<?php

namespace App\Classes\File;

use Exception;
use Illuminate\Support\Collection;
use Illuminate\Support\Facades\Log;
use Symfony\Component\HttpFoundation\File\File;
use Symfony\Component\HttpFoundation\File\Exception\FileException;

use App\Classes\FTN\InvalidPacketException;
use App\Classes\FTN\Packet;
use App\Jobs\ProcessPacket;
use App\Models\Address;

/**
 * Object representing the files we are receiving
 *
 * @property-read resource $fd
 * @property-read int total_recv
 * @property-read int total_recv_bytes
 */
final class Receive extends Item
{
	private Address $ao;
	private Collection $list;
	private ?Item $receiving;

	private mixed $f;				// File descriptor
	private int $start;				// Time we started receiving
	private int $file_pos;			// Current write pointer
	private string $file;			// Local filename for file received

	public function __construct()
	{
		// Initialise our variables
		$this->list = collect();
		$this->receiving = NULL;
		$this->file_pos = 0;
		$this->f = NULL;
	}

	public function __get($key)
	{
		switch ($key) {
			case 'fd':
				return is_resource($this->f);

			case 'filepos':
				return $this->file_pos;

			case 'mtime':
			case 'name':
			case 'size':
				return $this->receiving ? $this->receiving->{'file_'.$key} : NULL;

			case 'name_size_time':
				return sprintf('%s %lu %lu',$this->name,$this->size,$this->mtime);

			case 'to_get':
				return $this->list
					->filter(function($item) { return ($item->action & self::I_RECV) && $item->received === FALSE; })
					->count();

			case 'total_recv':
				return $this->list
					->filter(function($item) { return ($item->action & self::I_RECV) && $item->received === TRUE; })
					->count();

			case 'total_recv_bytes':
				return $this->list
					->filter(function($item) { return ($item->action & self::I_RECV) && $item->received === TRUE; })
					->sum(function($item) { return $item->file_size; });

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

	/**
	 * Close the file descriptor for our incoming file
	 *
	 * @throws Exception
	 */
	public function close(): void
	{
		if (! $this->f)
			throw new Exception('No file to close');

		if ($this->file_pos != $this->receiving->file_size) {
			Log::warning(sprintf('%s: - Closing [%s], but missing [%d] bytes',__METHOD__,$this->receiving->file_name,$this->receiving->file_size-$this->file_pos));
			$this->receiving->incomplete = TRUE;
		}

		$this->receiving->received = TRUE;

		$end = time()-$this->start;
		Log::debug(sprintf('%s: - Closing [%s], received in [%d]',__METHOD__,$this->receiving->file_name,$end));

		fclose($this->f);
		$this->file_pos = 0;
		$this->f = NULL;

		// If the packet has been received but not the right size, dont process it any more.

		// If we received a packet, we'll dispatch a job to process it
		if (! $this->receiving->incomplete)
			switch ($this->receiving->file_type) {
				case self::IS_PKT:
					Log::info(sprintf('%s: - Processing mail packet [%s]',__METHOD__,$this->file));

					try {
						$po = Packet::open(new File($this->file),$this->ao->zone->domain);

					} catch (InvalidPacketException $e) {
						Log::error(sprintf('%s:   - Not deleting packet [%s], as it generated an exception',__METHOD__,$this->file));

						break;
					}

					foreach ($po->messages as $msg) {
						Log::info(sprintf('%s:   - Mail from [%s] to [%s]',__METHOD__,$msg->fftn,$msg->tftn));

						// @todo Quick check that the packet should be processed by us.
						// @todo validate that the packet's zone is in the domain.

						// Dispatch job.
						ProcessPacket::dispatchSync($msg);
					}

					if ($po->errors->count()) {
						Log::info(sprintf('%s:   - Not deleting packet [%s], as it has validation errors',__METHOD__,$this->file));

					// If we want to keep the packet, we could do that logic here
					} elseif (! config('app.packet_keep')) {
						Log::debug(sprintf('%s:   - Deleting processed packet [%s]',__METHOD__,$this->file));
						unlink($this->file);
					}

					break;

				default:
					Log::debug(sprintf('%s: - Leaving file [%s] in the inbound dir',__METHOD__,$this->file));
			}

		$this->receiving = NULL;
	}

	/**
	 * Open the file descriptor to receive a file
	 *
	 * @param bool $check
	 * @return bool
	 * @throws Exception
	 */
	public function open(Address $ao,bool $check=FALSE): bool
	{
		Log::debug(sprintf('%s: + Start [%d]',__METHOD__,$check));

		// Check we can open this file
		// @todo
		// @todo implement return 2 - SKIP file
		// @todo implement return 4 - SUSPEND(?) file
		if ($check) {
			return 0;
		}

		if (! $this->receiving)
			throw new Exception('No files currently receiving');

		$this->ao = $ao;
		$this->file_pos = 0;
		$this->start = time();
		$this->file = sprintf('storage/app/%s/%04X-%s',config('app.fido'),$this->ao->id,$this->receiving->recvas);

		Log::debug(sprintf('%s:   - Opening [%s]',__METHOD__,$this->file));
		$this->f = fopen($this->file,'wb');
		if (! $this->f) {
			Log::error(sprintf('%s:   ! Unable to open file [%s] for writing',__METHOD__,$this->receiving->file_name));
			return 3;	// @todo change to const
		}

		Log::info(sprintf('%s: = End - File [%s] opened for writing',__METHOD__,$this->receiving->file_name));
		return 0;		// @todo change to const
	}

	/**
	 * Add a new file to receive
	 *
	 * @param array $file
	 * @throws Exception
	 */
	public function new(array $file): void
	{
		Log::debug(sprintf('%s: + Start',__METHOD__),['file'=>$file]);

		if ($this->receiving)
			throw new Exception('Can only have 1 file receiving at a time');

		$o = new Item($file,self::I_RECV);
		$this->list->push($o);

		$this->receiving = $o;
	}

	/**
	 * Write data to the file we are receiving
	 *
	 * @param string $buf
	 * @return int
	 * @throws Exception
	 */
	public function write(string $buf): int
	{
		if (! $this->f)
			throw new Exception('No file open for read');

		if ($this->file_pos+strlen($buf) > $this->receiving->file_size)
			throw new Exception(sprintf('Too many bytes received [%d] (%d)?',$this->file_pos+strlen($buf),$this->receiving->file_size));

		$rc = fwrite($this->f,$buf);

		if ($rc === FALSE)
			throw new FileException('Error while writing to file');

		$this->file_pos += $rc;
		Log::debug(sprintf('%s: - Write [%d] bytes, file pos now [%d] of [%d]',__METHOD__,$rc,$this->file_pos,$this->receiving->file_size));

		return $rc;
	}
}