import module java.xml;

void main() throws Exception {
    var verses = loadVerses();
    var cumalativeLength = 0;
    var versePositions = new TreeMap<Integer, Verse>();
    for (var verse : verses) {
        versePositions.put(cumalativeLength, verse);
        cumalativeLength += verse.text.length();
    }
    var one_thirtieth = cumalativeLength / 30;
    for (int juzIndex = 0; juzIndex < 30; juzIndex++) {
        var firstVerseOfJuz = versePositions.ceilingEntry(one_thirtieth * juzIndex).getValue();
        println((juzIndex + 1) + ". " + firstVerseOfJuz);
    }
}

List<Verse> loadVerses() throws Exception {
    var quranBytes = Files.readAllBytes(Path.of("quran-simple-clean.xml"));
    var sha256Hex = HexFormat.of().formatHex(MessageDigest.getInstance("SHA256").digest(quranBytes));
    if (!sha256Hex.equals("bc1cf471e8d9df2f265aae2de23810916dcbb70d6bb1c167453b1647ba1d54c7")) {
        throw new IllegalStateException("Qur'an XML file doesn't match");
    }
    var builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
    var document = builder.parse(new ByteArrayInputStream(quranBytes));
    var verses = new ArrayList<Verse>();
    for (var suraNode : getChildren(document.getDocumentElement(), "sura")) {
        var surahNumber = Integer.parseInt(suraNode.getAttribute("index"));
        for (var ayaNode : getChildren(suraNode, "aya")) {
            var ayaNumber = Integer.parseInt(ayaNode.getAttribute("index"));
            verses.add(new Verse(surahNumber, ayaNumber, ayaNode.getAttribute("text")));
        }
    }
    return verses;
}

List<Element> getChildren(Element element, String tagName) {
    return asList(element.getElementsByTagName(tagName));
}

List<Element> asList(NodeList nodeList) {
    return new AbstractList<>() {
        @Override
        public int size() {
            return nodeList.getLength();
        }

        @Override
        public Element get(int index) {
            return (Element)nodeList.item(index);
        }
    };
}

record Verse(int surahNumber, int verseNumber, String text) {
    @Override
    public String toString() {
        return "(" + surahNumber + ":" + verseNumber + ") " + text;
    }
}