using Printf
using FFTW
include("navier_stokes.jl")
include("driving.jl")
include("print.jl")

function main()
  ## defaults
  delta=0.0001220703125
  nsteps=10000000
  nu=0.00048828125
  print_freq=1000

  K1=16
  K2=K1
  N1=4*K1+1
  N2=4*K2+1

  # read cli arguments
  (params,driving,command)=read_args(ARGS)

  # whether N was set in parameters
  setN1=false
  setN2=false

  # read params
  if params!=""
    for param in split(params,";")
      terms=split(param,"=")
      if length(terms)!=2
	print(stderr,"error: could not read parameter '",param,"'.\n")
	exit(-1)
      end
      lhs=string(terms[1])
      rhs=string(terms[2])
      if lhs=="K1"
	K1=parse(Int64,rhs)
      elseif lhs=="K2"
	K2=parse(Int64,rhs)
      elseif lhs=="K"
	K1=parse(Int64,rhs)
	K2=K1
      elseif lhs=="N1"
	N1=parse(Int64,rhs)
	setN1=true
      elseif lhs=="N2"
	N2=parse(Int64,rhs)
	setN2=true
      elseif lhs=="N"
	N1=parse(Int64,rhs)
	N2=N1
	setN1=true
	setN2=true
      elseif lhs=="nsteps"
	nsteps=parse(Int64,rhs)
      elseif lhs=="nu"
	nu=parse(Float64,rhs)
      elseif lhs=="delta"
	delta=parse(Float64,rhs)
      elseif lhs=="print_freq"
	print_freq=parse(Int64,rhs)
      else
	print(stderr,"unrecognized parameter '",lhs,"'.\n")
	exit(-1)
      end
    end
  end

  ## read driving
  if driving=="test"
    g=(kx,ky)->g_test(kx,ky)
  end

  ## set parameters
  if ! setN1
    N1=4*K1+1
  end
  if ! setN2
    N2=4*K2+1
  end

  ## run command
  if command=="uk"
    navier_stokes_uk(nsteps,nu,g,N1,N2,K1,K2,delta,print_freq)
  elseif command=="alpha"
    navier_stokes_alpha(nsteps,nu,g,N1,N2,K1,K2,delta,print_freq)
  else
    print(stderr,"unrecognized command '",command,"'.\n")
    exit(-1)
  end
end

# read cli arguments
function read_args(ARGS)
  # flag
  flag=""

  # output strings
  command=""
  params=""
  # default driving force
  driving="test"

  # loop over arguments
  for arg in ARGS
    # argument that starts with a dash
    if arg[1]=='-'
      # go through characters after dash
      for char in arg[2:length(arg)]
	
	# set params
	if char=='p'
	  # raise flag
	  flag="params"
	elseif char=='g'
	  # raise flag
	  flag="driving"
	else
	  print_usage()
	  exit(-1)
	end
      end
    # arguments that do not start with a dash
    else
      if flag=="params"
	params=arg
      elseif flag=="driving"
	driving=arg
      else
	command=arg
      end
      # reset flag
      flag=""
    end
  end

  if command==""
    print_usage()
    exit(-1)
  end

  return (params,driving,command)
end

# usage
function print_usage()
  print(stderr,"usage:  nstrophy [-p params] [-g driving] <command>\n")
end

main()