 {
		return fmt.Errorf("Stack underflow")
	}
	tos := s.Pop()
	newTos := s.Pop()
	s.Push(tos)
	s.Push(newTos)
	return nil
}

func (s *stack) Pow() error {
	if s.Len() < 2 {
		return fmt.Errorf("Stack underflow")
	}
	exp := s.Pop()
	base := s.Pop()
	s.Push(math.Pow(base, exp))
	return nil
}

func (s *stack) Floor() error {
	if s.Len() < 1 {
		return fmt.Errorf("Stack underflow")
	}
	s.Push(math.Floor(s.Pop()))
	return nil
}

func (s *stack) Ceil() error {
	if s.Len() < 1 {
		return fmt.Errorf("Stack underflow")
	}
	s.Push(math.Ceil(s.Pop()))
	return nil
}

func (s *stack) Sum(rng string) error {
	points := strings.Split(rng[:len(rng)-1], ":")
	pointA, _, _ := Addr2Point(points[0])
	pointB, _, _ := Addr2Point(points[1])
	rowStart := pointA.row
	rowEnd := pointB.row
	colStart := pointA.col
	colEnd := pointB.col
	if rowEnd < rowStart || colEnd < colStart {
		return fmt.Errorf("Range starts after range end")
	}
	if colEnd > wb.sheets[wb.sheet].cols-1 || rowEnd > wb.sheets[wb.sheet].rows-1 || colStart < 0 || rowStart < 0 {
		return fmt.Errorf("Range out of bounds")
	}

	var sum float64 = 0.0
	var val float64
	var c cell
	var err error
	cells := wb.sheets[wb.sheet].cells

	for row := rowStart; row <= rowEnd; row++ {
		for col := colStart; col <= colEnd; col++ {
			c = cells[row][col]
			val = c.num
			if c.kind == Expr {
				val, err = strconv.ParseFloat(c.mask, 64)
				if err != nil {
					continue
				}
			}
			sum += val
		}
	}
	s.Push(sum)
	return nil
}