/*
 * Copyright (C) 2017 FIX94
 *
 * This software may be modified and distributed under the terms
 * of the MIT license.  See the LICENSE file for details.
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <inttypes.h>
#include <ctype.h>
#include <string.h>
#include <time.h>
#include <math.h>
#include "cpu.h"
#include "input.h"
#include "ppu.h"
#include "mem.h"
#include "apu.h"
#include "audio.h"
#if ZIPSUPPORT
#include "unzip/unzip.h"
#endif
#define DEBUG_HZ 0
#define DEBUG_MAIN_CALLS 0
#define DEBUG_KEY 0
#define DEBUG_LOAD_INFO 1

const char *VERSION_STRING = "fixGB Alpha v0.8.2";
static char window_title[256];
static char window_title_pause[256];

enum {
	FTYPE_UNK = 0,
	FTYPE_GB,
	FTYPE_GBC,
	FTYPE_GBS,
#if ZIPSUPPORT
	FTYPE_ZIP,
#endif
};

static void gbEmuFileOpen(const char *name);
static bool gbEmuFileRead();
static void gbEmuFileClose();
static void gbEmuResetRegs();
static void gbEmuDisplayFrame(void);
void gbEmuMainLoop(void);
void gbEmuDeinit(void);

static void gbEmuHandleKeyDown(unsigned char key, int x, int y);
static void gbEmuHandleKeyUp(unsigned char key, int x, int y);
static void gbEmuHandleSpecialDown(int key, int x, int y);
static void gbEmuHandleSpecialUp(int key, int x, int y);

volatile bool emuRenderFrame;

static int emuFileType;
static char emuFileName[1024];
uint8_t *emuGBROM = NULL;
uint32_t emuGBROMsize;
char emuSaveName[1024];
bool emuSaveEnabled;
//used externally
uint32_t textureImage[0x5A00];
bool gbPause;
bool gbEmuGBSPlayback;
bool gbsTimerMode;
uint16_t gbsLoadAddr;
uint16_t gbsInitAddr;
uint16_t gbsPlayAddr;
uint32_t gbsRomSize;
uint16_t gbsSP;
uint8_t gbsTracksTotal, gbsTMA, gbsTAC;
uint8_t cpuTimer;
bool gbCgbGame;
bool gbCgbMode;
bool gbCgbBootrom;
bool gbAllowInvVRAM;
bool gbIsMulticart;

static bool inPause;
static bool inResize;

//used externally
bool emuSkipVsync;
bool emuSkipFrame;

static uint8_t mainClock;
static uint8_t memClock;

#if WINDOWS_BUILD
#include <windows.h>
typedef bool (APIENTRY *PFNWGLSWAPINTERVALEXTPROC) (int interval);
PFNWGLSWAPINTERVALEXTPROC wglSwapIntervalEXT = NULL;
#if DEBUG_HZ
static DWORD emuFrameStart = 0;
static DWORD emuTimesCalled = 0;
static DWORD emuTotalElapsed = 0;
#endif
#if DEBUG_MAIN_CALLS
static DWORD emuMainFrameStart = 0;
static DWORD emuMainTimesCalled = 0;
static DWORD emuMainTimesSkipped = 0;
static DWORD emuMainTotalElapsed = 0;
#endif
#endif

#define VISIBLE_DOTS 160
#define VISIBLE_LINES 144

static uint32_t linesToDraw;
static const uint32_t visibleImg = VISIBLE_DOTS*VISIBLE_LINES*4;
static uint8_t scaleFactor;

static FILE *gbEmuFilePointer = NULL;
#if ZIPSUPPORT
static bool gbEmuFileIsZip;
static uint8_t *gbEmuZipBuf = NULL;
static uint32_t gbEmuZipLen;
static unzFile gbEmuZipObj;
static unz_file_info gbEmuZipObjInfo;
#endif

