public class FontUtils {

    public static final Pattern SPACE_OPTIMAL_PATTERN = Pattern.compile("(<lang:space\\.(-?\\d+)><lang:space\\.(-?\\d+)>)");

    public static final String ROW_1_CHAR = "\uE0A1";
    public static final String ROW_2_CHAR = "\uE0A2";
    public static final String ROW_3_CHAR = "\uE0A3";
    public static final String ROW_4_CHAR = "\uE0A4";
    public static final String ROW_5_CHAR = "\uE0A5";
    public static final String ROW_6_CHAR = "\uE0A6";

    private static final int INVENTORY_ROW_SIZE = 9;
    private static final int INVENTORY_SLOT_SIZE = 18;

    private static final String ONE_SPACE = space(1);
    private static final String INVENTORY_SLOT_SPACE = space(INVENTORY_SLOT_SIZE);
    private static final String INVENTORY_ROW_SPACE = space(-(INVENTORY_ROW_SIZE * INVENTORY_SLOT_SIZE));

    private FontUtils() {
    }


    public static String space(int size) {
        return "<lang:space." + size + ">";
    }

    public static String color(Color awtColor) {
        return "<color:#" + Integer.toHexString(awtColor.getRGB()).substring(2) + ">";
    }

    public static String mergeSpaces(String input) {
        Matcher matcher = SPACE_OPTIMAL_PATTERN.matcher(input);

        while (matcher.find()) {
            String line = matcher.group(1);
            String first = matcher.group(2);
            String second = matcher.group(3);

            int merged = Integer.parseInt(first) + Integer.parseInt(second);

            input = input.replace(line, "<lang:space." + merged + ">");
        }

        return input;
    }

    public static String renderLockedSlots(Map<Integer, Color> slotColors) {
        // We render the slots top to bottom, left to right
        StringBuilder builder = new StringBuilder();

        Color currentColor = null;

        for (int row = 0; row < 6; row++) {
            for (int column = 0; column < INVENTORY_ROW_SIZE; column++) {
                int slot = (row * INVENTORY_ROW_SIZE) + column;

                if (!slotColors.containsKey(slot)) {
                    builder.append(INVENTORY_SLOT_SPACE);
                    continue;
                }

                Color color = slotColors.get(slot);

                if (!color.equals(currentColor)) {
                    if (currentColor != null) {
                        builder.append("</color>");
                    }

                    builder.append(color(color));
                    currentColor = color;
                }

                builder.append(getRowChar(row + 1));
                builder.append(ONE_SPACE);

            }

            builder.append(INVENTORY_ROW_SPACE);
        }

        if (currentColor != null) {
            builder.append("</color>");
        }

        String output = builder.toString();
        return mergeSpaces(output);
    }

    private static String getRowChar(int row) {
        return switch (row) {
            case 1 -> ROW_1_CHAR;
            case 2 -> ROW_2_CHAR;
            case 3 -> ROW_3_CHAR;
            case 4 -> ROW_4_CHAR;
            case 5 -> ROW_5_CHAR;
            case 6 -> ROW_6_CHAR;
            default -> throw new IllegalArgumentException("Invalid row: " + row);
        };
    }
}