MarkdownParse.java

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ArrayList;

public class MarkdownParse {
    public static ArrayList<String> getLinks(String markdown) {
        ArrayList<String> toReturn = new ArrayList<>();
        // find the next [, then find the ], then find the (, then take up to
        // the next )
        int currentIndex = 0;
        int lastClosedParen = markdown.lastIndexOf(")");
        while(currentIndex < markdown.length()) {
            int nextOpenBracket = markdown.indexOf("[", currentIndex);

            boolean isImage = false;
            if (markdown.indexOf("!", nextOpenBracket-1) == nextOpenBracket - 1) {
                isImage = true;
            }

            if (nextOpenBracket == 0){
                isImage = false;
            }

            int nextCloseBracket = markdown.indexOf("]", nextOpenBracket);
            int openParen = markdown.indexOf("(", currentIndex);
            int closeParen = markdown.indexOf(")", openParen);

            if(nextOpenBracket == -1 || nextCloseBracket == -1 || openParen == -1 || closeParen == -1) {
		        break;
	        }

            if (openParen - nextCloseBracket > 2) {
                currentIndex = markdown.indexOf("[", currentIndex + 1);

                if (currentIndex == lastClosedParen) {
                    break;
                } else if (currentIndex < 0) {
                    break;
                }
                continue;
            }

            if(nextOpenBracket != 0 && markdown.substring(nextOpenBracket-1, nextOpenBracket).equals("!")){
                currentIndex = closeParen + 1;
                continue;
            }

            //System.out.println(markdown.substring(nextOpenBracket, nextCloseBracket)); 
            //if(markdown.substring(nextOpenBracket + 1, nextCloseBracket).equals("")){
            //    continue; 
            //} 

            if (isImage == false) {
                toReturn.add(markdown.substring(openParen + 1, closeParen));
            }

            if (closeParen > currentIndex){
                currentIndex = closeParen + 1;
            } else {
                break;
            }
        }
        return toReturn;
    }
    public static void main(String[] args) throws IOException {
        Path fileName = Path.of(args[0]);
        String contents = Files.readString(fileName);
        ArrayList<String> links = getLinks(contents);
        System.out.println(links);
    }
}