#!/usr/bin/env ruby
=begin
=gpaop

   Carrying out an arithmetric operation (addition, subtraction, 
   multiplication and division) multiple GPhys variables. 

==USAGE 

   Operation, gphys1 (+-*/) gphys2 (+-*/) gphys3 (+-*/) ... is performed 
   by the following  command formats. 

   % gpaop -f func [options] gturl1 gturl2 ...

     Format of 'gturl*' is 'path@varname[,dimname=pos1[:pos2[:thinning_intv]][,dimname=...]]'

   % gpaop -f func --var varname[,dimname=pos1[:pos2[:thinning_intv]][,dimname=...]] \
        [options] gtfile1 gtfile2 ...

  * Commands which compute arithmetric operation on gphys variables are 
    successively installed by linking this sciript as a 
    "gp+(add|sub|multi|div)". You can omit '--func' option by using 
    these commands.  

==OPTIONS

   -f func  --func func    : kind of operation (add|sub|multi|div|)
   -v url   --var url      : set the variable name and slicing parameters.
   -h,      --help         : print this message. 
   -o file, --output file  : output filename (optional). 
                           : Default output filename is 'gphys.nc'.

==EXAMPLE

   % gpaop -f add gtool.nc@temp gtool.nc@temp
   % gpaop -f sub gtool.nc@temp,t=1 gtool.nc@temp,t=2

   % gpaop -f multi --var temp gtool*.nc
   % gpaop -f div --var temp,t=1 gtool*.nc
   % gpaop -o temp.nc --var temp,t=1 gtool*.nc

==HISTORY

  2005/08/21  S Takehiro (created)
  2005/08/23  S Takehiro (common methods to gp* command moved to gpcommon.rb)

=end

require "numru/gphys"
require "numru/gphys/gpcommon"
include NumRu

require "getoptlong"

#------------------------ Default Settings ------------------------
Output_default = 'gphys.nc'                      # default ouptput file name
command = File.basename($0)+" "+ARGV.join(' ')   # keep an input command line 

#---------------------- Option Configuration ----------------------
parser = GetoptLong.new(
  ["--func",     "-f", GetoptLong::REQUIRED_ARGUMENT],
  ["--var",      "-v", GetoptLong::REQUIRED_ARGUMENT],
  ["--output",   "-o", GetoptLong::REQUIRED_ARGUMENT],
  ["--help",     "-h", GetoptLong::NO_ARGUMENT      ])
begin
  parser.each{|opt, arg|
    case opt
    when "--func" then eval "$OPT_func='#{arg}'"
    when "--var" then eval "$OPT_var='#{arg}'"
    when "--output" then eval "$OPT_output='#{arg}'"
    when "--help" then eval "$OPT_help=true"
    else
      raise "must not happen"
    end
  }
  rescue GetoptLong::AmbigousOption, GetoptLong::InvalidOption,
          GetoptLong::MissingArgument, 
          GetoptLong::NeedlessArgument => err
    help
    $srderr.puts err.message
    exit 1
end

#------------------------ Help message ------------------------
if $OPT_help then
  help
  exit(0)
end  

#------------------------ Option check ------------------------
$OPT_output ||= Output_default 
$OPT_func ||= $0.sub(/^gp/,'')
raise "Operation '#{$OPT_func}' not supported. It should be add,sub,multi or div." unless /(add|sub|multi|div)/ =~ $OPT_func 

unless ARGV[0]
  help
  exit 1
end

#------------------------ Output file check  --------------------------
raise "#{$OPT_output} already exists." if FileTest.exist?($OPT_output) 
outncfile=NetCDF.create($OPT_output)

#------------------------ Open gphys variable ------------------------
# Reading the first Gphys variable
gturl = ARGV[0]
gturl = gturl+'@'+$OPT_var if $OPT_var
gphys = GPhys::IO.open_gturl(gturl)
print "  Reading #{gturl}\n"
gphys_aop = gphys.copy
outncfile.copy_global_att(gphys) # Copy global attributes (only for NetCDF)
ARGV.shift 


# Reading Gphys variables after the first one.
while ARGV[0] do
  gturl = ARGV[0]
  gturl = gturl+'@'+$OPT_var if $OPT_var
  gphys = GPhys::IO.open_gturl(gturl)
  print "  Reading #{gturl}\n"

  gphys_aop = gphys_aop + gphys if $OPT_func=="add"
  gphys_aop = gphys_aop - gphys if $OPT_func=="sub"
  gphys_aop = gphys_aop * gphys if $OPT_func=="multi"
  gphys_aop = gphys_aop / gphys if $OPT_func=="div"
  ARGV.shift 
end

#---------------------- Output GPhys variable  ------------------------
GPhys::IO.write( outncfile, gphys_aop )
NetCDF_Conventions.add_history(outncfile, command) # Exec command written as a history
outncfile.close

print File.basename($0) +": Output is written to #{$OPT_output}.\n"