#!/usr/bin/ruby
require "ftools"
if ARGV.length<4 || !File.exist?(ARGV[0]) then
  puts "Argumets: [Poisson input file] [I1] [I2] [Btarg] [precision]"
  puts "   where I1 and I2 represent the current range to search for the Btarg"
  puts "   field. 0.5% of Btarg is the default if precision is not specified"
  exit
end

WorkFilePre="CurAdj_"


Dir.chdir(File.dirname(ARGV[0]))
InFName=File.basename(ARGV[0])
FName_base=get_fname_base(InFName)
  File.open("TaggerPoleCenter.in7","w") {|file|
    file.printf("Line\n0 0 0 0\n1\nEnd")}

i1=ARGV[1].to_f
i2=ARGV[2].to_f
Btarg=ARGV[3].to_f 
Bsol_eps= ARGV[4]==nil ? Btarg*0.005 : ARGV[4].to_f
if i1>i2 then i=i1; i1=i2; i2=i; end


# Get initial B value bounds
b1=get_B0(InFName,i1) ; b=b2=get_B0(InFName,i2)


# Iterate via secant method match the current to Btarg
while (b-Btarg).abs() > Bsol_eps
  i=i1+(Btarg-b1)*(i2-i1)/(b2-b1)
  b=get_B0(InFName,i)
  
  if b>Btarg then b2=b; i2=i
  else            b1=b; i1=i;  end

end
File.copy(InFName,InFName+".bak")
File.copy(WorkFilePre+InFName,InFName)
#File.move((WorkFilePre+FName_base).upcase+"T35",FName_base.upcase+"T35")
puts i



# Functions:

BEGIN{
  

  # Define origin B-field search function in SF7 output file
  def get_B0(fname,current)
    fname2=get_upd_cur_fname(fname,current)
    system("cmd /c start /low /w /min automesh " + fname2)
    system("cmd /c start /low /w /min poisson")
    system("SF7 TaggerPoleCenter.in7 " + get_fname_base(fname2) + "T35")
    
    File.open("OUTSF7.TXT") do |io|
      io.each {|line| line.chomp!
        return line.split(' ')[2].to_f.abs() if line.include? "   0.00000       0.00000"}
    end
    0
  end

  def get_fname_base(fname)
    fname_split=fname.split('.'); 
    return fname.chomp(fname_split[fname_split.length-1])
  end

  def get_upd_cur_fname(fin,current)
    fout=WorkFilePre+get_fname_base(fin)+"am"

    fid_in=File.open(fin,"r")
    fid_out=File.open(fout,"w")

    fid_in.readlines.each {|line|
      if line.index("cur")!=nil then
        fid_out.write("cur="+(line.gsub(' ','').index("=-") ? "-":"")+"#{current}\r\n")
      else
        fid_out.write(line)
      end
    }
    
    fid_in.close; fid_out.close
    return fout
  end
}