textitem = nil

projectile = nil
projectileDistance = 200
projectileSpeed = 6000
tau = math.pi * 2


function removeObject(object)
	object:removeFromGame()
end

function removeText() removeObject(textitem) textitem = nil end
function removeProjectile() removeObject(projectile) projectile = nil end

-- pass 'nil' for angleOfAttack to attack from a random vector
-- RADIANS!
function kineticTrap(objectToHit, angleOfAttack)
	if(angleOfAttack == nil) then
		angleOfAttack = math.random(0, tau * 10)
		angleOfAttack = angleOfAttack * .1
	end

	if(projectile == nil) then
		local currentPos = objectToHit:getLoc()
		local x = currentPos.x + (projectileDistance * math.cos(angleOfAttack))
		local y = currentPos.y + (projectileDistance * math.sin(angleOfAttack))

		projectile = ResourceItem.new()
		projectile:setLoc(x, y)
		projectile:setVel(point.new(-projectileSpeed * math.cos(angleOfAttack), -projectileSpeed * math.sin(angleOfAttack)))
      
		levelgen:addItem(projectile)

		Timer:scheduleOnce(removeProjectile, 4000)
	end
end


function textNearShip(ship, textMsg)
	if(textitem == nil) then
		local loc = ship:getLoc()
		textitem = TextItem.new()
		textitem:setText(textMsg)

		local textGeom = { 
			point.new(loc.x - 150, loc.y + 25), 
			point.new(loc.x + 150, loc.y + 25) 
		}
		textitem:setGeom(textGeom)

		levelgen:addItem(textitem)

		Timer:scheduleOnce(removeText, 4000)
	end
end


function changeTeleportDest(teleporterId, dest)
	local teleporter = levelgen:findObjectById(teleporterId)

	if(teleporter ~= nil) then
		teleporter:clearDests()
		teleporter:addDest(dest)
	end
end


playersInWell = {}
gravityWellCenter = levelgen:findObjectById(5):getLoc()
gravityWellRadius = 255  -- roughly the radius of the zone
gravityWellMaxVelocity = 600  -- equal to normal ship velocity

-- This does a gravity well effect on any ship in the well.  note that this
-- only allows for one gravity well in the level
function doGravityWellEffect()
	for i, v in ipairs(playersInWell)
	do
		local ship = v:getShip()
		local shipLoc = ship:getLoc()
		
		-- Find the vector and its distance from the ship to the center of the well
		local delta = point.new(shipLoc.x - gravityWellCenter.x, shipLoc.y - gravityWellCenter.y)
		local dist = point.length(delta)

		-- Calculate the pull based on how far from the center, pull harder (linearly)
		-- the closer you are (based on radius of well)
		-- local gravityPull = gravityWellMaxVelocity * (1 - (dist / gravityWellRadius))

		-- quadratic  x^2
		-- local gravityPull = gravityWellMaxVelocity * (1 - ((dist * dist) / (gravityWellRadius * gravityWellRadius))

		-- constant  x^0
		local gravityPull = gravityWellMaxVelocity * .333


		local normalizedWellVel = point.normalize(delta)
		local wellVel = point.new(normalizedWellVel.x * gravityPull, normalizedWellVel.y * gravityPull)

		-- Now adjust the ship's velocity
		local shipVel = ship:getVel()
		ship:setVel(shipVel.x - wellVel.x, shipVel.y - wellVel.y)
	end
end

repairItem = levelgen:findObjectById(30)

function testVision(ship)
	logprint(repairItem:isVis())
	if(repairItem:isVis() == false) then
		local loc = ship:getLoc()
		resourceitem = ResourceItem.new()
		resourceitem:setLoc(loc)
		levelgen:addItem(resourceitem)
	end
end


function onShipEnteredZone(ship, zone, zoneType, zoneId)
   -- Do zone specific evilness
	if(zoneId == 6) then
		testVision(ship)
	elseif(zoneId == 5) then
		table.insert(playersInWell, ship:getPlayerInfo()) --ultimately handled in onTick()
	elseif(zoneId == 4) then
		local x = math.random(1, 1000) - 400  -- can't call random with negative numbers?
		local y = math.random(1, 1000) - 400
		changeTeleportDest(10, point.new(x, y))
	elseif(zoneId == 3) then
		kineticTrap(ship, nil)
	elseif(zoneId == 2) then
		textNearShip(ship, "Beware!")
	elseif(zoneId == 1) then
		textNearShip(ship, "Secret Zone!")
	end
end


function onShipLeftZone(ship, zone, zoneType, zoneId)
	if(zoneId == 5) then
		for i, v in ipairs(playersInWell)
		do
			if(v == ship:getPlayerInfo()) then
				table.remove(playersInWell, i)
				break
			end
		end
	end
end


function onTick(deltaTime)
	doGravityWellEffect()
end


-- main!
function main()
   subscribe(Event.ShipEnteredZone)
   subscribe(Event.ShipLeftZone)
   subscribe(Event.Tick)
end