<?php

declare(strict_types=1);

/**
 * SPDX-FileCopyrightText: Sebastian Krupinski <krupinski01@gmail.com>
 * SPDX-License-Identifier: AGPL-3.0-or-later
 */

namespace KTXM\ProviderJmapc\Service\Remote;

use Exception;
use JmapClient\Client;
use JmapClient\Requests\Blob\BlobGet;
use JmapClient\Requests\Blob\BlobSet;
use JmapClient\Requests\Mail\MailboxGet;
use JmapClient\Requests\Mail\MailboxParameters as MailboxParametersRequest;
use JmapClient\Requests\Mail\MailboxQuery;
use JmapClient\Requests\Mail\MailboxSet;
use JmapClient\Requests\Mail\MailChanges;
use JmapClient\Requests\Mail\MailGet;
use JmapClient\Requests\Mail\MailIdentityGet;
use JmapClient\Requests\Mail\MailParameters as MailParametersRequest;
use JmapClient\Requests\Mail\MailQuery;
use JmapClient\Requests\Mail\MailQueryChanges;
use JmapClient\Requests\Mail\MailSet;
use JmapClient\Requests\Mail\MailSubmissionSet;
use JmapClient\Responses\Mail\MailboxParameters as MailboxParametersResponse;
use JmapClient\Responses\Mail\MailParameters as MailParametersResponse;
use JmapClient\Responses\ResponseException;
use KTXF\Resource\Delta\Delta;
use KTXF\Resource\Delta\DeltaCollection;
use KTXF\Resource\Filter\Filter;
use KTXF\Resource\Filter\IFilter;
use KTXF\Resource\Range\IRange;
use KTXF\Resource\Range\IRangeTally;
use KTXF\Resource\Range\Range;
use KTXF\Resource\Range\RangeAnchorType;
use KTXF\Resource\Range\RangeTally;
use KTXF\Resource\Sort\ISort;
use KTXF\Resource\Sort\Sort;
use KTXM\ProviderJmapc\Exception\JmapUnknownMethod;
use KTXM\ProviderJmapc\Objects\Mail\Collection as MailCollectionObject;

class RemoteMailService {
	protected Client $dataStore;
	protected string $dataAccount;

	protected ?string $resourceNamespace = null;
	protected ?string $resourceCollectionLabel = null;
	protected ?string $resourceEntityLabel = null;

	protected array $defaultMailProperties = [
		'id', 'blobId', 'threadId', 'mailboxIds', 'keywords', 'size',
		'receivedAt', 'messageId', 'inReplyTo', 'references', 'sender', 'from',
		'to', 'cc', 'bcc', 'replyTo', 'subject', 'sentAt', 'hasAttachment',
		'attachments', 'preview', 'bodyStructure', 'bodyValues'
	];

	public function __construct() {
	}

	public function initialize(Client $dataStore, ?string $dataAccount = null) {

		$this->dataStore = $dataStore;
		// evaluate if client is connected
		if (!$this->dataStore->sessionStatus()) {
			$this->dataStore->connect();
		}
		// determine account
		if ($dataAccount === null) {
			if ($this->resourceNamespace !== null) {
				$account = $dataStore->sessionAccountDefault($this->resourceNamespace, false);
			} else {
				$account = $dataStore->sessionAccountDefault('mail');
			}
			$this->dataAccount = $account !== null ? $account->id() : '';
		} else {
			$this->dataAccount = $dataAccount;
		}

