package com.ts3client.ui;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Parses TeamSpeak 3 "spacer" channel names — cosmetic root channels used as
 * separators, e.g. {@code [spacer0]---}, {@code [*spacer1]=}, {@code [cspacer]Rules}.
 * The tag selects alignment ({@code l}/{@code c}/{@code r}) or fill ({@code *}).
 */
public final class Spacers {

    /** Result of parsing a spacer name. */
    public static final class Spacer {
        public final char align;   // 'l', 'c', 'r', or '*' (repeat/fill)
        public final String caption;

        Spacer(char align, String caption) {
            this.align = align;
            this.caption = caption;
        }
    }

    private static final Pattern PATTERN =
            Pattern.compile("^\\[(\\*|[lcr])?spacer[^\\]]*\\](.*)$");

    private Spacers() {
    }

    /** Returns spacer info if {@code channelName} is a spacer, else {@code null}. */
    public static Spacer parse(String channelName) {
        if (channelName == null) return null;
        Matcher m = PATTERN.matcher(channelName);
        if (!m.matches()) return null;
        String tag = m.group(1);
        char align = (tag == null || tag.isEmpty()) ? 'l' : tag.charAt(0);
        return new Spacer(align, m.group(2));
    }

    public static boolean isSpacer(String channelName) {
        return parse(channelName) != null;
    }

    /** Builds the visible label for a spacer at roughly the given character width. */
    public static String render(Spacer s, int width) {
        String caption = s.caption == null ? "" : s.caption;
        if (s.align == '*') {
            if (caption.isEmpty()) return "";
            StringBuilder sb = new StringBuilder();
            while (sb.length() < width) sb.append(caption);
            return sb.substring(0, Math.max(caption.length(), Math.min(sb.length(), width)));
        }
        if (s.align == 'c') {
            int pad = Math.max(0, (width - caption.length()) / 2);
            return " ".repeat(pad) + caption;
        }
        if (s.align == 'r') {
            int pad = Math.max(0, width - caption.length());
            return " ".repeat(pad) + caption;
        }
        return caption;
    }
}