#include "grid.h"
#include <iostream>
#include <SDL/SDL.h>

extern SDL_Surface *loadImg(std::string filename);
extern void drawSurface(int x, int y, SDL_Surface *src, SDL_Surface *dest);

const int Grid::SIZE = 25;

Grid::Grid(std::string back, std::string block, int w, int l) {
	bgImg = loadImg(back);
	blockImg = loadImg(block);
	
	for (int i = 0; i<20; i++) {
		for (int j = 0; j < 10; j++)
			grid[i][j] = 0;
	}
}

Grid::~Grid() {	
	SDL_FreeSurface(bgImg); 
	SDL_FreeSurface(blockImg); 
}

// removes filled in rows and moves remaining rows accordingly
void Grid::process() {	
	// start at bottom of grid
	int i = 19;

	while (i>=0) {
		// if there are no empty spaces in this row, remove it and move the rows 
		// above down
		if (!checkRow(i)) {
			moveRows(i);
		}
		else 
			i--;						
	}
}

bool Grid::gameOver() {
	if (checkRow(3) < 10)
		return true;
	else
		return false;
} 

bool Grid::checkBlock(Block *block) {
	int blockRow = ((block->getY()) / SIZE);
	int blockCol = ((block->getX()) / SIZE)-1;
	int bottom = 1;	
	
	if (block->getGrid(2,0) || block->getGrid(2,1) || block->getGrid(2,2))
		bottom = 0;
		
	// if the block has reached the bottom of the grid, it should be stopped 
	// and added
	if (blockRow == (17+bottom)) {
		addBlock(block, blockRow, blockCol);
		return true;		
	}
	// if the object is above all filled in rows we don't have to check it
	else if (checkRow(blockRow+3) < 10) {
		for (int i = 2; i>=0; i--) {
			for (int j = 2; j>=0; j--) {
				// there is a filled in block here
				if (block->getGrid(i,j)) {
					int thisRow = blockRow+i;
					int thisCol = blockCol+j;
					
					// check if the grid has a block under this one, and if so 
					// add the block to the grid and return true
					if (grid[(blockRow+i)+1][blockCol+j]) {
						addBlock(block, blockRow, blockCol);
						return true;
					}
				}
			}
		}
	}

	return false;
}

void Grid::draw(SDL_Surface *screen) {
	drawSurface(0,0,bgImg,screen);

	for (int i = 0; i < 20; i++) {
		for (int j = 0; j < 10; j++) { 
			if (grid[i][j]) 
				drawSurface((SIZE*(j+1)), (SIZE*(i+1)), blockImg, screen);				
		}
	}
}

// checkRow returns the number of empty blocks in each row (it counts empty so 
// !checkRow(#) will mean a full row)
int Grid::checkRow(int row) {
	int ret = 0;

	for (int i = 0; i < 10; i++) {
		if (!grid[row][i]) 
			ret++;
	}
	
	return ret;		
}

void Grid::addBlock(Block *block, int row, int col) {
	for (int i = 0; i<3; i++) {
		for (int j = 0; j<3; j++) {
			// only replace filled in blocks (otherwise it may erase blocks)
			if (block->getGrid(i,j)) {
				grid[row+i][col+j] = 1;
			}
		}
	}	
}

// move all of the rows above this row down one (removing the current row)
void Grid::moveRows(int row) {
	for (int i = row; i>0; i--) {
		for (int j=0; j<10; j++)
			grid[i][j] = grid[i-1][j];			
	}
	
	for (int j=0; j<10; j++)
		grid[0][j] = 0;			
}