max_reformation_duration=300
cfs_online_timeout_changes=200
max_configured_packages=100
node:nodeA|name=nodeA
node:nodeA|status=up
node:nodeA|interface:lan900|name=lan900
node:nodeA|interface:lan900|status=up
node:nodeA|interface:lan900|ip_address:IP_A|name=IP_A
node:nodeA|interface:lan900|ip_address:IP_A|netmask=255.255.255.0
node:nodeA|interface:lan901|name=lan901
node:nodeA|interface:lan901|status=up
node:nodeA|interface:lan901|ip_address:IP_C|name=IP_C
node:nodeA|interface:lan901|ip_address:IP_C|netmask=255.255.255.0
node:nodeA|subnet:SUBNET_A|name=SUBNET_A
node:nodeA|subnet:SUBNET_A|status=up
node:nodeA|subnet:SUBNET_B|name=SUBNET_B
node:nodeA|subnet:SUBNET_B|status=up
node:nodeB|name=nodeB
node:nodeB|status=up
node:nodeB|interface:lan900|name=lan900
node:nodeB|interface:lan900|status=up
node:nodeB|interface:lan900|ip_address:IP_B|name=IP_B
node:nodeB|interface:lan900|ip_address:IP_B|netmask=255.255.255.0
node:nodeB|interface:lan901|name=lan901
node:nodeB|interface:lan901|status=up
node:nodeB|interface:lan901|ip_address:IP_D|name=IP_D
node:nodeB|interface:lan901|ip_address:IP_D|netmask=255.255.255.0
node:nodeB|subnet:SUBNET_A|name=SUBNET_A
node:nodeB|subnet:SUBNET_A|status=up
node:nodeB|subnet:SUBNET_B|name=SUBNET_B
node:nodeB|subnet:SUBNET_B|status=up

##</code><code>##

%config = {
	max_reformation_duration => 300,
	cfs_online_timeout_changes => 200,
	max_configured_packages => 100,
	node => {
		nodeA => {
			name => nodeA,
			status => up,
			interface => {
				lan900 => {
					name => lan900,
					status => up,
					ip_adress => {
						IP_A => {
							name => IP_A,
							netmask => 255.255.255.0,
						},
					},
				},
				lan901 => {
					name => lan901,
					status => up,
					ip_adress => {
						IP_C => {
							name => IP_C,
							netmask => 255.255.255.0,
						},
					},
				},
			},
			subnet => {
				SUBNET_A => {
					name => SUBNET_A,
					status => up,
				},
				SUBNET_B => {
					name => SUBNET_B,
					status => up,
				},
			},
		},
		nodeB => {
			name 	=> nodeB,
			status 	=> up,
			interface => {
				lan900 => {
					name => lan900,
					status => up,
					ip_adress => {
						IP_A => {
							name => IP_B,
							netmask => 255.255.255.0,
						},
					},
				},
				lan901 => {
					name => lan901,
					status => up,
					ip_adress => {
						IP_C => {
							name => IP_D,
							netmask => 255.255.255.0,
						},
					},
				},
			},
			subnet => {
				SUBNET_A => {
					name => SUBNET_A,
					status => up,
				},
				SUBNET_B => {
					name => SUBNET_B,
					status => up,
				},
			},
		},
	},
}

##</code><code>##

#!/usr/bin/perl

use strict;
use warnings;

use Data::Dumper;

$Data::Dumper::Indent = 1;
$Data::Dumper::Sortkeys = 1;

sub read_input {
	open(my $io, '<', 'input.txt') or die $!;
	return <$io>;
}

my @lines = read_input();

my %config;
my $hashref = \%config;

# stack of hash references
my @ref;

# count of | characters in a respective line
my $level = 0;

# count of | characters in the previous line
my $prev_level = 0;

my $key;
my $fkey;

for (@lines) {
	chomp;
	my @f = split(/\|/);
	$level = @f - 1;
	
	if ($level == 0) {
		my @f = split(/=/);
		$hashref->{ $f[0] } = $f[1];
	} else {
		my @q = split(/:/, $f[$level - 1]);
		if ($key && $level <= $prev_level) {
			if (/\Q$key\E/) {
				my @f = split(/=/, $f[$level]);
				$hashref->{ $f[0] } = $f[1];
				$prev_level = $level;
			} elsif (/\Q$fkey\E/) {
				$hashref = $ref[-1];
				
				$hashref->{$q[1]} = {};
				$hashref = $hashref->{$q[1]};
				
				$key = join(':', @q);
				$prev_level = $level;
				redo;
			} else {
				pop @ref;
				if ($level < $prev_level) {
					my $diff = $prev_level - $level;
					while ($diff--) { pop @ref; pop @ref; }
				}
				$hashref = pop @ref;
				$key = '';
				$prev_level = $level;
				redo;
			}
		} else {
			if (exists $hashref->{$q[0]}) {
				push @ref, $hashref;
				$hashref->{$q[0]}->{$q[1]} = {};
				$hashref = $hashref->{$q[0]}->{$q[1]};
			} else {
				push @ref, $hashref;
				$hashref->{$q[0]} = {};
				$hashref = $hashref->{$q[0]};
			
				push @ref, $hashref;
				$hashref->{$q[1]} = {};
				$hashref = $hashref->{$q[1]};
			}
			$key = join(':', @q);
			$fkey = $q[0];
			
			$prev_level = $level;
			redo;
		}
	
	}
}

print Dumper( \%config );

##</code><code>##

$VAR1 = {
  'cfs_online_timeout_changes' => '200',
  'max_configured_packages' => '100',
  'max_reformation_duration' => '300',
  'node' => {
    'nodeA' => {
      'interface' => {
        'lan900' => {
          'ip_address' => {
            'IP_A' => {
              'name' => 'IP_A',
              'netmask' => '255.255.255.0'
            }
          },
          'name' => 'lan900',
          'status' => 'up'
        },
        'lan901' => {
          'ip_address' => {
            'IP_C' => {
              'name' => 'IP_C',
              'netmask' => '255.255.255.0'
            }
          },
          'name' => 'lan901',
          'status' => 'up'
        }
      },
      'name' => 'nodeA',
      'status' => 'up'
    },
    'subnet' => {
      'SUBNET_A' => {
        'name' => 'SUBNET_A',
        'status' => 'up'
      },
      'SUBNET_B' => {
        'name' => 'SUBNET_B',
        'status' => 'up'
      }
    }
  }
};