const MaxInt32 = 1<<31 - 1
const MinInt32 = -1 << 31

func myAtoi(str string) int {
    var gotTheFirstNumber bool = false
    var isNegative bool = false
    var isPositive bool = false
    digits := make([]int, 0)

    for _, c := range str {
        if !gotTheFirstNumber && !isMinus(c) && !isPlus(c) && !isSpace(c) && !isDigit(c) {
            return 0;
        }
        if isPositive && isNegative {
            return 0;
        }
        if !gotTheFirstNumber && isMinus(c) {
            if isNegative {
                return 0
            }
            isNegative = true
            gotTheFirstNumber = true
            continue
        }
        if !gotTheFirstNumber && isPlus(c) {
            if isPositive {
                return 0
            }
            isPositive = true
            gotTheFirstNumber = true
            continue
        }
        if gotTheFirstNumber && !isDigit(c) {
            break
        }
        if isDigit(c) {
            digits = append(digits, toNumber(c))
            gotTheFirstNumber = true
        }
    }

    out := 0
    multiplyFactor := 1
    if isNegative {
        multiplyFactor = -1
    }
    for i := len(digits) - 1; i > -1 ; i-- {
        if digits[i] == 0 {
            continue
        }
        fmt.Println("i =", i, "digits[i] = ", digits[i])
        out += digits[i] * powOf10(len(digits) - 1 - i) * multiplyFactor
        if out > MaxInt32 {
            return MaxInt32
        }
        if out < MinInt32 {
            return MinInt32
        }
    }

    return out
}

func isDigit(input rune) bool {
    return input <= '9' && input >= '0'
}

func isMinus(input rune) bool {
    return input == '-'
}

func isPlus(input rune) bool {
    return input == '+'
}

func isSpace(input rune) bool {
    return input == ' '
}

func toNumber(input rune) int {
    return int(input - '0')
}

func powOf10(in int) int {
    fmt.Println("in =", in)
    out := 1
    if in == 0 {
        return out
    }
    for i := 0; i < in; i++ {
        out = out*10
        if out > MaxInt32 {
            return MaxInt32
        }
    }
    return out
}