#include <stdlib.h>
#include <string.h>
#define _USE_MATH_DEFINES
#include <math.h>

#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif

#include "resampler.h"

#include "rsp_hle/audio.h"

enum { RESAMPLER_SHIFT = 16 };
enum { RESAMPLER_RESOLUTION = 1 << RESAMPLER_SHIFT };

enum { resampler_buffer_size = 64 * 4 };

typedef struct resampler {
	int write_pos, write_filled;
	int read_pos, read_filled;
	int phase;
	int phase_inc;
	signed char delay_added;
	signed char delay_removed;
	short buffer_in[2][resampler_buffer_size * 2];
	short buffer_out[resampler_buffer_size * 2];
} resampler;

void * resampler_create(void) {
	resampler * r = ( resampler * ) malloc( sizeof(resampler) );
	if ( !r ) return 0;

	r->write_pos = 1;
	r->write_filled = 0;
	r->read_pos = 0;
	r->read_filled = 0;
	r->phase = 0;
	r->phase_inc = 0;
	r->delay_added = -1;
	r->delay_removed = -1;
	memset( r->buffer_in, 0, sizeof(r->buffer_in) );
	memset( r->buffer_out, 0, sizeof(r->buffer_out) );

	return r;
}

void resampler_delete(void * _r) {
	free( _r );
}

void * resampler_dup(const void * _r) {
	void * r_out = malloc( sizeof(resampler) );
	if ( !r_out ) return 0;

	resampler_dup_inplace(r_out, _r);

	return r_out;
}

void resampler_dup_inplace(void *_d, const void *_s) {
	const resampler * r_in = ( const resampler * ) _s;
	resampler * r_out = ( resampler * ) _d;

	r_out->write_pos = r_in->write_pos;
	r_out->write_filled = r_in->write_filled;
	r_out->read_pos = r_in->read_pos;
	r_out->read_filled = r_in->read_filled;
	r_out->phase = r_in->phase;
	r_out->phase_inc = r_in->phase_inc;
	r_out->delay_added = r_in->delay_added;
	r_out->delay_removed = r_in->delay_removed;
	memcpy( r_out->buffer_in, r_in->buffer_in, sizeof(r_in->buffer_in) );
	memcpy( r_out->buffer_out, r_in->buffer_out, sizeof(r_in->buffer_out) );
}

int resampler_get_free_count(void *_r) {
	resampler * r = ( resampler * ) _r;
	return resampler_buffer_size - r->write_filled;
}

static int resampler_min_filled(resampler *r) {
	return 4;
}

static int resampler_input_delay(resampler *r) {
	return 1;
}

static int resampler_output_delay(resampler *r) {
	return 0;
}

int resampler_ready(void *_r) {
	resampler * r = ( resampler * ) _r;
	return r->write_filled > resampler_min_filled(r);
}

void resampler_clear(void *_r) {
	resampler * r = ( resampler * ) _r;
	r->write_pos = 1;
	r->write_filled = 0;
	r->read_pos = 0;
	r->read_filled = 0;
	r->phase = 0;
	r->delay_added = -1;
	r->delay_removed = -1;
}

void resampler_set_rate(void *_r, double new_factor) {
	resampler * r = ( resampler * ) _r;
	r->phase_inc = new_factor * RESAMPLER_RESOLUTION;
}

void resampler_write_sample(void *_r, short ls, short rs) {
	resampler * r = ( resampler * ) _r;

	if ( r->delay_added < 0 ) {
		r->delay_added = 0;
		r->write_filled = resampler_input_delay( r );
	}

	if ( r->write_filled < resampler_buffer_size ) {
		r->buffer_in[ 0 ][ r->write_pos ] = ls;
		r->buffer_in[ 0 ][ r->write_pos + resampler_buffer_size ] = ls;

		r->buffer_in[ 1 ][ r->write_pos ] = rs;
		r->buffer_in[ 1 ][ r->write_pos + resampler_buffer_size ] = rs;

