#include <stdint.h>
#include <string.h>

#include "usf.h"
#include "cpu.h"
#include "memory.h"
#include "audio.h"

#include <stdio.h>
#include <stdlib.h>

#include "types.h"

#include "resampler.h"

#include "usf_internal.h"

size_t usf_get_state_size() {
	return sizeof(usf_state_t) + 8192;
}

void usf_clear(void * state) {
	size_t offset;
	memset(state, 0, usf_get_state_size());
	offset = 4096 - (((uintptr_t)state) & 4095);
	USF_STATE_HELPER->offset_to_structure = offset;
    
	//USF_STATE->savestatespace = NULL;
	//USF_STATE->cpu_running = 0;
	USF_STATE->cpu_stopped = 1;

	//USF_STATE->enablecompare = 0;
	//USF_STATE->enableFIFOfull = 0;

	//USF_STATE->enable_hle_audio = 0;

	//USF_STATE->NextInstruction = 0;
	//USF_STATE->JumpToLocation = 0;
	//USF_STATE->AudioIntrReg = 0;
	//USF_STATE->CPU_Action = 0;
	//USF_STATE->Timers = 0;
	//USF_STATE->CPURunning = 0;
	//USF_STATE->SPHack = 0;
	//USF_STATE->WaitMode = 0;

	//USF_STATE->TLB_Map = 0;
	//USF_STATE->MemChunk = 0;
	USF_STATE->RdramSize = 0x800000;
	USF_STATE->SystemRdramSize = 0x800000;
	USF_STATE->RomFileSize = 0x4000000;

	//USF_STATE->N64MEM = 0;
	//USF_STATE->RDRAM = 0;
	//USF_STATE->DMEM = 0;
	//USF_STATE->IMEM = 0;

	//memset(USF_STATE->ROMPages, 0, sizeof(USF_STATE->ROMPages));
	//USF_STATE->savestatespace = 0;
	//USF_STATE->NOMEM = 0;

	//USF_STATE->WrittenToRom = 0;
	//USF_STATE->WroteToRom = 0;
	//USF_STATE->TempValue = 0;
	//USF_STATE->MemoryState = 0;
	//USF_STATE->EmptySpace = 0;

	//USF_STATE->Registers = 0;

	//USF_STATE->PIF_Ram = 0;

	PreAllocate_Memory(USF_STATE);
    
	USF_STATE->resampler = resampler_create();

#ifdef DEBUG_INFO
	USF_STATE->debug_log = fopen("/tmp/lazyusf.log", "w");
#endif
}

void usf_set_compare(void * state, int enable) {
	USF_STATE->enablecompare = enable;
}

void usf_set_fifo_full(void * state, int enable) {
	USF_STATE->enableFIFOfull = enable;
}

void usf_set_hle_audio(void * state, int enable) {
	USF_STATE->enable_hle_audio = enable;
}

static uint32_t get_le32( const void * _p ) {
	const uint8_t * p = (const uint8_t *) _p;
	return p[0] + p[1] * 0x100 + p[2] * 0x10000 + p[3] * 0x1000000;
}

int usf_upload_section(void * state, const uint8_t * data, size_t size) {
	uint32_t temp;

	if ( size < 4 ) return -1;
	temp = get_le32( data ); data += 4; size -= 4;

	if(temp == 0x34365253) { //there is a rom section
		uint32_t len, start;

		if ( size < 4 ) return -1;
		len = get_le32( data ); data += 4; size -= 4;

		while(len) {
			if ( size < 4 ) return -1;
			start = get_le32( data ); data += 4; size -= 4;

			while(len) {
				uint32_t page = start >> 16;
				uint32_t readLen = ( ((start + len) >> 16) > page) ? (((page + 1) << 16) - start) : len;

				if( USF_STATE->ROMPages[page] == 0 ) {
					USF_STATE->ROMPages[page] = malloc(0x10000);
					if ( USF_STATE->ROMPages[page] == 0 )
						return -1;

					memset(USF_STATE->ROMPages[page], 0, 0x10000);
				}

				if ( size < readLen )
					return -1;

				memcpy( USF_STATE->ROMPages[page] + (start & 0xffff), data, readLen );
				data += readLen; size -= readLen;

				start += readLen;
				len -= readLen;
			}

			if ( size < 4 ) return -1;
			len = get_le32( data ); data += 4; size -= 4;
		}
	}

	if ( size < 4 ) return -1;
	temp = get_le32( data ); data += 4; size -= 4;

	if(temp == 0x34365253) {
		uint32_t len, start;
        
		if ( size < 4 ) return -1;
		len = get_le32( data ); data += 4; size -= 4;

		while(len) {
			if ( size < 4 ) return -1;
			start = get_le32( data ); data += 4; size -= 4;

