#!/usr/bin/ruby -Ku

class File
  def each_rec recl
    self.binmode
    loop {
      hdr = self.read(4)
      break if hdr.nil?
      frecl = hdr.unpack('L').first
      unless frecl == recl
	raise "recl file:#{frecl} != #{recl}"
      end
      body = self.read(recl)
      yield body
      body = nil
      frecl2 = self.read(4).unpack('L').first
      unless frecl2 == recl
	raise "recl2 file:#{frecl} != #{recl}"
      end
    }
  end
end

class App

  def initialize argv
    @fbin, fcfg, time, span, yygg = argv
    unless span
      puts "usage: ruby #$0 file.bin file.cfg time span"
      exit 1
    end
    @yygg = yygg ? format('%04u', yygg.to_i) : 'YYGG'
    @cfg = {
      :nx => 144, :ny => 37,
      :x0 => 0.0, :y0 => 90.0,
      :dx => 2.5, :dy => 2.5,
      :param => [:u0,:u1,:v0,:v1],
      :t => time.to_f / span.to_f
    }
    @stns = []
    File.open(fcfg, 'r') {|ifp|
      for line in ifp
        line.chomp!
	case line
	when /^:(n\w+)\s+/ then @cfg[$1.to_sym] = $'.to_i
	when /^:([xyd]\w+)\s+/ then @cfg[$1.to_sym] = $'.to_f
	when /^:(p\w+)\s+/ then @cfg[$1.to_sym] = $'.split(/,/).map{|s|s.to_sym}
	when /^([-+]\d\d)([-+]\d\d\d)\// then
	  stn = { :reqlat => $1.to_i, :reqlon => $2.to_i }
          @stns.push stn
	else STDERR.puts "err #{line.inspect}"
	end
      end
    }
    @result = nil
  end

  def prepare
    @cfg[:wrecl] = @cfg[:nx] * @cfg[:ny]
    @cfg[:brecl] = @cfg[:wrecl] * 4
    for stn in @stns
      j = ((stn[:reqlat] - @cfg[:y0]) / @cfg[:dy] + 0.5).floor
      i = ((stn[:reqlon] - @cfg[:x0]) / @cfg[:dx] + 0.5).floor
      unless 0...(@cfg[:ny]) === j
	raise "j=#{j} out of range 0...#{@cfg[:ny]}"
      end
      unless 0...(@cfg[:nx]) === i
	raise "i=#{j} out of range 0...#{@cfg[:nx]}"
      end
      stn[:lat] = @cfg[:y0] + j * @cfg[:dy]
      stn[:lon] = @cfg[:x0] + i * @cfg[:dx]
      stn[:ofs] = i + j * @cfg[:nx]
    end
  end

  def readbin
    recname = @cfg[:param].dup
    File.open(@fbin, 'r') { |fp|
      fp.each_rec(@cfg[:brecl]) { |rec|
        param = recname.shift.to_sym
	for stn in @stns
	  fmt = format('@%uf', stn[:ofs] * 4)
	  val = rec.unpack(fmt).first
	  stn[param] = val
	end
      }
    }
  end

  def guess
    w0 = 1.0 - @cfg[:t]
    w1 = @cfg[:t]
    for stn in @stns
      f0 = Math::hypot(stn[:u0], stn[:v0])
      f1 = Math::hypot(stn[:u1], stn[:v1])
      u = w0 * stn[:u0] + w1 * stn[:u1]
      v = w0 * stn[:v0] + w1 * stn[:v1]
      f = w0 * f0 + w1 * f1
      f_tmp = Math::hypot(u, v)
      stn[:f] = (1.9438 * f + 0.5).floor
      if stn[:f].zero? then
        stn[:d] = 0
      else
	d = ((Math::atan2(u, v) / Math::PI + 1.0) * 18 + 0.5).floor
	d = 36 if d.zero?
	stn[:d] = d
      end
    end
  end

  def report
    puts "SMVB11 DUMY #{@yygg}00\r\r\n"
    puts "BBXX\r\r\n"
    for stn in @stns
      alat = (stn[:lat].abs * 10).floor
      alon = (stn[:lon].abs * 10).floor
      qc = if stn[:lat] < 0 then
          (stn[:lon] < 0) ? 5 : 3
        else
          (stn[:lon] < 0) ? 7 : 1
	end
      printf("BOGUS %.4s3 99%0.3u %1u%0.4u ", @yygg, alat, qc, alon)
      f = (stn[:f] > 99) ? 99 : stn[:f]
      printf("46/// /%02d%02d 1//// =\r\r\n", stn[:d], f)
    end
  end

  def run
    prepare
    readbin
    guess
    report
  end

end

App.new(ARGV).run