#!/usr/bin/perl -w

use Time::Local;
use File::Basename;


local $MYFULLNAME = $0;
local $MYNAME = basename($0);
local $LOG_PREFIX = "[$MYNAME]:";

# Read in the environment variables.
local $data         = $ENV{"DATA"};
local $comout       = $ENV{"COMOUT"};
local $maparea      = $ENV{"MAPAREA"};
local $run          = $ENV{"RUN"};

local $ruc_output_dir = $comout . "/" . $maparea . "/" . $run;
local $mdates_old     = "$data/mdates.$run.$maparea.old";
local $fourhour_old   = "$data/fourhour.old";
local $mdates_ruc     = "$data/mdates.ruc";

# Print out informational note
print <<ENDOFTEXT;
$LOG_PREFIX Starting $MYNAME.
$LOG_PREFIX
$LOG_PREFIX Command line:
$LOG_PREFIX     $MYFULLNAME @ARGV
$LOG_PREFIX
$LOG_PREFIX Environment variables used:
$LOG_PREFIX     DATA    = $data
$LOG_PREFIX     COMOUT  = $comout
$LOG_PREFIX     MAPAREA = $maparea
$LOG_PREFIX     RUN     = $run
$LOG_PREFIX
ENDOFTEXT

# Read in the new cycle and date.
$new_cycle = $ARGV[0];
$new_date  = $ARGV[1];

# Determine the day of year for the new cycle and date.
($yyyy, $new_day_of_year) = &get_day_of_year($new_cycle, $new_date);
print "$LOG_PREFIX New cycle is $new_cycle.  New date is $new_date.  Day of year is $new_day_of_year.\n";

# Establish hash index key for new cycle and date.
$new_key = &set_key($yyyy, $new_day_of_year, $new_cycle);

# cd to the ruc hour directory:
&goto_dir($ruc_output_dir);

# Get the old cycles and dates.
$model_hours = &get_dates($mdates_old);

($model, @dates) = split(/:/, $model_hours);
$num_hours = @dates;
print "$LOG_PREFIX Model is $model. Hours are @dates. Number of hours: $num_hours.\n";

# Create hash of the mdates using a unique hash index created
# from the year, day of year, and cycle.
for ($index=0; $index < $num_hours; $index++) {
  ($cycle, $date) = split (/-/, $dates[$index]);

  # Determine the day of year for the cycle and date.
  ($yyyy, $day_of_year) = &get_day_of_year($cycle, $date);

  # Establish hash index key for new cycle and date.
  $key = &set_key($yyyy, $day_of_year, $cycle);

  # Add the cycle to the hours hash.
  $HoJ{$key} = [$cycle, $date];
  print $LOG_PREFIX . " Stored " . $key . " => " . $HoJ{$key}[0] . "-" . $HoJ{$key}[1] . "\n";
}

if ( ! exists ( $HoJ{$new_key} )) {

  # Add the new cycle to the hours hash.
  $HoJ{$new_key} = [$new_cycle, $new_date];
  print $LOG_PREFIX . " Processing new cycle: " . $HoJ{$new_key}[0] . "-" . $HoJ{$new_key}[1] . "\n";

  open (OUTFILE,"> $mdates_ruc") || die "$LOG_PREFIX Error opening file $mdates_ruc: $!\n";
  print OUTFILE $model;

  $count = 0;
  foreach $key (sort keys %HoJ) {

    if ( $count == 0 ) {
      # Store the oldest forecast cycle.
      &print_and_close( $fourhour_old, $HoJ{$key}[0] . "-" . $HoJ{$key}[1], 1 );
    }
    else {

      # Update the model dates file.
      print OUTFILE ":" . $HoJ{$key}[0] . "-" . $HoJ{$key}[1]; 

      # Add the cycle to the symlink hash.
      $symlinkname = "hr" . $count;

      if ( -e $symlinkname ) {
        unlink $symlinkname || die "$LOG_PREFIX Error removing symlink $symlinkname: $!\n";
      }

      # Create the link to point to it's cycle
      symlink ($HoJ{$key}[0], $symlinkname);
      print "Doing symlink $HoJ{$key}[0], $symlinkname\n";

      # Update the link text file with the symlink cycle
      &print_and_close( ${symlinkname} . ".cycle", $HoJ{$key}[0], 0 );
    }

    $count++;
  }
  print OUTFILE "\n";
  &close_file(OUTFILE, $mdates_ruc);
}
else {
  print "$LOG_PREFIX The new cycle($new_cycle) already exists, no need to update model dates and symlinks.\n";
}

# cd to the working directory:
&goto_dir($data);

print "$LOG_PREFIX Finished $MYNAME.\n";

exit 0;

# Open a specified file, print a string to it, then close it.
sub print_and_close() {

  my ($filename, $line, $new_line) = @_;

  open (OUT, "> $filename") || die "$LOG_PREFIX Error opening file $filename: $!\n";
  print OUT "$line";
  if ($new_line == 1) { print OUT "\n"; }
  &close_file(OUT, $filename);

}

# Read in the most recent model date file.
sub get_dates() {

  my ($datefile) = @_;

  open (INFILE, "< $datefile") || die "$LOG_PREFIX Error opening file $datefile: $!\n";
  $line = <INFILE>;
  chomp $line;
  &close_file(INFILE, $datefile);

  return $line;
}

# Close an open file.
sub close_file() {

  my ($filehandle, $filename) = @_;

  close ($filehandle) || die "$LOG_PREFIX Error closing file $filename: $!\n";

}

# Determine the day of the year for a given date.
sub get_day_of_year() {
  my ($cycle, $date) = @_;

  my ($day_of_year, $year, $time, $mm, $dd, $yy);

  ($mm, $dd, $yy) = ( $date =~ /(\d{2})(\d{2})(\d{2})/ );
  $year = $yy + 2000;
  $time = timegm(0, 0, $cycle, $dd, $mm - 1, $year - 1900);
  $day_of_year = (gmtime $time)[7];

  return $year, $day_of_year;
}

# Create a key to be used in a hash.
sub set_key() {
  my ($year, $day, $cycle) = @_;

  my ($key);

  $key = sprintf("%04d%03d%02d", $year, $day, $cycle);

  return $key;
}

# Change to a specified directory.
sub goto_dir() {

  my ($dirname) = @_;

  chdir ("$dirname") || die "$LOG_PREFIX Can't cd to $dirname: $! \n";
}