#include "SystemInfo.h"

#include <QDir>
#include <QFile>
#include <QFileInfo>
#include <QTextStream>

SystemInfo::SystemInfo(QObject *parent)
    : QObject(parent)
{
    m_capacityPath = findBatteryCapacityPath();

    updateBattery();

    connect(&m_batteryTimer,
            &QTimer::timeout,
            this,
            &SystemInfo::updateBattery);

    // Battery percentage and charging state don't need
    // millisecond precision.
    m_batteryTimer.start(10000);
}

int SystemInfo::batteryPercent() const
{
    return m_batteryPercent;
}

bool SystemInfo::charging() const
{
    return m_charging;
}

QString SystemInfo::findBatteryCapacityPath() const
{
    QDir powerSupply("/sys/class/power_supply");

    const QStringList devices =
        powerSupply.entryList(QDir::Dirs | QDir::NoDotAndDotDot);

    for (const QString &device : devices) {
        const QString base =
            powerSupply.absoluteFilePath(device);

        QFile typeFile(base + "/type");

        if (!typeFile.open(QIODevice::ReadOnly | QIODevice::Text))
            continue;

        const QString type =
            QString::fromUtf8(typeFile.readAll()).trimmed();

        if (type != "Battery")
            continue;

        const QString capacityPath = base + "/capacity";

        if (QFile::exists(capacityPath))
            return capacityPath;
    }

    return {};
}

void SystemInfo::updateBattery()
{
    if (m_capacityPath.isEmpty())
        m_capacityPath = findBatteryCapacityPath();

    if (m_capacityPath.isEmpty())
        return;

    // ─────────────────────────────────────────────────────────────
    // Battery percentage
    // ─────────────────────────────────────────────────────────────

    QFile capacityFile(m_capacityPath);

    if (capacityFile.open(QIODevice::ReadOnly | QIODevice::Text)) {
        bool ok = false;

        int percent =
            QString::fromUtf8(capacityFile.readAll())
                .trimmed()
                .toInt(&ok);

        if (ok) {
            percent = qBound(0, percent, 100);

            if (percent != m_batteryPercent) {
                m_batteryPercent = percent;
                emit batteryPercentChanged();
            }
        }
    }

    // ─────────────────────────────────────────────────────────────
    // Charging state
    // ─────────────────────────────────────────────────────────────

    // m_capacityPath is something like:
    // /sys/class/power_supply/battery/capacity
    //
    // The status file lives beside it.
    const QString batteryDirectory =
        QFileInfo(m_capacityPath).absolutePath();

    QFile statusFile(batteryDirectory + "/status");

    if (statusFile.open(QIODevice::ReadOnly | QIODevice::Text)) {
        const QString status =
            QString::fromUtf8(statusFile.readAll()).trimmed();

        const bool charging = (status == "Charging");

        if (charging != m_charging) {
            m_charging = charging;
            emit chargingChanged();
        }
    }
}