	}

	/**
	 * list of collections in remote storage
	 *
	 * @since Release 1.0.0
	 */
	public function collectionList(?string $location = null, IFilter|null $filter = null, ISort|null $sort = null, IRange|null $range = null): array {
		// construct request
		$r0 = new MailboxQuery($this->dataAccount, null, $this->resourceNamespace, $this->resourceEntityLabel);
		// define location
		if (!empty($location)) {
			$r0->filter()->in($location);
		}
		// define filter
		if ($filter !== null) {
			foreach ($filter->conditions() as $condition) {
				$value = $condition['value'];
				match($condition['attribute']) {
					'in' => $r0->filter()->in($value),
					'name' => $r0->filter()->name($value),
					'role' => $r0->filter()->role($value),
					'hasRoles' => $r0->filter()->hasRoles($value),
					'subscribed' => $r0->filter()->isSubscribed($value),
					default => null
				};
			}
		}
		// define order
		if ($sort !== null) {
			foreach ($sort->conditions() as $condition) {
				$direction = $condition['direction'];
				match($condition['attribute']) {
					'name' => $r0->sort()->name($direction),
					'order' => $r0->sort()->order($direction),
					default => null
				};
			}
		}
		// construct request
		$r1 = new MailboxGet($this->dataAccount, null, $this->resourceNamespace, $this->resourceEntityLabel);
		// define target
		$r1->targetFromRequest($r0, '/ids');
		// transceive
		$bundle = $this->dataStore->perform([$r0, $r1]);
		// extract response
		$response = $bundle->response(1);
		// check for command error
		if ($response instanceof ResponseException) {
			if ($response->type() === 'unknownMethod') {
				throw new JmapUnknownMethod($response->description(), 1);
			} else {
				throw new Exception($response->type() . ': ' . $response->description(), 1);
			}
		}
		// convert jmap objects to collection objects
		$list = [];
		foreach ($response->objects() as $so) {
			if (!$so instanceof MailboxParametersResponse) {
				continue;
			}
			$id = $so->id();
			$list[$id] = $so->parametersRaw();
			$list[$id]['signature'] = $response->state();
		}
		// return collection of collections
		return $list;
	}

	/**
	 * fresh instance of collection filter object
	 *
	 * @since Release 1.0.0
	 */
	public function collectionListFilter(): Filter {
		return new Filter(['in', 'name', 'role', 'hasRoles', 'subscribed']);
	}

	/**
	 * fresh instance of collection sort object
	 *
	 * @since Release 1.0.0
	 */
	public function collectionListSort(): Sort {
		return new Sort(['name', 'order']);
	}

	/**
	 * check existence of collections in remote storage
	 *
	 * @since Release 1.0.0
	 */
	public function collectionExtant(string ...$identifiers): array {
		$extant = [];
		// construct request
		$r0 = new MailboxGet($this->dataAccount, null, $this->resourceNamespace, $this->resourceEntityLabel);
		$r0->target(...$identifiers);
		$r0->property('id');
		// transceive
		$bundle = $this->dataStore->perform([$r0]);
		// extract response
		$response = $bundle->response(0);
		// check for command error
		if ($response instanceof ResponseException) {
			if ($response->type() === 'unknownMethod') {
				throw new JmapUnknownMethod($response->description(), 1);
			} else {
				throw new Exception($response->type() . ': ' . $response->description(), 1);
			}
		}
		// convert jmap objects to collection objects
		foreach ($response->objects() as $so) {
			if (!$so instanceof MailboxParametersResponse) {
				continue;
			}
			$extant[$so->id()] = true;
		}
		return $extant;
	}

	/**
	 * retrieve properties for specific collection
	 *
	 * @since Release 1.0.0
	 */
	public function collectionFetch(string $identifier): ?array {
		// construct request
		$r0 = new MailboxGet($this->dataAccount, null, $this->resourceNamespace, $this->resourceEntityLabel);
		$r0->target($identifier);
		// transceive
		$bundle = $this->dataStore->perform([$r0]);
		// extract response
		$response = $bundle->response(0);
		// check for command error
		if ($response instanceof ResponseException) {
			if ($response->type() === 'unknownMethod') {
				throw new JmapUnknownMethod($response->description(), 1);
			} else {
				throw new Exception($response->type() . ': ' . $response->description(), 1);
			}
		}
		// convert jmap object to collection object
		$so = $response->object(0);
		$to = null;
		if ($so instanceof MailboxParametersResponse) {
			$to = $so->parametersRaw();
			$to['signature'] = $response->state();
		}
		return $to;
	}

