import os
import rand

fn main() {
    mut arg := '31'
    if os.args.len != 2 {
        println('Usage: rule110 [<n>]')
        println('Using default `n` value: 31')
    } else {
        arg = os.args[1]
    }

    mut n := arg.int()
    if n > 200 || n < 3 {
        eprintln('`n` must be between 3 and 200!')
        exit(1)
    }

    print('\n')
    title := ' Rule 110 V Implementation '
    title_len := title.len
    if n > title_len {
        for _ in 0 .. (n - title_len) / 2 {
            print('=')
        }
        print(title)
        for _ in 0 .. (n - title_len) / 2 {
            print('=')
        }
    } else {
        println(title[1..(title_len - 1)])
    }

    mut generation_bin := []int{len: n}
    for i in 0 .. n {
        generation_bin[i] = rand.intn(2) or { 0 }
    }
    print('\n')

    // println('Random generated first automaton content: $generation_bin')
    for _ in 0 .. n {
        print_generation(generation_bin)
        next_generation(mut generation_bin)
    }
}

fn print_generation(arr []int) {
    symbols := [' ', '*']!
    for i in 0 .. arr.len {
        print(symbols[arr[i]])
    }
    print('\n')
}

fn next_generation(mut gen []int) {
    mut arr := gen.clone()
    mut prev := 0
    mut curr := 0
    mut next := 0
    for i in 0 .. arr.len {
        if (i - 1) % gen.len < 0 {
            prev = gen[gen.len - 1]
        } else {
            prev = gen[(i - 1) % gen.len]
        }
        curr = gen[i]
        next = gen[(i + 1) % gen.len]

        if prev == 1 {
            if curr == 1 {
                if next == 1 { // 111
                    arr[i] = 0
                } else { // 110
                    arr[i] = 1
                }
            } else {
                if next == 1 { // 101
                    arr[i] = 1
                } else { // 100
                    arr[i] = 0
                }
            }
        } else {
            if curr == 1 {
                if next == 1 { // 011
                    arr[i] = 1
                } else { // 010
                    arr[i] = 1
                }
            } else {
                if next == 1 { // 001
                    arr[i] = 1
                } else { // 000
                    arr[i] = 0
                }
            }
        }
    }
    gen = arr.clone()
}