use strict;
use warnings;

use MCE::Loop;
use MCE::Candy;

## Input and output files defined here as well as what we are searching for in the input file
my $input_file  = shift || 'InputFile.OH1';
my $output_file = shift || 'OutputFile.csv';
my $match_string = "+                          ";

open my $ofh, ">", $output_file
   or die "cannot open '$output_file' for writing: $!\n";

## This writes a header row that GIS sees as the column heading
print $ofh "HEC1_ID,Q100_Base,TTP,Area\n";
   
MCE::Loop::init {
   use_slurpio => 1, chunk_size => 1, max_workers => 4,
   gather => MCE::Candy::out_iter_fh($ofh),
   RS => "\n${match_string}",
};

## Below, each worker receives one record at a time
## Output order is preserved via MCE::Candy::out_iter_fh

## EXAMPLE INPUT FILE
Line  1##+                           BPI30      1319.   13.50         477.        147.         49.       4.64
Line  2##
Line  3##          ROUTED TO
Line  4##+                           RPI30      1220.   13.75         475.        147.         49.       4.64
Line  5##
Line  6##          HYDROGRAPH AT
Line  7##+                           BPI31       765.   12.42         102.         26.          9.        .73
Line  8##
Line  9##          2 COMBINED AT
Line 10##+                           CPI31      1242.   13.75         571.        172.         58.       5.37

mce_loop_f {
   my ( $mce, $chunk_ref, $chunk_id ) = @_;

   ## Skip initial record containing header lines including *** ***
   if ( $chunk_id == 1 && $$chunk_ref !~ /^${match_string}/ ) {
      ## Gathering here is necessary when preserving output order,
      ## to let the manager process know chunk_id 1 has completed.
      MCE->gather( $chunk_id, "" );
      MCE->next;
   }

   ## Each record begins with "+                          "
   my ( $k1, $k2, $k3, $k4 ) = ( "", "", "", "" );
   open my $ifh, "<", $chunk_ref;
   while ( <$ifh> ) {
      $k1 = $1 and next if $. == 1 && /^\S\s+(\S+)/;
      $k2 = $1 and next if $. == 1 && /^\S\s+\S+\s+(\S+)/;
      $k3 = $1 and next if $. == 1 && /^\S\s+\S+\s+\S+\s+(\S+)/;
      $k4 = $1 and last if $. == 1 && /(\S+)\s*$/;
   }
   close $ifh;

## Gather values.
## This outputs everything to the output file in the format below.
   MCE->gather( $chunk_id, "$k1,$k2,$k3,$k4\n" );
} $input_file;