<?php

namespace App\Classes\FTN;

use Carbon\Carbon;
use Illuminate\Support\Arr;
use Illuminate\Support\Collection;
use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\Log;
use Symfony\Component\HttpFoundation\File\File;

use App\Classes\FTN as FTNBase;
use App\Models\{Address,Setup,Software,System,Zone};

class Packet extends FTNBase implements \Iterator, \Countable
{
	private const LOGKEY = 'PKT';

	private const HEADER_LEN		= 0x3a;
	private const VERSION_OFFSET	= 0x12;
	private const BLOCKSIZE			= 1024;
	private const PACKED_MSG_HEADER_LEN = 0x22;

	// V2 Packet Header (2/2e/2+)
	private const v2header = [
		'onode'			=> [0x00,'v',2],	// Originating Node
		'dnode'			=> [0x02,'v',2],	// Destination Node
		'y'				=> [0x04,'v',2],	// Year
		'm'				=> [0x06,'v',2],	// Month
		'd'				=> [0x08,'v',2],	// Day
		'H'				=> [0x0a,'v',2],	// Hour
		'M'				=> [0x0c,'v',2],	// Minute
		'S'				=> [0x0e,'v',2],	// Second
		'baud'			=> [0x10,'v',2],	// Baud
		'pktver'		=> [0x12,'v',2],	// Packet Version
		'onet'			=> [0x14,'v',2],	// Originating Net	(0xffff when origPoint !=0 2+)
		'dnet'			=> [0x16,'v',2],	// Destination Net
		'prodcode-lo'	=> [0x18,'C',1],
		'prodrev-maj'	=> [0x19,'C',1],	// Product Version Major (serialNum 2)
		'password'		=> [0x1a,'Z8',8],	// Packet Password
		'qozone'		=> [0x22,'v',2],
		'qdzone'		=> [0x24,'v',2],
		'filler'		=> [0x26,'v',2],	// Reserved	(auxnet 2+ - contains Orignet if Origin is a point) fsc-0048.001
		'capvalid'		=> [0x28,'n',2],	// fsc-0039.004 (Not used 2) (copy of 0x2c)
		'prodcode-hi'	=> [0x2a,'C',1],	// (Not used 2)
		'prodrev-min'	=> [0x2b,'C',1],	// (Not used 2)
		'capword'		=> [0x2c,'v',2],	// fsc-0039.001 (Not used 2)
		'ozone'			=> [0x2e,'v',2],	// Originating Zone (Not used 2)
		'dzone'			=> [0x30,'v',2],	// Destination Zone (Not used 2)
		'opoint'		=> [0x32,'v',2],	// Originating Point (Not used 2)
		'dpoint'		=> [0x34,'v',2],	// Destination Point (Not used 2)
		'proddata'		=> [0x36,'a4',4],	// ProdData (Not used 2)		// FSC-39/FSC-48
	];

	private array $header;				// Packet Header

	public File $file;					// Packet filename
	public Collection $messages;		// Messages in the Packet
	public Collection $errors;			// Messages that fail validation
	private string $name;				// Packet name
	public bool $use_cache = TRUE;		// Use a cache for messages.
	private int $index;					// Our array index

	/**
	 * Number of messages in this packet
	 */
	public function count(): int
	{
		return $this->messages->count();
	}

	public function current(): Message
	{
		return $this->use_cache ? unserialize(Cache::pull($this->key())) : $this->messages->get($this->index);
	}

	public function key(): mixed
	{
		return $this->use_cache ? $this->messages->get($this->index) : $this->index;
	}

	public function next(): void
	{
		$this->index++;
	}

	public function rewind(): void
	{
		$this->index = 0;
	}

	public function valid(): bool
	{
		return (! is_null($this->key())) && ($this->use_cache ? Cache::has($this->key()) : $this->messages->has($this->key()));
	}

	/**
	 * @param Address|NULL $oo Origin Address
	 * @param Address|NULL $o Destination Address
	 */
	public function __construct(Address $oo=NULL,Address $o=NULL)
	{
		$this->messages = collect();
		$this->errors = collect();
		$this->domain = NULL;

		// If we are creating an outbound packet, we need to set our header
		if ($oo && $o) {
			$this->name = sprintf('%08x',timew());
			Log::debug(sprintf('%s:Creating packet [%s]',self::LOGKEY,$this->name));
			$this->newHeader($oo,$o);
		}
	}