	/**
	 * create collection in remote storage
	 *
	 * @since Release 1.0.0
	 */
	public function collectionCreate(string|null $location, array $so): ?array {
		// convert entity
		$to = new MailboxParametersRequest();
		$to->parametersRaw($so);
		// define location
		if (!empty($location)) {
			$to->in($location);
		}
		$id = uniqid();
		// construct request
		$r0 = new MailboxSet($this->dataAccount, null, $this->resourceNamespace, $this->resourceEntityLabel);
		$r0->create($id, $to);
		// transceive
		$bundle = $this->dataStore->perform([$r0]);
		// extract response
		$response = $bundle->response(0);
		// check for command error
		if ($response instanceof ResponseException) {
			if ($response->type() === 'unknownMethod') {
				throw new JmapUnknownMethod($response->description(), 1);
			} else {
				throw new Exception($response->type() . ': ' . $response->description(), 1);
			}
		}
		// check for success
		$result = $response->createSuccess($id);
		if ($result !== null) {
			return array_merge($so, $result);
		}
		// check for failure
		$result = $response->createFailure($id);
		if ($result !== null) {
			$type = $result['type'] ?? 'unknownError';
			$description = $result['description'] ?? 'An unknown error occurred during collection creation.';
			throw new Exception("$type: $description", 1);
		}
		// return null if creation failed without failure reason
		return null;
	}

	/**
	 * modify collection in remote storage
	 *
	 * @since Release 1.0.0
	 *
	 */
	public function collectionModify(string $identifier, array $so): ?array {
		// convert entity
		$to = new MailboxParametersRequest();
		$to->parametersRaw($so);
		// construct request
		$r0 = new MailboxSet($this->dataAccount, null, $this->resourceNamespace, $this->resourceEntityLabel);
		$r0->update($identifier, $to);
		// transceive
		$bundle = $this->dataStore->perform([$r0]);
		// extract response
		$response = $bundle->response(0);
		// check for command error
		if ($response instanceof ResponseException) {
			if ($response->type() === 'unknownMethod') {
				throw new JmapUnknownMethod($response->description(), 1);
			} else {
				throw new Exception($response->type() . ': ' . $response->description(), 1);
			}
		}
		// check for success
		$result = $response->updateSuccess($identifier);
		if ($result !== null) {
			return array_merge($so, $result);
		}
		// check for failure
		$result = $response->updateFailure($identifier);
		if ($result !== null) {
			$type = $result['type'] ?? 'unknownError';
			$description = $result['description'] ?? 'An unknown error occurred during collection modification.';
			throw new Exception("$type: $description", 1);
		}
		// return null if modification failed without failure reason
		return null;
	}

	/**
	 * delete collection in remote storage
	 *
	 * @since Release 1.0.0
	 *
	 */
	public function collectionDestroy(string $identifier, bool $force = false, bool $recursive = false): ?string {
		// construct request
		$r0 = new MailboxSet($this->dataAccount, null, $this->resourceNamespace, $this->resourceEntityLabel);
		$r0->delete($identifier);
		if ($force) {
			$r0->destroyContents(true);
		}
		// transceive
		$bundle = $this->dataStore->perform([$r0]);
		// extract response
		$response = $bundle->response(0);
		// check for command error
		if ($response instanceof ResponseException) {
			if ($response->type() === 'unknownMethod') {
				throw new JmapUnknownMethod($response->description(), 1);
			} else {
				throw new Exception($response->type() . ': ' . $response->description(), 1);
			}
		}
		// check for success
		$result = $response->deleteSuccess($identifier);
		if ($result !== null) {
			return (string)$result['id'];
		}
		// check for failure
		$result = $response->deleteFailure($identifier);
		if ($result !== null) {
			$type = $result['type'] ?? 'unknownError';
			$description = $result['description'] ?? 'An unknown error occurred during collection deletion.';
			throw new Exception("$type: $description", 1);
		}
		// return null if deletion failed without failure reason
		return null;
	}

