#!/usr/bin/perl
# 
# This is the main ScanCore program. It is started/killed/recovered by anvil-daemon.
# 
# Examples;
# 
# Exit codes;
# 0 = Normal exit.
# 1 = No database connections available.
# 
# TODO: 
# - Decide if it's worth having a separate ScanCore.log file or just feed into anvil.log.
# - Examine limits in: https://www.freedesktop.org/software/systemd/man/systemd.exec.html#LimitCPU=

use strict;
use warnings;
use Anvil::Tools;
use Data::Dumper;

# Disable buffering
$| = 1;

my $THIS_FILE           =  ($0 =~ /^.*\/(.*)$/)[0];
my $running_directory   =  ($0 =~ /^(.*?)\/$THIS_FILE$/)[0];
if (($running_directory =~ /^\./) && ($ENV{PWD}))
{
	$running_directory =~ s/^\./$ENV{PWD}/;
}

my $anvil = Anvil::Tools->new({log_level => 2, log_secure => 1});

$anvil->Storage->read_config();
$anvil->Log->entry({source => $THIS_FILE, line => __LINE__, 'print' => 1, level => 1, key => "log_0115", variables => { program => $THIS_FILE }});

# Read switches
$anvil->data->{switches}{'run-once'} = "";
$anvil->Get->switches;

# Calculate my sum so that we can exit if it changes later.
$anvil->Storage->record_md5sums;

# Connect to DBs.
wait_for_database($anvil);

# If we're not configured, sleep.
wait_until_configured($anvil);

# Send a startup 

# Disconnect. We'll reconnect inside the loop
$anvil->Database->disconnect();
$anvil->Log->entry({source => $THIS_FILE, line => __LINE__, 'print' => 1, level => 3, key => "log_0203"});

# The main loop
$anvil->Log->entry({source => $THIS_FILE, line => __LINE__, 'print' => 1, level => 2, key => "log_0248"});
while(1)
{
	# Do the various pre-run tasks.
	prepare_for_run($anvil);
	
	# Do we have at least one database?
	if ($anvil->data->{sys}{database}{connections})
	{
		# Run the normal tasks
		call_agents($anvil);
	}
	else
	{
		# No databases available, we can't do anything this run. Sleep for a couple of seconds and 
		# then try again.
		$anvil->Log->entry({source => $THIS_FILE, line => __LINE__, 'print' => 1, level => 0, key => "log_0202"});
		
		my $db_retry_interval = 2;
 		if ((exists $anvil->data->{scancore}{timing}{db_retry_interval}) && ($anvil->data->{scancore}{timing}{db_retry_interval} =~ /^\d+$/))
		{
			$db_retry_interval = $anvil->data->{scancore}{timing}{db_retry_interval};
		}
		sleep($db_retry_interval);
		next;
	}
	
	# Exit if 'run-once' selected.
	if ($anvil->data->{switches}{'run-once'})
	{
		$anvil->Log->entry({source => $THIS_FILE, line => __LINE__, 'print' => 1, level => 0, key => "message_0055"});
		$anvil->nice_exit({exit_code => 0});
	}
	
	# Clean up
	cleanup_after_run($anvil);
	
	# Sleep until it's time to run again.
	my $run_interval = 30;
	if ((exists $anvil->data->{scancore}{timing}{run_interval}) && ($anvil->data->{scancore}{timing}{run_interval} =~ /^\d+$/))
	{
		$run_interval = $anvil->data->{scancore}{timing}{run_interval};
	}
	$anvil->Log->entry({source => $THIS_FILE, line => __LINE__, 'print' => 1, level => 2, key => "log_0249", variables => { run_interval => $run_interval }});
	sleep($run_interval);
	
	# In case something has changed, exit.
	exit_if_sums_changed($anvil);
}

$anvil->nice_exit({exit_code => 0});


#############################################################################################################
# Functions                                                                                                 #
#############################################################################################################

# This invokes all scan agents found in 'path::directories::scan_agents'
sub call_agents
{
	my ($anvil) = @_;
	
	# Get the current list of scan agents on this system.
	$anvil->Log->variables({source => $THIS_FILE, line => __LINE__, level => 2, list => { 
		"path::directories::scan_agents" => $anvil->data->{path}{directories}{scan_agents},
	}});
	scan_directory($anvil, $anvil->data->{path}{directories}{scan_agents});
	
