# Interface implementation Ball And Beam ====================================================

export ETHHelicopter, ETHHelicopterSimulator, ETHHelicopterType

struct ETHHelicopter <: PhysicalProcess
    h::Float64
    bias::Float64
end
ETHHelicopter() = ETHHelicopter(0.050)

struct ETHHelicopterSimulator <: SimulatedProcess
    h::Float64
    bias::Float64
    state::Vector{Float64}
end
ETHHelicopterSimulator() = ETHHelicopterSimulator(0.01, zeros(4))

const ETHHelicopterType = Union{ETHHelicopter, ETHHelicopterSimulator}
num_outputs(p::ETHHelicopterType) = 2
num_inputs(p::ETHHelicopterType)  = 2
outputrange(p::ETHHelicopterType) = [(-10,10),(-10,10)] # Beam angle, Ball position
inputrange(p::ETHHelicopterType)  = [(-10,10)]
isstable(p::ETHHelicopterType)    = false
isasstable(p::ETHHelicopterType)  = false
sampletime(p::ETHHelicopterType)  = p.h
bias(p::ETHHelicopterType)        = p.bias


function control(p::ETHHelicopter, u)
	ccall((:comedi_write, comedipath),Int32,(Int32,Int32,Int32,Int32), 0,1,0,num2io(u[1]))
	ccall((:comedi_write, comedipath),Int32,(Int32,Int32,Int32,Int32), 0,1,1,num2io(u[2]))
end

measure(p::ETHHelicopter) = [io2num(ccall((:comedi_read, comedipath),Int32,(Int32,Int32,Int32), 0,0,i)) for i = 0:1] #i=0 for pitch, i=1 for yaw


control(p::ETHHelicopterSimulator, u)  = error("Not yet implemented")
measure(p::ETHHelicopterSimulator)     = error("Not yet implemented")

const comedipath = Pkg.dir("LabProcesses","c","comedi_bridge.so")
const conversion = 65535/20
io2num(x) = x/conversion -10            # Converts from io to float
num2io(x) = round(Int32,(x + 10)*conversion)   # Converts from regular number to io

initialize(p::ETHHelicopter)  = ccall((:comedi_start, comedipath),Int32,(Int32,), 0)
finalize(p::ETHHelicopter)    = (control(p,0);ccall((:comedi_stop, comedipath),Int32,(Int32,), 0))
initialize(p::ETHHelicopterSimulator)  = nothing
finalize(p::ETHHelicopterSimulator)    = nothing