package dev.colors.physics;

import java.util.ArrayList;
import dev.colors.level.Level;
import dev.colors.level.LevelObject;
import dev.colors.level.tile.Tile;

public class Physics {

	private final float gravity = 0.0015f;

	private boolean checkCollision(LevelObject obj, Tile[][] mapTiles) {

		ArrayList<Tile> tiles = obj.getBoundingShape().getTilesOccupying(mapTiles);

		for (Tile t : tiles) {
			if (t.getBoundingShape() != null) {
				if ((t.getBoundingShape()).checkCollision(obj.getBoundingShape())) {
					return true;
				}
			}
		}
		return false;
	}

	private boolean isOnGroud(LevelObject obj, Tile[][] mapTiles) {

		ArrayList<Tile> tiles = obj.getBoundingShape().getGroundTiles(mapTiles);

		obj.getBoundingShape().movePosition(0, 1);

		for (Tile t : tiles) {
			if (t.getBoundingShape() != null) {
				if ((t.getBoundingShape()).checkCollision(obj.getBoundingShape())) {
					obj.getBoundingShape().movePosition(0, -1);
					return true;
				}
			}
		}

		// and obviously we have to move the object back up if we don't hit the
		// ground
		obj.getBoundingShape().movePosition(0, -1);

		return false;
	}

	private void handleCharacters(Level level, int delta) {
		for (dev.colors.character.Character c : level.getCharacters()) {

			// and now decelerate the character if he is not moving anymore
			if (!c.isMoving()) {
				c.decelerate(delta);
			}

			handleGameObject(c, level, delta);
		}
	}

	public void handlePhysics(Level level, int delta) {
		handleCharacters(level, delta);
	}

	private void handleGameObject(LevelObject obj, Level level, int delta) {

		// first update the onGround of the object
		obj.setOnGround(isOnGroud(obj, level.getTiles()));

		// now apply gravitational force if we are not on the ground or when we
		// are about to jump
		if (!obj.isOnGround() || obj.getYVelocity() < 0)
			obj.applyGravity(gravity * delta);
		else
			obj.setYVelocity(0);

		// calculate how much we actually have to move
		float x_movement = obj.getXVelocity() * delta;
		float y_movement = obj.getYVelocity() * delta;

		// we have to calculate the step we have to take
		float step_y = 0;
		float step_x = 0;

		if (x_movement != 0) {
			step_y = Math.abs(y_movement) / Math.abs(x_movement);
			if (y_movement < 0)
				step_y = -step_y;

			if (x_movement > 0)
				step_x = 1;
			else
				step_x = -1;

			if ((step_y > 1 || step_y < -1) && step_y != 0) {
				step_x = Math.abs(step_x) / Math.abs(step_y);
				if (x_movement < 0)
					step_x = -step_x;
				if (y_movement < 0)
					step_y = -1;
				else
					step_y = 1;
			}
		} else if (y_movement != 0) {
			// if we only have vertical movement, we can just use a step of 1
			if (y_movement > 0)
				step_y = 1;
			else
				step_y = -1;
		}

		// and then do little steps until we are done moving
		while (x_movement != 0 || y_movement != 0) {

			// we first move in the x direction
			if (x_movement != 0) {
				// when we do a step, we have to update the amount we have to
				// move after this
				if ((x_movement > 0 && x_movement < step_x)
						|| (x_movement > step_x && x_movement < 0)) {
					step_x = x_movement;
					x_movement = 0;
				} else
					x_movement -= step_x;

				// then we move the object one step
				obj.setX(obj.getX() + step_x);

				// if we collide with any of the bounding shapes of the tiles we
				// have to revert to our original position
				if (checkCollision(obj, level.getTiles())) {

					// undo our step, and set the velocity and amount we still
					// have to move to 0, because we can't move in that
					// direction
					obj.setX(obj.getX() - step_x);
					obj.setXVelocity(0);
					x_movement = 0;
				}

			}
			// same thing for the vertical, or y movement
			if (y_movement != 0) {
				if ((y_movement > 0 && y_movement < step_y)
						|| (y_movement > step_y && y_movement < 0)) {
					step_y = y_movement;
					y_movement = 0;
				} else
					y_movement -= step_y;

				obj.setY(obj.getY() + step_y);

				if (checkCollision(obj, level.getTiles())) {
					obj.setY(obj.getY() - step_y);
					obj.setYVelocity(0);
					y_movement = 0;
					break;
				}
			}
		}
	}

}