//===========================================================================
//                                                        SNAKE w/ arrow keys
//===========================================================================
// revised 2005
// Arrow Keys have been added to direct the snake.
//
// To enable the ArrowKeys:
//
// 1) Set Form1->KeyPreview to true;
// 2) Create the Form1->OnKeyDown handler...
// 3) In that handler include instructions for the VK_LEFT and other keys
//
// For the arrow keys to be recognized, you must return FOCUS away from
// the buttons when they are pressed.  To do this, include an
// EditLength->SetFocus(); call at the end of each Button event handler.
//===========================================================================

#include <vcl.h>
#pragma hdrstopFlag

#include "Unit1.h"
#include <stdlib.h>
#include "math.h"                          // Needed to make randomize() work
#include "time.h"                          // Needed to make randomize() work
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;

//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}

// ==========================================================================
//                                                                  VARIABLES
// ==========================================================================

bool ateFood = false;
// the world
int world[25][25];                                           
// these take care of the toroidal world
int east, south, relativeE, relativeS, wrappedE, wrappedS;
// the positions of each segment in the snake
int snakeE[650], snakeS[650];
int snakeHeadE, snakeHeadS;
int snakeTailE, snakeTailS;
int snakeLength;
int segment;
int direction, lastDirection, reverseDirection;
int span;
int maxSize = 25;
int iterations = 0;

// ==========================================================================
//                                                                  FUNCTIONS
// ==========================================================================

//------------------------------------------------------------------- Render
void render(void) {
   for (east=0; east<maxSize; east++) {
      for (south=0; south<maxSize; south++) {
         switch (world[east][south]) {
            case 0:
               Form1->Canvas->Pen->Color=clRed;
               Form1->Canvas->Brush->Color=clRed;
               Form1->Canvas->Rectangle
                  (east*20,south*20,east*20+20,south*20+20);
               break;
            case 1:
               Form1->Canvas->Pen->Color=clLime;
               Form1->Canvas->Brush->Color=clLime;
               Form1->Canvas->Rectangle
                  (east*20,south*20,east*20+20,south*20+20);
               break;
            case 2:
               Form1->Canvas->Pen->Color=clBlue;
               Form1->Canvas->Brush->Color=clBlue;
               Form1->Canvas->Rectangle
                  (east*20,south*20,east*20+20,south*20+20);
               break;
            case 3:
               Form1->Canvas->Pen->Color=clFuchsia;
               Form1->Canvas->Brush->Color=clFuchsia;
               Form1->Canvas->Rectangle
                  (east*20,south*20,east*20+20,south*20+20);
               break;
         }
      }
   }
}

//---------------------------------------------------------------- Game Over
void gameOver (void) {
   Form1->Timer1->Enabled = false;
   Form1->Color = clBlack;
   render();
   Application->ProcessMessages();
}

//----------------------------------------------------------------- Clear All
void clearAll (void) {
   for (east=0; east<maxSize; east++) {
      for (south=0; south<maxSize; south++) {
         world[east][south]=false;
      }
   }
      for (int i = 0; i < 650; i++) {
         snakeE[i] = -1;
         snakeS[i] = -1;
      }
   render();      
}

//---------------------------------------------------------- make random food
void makeRandomFood (void) {
   // make 30 random food
   for (int i = 0; i < 30; i++) {
      world[random(25)][random(25)] = 2;
   }
}

//-------------------------------------------------------- make random poison
void makeRandomPoison (void) {
   // make 20 random poison
   for (int i = 0; i < 20; i++) {
      world[random(25)][random(25)] = 3;
   }
}

//--------------------------------------------------------- make random snake
// always start snake horizontal
// turned up or down, away from the edges
void makeRandomSnake (void) {
   Randomize();
   // begin with direction either up or down
   lastDirection = 1;
   int flip = random(2);
   switch (flip) {
      case 0:
         direction = 0;
         break;
      case 1:
         direction = 2;
         break;
   }
   // begin with random head position
   snakeHeadE = 1 + random(15);
   snakeHeadS = 1 + random(23);
   // begin with random snake length
   snakeLength = 3 + random(7);
   // lay out the snake horizontally
   for (int span = 0; span < snakeLength; span++) {
      world[snakeHeadE + span][snakeHeadS] = true;
      snakeE[span] = snakeHeadE + span;
      snakeS[span] = snakeHeadS;
   }
   snakeTailE = snakeHeadE + snakeLength - 1;
   snakeTailS = snakeHeadS;
   Form1->Timer1->Enabled = true;
}