	# Now loop through the agents I found and call them.
	my $default_timeout = 30;
	if ((exists $anvil->data->{scancore}{timing}{agent_runtime}) && ($anvil->data->{scancore}{timing}{agent_runtime} =~ /^\d+$/))
	{
		$default_timeout = $anvil->data->{scancore}{timing}{agent_runtime};
	}
	foreach my $agent_name (sort {$a cmp $b} keys %{$anvil->data->{scancore}{agent}})
	{
		my $agent_path  = $anvil->data->{scancore}{agent}{$agent_name};
		my $agent_words = $agent_path.".xml";
		$anvil->Log->variables({source => $THIS_FILE, line => __LINE__, level => 2, list => { 
			agent_name  => $agent_name,
			agent_path  => $agent_path, 
			agent_words => $agent_words, 
		}});
		
		if ((-e $agent_words) && (-r $agent_words))
		{
			# Read the words file so that we can generate alerts later.
			$anvil->Log->entry({source => $THIS_FILE, line => __LINE__, level => 2, key => "log_0251", variables => {
				agent_name => $agent_name,
				file       => $agent_path,
			}});
			$anvil->Words->read({file => $agent_words});
		}
		
		# Now call the agent.
		my $start_time = time;
		my $timeout    = $default_timeout;
		if ((exists $anvil->data->{scancore}{agent}{$agent_name}{agent_runtime}) && ($anvil->data->{scancore}{agent}{$agent_name}{agent_runtime} =~ /^\d+$/))
		{
			$timeout = $anvil->data->{scancore}{agent}{$agent_name}{agent_runtime};
		}
		my $shell_call = $anvil->data->{path}{exe}{timeout}." ".$timeout." ".$agent_path;
		if ($anvil->data->{sys}{'log'}{level})
		{
			$shell_call .= " ".$anvil->data->{sys}{'log'}{level};
		}
		$anvil->Log->variables({source => $THIS_FILE, line => __LINE__, level => 2, list => { shell_call => $shell_call }});
		
		# Tell the user this agent is about to run...
		$anvil->Log->entry({source => $THIS_FILE, line => __LINE__, 'print' => 1, level => 2, key => "log_0252", variables => {
			agent_name => $agent_name,
			timeout    => $timeout,
		}});
		my ($output, $return_code) = $anvil->System->call({shell_call => $shell_call});
		$anvil->Log->variables({source => $THIS_FILE, line => __LINE__, level => 2, list => { output => $output, return_code => $return_code }});
		foreach my $line (split/\n/, $output)
		{
			$anvil->Log->variables({source => $THIS_FILE, line => __LINE__, level => 2, list => { line => $line }});
		}
		
		# If the return code is '124', timeout popped.
		if ($return_code eq "124")
		{
			# Register an alert...
			$anvil->Alert->register({
				alert_level => "notice", 
				set_by      => $THIS_FILE,
				message     => "alert_message_0001,!!agent_name!".$agent_name."!!,!!timeout!".$timeout."!!",
			});
		}
	}
	
	return(0);
}

# This cleans things up after a scan run has completed.
sub cleanup_after_run
{
	my ($anvil) = @_;
	
	# Delete what we know about existing scan agents so that the next scan freshens the data.
	foreach my $agent_name (sort {$a cmp $b} keys %{$anvil->data->{scancore}{agent}})
	{
		# Remove the agent's words file data.
		my $agent_words = $anvil->data->{scancore}{agent}{$agent_name}.".xml";
		delete $anvil->data->{words}{$agent_words};
	}
	
	# Disconnect from the database(s) and sleep now.
	$anvil->Database->disconnect();
	
	# Now delete all the remaining agent data.
	delete $anvil->data->{scancore}{agent};
}

# This checks to see if any files on disk have changed and, if so, exits.
sub exit_if_sums_changed
{
	my ($anvil) = @_;
	
	if ($anvil->Storage->check_md5sums)
	{
		# NOTE: We exit with '0' to prevent systemctl from showing a scary red message.
		$anvil->Log->entry({source => $THIS_FILE, line => __LINE__, 'print' => 1, level => 0, priority => "alert", key => "message_0014"});
		$anvil->nice_exit({exit_code => 0});
	}
	
	return(0);
}

# Handle pre-run tasks.
sub prepare_for_run
{
	my ($anvil) = @_;
	# Reload defaults, re-read the config and then connect to the database(s)
	$anvil->_set_paths();
	$anvil->_set_defaults();
	$anvil->Storage->read_config();
	$anvil->Words->read();
	$anvil->Database->connect();
	$anvil->Log->entry({source => $THIS_FILE, line => __LINE__, 'print' => 1, level => 1, key => "log_0132"});
	
	# TODO: Check/configure the mail server.
	check_email($anvil);
	
	return(0);
}

sub check_email
{
	my ($anvil) = @_;
	
	# We check to see if there are any emails in the queue. If we see queued emails for more than five 
	# minutes, and a second mail server is configured, we'll automatically reconfigure for the next 
	# known server.
	
