#include "invite_link.h"
#include "debug_ui.h"
#include <QByteArray>

static QByteArray encodeAddresses(const QList<NodeAddr>& addrs) {
    QByteArray buf;
    for (const auto& a : addrs) {
        buf.append(static_cast<char>(a.family));
        buf.append(a.address);
        buf.append(static_cast<char>((a.port >> 8) & 0xFF));
        buf.append(static_cast<char>(a.port & 0xFF));
    }
    return buf;
}

static QList<InviteAddr> decodeAddresses(const uint8_t* data, int len,
                                          int count) {
    QList<InviteAddr> list;
    int off = 0;
    for (int i = 0; i < count && off < len; i++) {
        if (off + 1 > len) break;
        InviteAddr a;
        a.family = data[off++];
        int alen = (a.family == 4) ? 4 : 16;
        if (off + alen + 2 > len) break;
        a.address = QByteArray(reinterpret_cast<const char*>(data + off), alen);
        off += alen;
        a.port = (static_cast<quint16>(data[off]) << 8) | data[off + 1];
        off += 2;
        list.append(a);
    }
    return list;
}

QString encodeInviteLink(const QString& channelId, const QByteArray& pubkey,
                         const QList<NodeAddr>& addrs) {
    QByteArray cid = channelId.toUtf8();
    if (cid.size() > 65535) {
        GUI_ERROR("encodeInviteLink: channelId too long (%d bytes)", cid.size());
        return {};
    }
    if (pubkey.size() != 32) {
        GUI_ERROR("encodeInviteLink: pubkey must be 32 bytes (got %d)", pubkey.size());
        return {};
    }

    QByteArray addrsEnc = encodeAddresses(addrs);
    int addrCount = addrs.size();
    if (addrCount > 65535) addrCount = 65535;

    QByteArray blob;
    blob.reserve(1 + 2 + cid.size() + 32 + 2 + addrsEnc.size());
    blob.append(static_cast<char>(INVITE_LINK_VERSION));
    blob.append(static_cast<char>((cid.size() >> 8) & 0xFF));
    blob.append(static_cast<char>(cid.size() & 0xFF));
    blob.append(cid);
    blob.append(pubkey);
    blob.append(static_cast<char>((addrCount >> 8) & 0xFF));
    blob.append(static_cast<char>(addrCount & 0xFF));
    blob.append(addrsEnc);

    return QString::fromLatin1("utun://") + QString::fromLatin1(blob.toBase64());
}

InviteData decodeInviteLink(const QString& link) {
    InviteData d;
    if (!link.startsWith(QLatin1String("utun://"))) {
        GUI_ERROR("decodeInviteLink: invalid prefix");
        return d;
    }
    QByteArray blob = QByteArray::fromBase64(
        link.mid(7).toLatin1());
    const auto* data = reinterpret_cast<const uint8_t*>(blob.constData());
    int len = blob.size();

    if (len < 5) {
        GUI_ERROR("decodeInviteLink: blob too short (%d bytes)", len);
        return d;
    }
    int off = 0;
    uint8_t ver = data[off++];
    if (ver != INVITE_LINK_VERSION) {
        GUI_ERROR("decodeInviteLink: unsupported version %d", ver);
        return d;
    }
    int cidLen = (static_cast<int>(data[off]) << 8) | data[off + 1];
    off += 2;
    if (off + cidLen + 32 + 2 > len) {
        GUI_ERROR("decodeInviteLink: truncated blob");
        return d;
    }
    d.channelId = QString::fromUtf8(reinterpret_cast<const char*>(data + off), cidLen);
    off += cidLen;
    d.pubkey = QByteArray(reinterpret_cast<const char*>(data + off), 32);
    off += 32;
    int addrCount = (static_cast<int>(data[off]) << 8) | data[off + 1];
    off += 2;
    d.addrs = decodeAddresses(data + off, len - off, addrCount);
    return d;
}