#include "diality_keys.h"

#include <QCoreApplication>
#include <QFile>
#include <QFileInfo>
#include <QJsonDocument>
#include <QJsonObject>

static bool parseHexField(const QJsonObject& obj, const char* name, int expectedBytes, QByteArray* out, QString* err)
{
    if (!obj.contains(name) || !obj.value(name).isString()) {
        if (err) *err = QString("Missing or invalid field: %1").arg(QString::fromLatin1(name));
        return false;
    }
    const QString s = obj.value(name).toString().trimmed();
    const QString h = QString(s).remove(' ');
    if (h.size() != expectedBytes * 2) {
        if (err) *err = QString("Field %1: wrong hex length (expected %2 hex chars)")
                            .arg(QString::fromLatin1(name))
                            .arg(expectedBytes * 2);
        return false;
    }
    const QByteArray bin = QByteArray::fromHex(h.toLatin1());
    if (bin.size() != expectedBytes) {
        if (err) *err = QString("Field %1: hex decode failed").arg(QString::fromLatin1(name));
        return false;
    }
    if (out) *out = bin;
    return true;
}

namespace diality {

bool loadKeysFromJsonFile(const QString& path, Keys* outKeys, QString* error)
{
    if (!outKeys) {
        if (error) *error = "Internal error: outKeys is null";
        return false;
    }

    QFile f(path);
    if (!f.open(QIODevice::ReadOnly)) {
        if (error) *error = QString("Cannot open keys file: %1").arg(path);
        return false;
    }

    const QByteArray data = f.readAll();
    f.close();

    QJsonParseError pe;
    const QJsonDocument doc = QJsonDocument::fromJson(data, &pe);
    if (doc.isNull() || !doc.isObject()) {
        if (error) *error = QString("Invalid JSON in %1: %2").arg(path, pe.errorString());
        return false;
    }

    const QJsonObject obj = doc.object();

    QString err;
    Keys k;

    if (!parseHexField(obj, "encKey32", 32, &k.encKey32, &err)) { if (error) *error = err; return false; }
    if (obj.contains("signSk32")) {
        if (!parseHexField(obj, "signSk32", 32, &k.signSk32, &err)) { if (error) *error = err; return false; }
    }
    if (!parseHexField(obj, "signPk32", 32, &k.signPk32, &err)) { if (error) *error = err; return false; }

    *outKeys = k;
    return true;
}

static QString exeDirKeysJson()
{
    const QString exe = QCoreApplication::applicationFilePath();
    const QFileInfo fi(exe);
    return fi.absolutePath() + "/keys.json";
}

bool loadPcKeys(Keys* outKeys, QString* loadedPath, QString* error)
{
    const QString p = exeDirKeysJson();
    Keys k;
    QString err;
    if (!loadKeysFromJsonFile(p, &k, &err)) {
        if (error) *error = err;
        return false;
    }
    if (k.signSk32.size() != 32) {
        if (error) *error = "keys.json is missing signSk32 (PC needs private key to sign)";
        return false;
    }
    *outKeys = k;
    if (loadedPath) *loadedPath = p;
    return true;
}

bool loadDeviceKeys(Keys* outKeys, QString* loadedPath, QString* error)
{
    const QStringList candidates = {
        "/etc/diality/keys.json",
        exeDirKeysJson()
    };

    QString lastErr;
    for (const QString& p : candidates) {
        Keys k;
        QString err;
        if (loadKeysFromJsonFile(p, &k, &err)) {
            k.signSk32.clear();
            *outKeys = k;
            if (loadedPath) *loadedPath = p;
            return true;
        }
        lastErr = err;
    }

    if (error) *error = lastErr.isEmpty() ? "No keys file found" : lastErr;
    return false;
}

} // namespace diality