//from input.c
extern uint8_t inValReads[8];
//from mbc.c
extern bool rtcUsed;
extern size_t extTotalSize;

int gbEmuLoadGame(const char* filename)
{
   int argc = 2;
   const char* argv[] = {"fixGB", filename};
   puts(VERSION_STRING);
   gbEmuResetRegs();
   if(argc >= 2)
      gbEmuFileOpen(argv[1]);
   if(emuFileType == FTYPE_GB || emuFileType == FTYPE_GBC)
   {
      if(!gbEmuFileRead())
      {
         gbEmuFileClose();
         printf("Main: Could not read %s!\n", emuFileName);
         puts("Press enter to exit");
         getc(stdin);
         return EXIT_SUCCESS;
      }
      gbEmuFileClose();
      memcpy(emuSaveName, emuFileName, 1024);
      if(emuFileType == FTYPE_GBC)
         memcpy(emuSaveName+strlen(emuSaveName)-3,"sav",3);
      else //.gb has one less character
         memcpy(emuSaveName+strlen(emuSaveName)-2,"sav",3);
      printf("Save Path: %s\n",emuSaveName); 
      //Set Invalid VRAM allowed
      gbAllowInvVRAM = (strstr(emuFileName,"InvVRAM") != NULL);
      printf("Main: Invalid VRAM Access is %sallowed\n", gbAllowInvVRAM?"":"dis");
      gbCgbBootrom = memInitCGBBootrom();
      //Verify Header CRC
      uint8_t hdrcrc = 0;
      uint16_t hdrpos;
      for(hdrpos = 0x134; hdrpos < 0x14D; hdrpos++)
         hdrcrc = hdrcrc-emuGBROM[hdrpos]-1;
      if(hdrcrc != emuGBROM[0x14D])
      {
         printf("Main: WARNING: Invalid ROM Header CRC, ROM may not work\n");
         if(gbCgbBootrom)
         {
            //Fix Header CRC for Bootrom
            emuGBROM[0x14D] = hdrcrc;
         }
      }
      //Set CGB Regs allowed
      gbCgbGame = (emuGBROM[0x143] == 0x80 || emuGBROM[0x143] == 0xC0);
      gbCgbMode = (gbCgbGame || gbCgbBootrom);
      printf("Main: CGB Regs are %sallowed\n", gbCgbMode?"":"dis");
      //Quick multicart check
      gbIsMulticart = (emuGBROMsize == 0x200000 && strcmp((char*)(emuGBROM+0x134), "QBILLION") == 0);
      if(!memInit(true,false))
      {
         free(emuGBROM);
         puts("Press enter to exit");
         getc(stdin);
         return EXIT_SUCCESS;
      }
      //CPU DMG Mode
      cpuSetSpeed(false);
      apuInitBufs();
      cpuInit();
      ppuInit();
      apuInit();
      inputInit();
      inputClear();
      if(emuGBROM[0x134] != 0)
      {
         if(gbCgbMode)
         {
            printf("Game: %.11s\n", (char*)(emuGBROM+0x134));
            sprintf(window_title, "%.11s (CGB) - %s\n", (char*)(emuGBROM+0x134), VERSION_STRING);
         }
         else
         {
            printf("Game: %.16s\n", (char*)(emuGBROM+0x134));
            sprintf(window_title, "%.16s (DMG) - %s\n", (char*)(emuGBROM+0x134), VERSION_STRING);
         }
      }
   }
   else if(emuFileType == FTYPE_GBS)
   {
      if(!gbEmuFileRead())
      {
         gbEmuFileClose();
         printf("Main: Could not read %s!\n", emuFileName);
         puts("Press enter to exit");
         getc(stdin);
         return EXIT_SUCCESS;
      }
      gbEmuFileClose();
      uint8_t *tmpROM = emuGBROM;
      uint32_t tmpROMsize = emuGBROMsize;
      gbsTracksTotal = tmpROM[4];
      gbsLoadAddr = (tmpROM[6])|(tmpROM[7]<<8);
      gbsInitAddr = (tmpROM[8])|(tmpROM[9]<<8);
      gbsPlayAddr = (tmpROM[0xA])|(tmpROM[0xB]<<8);
      gbsSP = (tmpROM[0xC])|(tmpROM[0xD]<<8);
      //should give more than enough room for everything
      gbsRomSize = emuGBROMsize = (tmpROMsize-0x70+gbsLoadAddr+0x7FFF)&(~0x7FFF);
      //printf("Main: gbsLoadAddr %04x gbsInitAddr %04x gbsPlayAddr %04x gbsSP %04x\n",
      //	gbsLoadAddr, gbsInitAddr, gbsPlayAddr, gbsSP);
      emuGBROM = malloc(emuGBROMsize);
      memset(emuGBROM,0xFF,emuGBROMsize);
      memcpy(emuGBROM+gbsLoadAddr,tmpROM+0x70,tmpROMsize-0x70);
      gbsTMA = tmpROM[0xE];
      gbsTAC = tmpROM[0xF];
      if(gbsTAC&0x80)
      {
         cpuSetSpeed(true);
         gbCgbGame = gbCgbMode = true;
      }
      else
      {
         cpuSetSpeed(false);
         gbCgbGame = gbCgbMode = false;
      }
      printf("Main: CGB Regs are %sallowed\n", gbCgbMode?"":"dis");
      if(gbsTAC&4)
      {
         printf("Main: GBS Play Timing: Timer\n");
         gbsTimerMode = true;
      }
      else
      {
         printf("Main: GBS Play Timing: VSync\n");
         gbsTimerMode = false;
      }
      memInit(true,true);
      if(tmpROM[0x10] != 0)
      {
         printf("Game: %.32s\n",(char*)(tmpROM+0x10));
         sprintf(window_title, "%.32s (GBS) - %s\n", (char*)(tmpROM+0x10), VERSION_STRING);
      }
      free(tmpROM);
      apuInitBufs();
      inputClear();
      //does all inits for us
      memStartGBS();
      gbEmuGBSPlayback = true;
      linesToDraw = 20;
      scaleFactor = 4;
   }
   if(emuGBROM == NULL)
   {
#if ZIPSUPPORT
      printf("Main: No File to Open! Make sure to call fixGB with a .gb/.gbc/.gbs/.zip File as Argument.\n");
#else
      printf("Main: No File to Open! Make sure to call fixGB with a .gb/.gbc/.gbs File as Argument.\n");
#endif
      puts("Press enter to exit");
      getc(stdin);
      return EXIT_SUCCESS;
   }
   sprintf(window_title_pause, "%s (Pause)", window_title);
#if WINDOWS_BUILD
#if DEBUG_HZ
   emuFrameStart = GetTickCount();
#endif
#if DEBUG_MAIN_CALLS
   emuMainFrameStart = GetTickCount();
#endif
#endif
   return EXIT_SUCCESS;
}