		++r->write_filled;

		r->write_pos = ( r->write_pos + 1 ) % resampler_buffer_size;
	}
}

static int resampler_run_cubic(resampler * r, short ** out_, short * out_end) {
	int in_size = r->write_filled;
	int in_offset = resampler_buffer_size + r->write_pos - r->write_filled;
	short const* inl_ = r->buffer_in[0] + in_offset;
	short const* inr_ = r->buffer_in[1] + in_offset;
	int used = 0;
	in_size -= 4;
	if ( in_size > 0 ) {
		short* out = *out_;
		short const* inl = inl_;
		short const* inr = inr_;
		short const* const in_end = inl + in_size;
		int phase = r->phase;
		int phase_inc = r->phase_inc;

		do {
			int samplel, sampler;
			const int16_t* lut;

			if ( out >= out_end )
				break;

			lut = RESAMPLE_LUT + ((phase & 0xfc00) >> 8);

			samplel = ((inl[0] * lut[0]) + (inl[1] * lut[1])
			        +  (inl[2] * lut[2]) + (inl[3] * lut[3])) >> 15;
			sampler = ((inr[0] * lut[0]) + (inr[1] * lut[1])
			        +  (inr[2] * lut[2]) + (inr[3] * lut[3])) >> 15;

			if ((samplel + 0x8000) & 0xffff0000) samplel = 0x7fff ^ (samplel >> 31);
			if ((sampler + 0x8000) & 0xffff0000) sampler = 0x7fff ^ (sampler >> 31);

			*out++ = (short)samplel;
			*out++ = (short)sampler;

			phase += phase_inc;

			inl += (phase >> 16);
			inr += (phase >> 16);

			phase &= 0xFFFF;
		}
		while ( inl < in_end );

		r->phase = phase;
		*out_ = out;

		used = (int)(inl - inl_);

		r->write_filled -= used;
	}

	return used;
}

static void resampler_fill(resampler * r) {
	int min_filled = resampler_min_filled(r);
	while ( r->write_filled > min_filled &&
	        r->read_filled < resampler_buffer_size ) {
		int write_pos = ( r->read_pos + r->read_filled ) % resampler_buffer_size;
		int write_size = resampler_buffer_size - write_pos;
		short * out = r->buffer_out + write_pos * 2;
		if ( write_size > ( resampler_buffer_size - r->read_filled ) )
			write_size = resampler_buffer_size - r->read_filled;
		resampler_run_cubic( r, &out, out + write_size * 2 );
		r->read_filled += ( out - r->buffer_out - write_pos * 2 ) / 2;
	}
}

static void resampler_fill_and_remove_delay(resampler * r) {
	resampler_fill( r );
	if ( r->delay_removed < 0 ) {
		int delay = resampler_output_delay( r );
		r->delay_removed = 0;
		while ( delay-- )
			resampler_remove_sample( r );
	}
}

int resampler_get_sample_count(void *_r) {
	resampler * r = ( resampler * ) _r;
	if ( r->read_filled < 1 )
		resampler_fill_and_remove_delay( r );
	return r->read_filled;
}

void resampler_get_sample(void *_r, short * ls, short * rs) {
	resampler * r = ( resampler * ) _r;
	if ( r->read_filled < 1 && r->phase_inc )
		resampler_fill_and_remove_delay( r );
	if ( r->read_filled < 1 ) {
		*ls = 0;
		*rs = 0;
	}
	else {
		*ls = r->buffer_out[ r->read_pos * 2 + 0 ];
		*rs = r->buffer_out[ r->read_pos * 2 + 1 ];
	}
}

void resampler_remove_sample(void *_r) {
	resampler * r = ( resampler * ) _r;
	if ( r->read_filled > 0 ) {
		--r->read_filled;
		r->read_pos = ( r->read_pos + 1 ) % resampler_buffer_size;
	}
}