//---------------------------------------------------------------------- STEP
void step (void) {
   // cannot fold back on yourself
   reverseDirection = direction + 2;
   if (reverseDirection > 3) reverseDirection = reverseDirection - 4;
   if (lastDirection == reverseDirection) direction = lastDirection;
   // figure out where new head will be
      switch (direction) {
         case 0: // up
            snakeHeadS--;
            if (snakeHeadS < 0) snakeHeadS = 24;
            break;
         case 1: // right
            snakeHeadE++;
            if (snakeHeadE > 24) snakeHeadE = 0;
            break;
         case 2: // down
            snakeHeadS++;
            if (snakeHeadS > 24) snakeHeadS = 0;
            break;
         case 3: // left
            snakeHeadE--;
            if (snakeHeadE  <0) snakeHeadE = 24;
            break;
      }
   // if you eat poison or eat yourself then the game is over
   if (world[snakeHeadE][snakeHeadS] == 3) gameOver();
   if (world[snakeHeadE][snakeHeadS] == 1) gameOver();   
   // if there is food there remember to add to length
   if (world[snakeHeadE][snakeHeadS] == 2) ateFood = true;
   world[snakeHeadE][snakeHeadS] = true;
   // move each segment's E and S position down the shake length
   for (segment = snakeLength + 1; segment > 0; segment --) {
      snakeE[segment] = snakeE[segment - 1];
      snakeS[segment] = snakeS[segment - 1];
   }
   // and the snake head at the front
   snakeE[segment] = snakeHeadE;
   snakeS[segment] = snakeHeadS;
   // remove the snake's last tail position if it hasn't eaten
   if (!ateFood) {
      snakeTailE = snakeE[snakeLength ];
      snakeTailS = snakeS[snakeLength ];
   }
   if (ateFood) {
      snakeLength++;
      ateFood = false;
   }
   lastDirection = direction;  // snake cannot double back on self
   world[snakeTailE][snakeTailS] = false;
   render();
   // show some statistics
   Form1->EditLength->Text = snakeLength;
}

// ==========================================================================
//                                                             EVENT HANDLERS
// ==========================================================================

//----------------------------------------------------------------- Form Show
void __fastcall TForm1::FormShow(TObject *Sender)
{
   randomize();
}

//-------------------------------------------------------------- Begin Button
void __fastcall TForm1::ButtonBeginClick(TObject *Sender)
{
   clearAll();
   makeRandomFood();
   makeRandomPoison();
   makeRandomSnake();
   render();
   EditLength->SetFocus();                      // Returns the Edit to focus
}

//--------------------------------------------------------------- Step Button
void __fastcall TForm1::ButtonStepClick(TObject *Sender)
{
   step();
   EditLength->SetFocus();                      // Returns the Edit to focus
}

//-------------------------------------------------------------- Pause Button
void __fastcall TForm1::ButtonPauseClick(TObject *Sender)
{
   Timer1->Enabled = !Timer1->Enabled;
   if (Timer1->Enabled == true) {
      ButtonPause->Caption = "Pause";
      PanelPause->Color = clRed;
      }
   else {
      ButtonPause->Caption = "Resume";
      PanelPause->Color = clLime;
   }
   EditLength->SetFocus();                      // Returns the Edit to focus
}

//-----------------------------------------------------------------  On Timer
void __fastcall TForm1::Timer1Timer(TObject *Sender)
{
   step();
   Application->ProcessMessages();
}

//------------------------------------------------------------- Form Key Down
void __fastcall TForm1::FormKeyDown(TObject *Sender, WORD &Key,
      TShiftState Shift)
{
   if (Key == VK_LEFT) direction = 3;
   if (Key == VK_RIGHT) direction = 1;
   if (Key == VK_UP) direction = 0;
   if (Key == VK_DOWN) direction = 2;
}

// ==========================================================================
//                                                           THAT'S ALL FOLKS
// ==========================================================================