	/**
	 * Process a packet file
	 *
	 * @param mixed $f
	 * @param string $name
	 * @param int $size
	 * @param System|null $system
	 * @param bool $use_cache
	 * @return Packet
	 * @throws InvalidPacketException
	 */

	public static function process(mixed $f,string $name,int $size,System $system=NULL,bool $use_cache=TRUE): self
	{
		Log::debug(sprintf('%s:+ Opening Packet [%s] with size [%d]',self::LOGKEY,$name,$size));

		$read_ptr = 0;

		// PKT Header
		$header = fread($f,self::HEADER_LEN);
		$read_ptr += strlen($header);

		// Could not read header
		if (strlen($header) != self::HEADER_LEN)
			throw new InvalidPacketException(sprintf('Length of header [%d] too short'.strlen($header)));

		// Not a type 2 packet
		$version = Arr::get(unpack('vv',substr($header,self::VERSION_OFFSET)),'v');
		if ($version != 2)
			throw new InvalidPacketException('Not a type 2 packet: '.$version);

		$o = new self;
		$o->use_cache = $use_cache;
		$o->name = $name;
		$o->header = unpack(self::unpackheader(self::v2header),$header);

		$x = fread($f,2);
		$read_ptr += strlen($x);

		// End of Packet?
		if (strlen($x) == 2 and $x == "\00\00")
			return new self;

		// Messages start with 02H 00H
		if (strlen($x) == 2 AND $x != "\02\00")
			throw new InvalidPacketException('Not a valid packet: '.bin2hex($x));

		// No message attached
		else if (! strlen($x))
			throw new InvalidPacketException('No message in packet: '.bin2hex($x));

		$o->zone = $system?->zones->firstWhere('zone_id',$o->fz);

		// If zone is null, we'll take the zone from the packet
		if (! $o->zone)
			$o->zone = Zone::where('zone_id',$o->fz)->where('default',TRUE)->single();

		$buf_ptr = 0;
		$message = '';
		$readbuf = '';
		$last = '';

		while ($buf_ptr || (! feof($f) && ($readbuf=fread($f,self::BLOCKSIZE)))) {
			if (! $buf_ptr)
				$read_ptr += strlen($readbuf);		// Could use ftell()

			if (strlen($message) < self::PACKED_MSG_HEADER_LEN) {
				$addchars = self::PACKED_MSG_HEADER_LEN-strlen($message);
				$message .= substr($readbuf,$buf_ptr,$addchars);
				$buf_ptr += $addchars;

				// If our buffer wasnt big enough...
				if ($buf_ptr >= strlen($readbuf)) {
					$buf_ptr = 0;
					continue;
				}
			}

			// Take 2 chars from the buffer and check if we have our end packet signature
			if ($last && ($buf_ptr == 0)) {
				$last .= substr($readbuf,0,2);

				if (($end=strpos($last,"\x00\x02\x00",$buf_ptr)) !== FALSE) {
					$o->parseMessage(substr($message,0,$end-2));
					$last = '';
					$message = '';
					$buf_ptr = 1+$end;

					// Loop to rebuild our header for the next message
					continue;
				}

				$last = '';
			}

			if (($end=strpos($readbuf,"\x00\x02\x00",$buf_ptr)) === FALSE) {
				// Just in case our packet break is at the end of the buffer
				$last = substr($readbuf,-2);

				if ((str_contains($last,"\x00")) && ($size-$read_ptr > 2)) {
					$message .= substr($readbuf,$buf_ptr);
					$buf_ptr = 0;

					continue;
				}

				$last = '';
				$end = strpos($readbuf,"\x00\x00\x00",$buf_ptr);
			}

			// See if we have found the end of the packet, if not read more.
			if ($end === FALSE && ($read_ptr < $size)) {
				$message .= substr($readbuf,$buf_ptr);
				$buf_ptr = 0;

				continue;

			} else {
				$message .= substr($readbuf,$buf_ptr,$end-$buf_ptr);
				$buf_ptr = $end+3;

				if ($buf_ptr >= strlen($readbuf))
					$buf_ptr = 0;
			}

			// Look for the next message
			$o->parseMessage($message);
			$message = '';
		}

		// If our message is still set, then we have an unprocessed message
		if ($message)
			$o->parseMessage($message);

		return $o;
	}

	/**
	 * @throws \Exception
	 */
	public function __get($key)
	{
		switch ($key) {
			// From Addresses
			case 'fz': return Arr::get($this->header,'ozone');
			case 'fn': return Arr::get($this->header,'onet');
			case 'ff': return Arr::get($this->header,'onode');
			case 'fp': return Arr::get($this->header,'opoint');
			case 'fd': return Arr::get($this->header,'odomain');