			if ( size < len ) return -1;
			memcpy( USF_STATE->savestatespace + start, data, len );
			data += len; size -= len;

			if ( size < 4 ) return -1;
			len = get_le32( data ); data += 4; size -= 4;
		}
	}

	return 0;
}

static int is_valid_rom(const unsigned char *buffer) {
	/* Test if rom is a native .z64 image with header 0x80371240. [ABCD] */
	if((buffer[0]==0x80)&&(buffer[1]==0x37)&&(buffer[2]==0x12)&&(buffer[3]==0x40))
		return 1;
	/* Test if rom is a byteswapped .v64 image with header 0x37804012. [BADC] */
	else if((buffer[0]==0x37)&&(buffer[1]==0x80)&&(buffer[2]==0x40)&&(buffer[3]==0x12))
		return 1;
	/* Test if rom is a wordswapped .n64 image with header  0x40123780. [DCBA] */
	else if((buffer[0]==0x40)&&(buffer[1]==0x12)&&(buffer[2]==0x37)&&(buffer[3]==0x80))
		return 1;
	else
		return 0;
}

static void swap_rom(const unsigned char* signature, unsigned char* localrom, int loadlength) {
	unsigned char temp;
	int i;

	/* Btyeswap if .v64 image. */
	if(signature[0]==0x37) {
		for (i = 0; i < loadlength; i+=2) {
			temp=localrom[i];
			localrom[i]=localrom[i+1];
			localrom[i+1]=temp;
		}
	}
	/* Wordswap if .n64 image. */
	else if(signature[0]==0x40) {
		for (i = 0; i < loadlength; i+=4) {
			temp=localrom[i];
			localrom[i]=localrom[i+3];
			localrom[i+3]=temp;
			temp=localrom[i+1];
			localrom[i+1]=localrom[i+2];
			localrom[i+2]=temp;
		}
	}
}

static _system_type rom_country_code_to_system_type(unsigned short country_code) {
	switch (country_code & 0xFF) {
		// PAL codes
		case 0x44:
		case 0x46:
		case 0x49:
		case 0x50:
		case 0x53:
		case 0x55:
		case 0x58:
		case 0x59:
			return SYSTEM_PAL;

		// NTSC codes
		case 0x37:
		case 0x41:
		case 0x45:
		case 0x4a:
		default: // Fallback for unknown codes
			return SYSTEM_NTSC;
	}
}

// Get the VI (vertical interrupt) limit associated to a ROM system type.
static int rom_system_type_to_vi_limit(_system_type system_type) {
	switch (system_type) {
		case SYSTEM_PAL:
		case SYSTEM_MPAL:
			return 50;

		case SYSTEM_NTSC:
		default:
			return 60;
	}
}

static int rom_system_type_to_ai_dac_rate(_system_type system_type) {
	switch (system_type) {
		case SYSTEM_PAL:
			return 49656530;
		case SYSTEM_MPAL:
			return 48628316;
		case SYSTEM_NTSC:
		default:
			return 48681812;
	}
}

void open_rom_header(usf_state_t * state, unsigned char * header, int header_size) {
	if (header_size >= sizeof(_rom_header))
		memcpy(&state->ROM_HEADER, header, sizeof(_rom_header));

	if (is_valid_rom((const unsigned char *)&state->ROM_HEADER))
		swap_rom((const unsigned char *)&state->ROM_HEADER, (unsigned char *)&state->ROM_HEADER, sizeof(_rom_header));
    
	/* add some useful properties to ROM_PARAMS */
	state->ROM_PARAMS.systemtype = rom_country_code_to_system_type(state->ROM_HEADER.Country_code);
	state->ROM_PARAMS.vilimit = rom_system_type_to_vi_limit(state->ROM_PARAMS.systemtype);
	state->ROM_PARAMS.aidacrate = rom_system_type_to_ai_dac_rate(state->ROM_PARAMS.systemtype);
	state->ROM_PARAMS.countperop = COUNT_PER_OP_DEFAULT;
}

static int usf_startup(usf_state_t * state) {
	// Detect region

	open_rom_header(state, state->savestatespace + 8, sizeof(_rom_header));

	// Detect the Ramsize before the memory allocation

	if(get_le32(state->savestatespace + 4) == 0x400000) {
		void * savestate;
		state->RdramSize = 0x400000;
		savestate = realloc(state->savestatespace, 0x40275c);
		if ( savestate )
			state->savestatespace = savestate;
	} else if(get_le32(USF_STATE->savestatespace + 4) == 0x800000)
		state->RdramSize = 0x800000;

	if ( !Allocate_Memory(state) )
		return -1;

