#ifndef GFX_FLAG_COMBINER_H
#define GFX_FLAG_COMBINER_H

#include "../../source/core/slang-list.h"

namespace gfx {

/* A default set of flags that can be used for checking devices */
typedef uint32_t DeviceCheckFlags;
struct DeviceCheckFlag
{
    enum Enum : DeviceCheckFlags
    {
        UseFullFeatureLevel = 0x1,      //< If set will use full feature level (on dx this is  D3D_FEATURE_LEVEL_11_1 else will try D3D_FEATURE_LEVEL_11_0)
        UseHardwareDevice = 0x2,        //< If set will try a hardware device
        UseDebug = 0x4,                 //< If set will enable use of debug
    };
};

/* Controls how and the order flags are changed, on the FlagCombiner */
enum class ChangeType
{
    On,                 ///< Always on
    Off,                ///< Always off
    OnOff,              ///< Initially on then off
    OffOn,              ///< Initially off then on
};

/* Calculates all the combinations of flags as controlled by the change types.

The order of adding flags can be considered to be like a nested loop
for (first added) {
    for (second added)
    {
        ///..
    }
}

So the last added flags will have the highest frequency. 
*/
class FlagCombiner
{
public:
        /// Add a flag and how it changes over the combinations
        /// NOTE! That the order flags are added controls the order they change when combinations are calculated - earlier added
        /// flags will change with the highest frequency
    void add(uint32_t flags, ChangeType changeType);
        /// Calculate all of the combinations and place in an array
    void calcCombinations(Slang::List<uint32_t>& outCombinations) const;

        /// Reset back to initial state
    void reset(); 

        /// Get the total amount of combinations
    int getNumCombinations() const { return 1 << m_numChangingBits; }

        /// Get the combination at i
    uint32_t getCombination(int i) const;

protected:
    uint32_t m_changingBits[32];
    int m_numChangingBits = 0;

    uint32_t m_usedFlags = 0;               
    uint32_t m_invertBits = 0;
};

} // namespace gfx

#endif // GFX_FLAG_COMBINER_H