#include "veml.h"

constexpr float BASE_LUX_PER_LSB = 0.0042f;

using namespace ocularium::veml;


uint16_t Config::to_reg() const
{
    uint16_t result = 0;
    
    result |= shutdown ? 1 : 0;
    result |= interrupt ? 1 : 0;
    result |= static_cast<uint8_t>(integration) << 6;
    result |= static_cast<uint8_t>(gain) << 11;

    return result;
}

bool VEML::init(const Config& config) {
    if (chipid() != CHIPID) return false;

    set_config(config);
    write_reg(Reg::POWER, 0);
    
    return true;
}

uint16_t VEML::chipid() const
{
    return read_reg(Reg::CHIPID);
}

float VEML::lux() const
{
    const auto val = read_reg(Reg::LUX) * config.gain_factor();

    return static_cast<float>(val) * BASE_LUX_PER_LSB;
}

void VEML::set_config(const Config& config)
{
    this->config = config;
    write_reg(Reg::CONFIG, config.to_reg());
}

void VEML::write_reg(const Reg reg, const uint16_t val) const
{
    wire.beginTransmission(ADDR);
    wire.write(static_cast<uint8_t>(reg));
    wire.write(val & 0xff);
    wire.write(val >> 8);
    wire.endTransmission();
}

uint16_t VEML::read_reg(const Reg reg) const
{
    wire.flush();
    
    wire.beginTransmission(ADDR);
    wire.write(static_cast<uint8_t>(reg));
    wire.endTransmission(false);
    wire.requestFrom(ADDR, 2);
    wire.endTransmission(true);
    
    auto result = static_cast<uint16_t>(wire.read());
    result |= wire.read() << 8;

    return result;
}