	/**
	 * retrieve entities from remote storage
	 *
	 * @since Release 1.0.0
	 */
	public function entityList(?string $location = null, IFilter|null $filter = null, ISort|null $sort = null, IRange|null $range = null, string|null $granularity = null): array {
		// construct request
		$r0 = new MailQuery($this->dataAccount, null, $this->resourceNamespace, $this->resourceEntityLabel);
		// define location
		if (!empty($location)) {
			$r0->filter()->in($location);
		}
		// define filter
		if ($filter !== null) {
			foreach ($filter->conditions() as $condition) {
				$value = $condition['value'];
				match($condition['attribute']) {
					'*' => $r0->filter()->text($value),
					'in' => $r0->filter()->in($value),
					'inOmit' => $r0->filter()->inOmit($value),
					'from' => $r0->filter()->from($value),
					'to' => $r0->filter()->to($value),
					'cc' => $r0->filter()->cc($value),
					'bcc' => $r0->filter()->bcc($value),
					'subject' => $r0->filter()->subject($value),
					'body' => $r0->filter()->body($value),
					'attachmentPresent' => $r0->filter()->hasAttachment($value),
					'tagPresent' => $r0->filter()->keywordPresent($value),
					'tagAbsent' => $r0->filter()->keywordAbsent($value),
					'before' => $r0->filter()->receivedBefore($value),
					'after' => $r0->filter()->receivedAfter($value),
					'min' => $r0->filter()->sizeMin((int)$value),
					'max' => $r0->filter()->sizeMax((int)$value),
					default => null
				};
			}
		}
		// define order
		if ($sort !== null) {
			foreach ($sort->conditions() as $condition) {
				$direction = $condition['direction'];
				match($condition['attribute']) {
					'from' => $r0->sort()->from($direction),
					'to' => $r0->sort()->to($direction),
					'subject' => $r0->sort()->subject($direction),
					'received' => $r0->sort()->received($direction),
					'sent' => $r0->sort()->sent($direction),
					'size' => $r0->sort()->size($direction),
					'tag' => $r0->sort()->keyword($direction),
					default => null
				};
			}
		}
		// define range
		if ($range !== null) {
			if ($range instanceof RangeTally && $range->getAnchor() === RangeAnchorType::ABSOLUTE) {
				$r0->limitAbsolute($range->getPosition(), $range->getTally());
			}
			if ($range instanceof RangeTally && $range->getAnchor() === RangeAnchorType::RELATIVE) {
				$r0->limitRelative($range->getPosition(), $range->getTally());
			}
		}
		// construct get request
		$r1 = new MailGet($this->dataAccount, null, $this->resourceNamespace, $this->resourceEntityLabel);
		// set target to query request
		$r1->targetFromRequest($r0, '/ids');
		// select properties to return
		$r1->property(...$this->defaultMailProperties);
		$r1->bodyAll(true);
		// transmit request and receive response
		$bundle = $this->dataStore->perform([$r0, $r1]);
		// extract response
		$response = $bundle->response(1);
		// convert json objects to message objects
		$state = $response->state();
		$list = $response->objects();
		foreach ($list as $id => $entry) {
			if (!$entry instanceof MailParametersResponse) {
				continue;
			}
			$list[$id] = $entry->parametersRaw();
		}
		// return message collection
		return ['list' => $list, 'state' => $state];
	}

	/**
	 * fresh instance of object filter
	 *
	 * @since Release 1.0.0
	 */
	public function entityListFilter(): Filter {
		return new Filter([
			'in', 
			'inOmit', 
			'text', 
			'from', 
			'to', 
			'cc', 
			'bcc', 
			'subject', 
			'body', 
			'attachmentPresent', 
			'tagPresent', 
			'tagAbsent', 
			'receivedBefore', 
			'receivedAfter', 
			'sizeMin', 
			'sizeMax'
		]);
	}

	/**
	 * fresh instance of object sort
	 *
	 * @since Release 1.0.0
	 */
	public function entityListSort(): Sort {
		return new Sort([
			'received', 
			'sent', 
			'from', 
			'to', 
			'subject', 
			'size', 
			'tag'
		]);
	}

	/**
	 * fresh instance of object range
	 *
	 * @since Release 1.0.0
	 */
	public function entityListRange(): RangeTally {
		return new RangeTally();
	}

