<?php

declare(strict_types=1);

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

namespace KTXM\ProviderImap\Providers;

use Generator;
use KTXF\Mail\Collection\CollectionBaseInterface;
use KTXF\Mail\Collection\CollectionPropertiesBaseInterface;
use KTXF\Mail\Object\Address;
use KTXF\Mail\Object\AddressInterface;
use KTXF\Mail\Service\ServiceBaseInterface;
use KTXF\Mail\Service\ServiceCollectionMutableInterface;
use KTXF\Mail\Service\ServiceEntityMutableInterface;
use KTXF\Mail\Service\ServiceEntitySubmitInterface;
use KTXF\Mail\Service\ServiceConfigurableInterface;
use KTXF\Mail\Service\ServiceMutableInterface;
use KTXF\Mail\Submission\EntitySubmitResult;
use KTXF\Resource\BinaryResource;
use KTXF\Resource\Provider\ResourceServiceIdentityInterface;
use KTXF\Resource\Provider\ResourceServiceLocationInterface;
use KTXF\Resource\Delta\Delta;
use KTXF\Resource\Filter\Filter;
use KTXF\Resource\Filter\IFilter;
use KTXF\Resource\Identifier\CollectionIdentifier;
use KTXF\Resource\Identifier\EntityIdentifier;
use KTXF\Resource\Range\IRange;
use KTXF\Resource\Range\Range;
use KTXF\Resource\Range\RangeTally;
use KTXF\Resource\Range\RangeType;
use KTXF\Resource\Sort\ISort;
use KTXF\Resource\Sort\Sort;
use KTXM\ProviderImap\Providers\ServiceIdentityBasic;
use KTXM\ProviderImap\Providers\ServiceLocation;
use KTXM\ProviderImap\Mime\MessageBuilder;
use KTXM\ProviderImap\Service\Live\LiveMailService;
use KTXM\ProviderImap\Providers\CollectionResource;
use KTXF\Mail\Collection\CollectionRoles;
use KTXF\Mail\Object\MessagePropertiesMutableInterface;
use KTXF\Resource\Identifier\EntityIdentifierInterface;
use KTXM\ProviderImap\Providers\EntityResource;

/**
 * IMAP mail service that talks to the server directly.
 *
 * Holds the mail API rules (validation, delete modes, submission, move / copy
 * result mapping); CachedService delegates writes here.
 */
class LiveService extends ServiceBase
{
    private LiveMailService $mailService;

    /**
     * @param LiveMailService|null $mailService share an existing IMAP connection (e.g. CachedService); created on demand otherwise
     */
    public function __construct(?LiveMailService $mailService = null)
    {
        if ($mailService !== null) {
            $this->mailService = $mailService;
        }
    }

    public function collectionList(string|int|null $location, ?IFilter $filter = null, ?ISort $sort = null): array
    {
        $this->initialize();
        
        return $this->mailService->collectionList($location === null ? null : (string) $location, $filter, $sort);
    }

    public function collectionExtant(string|int ...$identifiers): array
    {
        $this->initialize();

        $list = [];

        foreach ($identifiers as $identifier) {
            $key = (string) $identifier;
            $list[$key] = $this->mailService->collectionFetch($key) !== null;
        }

        return $list;
    }

    public function collectionFetch(string|int $identifier): ?CollectionResource
    {
        $this->initialize();
        
        return $this->mailService->collectionFetch((string) $identifier);
    }

    public function collectionCreate(CollectionIdentifier|null $target, CollectionPropertiesBaseInterface $properties, array $options = []): CollectionBaseInterface
    {
        $this->initialize();

        if (!$properties->getLabel()) {
            throw new \InvalidArgumentException('Collection label is required property');
        }
        $label = $properties->getLabel();

        // Resolve the full name: if a parent location is given, prepend it
        if ($target !== null) {
            $path = $target->collection();
            // Determine the hierarchy delimiter from an existing mailbox, default to '/'
            $delimiter = $this->mailService->collectionDelimiter();
            $label = rtrim((string) $path, $delimiter) . $delimiter . ltrim($label, $delimiter);
        }

        return $this->mailService->collectionCreate($label, $delimiter ?? null);
    }

    public function collectionUpdate(CollectionIdentifier $target, CollectionPropertiesBaseInterface $properties): CollectionBaseInterface
    {
        $this->initialize();

        if (!$properties->getLabel()) {
            throw new \InvalidArgumentException('Collection label is a required property');
        }
        $label = $properties->getLabel();

