#include "ships.h"  
#include "game.h"


void updateShip(ShipInfoDesc* ship){
  //local variables
  register signed int xaccel, yaccel;
  register unsigned char vx_frac, vy_frac;
  register unsigned char new_xfrac, new_yfrac;
  signed int tempvx, tempvy;
  signed char tempypix; 
  signed int negvmax , vmax;


  // Extract x/y-components of acceleration from precalculated table , with gravity
  if(ship->xpix < 81 && ship->xpix > 40 && ship->ypix <71 && ship->ypix >30){
    xaccel = (signed int)((ship->accel)? shipXaccel[ship->type][ship->theta >> 5]:0) + XGrav[ship->xpix-41][ship->ypix-31]; 
    yaccel = (signed int)((ship->accel)? shipYaccel[ship->type][ship->theta >> 5]:0) + YGrav[ship->xpix-41][ship->ypix-31]; 
  }
  else{       
    xaccel = (ship->accel)? shipXaccel[ship->type][ship->theta >> 5]:0;
    yaccel = (ship->accel)? shipYaccel[ship->type][ship->theta >> 5]:0;  

  }

  // X-section   
  tempvx= ship->vx + xaccel;     //euler integrator treatment of acceleration

  //update x-velocity, constrained by max
  //check if exceeds max positive veloc or max negative veloc       
  vmax = (signed int)shipTable[ship->type][SHIPVMAX];
  negvmax = -vmax;  
  if (tempvx < negvmax) {                             
    tempvx = negvmax;
  }
  else if (tempvx > vmax){
    tempvx = vmax;
  }

  // Save the new velocity
  ship->vx = tempvx;                 


  if(tempvx >=0) {
    //heading in positive x dir   		
    vx_frac = (unsigned char)(tempvx & 0xff);	          // %256 to get the remainder portion - This case, vx_frac is positive
    ship->xpix = ship->xpix + (unsigned char) (tempvx>>8);               //get whole pixel movement by divding by 256
    new_xfrac =	(ship->xfrac) + vx_frac;                                 //update x fraction - may overflow
    ship->xpix = (new_xfrac < ship->xfrac)? ship->xpix++:ship->xpix;     //get extra pixel movement from remainder portion based on overflow check
  }	else {			
    //heading in negative x dir
    vx_frac =  (unsigned char)(-tempvx & 0xff);              //negate tempvx to get abs value, &256 to get remainder
    ship->xpix = ship->xpix - (unsigned char) (-tempvx>>8);      
    new_xfrac =	(ship->xfrac) - vx_frac;
    ship->xpix = (new_xfrac > ship->xfrac)? ship->xpix--:ship->xpix;		//determine whether a pixel boundary was crossed based on overflow check
  }	

  ship->xfrac= new_xfrac;			//update x fractional position
  ship->xpix = ship->xpix & 0x7f;               //enforce x-wraparound



  //Y-section

  tempvy= ship->vy + yaccel;   //euler integrator treatment of acceleration

 

  //check if exceeds max positive veloc or max negative veloc       
  vmax = (signed int)shipTable[ship->type][SHIPVMAX];
  negvmax = -vmax;  
  if (tempvy < negvmax) {                             
    tempvy = negvmax;
  }
  else if (tempvy > vmax){
    tempvy = vmax;
  }

  // Save the new velocity
  ship->vy = tempvy;                 




  if(tempvy >=0)		//heading in positive y dir
  {
    vy_frac = (unsigned char)(tempvy & 0xff);	// %256 to get the remainder portion - This case, vy_frac is positive
    tempypix = ship->ypix + (unsigned char) (tempvy>>8);       //get whole pixel movement by divding by 256
    new_yfrac =	(ship->yfrac) + vy_frac;                       //update y fraction - may overflow
    tempypix = (new_yfrac < ship->yfrac)? tempypix++:tempypix;		//determine whether an extra pixel boundary was crossed based on overflow check
  }
  else 			//heading in negative y dir
  {
    vy_frac =  (unsigned char)(-tempvy & 0xff);            //negate tempvy to get abs value
    tempypix = ship->ypix - (unsigned char) (-tempvy>>8);

    new_yfrac =	(ship->yfrac) - vy_frac;
    tempypix = (new_yfrac > ship->yfrac)? tempypix--:tempypix;		//determine whether a pixel boundary was crossed based on overflow check

