#include <game.h>

struct HijackedStream {
	//const char *original;
	//const char *originalFast;
	u32 stringOffset;
	u32 stringOffsetFast;
	u8 originalID;
};

struct Hijacker {
	HijackedStream stream[2];
	u8 currentStream;
	u8 currentCustomTheme;
};


// Offsets are from the start of the INFO block, not the start of the brsar.
// INFO begins at 0x212C0, so that has to be subtracted from absolute offsets
// within the brsar.

#define _I(offs) ((offs)-0x212C0)

Hijacker Hijackers[2] = {
	{
		{
			{/*"athletic_lr.n.32.brstm", "athletic_fast_lr.n.32.brstm",*/ _I(0x4A8F8), _I(0x4A938), 4},
			{/*"BGM_SIRO.32.brstm", "BGM_SIRO_fast.32.brstm",*/ _I(0x4B2E8), _I(0x4B320), 10}
		},
		0, 0
	},

	{
		{
			{/*"STRM_BGM_CHIJOU.brstm", "STRM_BGM_CHIJOU_FAST.brstm",*/ _I(0x4A83C), _I(0x4A8B4), 1},
			{/*"STRM_BGM_CHIKA.brstm", "STRM_BGM_CHIKA_FAST.brstm",*/ _I(0x4A878), _I(0x4A780), 2},
		},
		0, 0
	}
};

extern void *SoundRelatedClass;
inline char *BrsarInfoOffset(u32 offset) {
	return (char*)(*(u32*)(((u32)SoundRelatedClass) + 0x5CC)) + offset;
}

extern "C" u8 after_course_getMusicForZone(u8 realThemeID) {
	if (realThemeID < 100)
		return realThemeID;

	// drums get to use type 1
	int hjIndex = (realThemeID >= 200) ? 1 : 0;

	Hijacker *hj = &Hijackers[hjIndex];

	// do we already have this theme in this slot?
	// if so, don't switch streams
	// if we do, NSMBW will think it's a different song, and restart it ...
	// but if it's just an area transition where both areas are using the same
	// song, we don't want that
	if (hj->currentCustomTheme == realThemeID)
		return hj->stream[hj->currentStream].originalID;

	// which one do we use this time...?
	int toUse = (hj->currentStream + 1) & 1;

	hj->currentStream = toUse;
	hj->currentCustomTheme = realThemeID;

	// write the stream's info
	HijackedStream *stream = &hj->stream[hj->currentStream];

	sprintf(BrsarInfoOffset(stream->stringOffset), "stream/theme%03d.brstm", realThemeID);
	sprintf(BrsarInfoOffset(stream->stringOffsetFast), "stream/theme%03d_fast.brstm", realThemeID);

	// done!

	return stream->originalID;
}