        // In IMAP, "update" = rename to the new label
        $oldPath = (string) $target->collection();
        $newName = $properties->getLabel();
        return $this->mailService->collectionRename($oldPath, $newName);
    }

    public function collectionDelete(CollectionIdentifier $target, bool $force = false): CollectionBaseInterface | true
    {
        $this->initialize();

        $deleteMode = $this->auxiliary['deleteMode'] ?? 'soft';

        if ($deleteMode !== 'soft' && $deleteMode !== 'hard') {
            throw new \InvalidArgumentException("Invalid delete mode: $deleteMode");
        }

        $deleteTarget = $deleteMode === 'soft' ? $this->resolveDeleteDestination() : null;

        // we need to determine if the folder being deleted is already in the trash
        if ($deleteTarget !== null && str_starts_with((string) $target->collection(), $deleteTarget)) {
            // if so, we should hard delete instead of moving to avoid duplicates in the trash
            $deleteMode = 'hard';
        }

        $result = match ($deleteMode) {
            'soft' => $this->collectionMove(new CollectionIdentifier($target->provider(), $target->service(), $deleteTarget), $target),
            'hard' => $this->mailService->collectionDestroy((string) $target->collection()),
        };
        return $result;
    }

    public function collectionMove(CollectionIdentifier $target, CollectionIdentifier $source): CollectionBaseInterface
    {
        $this->initialize();
        
        $sourceMailbox = $this->mailService->collectionFetch((string) $source->collection());
        $targetMailbox = $this->mailService->collectionFetch((string) $target->collection());
        if ($sourceMailbox === null) {
             throw new \RuntimeException('Source collection not found for move operation');
        }
        if ($targetMailbox === null) {
            throw new \RuntimeException('Target collection not found for move operation');
        }

        $sourceDelimiter = $sourceMailbox->getProperties()->getDelimiter() ?: '/';
        $targetDelimiter = $targetMailbox->getProperties()->getDelimiter() ?: '/';

        $extantPath = (string) $sourceMailbox->identifier();
        $extantPathLeafs = explode($sourceDelimiter, rtrim($extantPath, $sourceDelimiter));

        $freshPath = rtrim((string) $targetMailbox->identifier(), $targetDelimiter) . $targetDelimiter . end($extantPathLeafs);

        return $this->mailService->collectionRename($extantPath, $freshPath, $targetDelimiter);
    }

    public function entityListBulk(string|int $collection, ?IFilter $filter = null, ?ISort $sort = null, ?IRange $range = null, ?array $properties = null): array
    {
        return iterator_to_array($this->entityListStream((string) $collection, $filter, $sort, $range), true);
    }

    public function entityListStream(string|int $collection, ?IFilter $filter = null, ?ISort $sort = null, ?IRange $range = null, ?array $properties = null): Generator
    {
        $this->initialize();

        foreach ($this->mailService->entityList((string) $collection, $filter, $sort, $range) as $resource) {
            yield $resource->urn() => $resource;
        }
    }

    public function entityFetchBulk(EntityIdentifierInterface ...$identifiers): array
    {
        return iterator_to_array($this->entityFetchStream(...$identifiers), true);
    }

    public function entityFetchStream(EntityIdentifierInterface ...$identifiers): Generator
    {
        $this->initialize();

        $identifiers = $this->groupEntitiesByCollection(...$identifiers);

        foreach ($identifiers as $collection => $entities) {
            $uids = array_keys($entities);
            foreach ($this->mailService->entityFetch((string) $collection, ...$uids) as $resource) {
                yield $resource->urn() => $resource;
            }
        }
    }

    public function entityDownload(EntityIdentifierInterface $target, array|null $part): BinaryResource {
        $this->initialize();

        $collection = $target->collection();
        $uid        = (int) $target->entity();
        $partId     = isset($part['partId']) ? (string) $part['partId'] : null;

        return $this->mailService->entityDownload($collection, $uid, $partId);
    }

    public function entityDelta(string|int $collection, string $signature, string $detail = 'ids'): Delta
    {
        return new Delta(signature: $signature);
    }

    public function entityExtant(string|int $collection, string|int ...$identifiers): array
    {
        $this->initialize();

        // only positive integers are valid UIDs; anything else cannot exist
        $uids = array_values(array_filter(
            array_map(static fn (string|int $id): int => (int) $id, $identifiers),
            static fn (int $uid): bool => $uid > 0,
        ));

        $existing = array_flip($this->mailService->entityExtant((string) $collection, ...$uids));