	/**
	 * check existence of entities in remote storage
	 *
	 * @since Release 1.0.0
	 */
	public function entityExtant(string ...$identifiers): array {
		$extant = [];
		// construct request
		$r0 = new MailGet($this->dataAccount, null, $this->resourceNamespace, $this->resourceEntityLabel);
		$r0->target(...$identifiers);
		$r0->property('id');
		// transmit request and receive response
		$bundle = $this->dataStore->perform([$r0]);
		// extract response
		$response = $bundle->response(0);
		// convert json objects to message objects
		foreach ($response->objects() as $so) {
			if (!$so instanceof MailParametersResponse) {
				continue;
			}
			$extant[$so->id()] = true;
		}
		return $extant;
	}

	/**
	 * delta for entities in remote storage
	 *
	 * @since Release 1.0.0
	 *
	 * @return Delta
	 */
	public function entityDelta(?string $location, string $state, string $granularity = 'D'): Delta {

		if (empty($state)) {
			$results = $this->entityList($location, null, null, null, 'B');
			$delta = new Delta();
			$delta->signature = $results['state'];
			foreach ($results['list'] as $entry) {
				$delta->additions[] = $entry['id'];
			}
			return $delta;
		}
		if (empty($location)) {
			return $this->entityDeltaDefault($state, $granularity);
		} else {
			return $this->entityDeltaSpecific($location, $state, $granularity);
		}
	}

	/**
	 * delta of changes for specific collection in remote storage
	 *
	 * @since Release 1.0.0
	 *
	 */
	public function entityDeltaSpecific(?string $location, string $state, string $granularity = 'D'): Delta {
		// construct set request
		$r0 = new MailQueryChanges($this->dataAccount, null, $this->resourceNamespace, $this->resourceEntityLabel);
		// set location constraint
		if (!empty($location)) {
			$r0->filter()->in($location);
		}
		// set state constraint
		if (!empty($state)) {
			$r0->state($state);
		} else {
			$r0->state('0');
		}
		// transceive
		$bundle = $this->dataStore->perform([$r0]);
		// extract response
		$response = $bundle->response(0);
		// check for command error
		if ($response instanceof ResponseException) {
			if ($response->type() === 'unknownMethod') {
				throw new JmapUnknownMethod($response->description(), 1);
			} else {
				throw new Exception($response->type() . ': ' . $response->description(), 1);
			}
		}
		// convert jmap object to delta object
		$delta = new Delta();
		$delta->signature = $response->stateNew();
		$delta->additions = new DeltaCollection(array_column($response->added(), 'id'));
		$delta->modifications = new DeltaCollection([]);
		$delta->deletions = new DeltaCollection(array_column($response->removed(), 'id'));

		return $delta;
	}

	/**
	 * delta of changes in remote storage
	 *
	 * @since Release 1.0.0
	 *
	 */
	public function entityDeltaDefault(string $state, string $granularity = 'D'): Delta {
		// construct set request
		$r0 = new MailChanges($this->dataAccount, null, $this->resourceNamespace, $this->resourceEntityLabel);
		// set state constraint
		if (!empty($state)) {
			$r0->state($state);
		} else {
			$r0->state('');
		}
		// transceive
		$bundle = $this->dataStore->perform([$r0]);
		// extract response
		$response = $bundle->response(0);
		// check for command error
		if ($response instanceof ResponseException) {
			if ($response->type() === 'unknownMethod') {
				throw new JmapUnknownMethod($response->description(), 1);
			} else {
				throw new Exception($response->type() . ': ' . $response->description(), 1);
			}
		}
		// convert jmap object to delta object
		$delta = new Delta();
		$delta->signature = $response->stateNew();
		$delta->additions = new DeltaCollection(array_column($response->added(), 'id'));
		$delta->modifications = new DeltaCollection([]);
		$delta->deletions = new DeltaCollection(array_column($response->removed(), 'id'));

