// Terrier.java
// Description: Acts like a vicious terrier!
// Author: Chris Wilcox
// Date: 4/28/2015

package myPackage;
import myPackage.Interface.eMove;

public class Terrier {

	// Current location of terrier
	public int currentRow;
	public int currentCol;
	private char board[][];

	// Information about closest squirrel
	private int closestRow;
	private int closestCol;
	public boolean ateSquirrel;
	
	// Create a terrier
	public Terrier(int row, int Col, char board[][]) {
		this.currentRow = row;
		this.currentCol = Col;
		this.board = board;
		this.ateSquirrel = false;
	}

	// Getters for terrier
	public int getCurrentRow() {
		return currentRow;
	}

	public int getCurrentCol() {
		return currentCol;
	}

	// Move the terrier
	public eMove move() {

		// Find closest squirrel
		findClosest();

		// Figure out move
		eMove e = selectMove();

		// Keep the terrier on the board
		if ((e == eMove.DOWN_LEFT || e == eMove.DOWN || e == eMove.DOWN_RIGHT)
				&& currentRow == board.length - 1)
			e = eMove.LEFT;
		if ((e == eMove.UP_LEFT || e == eMove.LEFT || e == eMove.DOWN_LEFT)
				&& currentCol == 0)
			e = eMove.UP;
		if ((e == eMove.UP_LEFT || e == eMove.UP || e == eMove.UP_RIGHT)
				&& currentRow == 0)
			e = eMove.RIGHT;
		if ((e == eMove.UP_RIGHT || e == eMove.RIGHT || e == eMove.DOWN_RIGHT)
				&& currentCol == board[0].length - 1)
			e = eMove.DOWN;
		
		// Update board
		if (!updateBoard(e))
			e = eMove.NO_MOVE;

		return e;
	}

	// Find closest squirrel
	public void findClosest() {

		double minimum = Double.MAX_VALUE;
		closestRow = -1;
		closestCol = -1;

		for (int row = 0; row < board.length; row++) {
			for (int col = 0; col < board[0].length; col++) {
				if (board[row][col] == 'S') {

					// Found a squirrel
					double distance = computeDistance(row, currentRow, col, currentCol);
					if (distance < minimum) {

						// Store the closest
						minimum = distance;
						closestRow = row;
						closestCol = col;
					}
				}
			}
		}
	}

	// Figure out move
	public eMove selectMove() {

		eMove move;

		if (closestRow < currentRow) {
			if (closestCol < currentCol)
				move = eMove.UP_LEFT;
			else if (closestCol == currentCol)
				move = eMove.UP;
			else
				move = eMove.UP_RIGHT;
		} else if (closestRow == currentRow) {
			if (closestCol < currentCol)
				move = eMove.LEFT;
			else
				move = eMove.RIGHT;
		} else { // if (closestRow > currentRow
			if (closestCol < currentCol)
				move = eMove.DOWN_LEFT;
			else if (closestCol == currentCol)
				move = eMove.DOWN;
			else
				move = eMove.DOWN_RIGHT;
		}
		return move;
	}
	
	// Update board with current location
	public boolean updateBoard(eMove e) {

		// Remove terrier
		board[currentRow][currentCol] = '-';
		
		// Save previous position
		int saveRow = currentRow;
		int saveCol = currentCol;
		
		// Move terrier
		switch (e) {
		case LEFT: currentCol--; break;
		case UP_LEFT: currentRow--; currentCol--; break;
		case UP: currentRow--; break;
		case UP_RIGHT: currentRow--; currentCol++; break;
		case RIGHT: currentCol++; break;
		case DOWN_RIGHT: currentRow++; currentCol++; break;
		case DOWN: currentRow++; break;
		case DOWN_LEFT: currentRow++; currentCol--; break;
		default:
		}

		// Replace terrier
		if (board[currentRow][currentCol] == '-') {
			board[currentRow][currentCol] = 'T';
			return true;
		}
		// Eat squirrel!
		else if (board[currentRow][currentCol] == 'S') {
			board[currentRow][currentCol] = 'A';
			ateSquirrel = true;
			return true;
		}

		// Avoid collisions, do not move
		currentRow = saveRow;
		currentCol = saveCol;
		board[currentRow][currentCol] = 'T';
		return false;
	}

	// Compute euclidean distance
	private double computeDistance(int row0, int row1, int col0, int col1) {
		double rowDiff = Math.pow(row1 - row0, 2);
		double colDiff = Math.pow(col1 - col0, 2);
		return Math.sqrt(rowDiff + colDiff);
	}
}