/* ---------------------- */
/* 			 ref    				*/
/* ---------------------- */
// https://twitter.com/monfera/status/761355001474187268

/* ---------------------- */
/* 			 config    				*/
/* ---------------------- */
var state =  {}	// state
state.epsilon = 1e-6
state.tau = 2 * Math.PI
state.pi = Math.PI

state.distance2 = (s, t) => (t.x - s.x) * (t.x - s.x) + (t.y - s.y) * (t.y - s.y)
state.distance = (s, t) => Math.sqrt(state.distance2(s, t))

state.quad = d3c.quad()																	// quadtree for multifind 
		.x(function(d) {return d.x})
		.y(function(d) {return d.y})
state.diabonalv = d => state.quad.diagonal(d, v = 1.1)		// cords vibration

state.debug = false
state.started = true
state.mousedown = function() {
	if (state.debug && state.started) {simulation.stop(), state.started = false}
	 else {simulation.restart(), state.started = true}
}			
state.linkId = (s, t) => s.idx + ':' + t.idx

state.width = 600
state.height = 400

state.imagePath = "./space.jpg"

state.raptorCount = 10		/ 1
state.raptorLineWidth = 1
state.raptorFill = 'yellow' //  "red"
state.raptorArmsStroke = "orange"
state.raptorArmsFactor = 4  / 1 // Infinity
state.raptorRadius = 3	//		* 10
state.raptorSearchRange = Infinity
state.raptorAttractionFactor = 1.1			// plays with arms factors against impact factors
state.raptorAbsorbfn = function(node) { return node.radius * state.raptorAttractionFactor}		// collision effect
state.raptorRadiusPostAbsorb = (s, t) => Math.sqrt((s.radius * s.radius) + (t.radius * t.radius))
state.raptorColorPostAbsorb = function(s, t) {
	let scal = d3.scaleLinear()
	.domain([state.preyCount,  0 ])
	.range([state.raptorFill, state.preyFill])
	return scal(state.preyLiving(state.nodes).length)
}
state.collideRadius = function(node) { return node.radius * state.prayImpactFactor}		 

state.preyCount = 3000	// / 30 // Infinity
state.preyRadius = 0.5	// 		* 10
state.preyFill = 'grey' // 'blue'
state.preyStroke = 'blue'
state.preyStrokeWidth = 0
state.preyPostFill = 'red'
state.preyPostStroke = 'yellow'
state.preyPostStrokeWidth = 0.2
state.prayImpactFactor = state.raptorAttractionFactor  * 2 || 1 // collision effect behavior factor


state.traceLineWidth = state.raptorRadius
state.traceStrokeStyleLight = "rgba(128, 0, 255, 0.02)"
state.traceStroke = 'yellow' // "red"
state.traceOpacity = 0.1
state.traceFill = 'transparent'
state.traceLength = 5000
state.tracePath = d => "M" + d.join("L")



/* ---------------------- */
/* 			 data     				*/
/* ---------------------- */
state.raptorItems = d3.range(state.raptorCount).map(function(d, i) {
  return {
    radius: state.raptorRadius,
    x: Math.random() * state.width,
    y: Math.random() * state.height,
    vx: 0.1,
    vy: 0.5,
		links: [],		// ref to prey
		type: 'raptor',
		color: state.raptorFill,
		idx: i		
  }})

state.traceItems = d3.range(state.raptorCount).map(function(d, i) {
	var p0 = [state.raptorItems[i].x, state.raptorItems[i].y]
	return [p0]
}) 

state.preyItems = d3.range(state.preyCount).map(function(d, i) {
  var randomAngle = Math.random() * 2 * Math.PI
  return {
    radius: state.preyRadius,
    x: Math.random() * state.width,
    y: Math.random() * state.height,
    vx: 5 * Math.cos(randomAngle),		// browninan movement
    vy: 5 * Math.sin(randomAngle),		// as per Robert Monfera
		saugs: [],		// ref to raptors
		type: 'prey',
		color: state.preyFill,
		idx: i
  }
})

state.preyLiving = d => d.filter(d => d.type === 'prey')			// prey
									 .filter(d => d.radius > 1e-6)

									 
state.links = state.raptorItems.reduce(function(p, c, i, a) {
	return p.concat(c.links)
}, [])
				
state.nodes = [...state.raptorItems, ...state.preyItems]	 
									 
/* ---------------------- */
/* 			 svg layer				*/
/* ---------------------- */
var svg = d3c.layer()
      .on("mousedown", state.mousedown)

/* ---------------------- */
/* 			 image layer			*/
/* ---------------------- */
function showimage() {
		var imgLayer = d3c.layer({cls: 'background', item: 'image.image', data: ['image']}).e
			.attr("xlink:href", state.imagePath)
				.attr("x", "0")
				.attr("y", "0")
				.attr("width", "600")
				.attr("height", "400")
}
if (state.debug !== true) showimage()
			
/* ---------------------- */
/* 			 forces   				*/
/* ---------------------- */

// container
var container = function(alpha, nodes) {

  var node
  var i
  for (i = 0; i < nodes.length; i++) {
    node = nodes[i]
		
    if(Math.abs(node.x) < 0 + node.radius) {
      node.vx *= -1
    }
    if(Math.abs(node.x) > state.width - node.radius) {
      node.vx *= -1
    }
    if(Math.abs(node.y) < 0 + node.radius) {
      node.vy *= -1
    }
   if(Math.abs(node.y) > state.height - node.radius) {
      node.vy *= -1
    }
  }
}