			// To Addresses
			case 'tz': return Arr::get($this->header,'dzone');
			case 'tn': return Arr::get($this->header,'dnet');
			case 'tf': return Arr::get($this->header,'dnode');
			case 'tp': return Arr::get($this->header,'dpoint');
			case 'td': return Arr::get($this->header,'ddomain');

			case 'date':
				return Carbon::create(
					Arr::get($this->header,'y'),
					Arr::get($this->header,'m')+1,
					Arr::get($this->header,'d'),
					Arr::get($this->header,'H'),
					Arr::get($this->header,'M'),
					Arr::get($this->header,'S')
				);

			case 'capability':
				return Arr::get($this->header,'capword') == Arr::get($this->header,'capvalid') ? sprintf('%016b',Arr::get($this->header,'capword')) : 'FTS-1';

			case 'password':
				return Arr::get($this->header,$key);

			case 'fftn':
			case 'fftn_o':
			case 'tftn':
			case 'tftn_o':
				return parent::__get($key);

			case 'software':
				$code = Arr::get($this->header,'prodcode-hi')<<8|Arr::get($this->header,'prodcode-lo');
				Software::unguard();
				$o = Software::singleOrNew(['code'=>$code,'type'=>Software::SOFTWARE_TOSSER]);
				Software::reguard();

				return $o;

			case 'software_ver':
				return sprintf('%d.%d',Arr::get($this->header,'prodrev-maj'),Arr::get($this->header,'prodrev-min'));

			// Packet Type
			case 'type':
				if ((Arr::get($this->header,'onet') == 0xffff) && (Arr::get($this->header,'opoint') != 0) && Arr::get($this->header,'filler'))
					return '2+';
				elseif (Arr::get($this->header,'prodrev-maj') && ! Arr::get($this->header,'capword'))
					return '2';
				else
					return '2e';

			// Packet name:
			case 'name':
				return $this->{$key};

			default:
				throw new \Exception('Unknown key: '.$key);
		}
	}

	/**
	 * Return the packet
	 *
	 * @return string
	 * @throws \Exception
	 */
	public function __toString(): string
	{
		$return = $this->createHeader();

		foreach ($this->messages as $o) {
			if ($o->packed)
				$return .= "\02\00".(string)$o;
		}

		$return .= "\00\00";

		return $return;
	}

	/**
	 * Create our message packet header
	 */
	private function createHeader(): string
	{
		try {
			$a = pack(collect(self::v2header)->merge(['password' => [0x1a,'a8',8]])->pluck(1)->join(''),
				$this->ff,
				$this->tf,
				Arr::get($this->header,'y'),
				Arr::get($this->header,'m'),
				Arr::get($this->header,'d'),
				Arr::get($this->header,'H'),
				Arr::get($this->header,'M'),
				Arr::get($this->header,'S'),
				Arr::get($this->header,'baud',0),
				Arr::get($this->header,'pktver',2),
				$this->fn,										// @todo if point, this needs to be 0xff
				$this->tn,
				Arr::get($this->header,'prodcode-lo',(Setup::PRODUCT_ID & 0xff)),
				Arr::get($this->header,'prodrev-maj',Setup::PRODUCT_VERSION_MAJ),
				$this->password,
				$this->fz,
				$this->tz,
				Arr::get($this->header,'filler',''),
				Arr::get($this->header,'capvalid',1<<0),
				Arr::get($this->header,'prodcode-hi',(Setup::PRODUCT_ID >> 8) & 0xff),
				Arr::get($this->header,'prodrev-min',Setup::PRODUCT_VERSION_MIN),
				Arr::get($this->header,'capword',1<<0),
				$this->fz,
				$this->tz,
				$this->fp,
				$this->tp,
				Arr::get($this->header,'proddata','AB8D'),
			);

			return $a;

		} catch (\Exception $e) {
			return $e->getMessage();
		}
	}

	/**
	 * Add a netmail message to this packet
	 *
	 * @param Message $o
	 */
	public function addMail(Message $o): void
	{
		$this->messages->push($o);
	}

	/**
	 * When creating a new packet, set the header.
	 *
	 * @param Address $oo
	 * @param Address $o
	 */
	private function newHeader(Address $oo,Address $o): void
	{
		$date = Carbon::now();

