package main

import (
	"fmt"
	"io/ioutil"
	"os"
	"strings"
)

// so far letters and numbers work, symbols and punctuation are not ok
// input file has data vertically, I assume it must be switches to horisontal...?
// example command: go run . --reverse=inputfile.txt

func main() {
	args_slice := os.Args[1:]
	reference_file := "shadow.txt"
	var file_name string

	for i, name := range args_slice {
		if strings.Contains(name, "--reverse=") { // looking for flag
			file_name = name[10:]
			break
		}
		if len(args_slice)-1 == i {
			fmt.Println("EX: go run . something standard --reverse=<fileName>")
		}
	}

	input, err1 := ioutil.ReadFile(file_name) // reading graphic input file
	text_slices := strings.Split(string(input), "\n")

	if err1 != nil {
		fmt.Println("file does not exist")
		os.Exit(1)
	}

	reference, err2 := ioutil.ReadFile(reference_file) // reading example file standard-shadow-thinkerboy
	reference_slices := strings.Split(string(reference), "\n")

	if err2 != nil {
		fmt.Println("reference not found")
		os.Exit(2)
	}

	indexes := make([]int, 0) // contains indexes to reverse-calculate ascii values

	for x := 0; x < len(text_slices)-9; x += 9 {
		for i := 0; i < len(reference_slices)-9; i += 9 {
			for y := 0; y < 9; y++ {
				if text_slices[x+y] == reference_slices[i+y] && y != 8 {
					continue
				} else if y == 8 && text_slices[y] == reference_slices[i+y] {
					indexes = append(indexes, i)
					break
				} else {
					break
				}
			}
		}
	}

	// fmt.Println(len(indexes))
	// fmt.Println(indexes)

	var str_output string

	for id := range indexes {
		str_output += string(byte(indexes[id]/9 + 32))
	}

	fmt.Println(str_output)
}