static void gbEmuResetRegs()
{
	strcpy(window_title, VERSION_STRING);

	emuRenderFrame = false;
	linesToDraw = VISIBLE_LINES;
	scaleFactor = 3;

	memset(textureImage,0,visibleImg);
	emuFileType = FTYPE_UNK;
	memset(emuFileName,0,1024);
	memset(emuSaveName,0,1024);
	emuSaveEnabled = false;
	if(emuGBROM)
		free(emuGBROM);
	emuGBROM = NULL;
	emuGBROMsize = 0;

	gbPause = false;
	gbEmuGBSPlayback = false;
	gbsTimerMode = false;
	gbsLoadAddr = 0, gbsInitAddr = 0;
	gbsPlayAddr = 0, gbsRomSize = 0;
	gbsSP = 0;
	gbsTracksTotal = 0, gbsTMA = 0, gbsTAC = 0;
	cpuTimer = 3;
	gbCgbGame = false;
	gbCgbMode = false;
	gbCgbBootrom = false;
	gbAllowInvVRAM = false;
	gbIsMulticart = false;

	inPause = false;
	inResize = false;

	emuSkipVsync = false;
	emuSkipFrame = false;

	mainClock = 0;
	memClock = 0;

	if(gbEmuFilePointer)
		fclose(gbEmuFilePointer);
	gbEmuFilePointer = NULL;
#if ZIPSUPPORT
	gbEmuFileIsZip = false;
	if(gbEmuZipBuf)
		free(gbEmuZipBuf);
	gbEmuZipBuf = NULL;
	gbEmuZipLen = 0;
#endif
}

