/*

    Copyright (C) 2015 Apple Inc. All Rights Reserved.

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    Demonstrates flocking behavior -- a combination of separation, alignment, and cohesion goals. Click (OS X) or touch (iOS) and drag and the flock of agents follows the mouse/touch location together.

 */

#import "AAPLFlockScene.h"

#import "AAPLAgentNode.h"

@interface AAPLFlockScene ()

@property NSArray<AAPLAgentNode *> *flock;

@property GKGoal *seekGoal;

@end

@implementation AAPLFlockScene

- (NSString *)sceneName {

    return @"FLOCKING";

}

- (void)didMoveToView:(nonnull SKView *)view {

    [super didMoveToView:view];

    // Create a flock of similar agents.

    NSMutableArray<GKAgent2D *> *agents = [NSMutableArray arrayWithCapacity:20];

    NSInteger agentsPerRow = 4;

    for (NSInteger i = 0; i < agentsPerRow*agentsPerRow; i++) {

        CGFloat x = CGRectGetMidX(self.frame) + i % agentsPerRow * 20;

        CGFloat y = CGRectGetMidY(self.frame) + i / agentsPerRow * 20;

        AAPLAgentNode *boid = [[AAPLAgentNode alloc] initWithScene:self

                                                            radius:10

                                                          position:CGPointMake(x, y)];

        [self.agentSystem addComponent:boid.agent];

        [agents addObject:boid.agent];

        boid.drawsTrail = NO;

    }

    self.flock = [agents copy];

    static const float separationRadius =  0.553f * 50;

    static const float separationAngle  = 3 * M_PI / 4.0f;

    static const float separationWeight =  10.0f;

    static const float alignmentRadius = 0.83333f * 50;

    static const float alignmentAngle  = M_PI / 4.0f;

    static const float alignmentWeight = 12.66f;

    static const float cohesionRadius = 1.0f * 100;

    static const float cohesionAngle  = M_PI / 2.0f;

    static const float cohesionWeight = 8.66f;

    // Separation, alignment, and cohesion goals combined cause the flock to move as a group.

    GKBehavior* behavior = [[GKBehavior alloc] init];

    [behavior setWeight:separationWeight forGoal:[GKGoal goalToSeparateFromAgents:agents maxDistance:separationRadius maxAngle:separationAngle]];

    [behavior setWeight:alignmentWeight forGoal:[GKGoal goalToAlignWithAgents:agents maxDistance:alignmentRadius maxAngle:alignmentAngle]];

    [behavior setWeight:cohesionWeight forGoal:[GKGoal goalToCohereWithAgents:agents maxDistance:cohesionRadius maxAngle:cohesionAngle]];

    for (GKAgent2D *agent in agents) {

        agent.behavior = behavior;

    }

    // Create the seek goal, but add it to the behavior only in -setSeeking:.

    self.seekGoal = [GKGoal goalToSeekAgent:self.trackingAgent];

}

- (void)setSeeking:(BOOL)seeking {

    [super setSeeking:seeking];

    for (GKAgent2D *agent in self.agentSystem) {

        if (seeking) {

            [agent.behavior setWeight:1 forGoal:self.seekGoal];

        }

        else {

            [agent.behavior setWeight:0 forGoal:self.seekGoal];

        }

    }

}

@end