        $extant = [];
        foreach ($identifiers as $id) {
            $extant[$id] = isset($existing[(int) $id]) && (string) (int) $id === (string) $id;
        }
        return $extant;
    }

    public function entitySubmit(AddressInterface $sender, EntityIdentifierInterface|null $source = null, MessagePropertiesMutableInterface|null $message = null): EntitySubmitResult
    {
        if ($message === null) {
            return new EntitySubmitResult(
                EntitySubmitResult::DISPOSITION_ERROR,
                errorCode: 'invalid_message',
                errorMessage: 'No message properties were provided for submission.',
            );
        }

        // Outbound submission via SMTP — independent of the IMAP connection.
        try {
            $raw = (new MessageBuilder())->build($message);
            $recipients = MessageBuilder::recipients($message);
            if ($recipients === []) {
                throw new \RuntimeException('Message has no recipients.');
            }

            $this->initialize();
            $smtp = $this->mailService->smtpClient();
            try {
                $queueId = $smtp->send(trim($sender->getAddress()), $recipients, $raw);
            } finally {
                $smtp->quit();
            }
        } catch (\Throwable $e) {
            return new EntitySubmitResult(
                EntitySubmitResult::DISPOSITION_ERROR,
                errorCode: 'submission_failed',
                errorMessage: $e->getMessage(),
            );
        }

        // Best-effort: store a copy in the Sent collection. A failure here must
        // not turn a successful delivery into an error.
        $sentEntity = null;
        try {
            $this->initialize();
            $sentCollection = $this->resolveSentCollection();
            if ($sentCollection !== null) {
                $uid = $this->mailService->entityCreate($sentCollection, $raw, ['\\Seen']);
                if ($uid !== null && $uid > 0) {
                    $sentEntity = new EntityIdentifier($this->provider(), $this->identifier(), $sentCollection, (string) $uid);
                }
            }
        } catch (\Throwable) {
            // ignore — the message was already delivered
        }

        // Best-effort: IMAP has no native "submit existing draft" operation, so the
        // message above was always sent fresh. If it originated from a synced draft,
        // remove the now-superseded draft UID. A failure here must not turn a
        // successful delivery into an error; the draft is simply left for a later
        // discard or retry.
        if ($source !== null
            && $source->provider() === $this->provider()
            && $source->service() === $this->identifier()) {
            try {
                $this->initialize();
                $this->mailService->entityDestroy($source->collection(), (int) $source->entity());
            } catch (\Throwable) {
                // ignore — the message was already delivered
            }
        }

        return new EntitySubmitResult(
            disposition: EntitySubmitResult::DISPOSITION_SENT,
            transportId: $queueId !== '' ? $queueId : null,
            sentEntity: $sentEntity,
            sourceDraft: $source instanceof EntityIdentifier ? $source : null,
        );
    }

    public function entityCreate(CollectionIdentifier $target, MessagePropertiesMutableInterface $properties, array $options = []): EntityResource
    {
        if ($target->provider() !== $this->provider() || (string)$target->service() !== (string)$this->identifier()) {
            throw new \InvalidArgumentException('Target collection does not belong to this service: ' . (string)$target);
        }

        $this->initialize();

        [$nativeMessage, $nativeFlags] = $this->messagePayload($properties, $options);
        $created = $this->mailService->entityCreate(
            (string)$target->collection(),
            $nativeMessage,
            $nativeFlags,
        );
        if ($created === null || $created <= 0) {
            throw new \RuntimeException('IMAP APPEND did not return a valid UID');
        }

        return $this->entityFresh()->fromMutation((string)$target->collection(), $created, $properties);
    }

    public function entityModify(EntityIdentifier $target, MessagePropertiesMutableInterface $properties): EntityResource
    {
        if ($target->provider() !== $this->provider() || (string)$target->service() !== (string)$this->identifier()) {
            throw new \InvalidArgumentException('Target entity does not belong to this service: ' . (string)$target);
        }

        $this->initialize();

        [$nativeMessage, $nativeFlags] = $this->messagePayload($properties);
        $modified = $this->mailService->entityReplace(
            (string)$target->collection(),
            (int)$target->entity(),
            $nativeMessage,
            $nativeFlags,
        );
        if ($modified === null || $modified <= 0) {
            throw new \RuntimeException('IMAP replacement did not return a valid UID');
        }

        return $this->entityFresh()->fromMutation((string)$target->collection(), $modified, $properties);
    }

    public function entityPatch(MessagePropertiesMutableInterface $properties, EntityIdentifier ...$targets): array
    {
        // validate identifiers and group by collection
        $targets = $this->groupEntitiesByCollection(...$targets);

         // move entities on remote store and construct result map
        $this->initialize();
        
