package dev.plex.toml;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

public class ArrayValueReader implements ValueReader
{

    public static final ArrayValueReader ARRAY_VALUE_READER = new ArrayValueReader();

    @Override
    public boolean canRead(String s)
    {
        return s.startsWith("[");
    }

    @Override
    public Object read(String s, AtomicInteger index, dev.plex.toml.Context context)
    {
        AtomicInteger line = context.line;
        int startLine = line.get();
        int startIndex = index.get();
        List<Object> arrayItems = new ArrayList<Object>();
        boolean terminated = false;
        boolean inComment = false;
        dev.plex.toml.Results.Errors errors = new dev.plex.toml.Results.Errors();

        for (int i = index.incrementAndGet(); i < s.length(); i = index.incrementAndGet())
        {

            char c = s.charAt(i);

            if (c == '#' && !inComment)
            {
                inComment = true;
            }
            else if (c == '\n')
            {
                inComment = false;
                line.incrementAndGet();
            }
            else if (inComment || Character.isWhitespace(c) || c == ',')
            {
                continue;
            }
            else if (c == '[')
            {
                Object converted = read(s, index, context);
                if (converted instanceof dev.plex.toml.Results.Errors)
                {
                    errors.add((dev.plex.toml.Results.Errors) converted);
                }
                else if (!isHomogenousArray(converted, arrayItems))
                {
                    errors.heterogenous(context.identifier.getName(), line.get());
                }
                else
                {
                    arrayItems.add(converted);
                }
                continue;
            }
            else if (c == ']')
            {
                terminated = true;
                break;
            }
            else
            {
                Object converted = ValueReaders.VALUE_READERS.convert(s, index, context);
                if (converted instanceof dev.plex.toml.Results.Errors)
                {
                    errors.add((dev.plex.toml.Results.Errors) converted);
                }
                else if (!isHomogenousArray(converted, arrayItems))
                {
                    errors.heterogenous(context.identifier.getName(), line.get());
                }
                else
                {
                    arrayItems.add(converted);
                }
            }
        }

        if (!terminated)
        {
            errors.unterminated(context.identifier.getName(), s.substring(startIndex), startLine);
        }

        if (errors.hasErrors())
        {
            return errors;
        }

        return arrayItems;
    }

    private boolean isHomogenousArray(Object o, List<?> values)
    {
        return values.isEmpty() || values.get(0).getClass().isAssignableFrom(o.getClass()) || o.getClass().isAssignableFrom(values.get(0).getClass());
    }

    private ArrayValueReader()
    {
    }
}