		// Create Header
		$this->header = [
			'onode'			=> $oo->node_id,						// Originating Node
			'dnode'			=> $o->node_id,							// Destination Node
			'y'				=> $date->format('Y'),			// Year
			'm'				=> $date->format('m')-1,			// Month
			'd'				=> $date->format('d'),			// Day
			'H'				=> $date->format('H'),			// Hour
			'M'				=> $date->format('i'),			// Minute
			'S'				=> $date->format('s'),			// Second
			'onet'			=> $oo->host_id ?: $oo->region_id,		// Originating Net	(0xffff when origPoint !=0 2+)
			'dnet'			=> $o->host_id ?: $o->region_id,		// Destination Net
			'password'		=> $o->session('pktpass'),		// Packet Password
			'qozone'		=> $oo->zone->zone_id,
			'qdzone'		=> $o->zone->zone_id,
			'ozone'			=> $oo->zone->zone_id,					// Originating Zone (Not used 2)
			'dzone'			=> $o->zone->zone_id,					// Destination Zone (Not used 2)
			'opoint'		=> $oo->point_id,						// Originating Point (Not used 2)
			'dpoint'		=> $o->point_id,						// Destination Point (Not used 2)
		];
	}

	/**
	 * Parse a message in a mail packet
	 *
	 * @param string $message
	 * @throws InvalidPacketException|\Exception
	 */
	private function parseMessage(string $message): void
	{
		Log::info(sprintf('%s:Processing message [%d] bytes',self::LOGKEY,strlen($message)));

		$msg = Message::parseMessage($message,$this->zone);

		// If the message is invalid, we'll ignore it
		if ($msg->errors) {
			Log::info(sprintf('%s:- Message [%s] has errors',self::LOGKEY,$msg->msgid));

			// If the from address doenst exist, we'll create a new entry
			if ($msg->errors->messages()->has('to')) {
				$e = NULL;

				try {
					Address::unguard();
					$ao = Address::firstOrNew([
						'zone_id' => $msg->tzone->id,
						'region_id' => 0,
						'host_id' => $msg->tn,
						'node_id' => $msg->tf,
						'point_id' => $msg->tp,
					]);
					Address::reguard();

				} catch (\Exception $e) {
					Log::error(sprintf('%s:! Error finding/creating TO address [%s] for message',self::LOGKEY,$msg->tboss),['error'=>$e->getMessage()]);
				}

				// This shouldnt happen
				if ($e || $ao->exists) {
					Log::error(sprintf('%s:! Unexpected error attempting to create TO address [%s]',self::LOGKEY,$msg->tboss));
					$this->errors->push($msg);
					return;
				}

				$ao->active = TRUE;
				$ao->role = Address::NODE_UNKNOWN;

				System::unguard();
				$so = System::firstOrCreate([
					'name' => 'Discovered System',
					'sysop' => 'Unknown',
					'location' => '',
					'active' => TRUE,
				]);
				System::reguard();

				$so->addresses()->save($ao);

				Log::alert(sprintf('%s: - To FTN is not defined, creating new entry for [%s] (%d)',self::LOGKEY,$msg->tboss,$ao->id));
			}

			if ($msg->errors->messages()->has('from')) {
				$e = NULL;

				try {
					Address::unguard();
					$ao = Address::firstOrNew([
						'zone_id' => $msg->fzone->id,
						'region_id' => 0,
						'host_id' => $msg->fn,
						'node_id' => $msg->ff,
						'point_id' => $msg->fp,
					]);
					Address::reguard();

				} catch (\Exception $e) {
					Log::error(sprintf('%s:! Error finding/creating FROM address [%s] for message',self::LOGKEY,$msg->fboss),['error'=>$e->getMessage()]);
				}

				// This shouldnt happen
				if ($e || $ao->exists) {
					Log::error(sprintf('%s:! Unexpected error attempting to create FROM address [%s]',self::LOGKEY,$msg->fboss));
					$this->errors->push($msg);
					return;
				}

				$ao->active = TRUE;
				$ao->role = Address::NODE_UNKNOWN;

				System::unguard();
				$so = System::firstOrCreate([
					'name' => 'Discovered System',
					'sysop' => 'Unknown',
					'location' => '',
					'active' => TRUE,
				]);
				System::reguard();

				$so->addresses()->save($ao);

				Log::alert(sprintf('%s: - From FTN is not defined, creating new entry for [%s] (%d)',self::LOGKEY,$msg->fboss,$ao->id));
			}

			if ($msg->errors->messages()->has('user_from') || $msg->errors->messages()->has('user_to')) {
				Log::error(sprintf('%s:! Skipping message [%s] due to errors (%s)...',self::LOGKEY,$msg->msgid,join(',',$msg->errors->messages()->keys())));
				$this->errors->push($msg);
				return;
			}
		}

		if ($this->use_cache) {
			$key = urlencode($msg->msgid ?: sprintf('%s %s',$msg->fftn,Carbon::now()->timestamp));
			Cache::forever($key,serialize($msg));
			$this->messages->push($key);

		} else {
			$this->messages->push($msg);
		}
	}
}