#!/usr/bin/perl

#This file is the original file without support for html view (csv file generation only)

##################################################################################################

#usage: perl dods_filter_column.pl 'http://nccoos.unc.edu/cgi-bin/nph-dods/data/nws_metar/proc_data/latest_v2.0/nws-K11J-metar-latest.nc.ascii?wspd' 'seconds since 1970-1-1 00:00:00' 12345

#This perl program can be run stand-alone with the correct parameters and/or in conjunction with a sample calling php webpage - dods_filter_column.php (as a web service) which supplies the parameters from the URL session parameters.

##stand alone
#Run stand alone it can perform row-to-column transformation for other programs which need the data in a CSV(Comma Separated Value) format

#Run stand alone it can also serve as a base template for further modification to create relational database population files with additional row output tailoring for the specific INSERT or COPY file table need.

#Note that the NCO ( http://nco.sourceforge.net ) utility operator 'ncrcat' can also be used to concatenate similar files along the time axis to create a larger composite netCDF file which might be easier to query or transform.

##web service
#Run as called from a web service(see sample calling php webpage - dods_filter_column.php ) it can provide the same transformation within the browser clients (without the need for installing software and possibly as part of other pipelined web service processes) 

#If running locally change the $tmp_dir reference as needed

################### 
#The code below uses the UDUNITS perl package for transforming netCDF times to ISO type datetimes.  To install this package on a Redhat Linux server I had to perform the below steps(see the INSTALL document, talks about other prerequisites like perl 5.x, etc) as root:

#download and unzip version 1.12.2 from Unidata(also available at http://carocoops.org/resources/netcdf/udunits-1.12.2.tar.Z ) 

#add the following 3 lines to the /src/configure file to recognize a Linux system
#	CC=gcc
#	CFLAGS=-Df2cFortran
#	FC=g77

#run ./configure from /udunits-1.12.2/src 
#run perl Makefile.PL from /udunits-1.12.2/src/perl
#run make test from /udunits-1.12.2/src/perl
#run make install from /udunits-1.12.2/src/perl
###################

##netCDF file assumptions
#The code assumes that the time values line will be the third line listed and there are a corresponding number of elements for each of the datatypes included in the query.


##################################################################################################

use strict;

my $tmp_dir = '/tmp/ms_tmp';

my $dods_url = shift;
my $units_value = shift;
my $process_id = shift;

my $csv_filename = "cc_data_$process_id.csv";
open (CSV_FILE, ">$tmp_dir/$csv_filename");


use UDUNITS;

# udunits initialization
UDUNITS::init("/usr2/home/jcothran/udunits-1.12.2/src/lib/udunits.dat") == 0 
  || die "ABORT! Cannot initialize udunits.\n";

my $dods_input_filename = "dods_input_$process_id.txt";

`/usr/bin/wget -O $tmp_dir/$dods_input_filename $dods_url`;

open (DODS_INPUT, "$tmp_dir/$dods_input_filename");

my @time_values;

my $num_obs_type = 0;
my @obs_values;

my $line;
my $line_count = 0;

while ($line = <DODS_INPUT>) {
	$line_count++;

	#drop first dataset name line
        if ($line_count == 1) { next; }

	#get time elements
        if ($line_count == 2) {
                @time_values = split(/\,/,$line);
		next;
	}

        if ($line_count % 2) {
		$num_obs_type++;
		push (@obs_values, split(/\,/,$line));
		next;
	}

}

close (DODS_INPUT);

my $base_time = UDUNITS::scan($units_value)
    || die "ABORT! Error with time units.\n";
$base_time->istime()
    || die "ABORT! Invalid units for time.\n";

my ($i,$j);
my ($base_year, $base_month, $base_day, $base_hour, $base_minute, $base_second);
my $time_formatted_value;
my $obs_title_formatted;

#print header line
print CSV_FILE "time";

for ($j=0; $j < $num_obs_type; $j++) {
	$obs_title_formatted = @obs_values[$j*scalar(@time_values)];
	#reduce title.title to just title
	$obs_title_formatted =~ s/\.(.*)// ;
	print CSV_FILE ",".$obs_title_formatted;
}

print CSV_FILE "\n";

#print data
for ($i=1; $i < scalar(@time_values); $i++) 
{
  
    # convert the time value to new value based on the time units
    $base_time->valtocal($time_values[$i], $base_year, $base_month, $base_day, $base_hour, $base_minute, $base_second) == 0
      || die "ABORT! Invalid units for time.\n";
    $time_formatted_value = $base_year.'-'
      .sprintf("%02d",$base_month).'-'
      .sprintf("%02d",$base_day).' '
      .sprintf("%02d",$base_hour).':'
      .sprintf("%02d",$base_minute).':'
      .sprintf("%02d",$base_second);

	print CSV_FILE $time_formatted_value;

	for ($j=0; $j < $num_obs_type; $j++) {
		if ($i == scalar(@time_values)-1) {
			chomp(@obs_values[$i+($j*scalar(@time_values))]);	
		}

		print CSV_FILE ",".@obs_values[$i+($j*scalar(@time_values))];
	}

	print CSV_FILE "\n";
}

close (CSV_FILE);

`rm $tmp_dir/$dods_input_filename`;

exit 0;