-- LUA Script - precede every function and global member with lowercase name of script + '_main'
-- Default script - does nothing.

local Q = require "scriptbank\\quatlib"

local deg    = math.deg
local rad    = math.rad
local sin    = math.sin
local cos    = math.cos
local atan   = math.atan2
local pi     = math.pi
local abs    = math.abs
local random = math.random

local planes = {}

function helicopter_init(e)	
	Include("quatlib.lua")
end

local function CloserThan(Ent, dist)
	local dX, dZ = Ent.x - g_PlayerPosX, Ent.z - g_PlayerPosZ
	
	return (dX*dX + dZ*dZ) < dist*dist
end

local function TimerExpired(p)
	return g_Time > p.timer
end

local function SetTimerSecs(p, val)
	if TimerExpired(p) then
		p.timer = g_Time + val * 1000
	end
end

local function PlayerAngle(Ent)   -- gives angle to player from entity
	return 180 + deg(atan(Ent.x - g_PlayerPosX, Ent.z - g_PlayerPosZ))
end

local function turnAngle(tA, cA)  -- degrees
	local dA = tA - cA

	if dA > 0 then
		if dA < 180 then return dA end
		return -(360 - dA)
	else
		if dA > 180 then return -(360 + dA) end
		return dA
	end
end

local function Rotate3D (x, y, z, xrot, yrot, zrot) 

	function RotatePoint2D (x, y, Ang)  -- Ang in radians
		local Sa, Ca = sin(Ang), cos(Ang)
		return x*Ca - y*Sa, x*Sa + y*Ca
	end
 
	local NX, NY, NZ = x, y, z

	-- X
	NZ, NY = RotatePoint2D (NZ, NY, -xrot)
	
	-- Y
	NX, NZ = RotatePoint2D (NX, NZ, -yrot)
	
	-- Z
	NY, NX = RotatePoint2D (NY, NX, -zrot)

	return NX, NY, NZ
end

local function WrapAng(Ang)  -- Ang in radians
	local P2 = pi * 2
	local RAng = Ang
	while RAng > P2 do
		RAng = RAng - P2
	end
	while RAng < -P2 do
		RAng = RAng + P2
	end
	return RAng
end

local pitchQuat = {}
local bankQuat  = {}

local function updatePosition(e, Ent, plane)

	local FPSrel = 1 / g_scheduler[e].frames_per_second

	plane.angleLeft = turnAngle(plane.targAngle, plane.currAngle)
	
	-- do rotation here
	if abs(plane.angleLeft) > 0.5 then
	
		local turnAmount = plane.turnSpeed * FPSrel
		
		if turnAmount > abs(plane.angleLeft) then
			turnAmount = abs(plane.angleLeft)
		end
		
		local turnQuat 
		
		if plane.angleLeft > 0 then
			turnQuat = Q.FromEuler(0, rad(turnAmount), 0)
			plane.currAngle = plane.currAngle + turnAmount
			plane.targBank = 30
		else
			turnQuat = Q.FromEuler(0, -rad(turnAmount), 0)
			plane.currAngle = plane.currAngle - turnAmount
			plane.targBank = -30
		end
		
		plane.quat = Q.Mul(plane.quat, turnQuat)
	else
		plane.angleLeft = 0
		if plane.state ~= 'fall' and plane.state ~= 'startfall' then
			plane.targBank = 0 
		end
	end
	
	local quat = plane.quat
	
	--------------------------------------------------------------
	-- do bank here
	if plane.targBank ~= plane.currBank then
		local bA = (plane.targBank - plane.currBank) * FPSrel
		
		plane.currBank = bA + plane.currBank
		
		bankQuat[e] = Q.FromEuler(0, 0, rad(plane.currBank))
	end
	
	if plane.currBank ~= 0 then
		quat = Q.Mul(quat, bankQuat[e])
	end

	--------------------------------------------------------------
	-- do pitch here
	if plane.targPitch ~= plane.currPitch then
		local pA = (plane.targPitch - plane.currPitch) * FPSrel
		
		plane.currPitch = pA + plane.currPitch
		
		pitchQuat[e] = Q.FromEuler(rad(plane.currPitch), 0, 0)
	end
	
	if plane.currPitch ~= 0 then
		quat = Q.Mul(quat, pitchQuat[e])
	end
	
	--------------------------------------------------------------
	local xA, yA, zA = Q.ToEuler(quat)

