#!/usr/bin/perl
use strict;
use warnings;
use File::Path qw(make_path);

# --------------------------
# CONFIG
# --------------------------
my $homedir = "/home/ssm-user/GETD_IIJA/IMS_SNOW";
my $nomads  = "ftp://sidads.colorado.edu/DATASETS/NOAA/G02156/24km";

# Edit ranges as needed
my $year_start = 2023;
my $year_end   = 2023;
my $doy_start  = 180;
my $doy_end    = 243;

# Ensure base dir exists
make_path($homedir);

for (my $year = $year_start; $year <= $year_end; $year++) {
    my $out_dir = "$homedir/$year";
    make_path($out_dir);

    for (my $doy = $doy_start; $doy <= $doy_end; $doy++) {
        my $doy3 = sprintf("%03d", $doy);
        my (undef, $date2, undef) = GetDate($year, $doy);
        print "Year=$year DOY=$doy ($date2)\n";

        # Build the server directory and the accept pattern
        my $server_dir = "$nomads/$year/";
        my $accept     = "ims${year}${doy3}*.gz";

        # Use wget to fetch matching files from that directory into $out_dir
        # -q: quiet, -r: recursive (one dir), -nd: no dirs, -np: no parent
        # --accept: only files that match, --reject: skip index listings
        my @cmd = (
            'wget', '-q',
            '-r', '-nd', '-np',
            "--accept=$accept",
            '--reject=index.html*',
            '-P', $out_dir,
            $server_dir
        );

        my $rc = system(@cmd);
        if ($rc != 0) {
            warn "wget failed (rc=$rc) for $server_dir\n";
        }

        # Check what we got
        opendir(my $dh, $out_dir) or die "opendir $out_dir: $!";
        my @got = grep { /^ims${year}${doy3}.*\.gz$/ } readdir($dh);
        closedir($dh);

        if (@got) {
            print "Downloaded: @got\n";
            # If you want to gunzip after download, uncomment:
            # for my $f (@got) {
            #     system('gunzip', '-f', "$out_dir/$f");
            # }
        } else {
            print "No IMS file found for ${year}${doy3} under $server_dir\n";
        }
    }
}

exit 0;

# --------------------------
# Date helper (your original logic, cleaned up)
# Returns: ($date1, $date2, $date3)
# - date1: DDMonYYYY   e.g., 02Jan2024
# - date2: YYYYMMDD    e.g., 20240102
# - date3: YYYYMM      e.g., 202401
# --------------------------
sub GetDate {
    my ($year, $doy) = @_;

    my @month = qw(Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec);
    my @nday  = (31,28,31,30,31,30,31,31,30,31,30,31);

    # Proper leap-year rule
    if ( ($year % 4 == 0) && ( ($year % 100 != 0) || ($year % 400 == 0) ) ) {
        $nday[1] = 29;
    }

    my @cum = (0);
    for my $i (0..$#nday) {
        $cum[$i+1] = $cum[$i] + $nday[$i];
    }

    my $im = 0;
    $im++ while $im < 12 && $cum[$im+1] < $doy;
    my $id = $doy - $cum[$im];

    my $dom = sprintf("%02d", $id);
    my $moy = sprintf("%02d", $im + 1);

    my $date1 = sprintf("%s%s%d", $dom, $month[$im], $year);
    my $date2 = sprintf("%d%s%s",  $year, $moy, $dom);
    my $date3 = sprintf("%d%s",    $year, $moy);

    return ($date1, $date2, $date3);
}