		return $delta;
	}

	/**
	 * retrieve entity from remote storage
	 *
	 * @since Release 1.0.0
	 */
	public function entityFetch(string ...$identifiers): ?array {
		// construct request
		$r0 = new MailGet($this->dataAccount, null, $this->resourceNamespace, $this->resourceEntityLabel);
		$r0->target(...$identifiers);
		// select properties to return
		$r0->property(...$this->defaultMailProperties);
		$r0->bodyAll(true);
		// transmit request and receive response
		$bundle = $this->dataStore->perform([$r0]);
		// extract response
		$response = $bundle->response(0);
		// convert json objects to message objects
		$list = [];
		foreach ($response->objects() as $so) {
			if (!$so instanceof MailParametersResponse) {
				continue;
			}
			$id = $so->id();
			$list[$id] = $so->parametersRaw();
			$list[$id]['signature'] = $response->state();
		}
		// return message collection
		return $list;
	}

	/**
	 * create entity in remote storage
	 *
	 * @since Release 1.0.0
	 */
	public function entityCreate(string $location, array $so): ?array {
		// convert entity
		$to = new MailParametersRequest();
		$to->parametersRaw($so);
		$to->in($location);
		$id = uniqid();
		// construct request
		$r0 = new MailSet($this->dataAccount, null, $this->resourceNamespace, $this->resourceEntityLabel);
		$r0->create($id, $to);
		// transceive
		$bundle = $this->dataStore->perform([$r0]);
		// extract response
		$response = $bundle->response(0);
		// check for command error
		if ($response instanceof ResponseException) {
			if ($response->type() === 'unknownMethod') {
				throw new JmapUnknownMethod($response->description(), 1);
			} else {
				throw new Exception($response->type() . ': ' . $response->description(), 1);
			}
		}
		// check for success
		$result = $response->createSuccess($id);
		if ($result !== null) {
			return array_merge($so, $result);
		}
		// check for failure
		$result = $response->createFailure($id);
		if ($result !== null) {
			$type = $result['type'] ?? 'unknownError';
			$description = $result['description'] ?? 'An unknown error occurred during collection creation.';
			throw new Exception("$type: $description", 1);
		}
		// return null if creation failed without failure reason
		return null;
	}

	/**
	 * update entity in remote storage
	 *
	 * @since Release 1.0.0
	 */
	public function entityModify(array $so): ?array {
		// extract entity id
		$id = $so['id'];
		// convert entity
		$to = new MailParametersRequest();
		$to->parametersRaw($so);
		// construct request
		$r0 = new MailSet($this->dataAccount, null, $this->resourceNamespace, $this->resourceEntityLabel);
		$r0->update($id, $to);
		// transmit request and receive response
		$bundle = $this->dataStore->perform([$r0]);
		// extract response
		$response = $bundle->response(0);
		// determine if command succeeded
		if (array_key_exists($id, $response->updated())) {
			// update entity
			$ro = $response->updated()[$id];
			$so = array_merge($so, $ro);
			return $so;
		}
		return null;
	}

	/**
	 * delete entity from remote storage
	 *
	 * @since Release 1.0.0
	 */
	public function entityDelete(string $id): ?string {
		// construct set request
		$r0 = new MailSet($this->dataAccount, null, $this->resourceNamespace, $this->resourceEntityLabel);
		// construct object
		$r0->delete($id);
		// transmit request and receive response
		$bundle = $this->dataStore->perform([$r0]);
		// extract response
		$response = $bundle->response(0);
		// determine if command succeeded
		if (array_search($id, $response->deleted()) !== false) {
			return $response->stateNew();
		}
		return null;
	}

	/**
	 * copy entity in remote storage
	 *
	 * @since Release 1.0.0
	 *
	 */
	public function entityCopy(string $location, MailMessageObject $so): ?MailMessageObject {
		return null;
	}

	/**
	 * move entity in remote storage
	 *
	 * @since Release 1.0.0
	 *
	 */
	public function entityMove(string $location, array $so): ?array {
		// extract entity id
		$id = $so['id'];
		// construct request
		$r0 = new MailSet($this->dataAccount, null, $this->resourceNamespace, $this->resourceEntityLabel);
		$r0->update($id)->in($location);
		// transmit request and receive response
		$bundle = $this->dataStore->perform([$r0]);
		// extract response
		$response = $bundle->response(0);
		// determine if command succeeded
		if (array_key_exists($id, $response->updated())) {
			$so = array_merge($so, ['mailboxIds' => [$location => true]]);
			return $so;
		}
		return null;
	}