	# Before we do anything, we want to make sure all recipients have been registered against all hosts.
	$anvil->Email->check_alert_recipients();
	
	### TODO: 
	# If not configured look in variables for 'mail_server::last_used::<mail_server_uuid>'. The first one
	# that doesn't have an existing variable will be used. If all known mail servers have variables, the
	# oldest is used. 
	# 
	# If configured/running, the number of messages in queue is checked. If '0', 
	# 'mail_server::queue_empty' is updated with the current time. If 1 or more, the time since the queue
	# was last 0 is checked. If > 300, the mail server is reconfigured to use the mail server with the
	# oldest 'mail_server::last_used::<mail_server_uuid>' time.
	# 
	# In any case where the mail server is configured, the server that is used has their 
	# 'mail_server::last_used::<mail_server_uuid>' variable set to the current time stamp.
	
	# Is the postfix daemon running?
	
	return(0);
}

# This looks in the passed-in directory for scan agents or sub-directories (which will in turn be scanned).
sub scan_directory
{
	my ($anvil, $directory) = @_;
	
	$anvil->Log->variables({source => $THIS_FILE, line => __LINE__, level => 3, list => { directory => $directory }});
	local(*DIRECTORY);
	opendir(DIRECTORY, $directory);
	while(my $file = readdir(DIRECTORY))
	{
		next if $file eq ".";
		next if $file eq "..";
		my $full_path = $directory."/".$file;
		$anvil->Log->variables({source => $THIS_FILE, line => __LINE__, level => 3, list => { 
			file      => $file,
			full_path => $full_path,
		}});
		# If we're looking at a directory, scan it. Otherwise, see if it's an executable and that it
		# starts with 'scan-*'.
		if (-d $full_path)
		{
			# This is a directory, dive into it.
			scan_directory($anvil, $full_path);
		}
		elsif (-x $full_path)
		{
			# Now I only want to know if the file starts with 'scan-'
			next if $file !~ /^scan-/;
			
			# If I am still alive, I am looking at a scan agent!
			$anvil->data->{scancore}{agent}{$file} = $full_path;
			$anvil->Log->variables({source => $THIS_FILE, line => __LINE__, level => 2, list => { 
				"scancore::agent::${file}" => $anvil->data->{scancore}{agent}{$file},
			}});
		}
	}
	closedir(DIRECTORY);
	
	return(0);
}

# This loops until it can connect to at least one database.
sub wait_for_database
{
	my ($anvil) = @_;
	
	$anvil->Database->connect;
	$anvil->Log->entry({source => $THIS_FILE, line => __LINE__, level => 2, key => "log_0132"});
	if (not $anvil->data->{sys}{database}{connections})
	{
		# No databases, sleep until one comes online.
		$anvil->Log->entry({source => $THIS_FILE, line => __LINE__, 'print' => 1, level => 1, key => "log_0244"});
		
		until($anvil->data->{sys}{database}{connections})
		{
			# Disconnect, Sleep, then check again.
			$anvil->Database->disconnect();
			sleep 60;
			
			$anvil->_set_paths();
			$anvil->_set_defaults();
			$anvil->Storage->read_config();
			$anvil->Database->connect;
			if ($anvil->data->{sys}{database}{connections})
			{
				# We're good
				$anvil->Log->entry({source => $THIS_FILE, line => __LINE__, 'print' => 1, level => 1, key => "log_0245"});
			}
			else
			{
				# Not yet...
				$anvil->Log->entry({source => $THIS_FILE, line => __LINE__, 'print' => 1, level => 2, key => "log_0244"});
			}
			
			# In case something has changed, exit.
			exit_if_sums_changed($anvil);
		}
	}
	
	return(0);
}

# Wait until the local system has been configured.
sub wait_until_configured
{
	my ($anvil) = @_;
	
	my $configured = $anvil->System->check_if_configured;
	$anvil->Log->variables({source => $THIS_FILE, line => __LINE__, level => 3, list => { configured => $configured }});
	if (not $configured)
	{
		# Sleep for a minute and check again.
		$anvil->Log->entry({source => $THIS_FILE, line => __LINE__, level => 1, key => "log_0246"});
		until ($configured)
		{
			# Sleep, then check.
			sleep 60;
			
			$configured = $anvil->System->check_if_configured;
			$anvil->Log->variables({source => $THIS_FILE, line => __LINE__, level => 2, list => { configured => $configured }});
			if ($configured)
			{
				# We're good
				$anvil->Log->entry({source => $THIS_FILE, line => __LINE__, 'print' => 1, level => 1, key => "log_0247"});
			}
			else
			{
				# Not yet...
				$anvil->Log->entry({source => $THIS_FILE, line => __LINE__, 'print' => 1, level => 2, key => "log_0246"});
			}
			
			# In case something has changed, exit.
			exit_if_sums_changed($anvil);
		}
	}
	
	return(0);
}