  }	

  ship->yfrac= new_yfrac;	//update y fractional position

  //wraparound condition for Y 
  if (tempypix > 99) {
    ship->ypix = tempypix - 100;
  } else if (tempypix < 0) {
    ship->ypix = tempypix +100;
  } else {
    ship->ypix = tempypix;
  }

}

void updateBullets(ShipInfoDesc* ship, ShipInfoDesc* shiptarg) {
  //local variables

  register unsigned char new_xfrac, new_yfrac;
  signed int tempvx, tempvy;
  signed char tempypix; 
  register char index;		// Temporary variable for-loops


  //parse through ship's bullet array to check for active bullets...only operate on these
  for(index =0; index < MAX_BULLETS; index ++){
    ship->activebullets =0;
    if(ship->BulletActive[index]){ 

      ship->activebullets++;
      //X-dir update positions 
      tempvx = bulletVX[ship->BulletType[index]][ship->BulletDirection[index] >> 5];

      if(tempvx >=0){		//heading in positive x dir
        ship->BulletPosX[index]+=tempvx;
      }
      else{ 			//heading in negative x dir
        ship->BulletPosX[index]-= -tempvx;	
      }	
      ship->BulletXFrac[index]= new_xfrac;			//update x fractional position
      ship->BulletPosX[index] = ship->BulletPosX[index] & 0x7f; //enforce x-wraparound


      //Y-dir 
      tempvy = bulletVY[ship->BulletType[index]][ship->BulletDirection[index] >> 5];
      if(tempvy >=0){		//heading in positive y dir
        tempypix = ship->BulletPosY[index]+tempvy;
      }
      else {
        tempypix = ship->BulletPosY[index]- (-tempvy);
      }


      //update yfrac 
      ship->BulletYFrac[index] = new_yfrac;

      //wraparound condition for Y 
      if (tempypix > 99) {
        ship->BulletPosY[index] = tempypix - 100;
      } else if (tempypix < 0) {
        ship->BulletPosY[index] = tempypix +100;
      } else {
        ship->BulletPosY[index] = tempypix;
      }
      
      //use homing algorithm to update direction for homing weapons
      if((ship->BulletType[index] == 2) || (ship->BulletType[index] == 3)){
        homing(ship, shiptarg, index);
      }
    } //end if bullet active
  }//endfor
}//end updatebullet


void homing(ShipInfoDesc* shipmain, ShipInfoDesc* shipopp, char index){

  //  for (index = 0; index < MAX_BULLETS; index++) {
  signed int tempx=0, tempy5, tempx12, tempx2, tempx2n, tempx12n;
  signed int tempy=0;    
  //check if the bullet is active and homing type
  if (shipmain->BulletActive[index] && (shipmain->BulletType[index] == 2 || shipmain->BulletType[index] == 3)){

    //get xy distance of opponent from bullet
    tempx = (signed int)shipopp->xpix - (signed int)shipmain->BulletPosX[index];
    tempy = (signed int)shipopp->ypix - (signed int)shipmain->BulletPosY[index];  
   
    //split area around bullet into 8 radial zones, boundaries defined by 5y=+-12x and 5y=+-2x
    tempy5 = 5*tempy;
    tempx12 = 12*tempx;
    tempx2 = 2*tempx;
    tempx12n = -12*tempx;
    tempx2n = -2*tempx;
  
    
    //if directly on bullet...don't do anything
    if (tempy ==0 && tempx==0){
      shipmain->BulletPosX[index] = shipopp->xpix;
      shipmain->BulletPosY[index] = shipopp->ypix;
    }

    //check if opponent is in particular region, turn the shortest way towards him

    else if(tempy5 < tempx2 && tempy5 > tempx2n){
      if(shipmain->BulletDirection[index]<=THETA2 || shipmain->BulletDirection[index]>=THETA65){
        shipmain->BulletDirection[index] -= bulletTable[shipmain->BulletType[index]][TURNRATE];
      } else if(shipmain->BulletDirection[index]>=THETA2 && shipmain->BulletDirection[index]<=THETA55){
        shipmain->BulletDirection[index] += bulletTable[shipmain->BulletType[index]][TURNRATE];
      }