/* ---------------------- */
/* 			 simulation				*/
/* ---------------------- */

var simulation = d3.forceSimulation(state.nodes)
  .alphaDecay(0)
  .velocityDecay(5e-4)
  .force("collide", d3.forceCollide().radius(state.collideRadius).strength(2).iterations(1))
  .force("container", d => container(d, state.nodes))
  .on("tick", ticked)


/* ---------------------- */
/* 			 tick   				*/
/* ---------------------- */
	
function ticked() {

	if (state.debug === true) console.log('preys: ', state.preyLiving(state.nodes).length)

	simulation
			.nodes(state.nodes)
		
	let quad = d3c.quad()
			.x(function(d) {return d.x})
			.y(function(d) {return d.y})
			.addAll(state.preyLiving(state.nodes))
			
		for (let i = 0; i < state.raptorItems.length; i++) {
				let s = state.raptorItems[i]
				let ts = quad.findmany(s.x, s.y, state.raptorSearchRange, state.raptorArmsFactor)
				let ls = []
				let hs = []
				for (let i = 0; i < ts.length; i++) {
						let t = ts[i]
							let ln = {source: s, target: t, idx: state.linkId(s, t)}
							let hk = {source: t, target: s, idx: state.linkId(s, t)}
							ls.push(ln)		// raptor
							hs.push(hk)		// prey
							let dst = state.distance(s, t)
							let range = state.raptorAbsorbfn(s)
							
							if (dst < range) {				// absorbed
									s.radius = state.raptorRadiusPostAbsorb(s, t)
									s.color = state.raptorColorPostAbsorb(s, t)
									t.radius = state.epsilon
									t.isvoid = true
							}
						t.saugs = hs
				}
				s.links = ls
		}

	state.links = state.raptorItems.reduce(function(p, c, i, a) {
				return p.concat(c.links)
			}, [])

	render(state)					
}

/* ---------------------- */
/* 			 render   				*/
/* ---------------------- */
	
function render(s) {
	let state = Object.assign(s)

	// links
	var linksIds = (d, i) => state.linkId(d.source, d.target)
	var linksLayer = d3c.layer({cls: 'links', item: 'path.linkPath', data: state.links, idfn: linksIds})
	linksLayer.m
			.attr("d", state.diabonalv)
			.style("fill", "transparent")
			.style("stroke", state.raptorArmsStroke)
			.style("stroke-width", "1px")
			
	linksLayer.x
			.remove()
			
	// traces
	var tracesLayer = d3c.layer({cls: 'traces', item: 'path.trace', data: state.traceItems})
	tracesLayer.m
		.attr("d", function(d, i) { 
						d.push([state.raptorItems[i].x,  state.raptorItems[i].y])	// add present
						d.splice(0, d.length - state.traceLength)												// remove past
						var r = d ? state.tracePath(d) : null
						return r
				})
		.style("fill", function(d, i) { return state.traceFill })
		.style("stroke", function(d) { return state.traceStroke })			
		.style("stroke-width", function(d) { return state.traceLineWidth })	
		.style("opacity",  state.traceOpacity)
		
	// prey		
	var preysLayer = d3c.layer({cls: 'preys', item: 'circle.prey', data: state.preyItems})
	preysLayer.u
			.style("fill", function(d, i) { return  (d.isvoid === true) ? state.preyPostFill : state.preyFill })		
			.style("stroke", function(d) { return  (d.isvoid === true) ? state.preyPostStroke : state.preyFill })		
			.style("stroke-width", function(d) { return  (d.isvoid === true) ? state.preyPostStrokeWidth : state.preyStrokeWidth })	
			.style("opacity", function(d, i) { return  (d.isvoid === true) ? 0 : 1 })
		
			.attr("cx", function(d) { return d.x })
			.attr("cy", function(d) { return d.y })
			.attr("r", function(d) { return  (d.isvoid === true) ? 10 : d.radius })	
			
	preysLayer.e
			.attr("cx", function(d) { return d.x })
			.attr("cy", function(d) { return d.y })
			.attr("r", function(d) {return d.radius })	
			.style("fill", function(d, i) { return state.preyFill })
			.style("stroke", function(d) { return state.preyFill })	
			.style("stroke-width", function(d) { return 0.2 })	
			
	preysLayer.x
			.attr("cx", function(d) { return d.x })
			.attr("cy", function(d) { return d.y })
			.style("fill", function(d, i) { return 'transparent' })
			.style("stroke", function(d) { return "red" })					
			
	// raptors
	var raptorsLayer = d3c.layer({cls: 'particules', item: 'circle', data: state.raptorItems})	
	raptorsLayer.m
			.attr("cx", function(d) { return d.x })
			.attr("cy", function(d) { return d.y })
			.attr("r", function(d) { return d.radius })			
			.style("stroke-width", function(d) { return state.raptorLineWidth })			
			.style("fill", function(d) { 
						return d.color })			

	if (state.debug) d3c.drag(raptorsLayer.m)								
						
}