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#include "n900lightsensor.h"

#include <QFile>

#include <QDebug>

#include <time.h>

char const * const n900lightsensor::id("n900.ambientlight");

char const * const n900lightsensor::filename("/sys/class/i2c-adapter/i2c-2/2-0029/lux");

n900lightsensor::n900lightsensor(QSensor *sensor)

    : n900filebasedsensor(sensor)

{

    setReading<QAmbientLightReading>(&m_reading);

    // Sensor takes 12-400ms to complete one reading and is triggered by

    // a read of the /sys file (no interrupt/timing loop/etc. is used).

    // Since no continuous operation is possible, don't set a data rate.

    addDataRate(2, 2); // Close enough to 2 Hz

    setDescription(QLatin1String("tsl2563"));

}

void n900lightsensor::start()

{

    if (!QFile::exists(QLatin1String(filename)))

        goto error;

    n900filebasedsensor::start();

    return;

error:

    sensorStopped();

}

struct lux_limit {

    int min;

    int max;

};

// Defines the min and max lux values that a given level has.

// These are used to add histeresis to the sensor.

// If the previous level is below a level, the lux must be at or above the minimum.

// If the previous level is above a level, the lux muyt be at or below the maximum.

static lux_limit limits[] = {

    { 0,    0    }, // Undefined (not used)

    { 0,    5    }, // Dark

    { 10,   50   }, // Twilight

    { 100,  200  }, // Light

    { 500,  2000 }, // Bright

    { 5000, 0    }  // Sunny

};

#if 0

// Used for debugging

static QString light_level(int level)

{

    switch (level) {

    case 1:

        return QLatin1String("Dark");

    case 2:

        return QLatin1String("Twilight");

    case 3:

        return QLatin1String("Light");

    case 4:

        return QLatin1String("Bright");

    case 5:

        return QLatin1String("Sunny");

    default:

        return QLatin1String("Undefined");

    }

}

#endif

void n900lightsensor::poll()

{

    FILE *fd = fopen(filename, "r");

    if (!fd) return;

    int lux;

    int rs = fscanf(fd, "%i", &lux);

    fclose(fd);

    if (rs != 1) return;

    // It's unweildly dealing with these constants so make some

    // local aliases that are shorter. This makes the code below

    // much easier to read.

    enum {

        Undefined = QAmbientLightReading::Undefined,

        Dark = QAmbientLightReading::Dark,

        Twilight = QAmbientLightReading::Twilight,

        Light = QAmbientLightReading::Light,

        Bright = QAmbientLightReading::Bright,

        Sunny = QAmbientLightReading::Sunny

    };

    int lightLevel = m_reading.lightLevel();

    // Check for change direction to allow for histeresis

    if      (lightLevel < Sunny    && lux >= limits[Sunny   ].min) lightLevel = Sunny;

    else if (lightLevel < Bright   && lux >= limits[Bright  ].min) lightLevel = Bright;

    else if (lightLevel < Light    && lux >= limits[Light   ].min) lightLevel = Light;

    else if (lightLevel < Twilight && lux >= limits[Twilight].min) lightLevel = Twilight;

    else if (lightLevel < Dark     && lux >= limits[Dark    ].min) lightLevel = Dark;

    else if (lightLevel > Dark     && lux <= limits[Dark    ].max) lightLevel = Dark;

    else if (lightLevel > Twilight && lux <= limits[Twilight].max) lightLevel = Twilight;

    else if (lightLevel > Light    && lux <= limits[Light   ].max) lightLevel = Light;

    else if (lightLevel > Bright   && lux <= limits[Bright  ].max) lightLevel = Bright;

    //qDebug() << "lightLevel" << light_level(lightLevel) << "lux" << lux;

    if (static_cast<int>(m_reading.lightLevel()) != lightLevel) {

        m_reading.setTimestamp(clock());

        m_reading.setLightLevel(static_cast<QAmbientLightReading::LightLevel>(lightLevel));

        newReadingAvailable();

    }

}