	/**
	 * send entity
	 *
	 * @since Release 1.0.0
	 *
	 */
	public function entitySend(string $identity, MailMessageObject $message, ?string $presendLocation = null, ?string $postsendLocation = null): string {
		// determine if pre-send location is present
		if ($presendLocation === null || empty($presendLocation)) {
			throw new Exception('Pre-Send Location is missing', 1);
		}
		// determine if post-send location is present
		if ($postsendLocation === null || empty($postsendLocation)) {
			throw new Exception('Post-Send Location is missing', 1);
		}
		// determine if we have the basic required data and fail otherwise
		if (empty($message->getFrom())) {
			throw new Exception('Missing Requirements: Message MUST have a From address', 1);
		}
		if (empty($message->getTo())) {
			throw new Exception('Missing Requirements: Message MUST have a To address(es)', 1);
		}
		// determine if message has attachments
		if (count($message->getAttachments()) > 0) {
			// process attachments first
			$message = $this->depositAttachmentsFromMessage($message);
		}
		// convert from address object to string
		$from = $message->getFrom()->getAddress();
		// convert to, cc and bcc address object arrays to single strings array
		$to = array_map(
			function ($entry) { return $entry->getAddress(); },
			array_merge($message->getTo(), $message->getCc(), $message->getBcc())
		);
		unset($cc, $bcc);
		// construct set request
		$r0 = new MailSet($this->dataAccount, null, $this->resourceNamespace, $this->resourceEntityLabel);
		$r0->create('1', $message)->in($presendLocation);
		// construct set request
		$r1 = new MailSubmissionSet($this->dataAccount, null, $this->resourceNamespace, $this->resourceEntityLabel);
		// construct envelope
		$e1 = $r1->create('2');
		$e1->identity($identity);
		$e1->message('#1');
		$e1->from($from);
		$e1->to($to);
		// transmit request and receive response
		$bundle = $this->dataStore->perform([$r0, $r1]);
		// extract response
		$response = $bundle->response(1);
		// return collection information
		return (string)$response->created()['2']['id'];
	}

	/**
	 * retrieve collection entity attachment from remote storage
	 *
	 * @since Release 1.0.0
	 *
	 */
	public function depositAttachmentsFromMessage(MailMessageObject $message): MailMessageObject {

		$parameters = $message->toJmap();
		$attachments = $message->getAttachments();
		$matches = [];

		$this->findAttachmentParts($parameters['bodyStructure'], $matches);

		foreach ($attachments as $attachment) {
			$part = $attachment->toJmap();
			if (isset($matches[$part->getId()])) {
				// deposit attachment in data store
				$response = $this->blobDeposit($account, $part->getType(), $attachment->getContents());
				// transfer blobId and size to mail part
				$matches[$part->getId()]->blobId = $response['blobId'];
				$matches[$part->getId()]->size = $response['size'];
				unset($matches[$part->getId()]->partId);
			}
		}

		return (new MailMessageObject())->fromJmap($parameters);

	}

	protected function findAttachmentParts(object &$part, array &$matches) {

		if ($part->disposition === 'attachment' || $part->disposition === 'inline') {
			$matches[$part->partId] = $part;
		}

		foreach ($part->subParts as $entry) {
			$this->findAttachmentParts($entry, $matches);
		}

	}

	/**
	 * retrieve identity from remote storage
	 *
	 * @since Release 1.0.0
	 *
	 */
	public function identityFetch(?string $account = null): array {
		if ($account === null) {
			$account = $this->dataAccount;
		}
		// construct set request
		$r0 = new MailIdentityGet($this->dataAccount, null, $this->resourceNamespace, $this->resourceEntityLabel);
		// transmit request and receive response
		$bundle = $this->dataStore->perform([$r0]);
		// extract response
		$response = $bundle->response(0);
		// convert json object to message object and return
		return $response->objects();
	}

}