    } //end region 6
    else if( tempy5 < tempx2 && tempy5 > tempx12){
      if(shipmain->BulletDirection[index]<=THETA5 && shipmain->BulletDirection[index]>=THETA15){
        shipmain->BulletDirection[index] -= bulletTable[shipmain->BulletType[index]][TURNRATE];
      }
      else if(shipmain->BulletDirection[index]>=THETA5 || shipmain->BulletDirection[index]<=THETA05){
        shipmain->BulletDirection[index] += bulletTable[shipmain->BulletType[index]][TURNRATE];
      }     


    } //end region 1



    else if(tempy5 < tempx12 && tempy5 < tempx12n){
      if(shipmain->BulletDirection[index]<=THETA4 && shipmain->BulletDirection[index]>=THETA05){
        shipmain->BulletDirection[index] -= bulletTable[shipmain->BulletType[index]][TURNRATE];
      }
      else if(shipmain->BulletDirection[index]>=THETA4 && shipmain->BulletDirection[index]<=THETA75){
        shipmain->BulletDirection[index] += bulletTable[shipmain->BulletType[index]][TURNRATE];
      }	


    } //end region 0

    else if (tempy5 < tempx12 && tempy5 >tempx2){
      if(shipmain->BulletDirection[index]<=THETA1 || shipmain->BulletDirection[index]>=THETA55){
        shipmain->BulletDirection[index] -= bulletTable[shipmain->BulletType[index]][TURNRATE];
      }
      else if(shipmain->BulletDirection[index]>=THETA1 && shipmain->BulletDirection[index]<=THETA45){
        shipmain->BulletDirection[index] += bulletTable[shipmain->BulletType[index]][TURNRATE];
      }       


    } //end region 5



    else if(tempy5 < tempx12n && tempy5 > tempx2n){
      if(shipmain->BulletDirection[index]<=THETA7 && shipmain->BulletDirection[index]>=THETA35){
        shipmain->BulletDirection[index] -= bulletTable[shipmain->BulletType[index]][TURNRATE];
      }
      else if(shipmain->BulletDirection[index]>=THETA7 || shipmain->BulletDirection[index]<=THETA25){
        shipmain->BulletDirection[index] += bulletTable[shipmain->BulletType[index]][TURNRATE];
      }



    }//end region 3



    else if(tempy5 < tempx2n && tempy5 > tempx12n){
      if(shipmain->BulletDirection[index]<=THETA3 || shipmain->BulletDirection[index]>=THETA75){
        shipmain->BulletDirection[index] += bulletTable[shipmain->BulletType[index]][TURNRATE];
      }
      else if(shipmain->BulletDirection[index]>=THETA3 && shipmain->BulletDirection[index]<=THETA65){
        shipmain->BulletDirection[index] -= bulletTable[shipmain->BulletType[index]][TURNRATE];
      }


    } //end region 7

    else if (tempy5 < tempx2n && tempy5 >tempx2){
      if(shipmain->BulletDirection[index]<=THETA6 && shipmain->BulletDirection[index]>=THETA25){
        shipmain->BulletDirection[index] -= bulletTable[shipmain->BulletType[index]][TURNRATE];
      }
      else if(shipmain->BulletDirection[index]>=THETA6 || shipmain->BulletDirection[index]<=THETA15){
        shipmain->BulletDirection[index] += bulletTable[shipmain->BulletType[index]][TURNRATE];
      }



    } //end region 2


    else{
      if(shipmain->BulletDirection[index]<=0xff && shipmain->BulletDirection[index]>=THETA45){
        shipmain->BulletDirection[index] -= bulletTable[shipmain->BulletType[index]][TURNRATE];
      }
      else if(shipmain->BulletDirection[index]>=THETA0 && shipmain->BulletDirection[index]<=THETA35){
        shipmain->BulletDirection[index] += bulletTable[shipmain->BulletType[index]][TURNRATE];
      }



    }    //end region 4
  }  //endif bullet active
  //  } //endfor
} //end homing