/*
 * Pixel Dungeon
 * Copyright (C) 2012-2015 Oleg Dolya
 *
 * Shattered Pixel Dungeon
 * Copyright (C) 2014-2026 Evan Debenham
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 */

package com.shatteredpixel.shatteredpixeldungeon.levels.builders;

import com.shatteredpixel.shatteredpixeldungeon.levels.rooms.Room;
import com.shatteredpixel.shatteredpixeldungeon.levels.rooms.connection.ConnectionRoom;
import com.watabou.utils.PointF;
import com.watabou.utils.Random;

import java.util.ArrayList;

//A builder with one core loop as its primary element
public class LoopBuilder extends RegularBuilder {
	
	//These methods allow for the adjusting of the shape of the loop
	//by default the loop is a perfect circle, but it can be adjusted
	
	//increasing the exponent will increase the the curvature, making the loop more oval shaped.
	private int curveExponent = 0;
	
	//This is a percentage (range 0-1) of the intensity of the curve function
	// 0 makes for a perfect linear curve (circle)
	// 1 means the curve is completely determined by the curve exponent
	private float curveIntensity = 1;
	
	//Adjusts the starting point along the loop.
	// a common example, setting to 0.25 will make for a short fat oval instead of a long one.
	private float curveOffset = 0;
	
	public LoopBuilder setLoopShape(int exponent, float intensity, float offset){
		this.curveExponent = Math.abs(exponent);
		curveIntensity = intensity % 1f;
		curveOffset = offset % 0.5f;
		return this;
	}
	
	private float targetAngle( float percentAlong ){
		percentAlong += curveOffset;
		return 360f * (float)(
						curveIntensity * curveEquation(percentAlong)
						+ (1-curveIntensity)*(percentAlong)
						- curveOffset);
	}
	
	private double curveEquation( double x ){
		return Math.pow(4, 2*curveExponent)
				*(Math.pow((x % 0.5f )-0.25, 2*curveExponent + 1))
				+ 0.25 + 0.5*Math.floor(2*x);
	}
	
	private PointF loopCenter;
	
	@Override
	public ArrayList<Room> build(ArrayList<Room> rooms) {
		
		setupRooms(rooms);
		
		if (entrance == null){
			return null;
		}
		
		entrance.setSize();
		entrance.setPos(0, 0);
		
		float startAngle = Random.Float(0, 360);

		mainPathRooms.add(0, entrance);
		if (exit != null) mainPathRooms.add((mainPathRooms.size()+1)/2, exit);

		ArrayList<Room> loop = new ArrayList<>();
		float[] pathTunnels = pathTunnelChances.clone();
		for (Room r : mainPathRooms){
			loop.add(r);
			
			int tunnels = Random.chances(pathTunnels);
			if (tunnels == -1){
				pathTunnels = pathTunnelChances.clone();
				tunnels = Random.chances(pathTunnels);
			}
			pathTunnels[tunnels]--;
			
			for (int j = 0; j < tunnels; j++){
				loop.add(ConnectionRoom.createRoom());
			}
		}
		
		Room prev = entrance;
		float targetAngle;
		for (int i = 1; i < loop.size(); i++){
			Room r = loop.get(i);
			targetAngle = startAngle + targetAngle( i / (float)loop.size());
			if (placeRoom(rooms, prev, r, targetAngle) != -1) {
				prev = r;
				if (!rooms.contains(prev))
					rooms.add(prev);
			} else {
				//FIXME this is lazy, there are ways to do this without relying on chance
				return null;
			}
		}
		
		//FIXME this is still fairly chance reliant
		// should just write a general function for stitching two rooms together in builder
		while (!prev.connect(entrance)){
			
			ConnectionRoom c = ConnectionRoom.createRoom();
			if (placeRoom(loop, prev, c, angleBetweenRooms(prev, entrance)) == -1){
				return null;
			}
			loop.add(c);
			rooms.add(c);
			prev = c;
		}
		
		if (shop != null) {
			float angle;
			int tries = 10;
			do {
				angle = placeRoom(loop, entrance, shop, Random.Float(360f));
				tries--;
			} while (angle == -1 && tries >= 0);
			if (angle == -1) return null;
		}
		
		loopCenter = new PointF();
		for (Room r : loop){
			loopCenter.x += (r.left + r.right)/2f;
			loopCenter.y += (r.top + r.bottom)/2f;
		}
		loopCenter.x /= loop.size();
		loopCenter.y /= loop.size();
		
		ArrayList<Room> branchable = new ArrayList<>(loop);
		
		ArrayList<Room> roomsToBranch = new ArrayList<>();
		roomsToBranch.addAll(multiConnections);
		roomsToBranch.addAll(singleConnections);
		weightRooms(branchable);
		if (!createBranches(rooms, branchable, roomsToBranch, branchTunnelChances)){
			return null;
		}
		
		findNeighbours(rooms);
		
		for (Room r : rooms){
			for (Room n : r.neigbours){
				if (!n.connected.containsKey(r)
						&& Random.Float() < extraConnectionChance){
					r.connect(n);
				}
			}
		}
		
		return rooms;
	}
	
	@Override
	protected float randomBranchAngle( Room r ) {
		if (loopCenter == null)
			return super.randomBranchAngle( r );
		else {
			//generate four angles randomly and return the one which points closer to the center
			float toCenter = angleBetweenPoints( new PointF((r.left + r.right)/2f, (r.top + r.bottom)/2f), loopCenter);
			if (toCenter < 0) toCenter += 360f;
			
			float currAngle = Random.Float(360f);
			for( int i = 0; i < 4; i ++){
				float newAngle = Random.Float(360f);
				if (Math.abs(toCenter - newAngle) < Math.abs(toCenter - currAngle)){
					currAngle = newAngle;
				}
			}
			return currAngle;
		}
	}
}
