package common

import (
	"bufio"
	"fmt"
)


type Number []int8

func (number Number) Sum(otherNumber Number) Number {
  sum := Number{}
  var hold, n, o int8
  longest := len(number)
  if len(otherNumber) > longest {
    longest = len(otherNumber)
  }

  for i := 0; i < longest; i++ {
    n = 0
    o = 0
    if i < len(number) {
      n = number[i]
    }
    if i < len(otherNumber) {
      o = otherNumber[i]
    }
    current := n + o + hold
    if current <= 2 && current >= -2 {
      hold = 0
      sum = append(sum, current)
    } else if current > 2 {
      hold = 1
      sum = append(sum, current - 5)
    } else {
      hold = -1
      sum = append(sum, 5 + current)
    }
  }
  sum = append(sum, hold)

  for sum[len(sum)-1] == 0 {
    sum = sum[:len(sum)-1]
  }

  return sum
}

func (number Number) Print() {
  for i := len(number) - 1; i >= 0; i-- {
    switch number[i] {
      case -2:
        fmt.Print("=")
      case -1:
        fmt.Print("-")
      case 0:
        fmt.Print("0")
      case 1:
        fmt.Print("1")
      case 2:
        fmt.Print("2")
    }
  }
  fmt.Println()
}


func Parse(scanner bufio.Scanner) []Number {
  numbers := []Number{}

  for scanner.Scan() {
    line := scanner.Text()
    number := Number{}

    for i := len(line) - 1; i >= 0; i-- {
      switch line[i] {
        case '2':
          number = append(number, 2)
        case '1':
          number = append(number, 1)
        case '0':
          number = append(number, 0)
        case '-':
          number = append(number, -1)
        case '=':
          number = append(number, -2)
      }
    }
    numbers = append(numbers, number)
  }

  return numbers
}