static int gbEmuGetFileType(const char *name)
{
	int nLen = strlen(name);
	if(nLen > 4 && name[nLen-4] == '.')
	{
		if(tolower(name[nLen-3]) == 'g' && tolower(name[nLen-2]) == 'b' && tolower(name[nLen-1]) == 'c')
			return FTYPE_GBC;
		else if(tolower(name[nLen-3]) == 'g' && tolower(name[nLen-2]) == 'b' && tolower(name[nLen-1]) == 's')
			return FTYPE_GBS;
#if ZIPSUPPORT
		else if(tolower(name[nLen-3]) == 'z' && tolower(name[nLen-2]) == 'i' && tolower(name[nLen-1]) == 'p')
			return FTYPE_ZIP;
#endif
	}
	else if(nLen > 3 && name[nLen-3] == '.')
	{
		if(tolower(name[nLen-2]) == 'g' && tolower(name[nLen-1]) == 'b')
			return FTYPE_GB;
	}
	return FTYPE_UNK;
}

static void gbEmuFileOpen(const char *name)
{
	emuFileType = FTYPE_UNK;
	memset(emuFileName,0,1024);
	memset(emuSaveName,0,1024);
	int baseType = gbEmuGetFileType(name);
#if ZIPSUPPORT
	if(baseType == FTYPE_ZIP)
	{
		printf("Base ZIP File: %s\n", name);
		FILE *tmp = fopen(name,"rb");
		if(!tmp)
		{
			printf("Main: Could not open %s!\n", name);
			return;
		}
		fseek(tmp,0,SEEK_END);
		gbEmuZipLen = ftell(tmp);
		rewind(tmp);
		gbEmuZipBuf = malloc(gbEmuZipLen);
		if(!gbEmuZipBuf)
		{
			printf("Main: Could not allocate ZIP buffer!\n");
			fclose(tmp);
			return;
		}
		fread(gbEmuZipBuf,1,gbEmuZipLen,tmp);
		fclose(tmp);
		char filepath[20];
		snprintf(filepath,20,"%x+%x",(unsigned int)gbEmuZipBuf,gbEmuZipLen);
		gbEmuZipObj = unzOpen(filepath);
		int err = unzGoToFirstFile(gbEmuZipObj);
		while (err == UNZ_OK)
		{
			char tmpName[256];
			err = unzGetCurrentFileInfo(gbEmuZipObj,&gbEmuZipObjInfo,tmpName,256,NULL,0,NULL,0);
			if(err == UNZ_OK)
			{
				int curInZipType = gbEmuGetFileType(tmpName);
				if(curInZipType != FTYPE_ZIP && curInZipType != FTYPE_UNK)
				{
					emuFileType = curInZipType;
					gbEmuFileIsZip = true;
					if(strchr(name,'/') != NULL || strchr(name,'\\') != NULL)
					{
						const char *nPath = name;
						if(strchr(nPath,'/') != NULL)
							nPath = (strrchr(nPath,'/')+1);
						if(strchr(nPath,'\\') != NULL)
							nPath = (strrchr(nPath,'\\')+1);
						strncpy(emuFileName, name, nPath-name);
					}
					char *zName = tmpName;
					if(strchr(zName,'/') != NULL)
						zName = (strrchr(zName,'/')+1);
					if(strchr(zName,'\\') != NULL)
						zName = (strrchr(zName,'\\')+1);
					strcat(emuFileName, zName);
					printf("File in ZIP Type: %s\n", emuFileType == FTYPE_GB ? "GB" : (emuFileType == FTYPE_GBC ? "GBC" : "GBS"));
					printf("Full Path from ZIP: %s\n", emuFileName);
					break;
				}
				else
					err = unzGoToNextFile(gbEmuZipObj);
			}
		}
		if(emuFileType == FTYPE_UNK)
		{
			printf("Found no usable file in ZIP\n");
			unzClose(gbEmuZipObj);
			if(gbEmuZipBuf)
				free(gbEmuZipBuf);
			gbEmuZipBuf = NULL;
			gbEmuZipLen = 0;
		}
	}
	else if(baseType != FTYPE_UNK)
#else
	if(baseType != FTYPE_UNK)
#endif
	{
		gbEmuFilePointer = fopen(name,"rb");
		if(!gbEmuFilePointer)
			printf("Main: Could not open %s!\n", name);
		else
		{
			emuFileType = baseType;
			strncpy(emuFileName, name, 1024);
			printf("File Type: %s\n", baseType == FTYPE_GB ? "GB" : (baseType == FTYPE_GBC ? "GBC" : "GBS"));
			printf("Full Path: %s\n", emuFileName);
		}
	}
}