	-- change the vector to match 'forward' for the model, i.e. pointing up is 0,0,1 left would be -1,0,0 etc
	local vX, vY, vZ = Rotate3D (0, 0, 1, xA, yA, zA)

	
	local cX, cZ = vX * plane.speed * FPSrel, vZ * plane.speed * FPSrel
	
	-- climb code
	local cY = plane.climbSpeed * FPSrel
	
	plane.x, plane.y, plane.z = plane.x + cX, plane.y + cY, plane.z + cZ

	-- add collision tests here
	
	CollisionOff(e)
	ResetPosition(e, plane.x, plane.y, plane.z)
	ResetRotation(e, deg(xA), deg(yA), deg(zA))
	CollisionOn(e)

end

function helicopter_main(e)

	local Ent = g_Entity[e]
	
	if Ent == nil then return end

	local plane = planes[e]

	if plane == nil then
	
		local Ang = WrapAng(rad(Ent.angley))
		
		planes[e] = {x = Ent.x, y = Ent.y, z = Ent.z,
					 quat         = Q.FromEuler(0, Ang, 0),
					 state        = 'init',
					 timer        = 0,
					 lasttime     = 0,
					 speed        = 0,   -- units per second
					 turnSpeed    = 0,   -- degrees per second
					 climbSpeed   = 0,   -- units per second
					 targAngle    = deg(Ang),
					 currAngle	  = deg(Ang),
					 angleLeft    = 0,   -- radians
					 targPitch    = 0,
					 currPitch    = 0,
					 targBank     = 0,
					 currBank     = 0,
					 height       = 0,   -- units above terrain
					 soundPlaying = false
					};
		return
	end

	if plane.state ~= 'idle' and plane.state ~= 'init' then
		updatePosition(e, Ent, plane)
	end
	
	if plane.state == 'down' or not scheduler(e) then return end
	
	-- initialization 
	if plane.state == 'init' then
		plane.state = 'idle'
		GravityOff(e) 

	elseif plane.state == 'idle' and CloserThan(Ent, random(3000,4000)) then
		plane.state = 'takeoff'
		SetTimerSecs(plane, random(3,4))
		plane.climbSpeed = random(80,120)
		
	-- taking off
	elseif plane.state == 'takeoff' then 
		
		if TimerExpired(plane) then  
			plane.state = 'takeoff2'
			SetTimerSecs(plane, random(3,4))
			plane.targPitch = random(-35,-25)
		end
	
	elseif plane.state == 'takeoff2' then
	
		if not TimerExpired(plane)  then
			plane.climbSpeed = plane.climbSpeed + random(6,9)
			
			plane.speed = plane.speed + random(18,22)
		else
			plane.state = 'fly' 
			plane.targPitch = random(-15,-10)
		end
		
	-- flying straight 
	elseif plane.state == 'fly' then
	
		if plane.climbSpeed > 0 then
			plane.climbSpeed = plane.climbSpeed - random(6,9)
		else
			plane.climbSpeed = 0
		end
			
		if not CloserThan(Ent, random(7000,9000)) then
			plane.state = 'turn'
			plane.turnSpeed = random(20,30)
			plane.speed = plane.speed / 1.5
		else
			if not plane.soundPlaying then 
				LoopSound(e, 0)
				SetSoundVolume(80)
				plane.soundPlaying = true
			end
		end	
		
	-- turning 
	elseif plane.state == 'turn' then
	
		plane.targAngle = PlayerAngle(Ent)
		
		plane.state = 'turning'

	elseif plane.state == 'turning' then
	
		if plane.angleLeft == 0 and CloserThan(Ent, random(3000, 4000)) then 
			plane.state = 'fly' 
			plane.speed = plane.speed * 1.5
		else
			plane.targAngle = PlayerAngle(Ent)
		end		

