package HTMLTAGS;

import java.io.IOException;
import java.util.Scanner;
import java.util.Set;
import java.util.HashSet;
import java.util.Stack;

import htmlSupport.*;

public class HTML4 {
        private static Set<String> optionalTags = new HashSet<String>();

        private static void populateOptionalTags() {
            String [ ] optionals = {"p", "li", "html", "body", "tr", "td"};
            for (int i=0; i<optionals.length; i++)
                optionalTags.add(optionals[i]);
        }

        private static boolean isOptional(CSC300HTMLTag tag) {
            return optionalTags.contains(tag.getName());
        }

        public static void main(String[] args) throws IOException {
            Stack<CSC300HTMLTag> startTags = new Stack<CSC300HTMLTag>();
            Scanner console = new Scanner(System.in);
            CSC300HTMLTag nextTag, poppedTag;
            populateOptionalTags();
            System.out.println("Enter a URL");
            String url = console.next();
            HTMLTokenizer tokenizer = new HTMLTokenizer(url);

            while (tokenizer.hasNext()) {
                nextTag = tokenizer.next();
                if (nextTag.getType() == CSC300HTMLTag.START) {
                    startTags.push(nextTag);
                    //System.out.println("Tag Pushed");
                    // push the name of the tag onto the stack
                }
                else if (nextTag.getType() == CSC300HTMLTag.SIMPLE){
                    //System.out.println("SIMPLE");
                    continue;
                }

                else {
                    if(startTags.peek().getName().equals(nextTag.getName())){
                    poppedTag = startTags.pop();

                    //System.out.println("Valid so far");
                    }
                    else if(optionalTags.contains(startTags.peek().getName())){
                        while(optionalTags.contains(startTags.peek().getName())){
                        //System.out.println("HTML CODE IS VALID/BALANCED STUCK HERE");
                        startTags.pop();
                        //Was getting an empty stack exception so used the line below to fix that.
                        if (startTags.isEmpty()){
                            System.out.println("Code is Valid");
                            return;
                        }
                        }
                    }
                    else {
                        System.out.println("HTML CODE IS NOT VALID 1");

                        return;
                    }
                    if (startTags.isEmpty()){
                    System.out.println("HTML CODE IS NOT VALID 2");return;}

                    // if the tag names of nextTag and poppedTag are the same,
                    // continue

                    // otherwise, if poppedTag doesn't require an end tag,
                    // keep popping the stack until:
                    //
                    // (1) you find a matching tag (then HTML is valid so far)
                    // (2) hasNext returns false (then HTML is not valid)
                    // (3) the stack becomes empty (then HTML is not valid)
                }

            }
            System.out.println("HTML CODE IS VALID");
        }
}