static bool gbEmuFileRead()
{
#if ZIPSUPPORT
	if(gbEmuFileIsZip)
	{
		unzOpenCurrentFile(gbEmuZipObj);
		emuGBROMsize = gbEmuZipObjInfo.uncompressed_size;
		emuGBROM = malloc(emuGBROMsize);
		if(emuGBROM)
			unzReadCurrentFile(gbEmuZipObj,emuGBROM,emuGBROMsize);
		unzCloseCurrentFile(gbEmuZipObj);
	}
	else
#endif
	{
		fseek(gbEmuFilePointer,0,SEEK_END);
		emuGBROMsize = ftell(gbEmuFilePointer);
		rewind(gbEmuFilePointer);
		emuGBROM = malloc(emuGBROMsize);
		if(emuGBROM)
			fread(emuGBROM,1,emuGBROMsize,gbEmuFilePointer);
	}
	if(emuGBROM)
		return true;
	//else
	printf("Main: Could not allocate ROM buffer!\n");
	return false;
}

//cleans up vars from read
static void gbEmuFileClose()
{
#if ZIPSUPPORT
	if(gbEmuFileIsZip)
		unzClose(gbEmuZipObj);
	gbEmuFileIsZip = false;
	if(gbEmuZipBuf)
		free(gbEmuZipBuf);
	gbEmuZipBuf = NULL;
	gbEmuZipLen = 0;
#endif
	if(gbEmuFilePointer)
		fclose(gbEmuFilePointer);
	gbEmuFilePointer = NULL;
}

void gbEmuDeinit(void)
{
	//printf("\n");
	emuRenderFrame = false;
	audioDeinit();
	apuDeinitBufs();
	if(emuGBROM != NULL)
		free(emuGBROM);
	emuGBROM = NULL;
	emuFileType = FTYPE_UNK;
	memset(emuFileName,0,1024);
	memset(emuSaveName,0,1024);
	extTotalSize = 0;
	rtcUsed = false;
	memDeinit();
	gbIsMulticart = false;
	//printf("Bye!\n");
}

void gbEmuMainLoop(void)
{
   //do one scanline loop
   do
   {
      //run APU first to make sure its synced
      if(!(mainClock&15))
         apuCycle();
      //channel timer updates
      apuClockTimers();
      //run possible DMA next
      memDmaClockTimers();
      //run CPU (and mem clocks) next
      if(!(mainClock&cpuTimer))
      {
         //main CPU clock
         cpuCycle();
         //mem clock tied to CPU clock, so
         //double speed in CGB mode!
         if(!(memClock&3))
            memClockTimers();
         memClock++;
      }
      //run PPU last
      ppuCycle();
      if(ppuDrawDone())
      {
         emuRenderFrame = true;
         //update console stats if requested
#if (WINDOWS_BUILD && DEBUG_HZ)
         emuTimesCalled++;
         DWORD end = GetTickCount();
         emuTotalElapsed += end - emuFrameStart;
         if(emuTotalElapsed >= 1000)
         {
            printf("\r%iHz   ", emuTimesCalled);
            emuTimesCalled = 0;
            emuTotalElapsed = 0;
         }
         emuFrameStart = end;
#endif
         //send VSync to GBS Player if required
         if(gbEmuGBSPlayback && !gbsTimerMode)
            cpuPlayGBS();
      }
      mainClock++;
   }
   while(emuRenderFrame == false) ;
   //update console stats if requested
#if (WINDOWS_BUILD && DEBUG_MAIN_CALLS)
   emuMainTimesCalled++;
   DWORD end = GetTickCount();
   emuMainTotalElapsed += end - emuMainFrameStart;
   if(emuMainTotalElapsed >= 1000)
   {
      printf("\r%i calls, %i skips   ", emuMainTimesCalled, emuMainTimesSkipped);
      emuMainTimesCalled = 0;
      emuMainTimesSkipped = 0;
      emuMainTotalElapsed = 0;
   }
   emuMainFrameStart = end;
#endif
}