	-- falling down
	elseif plane.state == 'startfall' then

		plane.targBank  = random(-60,60)
		plane.targPitch = random(-60,60)
		plane.targAngle = random(0,359)
		
		plane.state = 'fall'
		
	elseif plane.state == 'fall' then
		
		if plane.speed > 10 then plane.speed = plane.speed - 7 end
		
		plane.climbSpeed = plane.climbSpeed - 5
		
		if TimerExpired(plane) then
			SetTimerSecs(plane, 3)
			plane.targBank  = random(-60,60)
			plane.targPitch = random(-60,60)
			plane.targAngle = random(0,359)
		end
		
		if Ent.y <= GetTerrainHeight(Ent.x, Ent.z) + 50 then -- if hit the ground 
			plane.state = 'down' -- change plane.state to down 
			plane.Timer = math.huge
			StopParticleEmitter(e) -- stop smoke 
			SetEntityHealth(e, 0)
		end
	end

	-- if flying and is shot to death (while keeping entity alive), set falling plane.state and start smoke 
	if Ent.health < 100 then
		SetEntityHealth(e, 1000)
		plane.state = 'startfall' 
		StartParticleEmitter(e) 
		StopSound(e, 0) 
		SetTimerSecs(plane, 4)
		GravityOn(e) 
	end	
end

----------------------------------------------------------------
-- Scheduler, this nifty little function keeps track of time. --
-- The main routine should be called every frame and returns  --
-- a flag indicating whether the passed in time has expired   --
-- since the last time it was called.                         --
-- If no time period is specified 100ms is used by default,   --
-- i.e. 1/10th of a second.                                   --
-- The caller can either ignore the return flag or use it to  --
-- trigger time sensitive functionality.                      --
-- A global value giving the frames per second count is also  --
-- generated, this can be used in script to make animations   --
-- independent of frames.                                     --
-- The reason this function is tied to an entity rather than  --
-- being global is so that each entity can be triggered at a  --
-- different time rather than all being triggered in the same --
-- frame. 
----------------------------------------------------------------
g_scheduler = {}

function scheduler(e, period)
	period = period or 100  -- defaults to tenths of a second (100ms)
 
	if g_Time == nil then return false end
	
	if g_scheduler[e] == nil then
	
		g_scheduler[e] = {frames_per_second      = 60,
						  period_accumulated     = math.random(0, period),
						  accumulated_time       = 0,
						  timer_value_last_frame = g_Time,
						  frame_counter          = 0};
						  
	-- 'test' mode sometimes doesn't clear Lua globals so if
	-- this appears to be the case initialise everything
    elseif g_scheduler[e].accumulated_time > 2000 then
	   
		g_scheduler[e].frames_per_second      = 60
		g_scheduler[e].period_accumulated     = math.random(0, period)
		g_scheduler[e].accumulated_time       = 0
		g_scheduler[e].timer_value_last_frame = g_Time
		g_scheduler[e].frame_counter          = 0
	end
	
	local entry = g_scheduler[e]
	local do_this_frame_flag = false
		
	entry.frame_counter = entry.frame_counter + 1

	local time_since_last_frame = g_Time - entry.timer_value_last_frame
	
	if (entry.period_accumulated + time_since_last_frame) > period then 
		
		entry.period_accumulated = (entry.period_accumulated + 
		                            time_since_last_frame) - period;  
		do_this_frame_flag = true
	else
		entry.period_accumulated = entry.period_accumulated + time_since_last_frame
	end

	if (entry.accumulated_time + time_since_last_frame) > 1000 then -- more than a second passed?

		entry.accumulated_time = (entry.accumulated_time + 
								  time_since_last_frame) - 1000;
		entry.frames_per_second = entry.frame_counter
		entry.frame_counter = 0
	else
		entry.accumulated_time = entry.accumulated_time + time_since_last_frame
	end

	entry.timer_value_last_frame = entry.timer_value_last_frame + time_since_last_frame 

	return do_this_frame_flag
end