	StartEmulationFromSave(state, USF_STATE->savestatespace);

	return 0;
}

const char * usf_render(void * state, int16_t * buffer, size_t count, int32_t * sample_rate) {
	USF_STATE->last_error = 0;
	USF_STATE->error_message[0] = '\0';

	if ( !USF_STATE->MemoryState ) {
		if ( usf_startup( USF_STATE ) < 0 )
			return USF_STATE->last_error;
	}

	if ( USF_STATE->samples_in_buffer ) {
		size_t do_max = USF_STATE->samples_in_buffer;
		if ( do_max > count )
			do_max = count;

		if ( buffer ) 
			memcpy( buffer, USF_STATE->samplebuf, sizeof(int16_t) * 2 * do_max );

		USF_STATE->samples_in_buffer -= do_max;

		if ( sample_rate )
			*sample_rate = USF_STATE->SampleRate;

		if ( USF_STATE->samples_in_buffer ) {
			memmove( USF_STATE->samplebuf, USF_STATE->samplebuf + do_max * 2, sizeof(int16_t) * 2 * USF_STATE->samples_in_buffer );
			return 0;
		}

		if ( buffer )
			buffer += 2 * do_max;
		count -= do_max;
	}

	USF_STATE->sample_buffer = buffer;
	USF_STATE->sample_buffer_count = count;

	USF_STATE->cpu_stopped = 0;
	USF_STATE->cpu_running = 1;

	StartInterpreterCPU(USF_STATE);

	if ( sample_rate )
		*sample_rate = USF_STATE->SampleRate;

	return USF_STATE->last_error;
}

const char * usf_render_resampled(void * state, int16_t * buffer, size_t count, int32_t sample_rate) {
	if ( !buffer ) {
		unsigned long samples_buffered = resampler_get_sample_count( USF_STATE->resampler );
		resampler_clear(USF_STATE->resampler);
		if (samples_buffered) {
			unsigned long samples_to_remove = samples_buffered;
			if (samples_to_remove > count)
				samples_to_remove = count;
			count -= samples_to_remove;
			while (samples_to_remove--)
				resampler_remove_sample(USF_STATE->resampler);
			if (!count)
				return 0;
		}
		count = (size_t)((uint64_t)count * USF_STATE->SampleRate / sample_rate);
		if (count > USF_STATE->samples_in_buffer_2) {
			count -= USF_STATE->samples_in_buffer_2;
			USF_STATE->samples_in_buffer_2 = 0;
		}
		else if (count) {
			USF_STATE->samples_in_buffer_2 -= count;
			memmove(USF_STATE->samplebuf2, USF_STATE->samplebuf2 + 8192 - USF_STATE->samples_in_buffer_2 * 2, USF_STATE->samples_in_buffer_2 * sizeof(short) * 2);
			return 0;
		}
		return usf_render(state, buffer, count, NULL);
	}
	while ( count ) {
		const char * err;

		while ( USF_STATE->samples_in_buffer_2 && resampler_get_free_count(USF_STATE->resampler) ) {
			int i = 0, j = resampler_get_free_count(USF_STATE->resampler);
			if (j > USF_STATE->samples_in_buffer_2)
				j = (int)USF_STATE->samples_in_buffer_2;
			for (i = 0; i < j; ++i) {
				resampler_write_sample(USF_STATE->resampler, USF_STATE->samplebuf2[i*2], USF_STATE->samplebuf2[i*2+1]);
			}
			if (i) {
				memmove(USF_STATE->samplebuf2, USF_STATE->samplebuf2 + i * 2, (USF_STATE->samples_in_buffer_2 - i) * sizeof(short) * 2);
				USF_STATE->samples_in_buffer_2 -= i;
			}
		}

		while ( count && resampler_get_sample_count(USF_STATE->resampler) ) {
			resampler_get_sample(USF_STATE->resampler, buffer, buffer + 1);
			resampler_remove_sample(USF_STATE->resampler);
			buffer += 2;
			--count;
		}

		if (!count)
			break;

		if (USF_STATE->samples_in_buffer_2)
			continue;

		err = usf_render(state, USF_STATE->samplebuf2, 4096, 0);
		if (err)
			return err;

		USF_STATE->samples_in_buffer_2 = 4096;

		resampler_set_rate(USF_STATE->resampler, (float)USF_STATE->SampleRate / (float)sample_rate);
	}

	return 0;
}

void usf_restart(void * state) {
	if ( USF_STATE->MemoryState )
		StartEmulationFromSave(USF_STATE, USF_STATE->savestatespace);

	USF_STATE->samples_in_buffer = 0;
	USF_STATE->samples_in_buffer_2 = 0;

	resampler_clear(USF_STATE->resampler);
}

void usf_shutdown(void * state) {
	Release_Memory(USF_STATE);
	resampler_delete(USF_STATE->resampler);
#ifdef DEBUG_INFO
	fclose(USF_STATE->debug_log);
#endif
}