#pragma once

namespace mcp23017 {

enum class reg : uint8_t {
    iodira, iodirb,
    ipola, ipolb,
    gpintena, gpintenb,
    defvala, defvalb,
    intcona, intconb,
    iocona, ioconb,
    gppua, gppub,
    intfa, intfb,
    intcapa, intcapb,
    gpioa, gpiob,
    olata, olatb,
};

enum class direction { out, in };

class extender
{
public:
    extender(uint8_t addr);

    bool init();

    void set_direction(unsigned bank, unsigned pin, direction dir);
    void set_polarity(unsigned bank, unsigned pin, bool reversed);
    void set_pullup(unsigned bank, unsigned pin, bool enabled);
    void set_irq(unsigned bank, unsigned pin, bool enabled);

    void set_gpio(unsigned bank, unsigned pin, bool on);
    void set_gpios(unsigned bank, uint8_t values);
    bool get_gpio(unsigned bank, unsigned pin);
    uint8_t get_gpios(unsigned bank);

private:
    template<reg base_reg, typename Value>
    void set_field(unsigned bank, unsigned pin, Value value, uint8_t (&current)[2]);

    int write(reg r, uint8_t value);
    int read(reg r, uint8_t *value, unsigned count);

    uint8_t m_addr;

    uint8_t m_direction[2];
    uint8_t m_polarity[2];
    uint8_t m_pullup[2];
    uint8_t m_irq[2];
};

} // namespace mcp23017