        $list = [];

        foreach ($targets as $targetCollection => $targetIdentifiers) {
            $uids = array_keys($targetIdentifiers);
            $flagsAdd = [];
            $flagsRemove = [];

            foreach ($properties->getFlags() as $flag => $value) {
                if ($value === true) {
                    $flagsAdd[] = $flag;
                } elseif ($value === false) {
                    $flagsRemove[] = $flag;
                }
            }

            $mutations = $this->mailService->entityPatch($targetCollection, $flagsAdd, $flagsRemove, ...$uids);

            foreach ($uids as $uid) {
                $list[(string)$targetIdentifiers[$uid]] = ['disposition' => 'patched'];
            }
        }

        return $list;
    }

    public function entityDelete(EntityIdentifier ...$targets): array
    {
        // validate identifiers and group by collection
        $targets = $this->groupEntitiesByCollection(...$targets);

        // determine delete mode and target collection (e.g. Trash) if applicable
        $deleteMode = $this->auxiliary['deleteMode'] ?? 'soft';
        
        if ($deleteMode !== 'soft' && $deleteMode !== 'hard') {
            throw new \InvalidArgumentException("Invalid delete mode: $deleteMode");
        }
        
        // connect to remote store
        $this->initialize();
        
        $deleteTargetNative = null;
        $deleteTargetIdentifier = null;
        if ($deleteMode === 'soft') {
            $deleteTargetNative = $this->resolveDeleteDestination();
            $deleteTargetIdentifier = new CollectionIdentifier($this->provider(), (string) $this->identifier(), $deleteTargetNative);
        }

        // if all targets are already in the delete target collection, we should hard delete instead of moving to avoid duplicates in the trash
        if (array_keys($targets) === [$deleteTargetNative]) {
            $deleteMode = 'hard';
        }

        // entities need to be moved or deleted by collection
        $list = [];
        foreach ($targets as $sourceCollection => $sourceEntities) {
            if ($deleteMode === 'soft' && $sourceCollection === $deleteTargetNative) {
                continue;
            }

            $uids = array_keys($sourceEntities);

            $mutations = match ($deleteMode) {
                'soft' => $this->mailService->entityMove($deleteTargetNative, $sourceCollection, ...$uids),
                'hard' => $this->mailService->entityDestroy($sourceCollection, ...$uids),
            };

            foreach ($uids as $uid) {
                $mutatedUid = !isset($mutations[$uid]) || $mutations[$uid] === true ? null : $mutations[$uid];
                $list[(string)$sourceEntities[$uid]] = [
                    'disposition' => $deleteMode === 'soft' ? 'moved' : 'deleted',
                    'destination' => $deleteMode === 'soft' ? $deleteTargetIdentifier : null,
                    'mutation' => $deleteMode === 'soft' && $mutatedUid !== null ? new EntityIdentifier($this->provider(), $this->identifier(), $deleteTargetIdentifier->collection(), $mutatedUid) : null,
                ];
            }
        }

        return $list;
    }

    public function entityMove(CollectionIdentifier $target, EntityIdentifier ...$sources): array
    {
        // validate target belongs to this service
        if ($target->provider() !== $this->provider() || $target->service() !== $this->identifier()) {
            throw new \InvalidArgumentException('Target collection does not belong to this service: ' . $target);
        }

        // validate identifiers and group by collection
        $sources = $this->groupEntitiesByCollection(...$sources);

        // move entities on remote store and construct result map
        $this->initialize();
        
        $list = [];

        foreach ($sources as $sourceCollection => $sourceEntities) {
            $uids = array_keys($sourceEntities);

            $mutations = $this->mailService->entityMove($target->collection(), $sourceCollection, ...$uids);

            foreach ($uids as $uid) {
                $mutatedUid = $mutations[$uid] ?? null;
                $list[(string)$sourceEntities[$uid]] = [
                    'disposition' => 'moved',
                    'destination' => $target,
                    'mutation' => $mutatedUid !== null ? new EntityIdentifier($this->provider(), $this->identifier(), $target->collection(), $mutatedUid) : null,
                ];
                unset($sourceEntities[$uid]);
            }
        }

        return $list;
    }

    public function entityCopy(CollectionIdentifier $target, EntityIdentifier ...$sources): array
    {
        // validate target belongs to this service
        if ($target->provider() !== $this->provider() || $target->service() !== $this->identifier()) {
            throw new \InvalidArgumentException('Target collection does not belong to this service: ' . $target);
        }

        // validate identifiers and group by collection
        $sources = $this->groupEntitiesByCollection(...$sources);

        // copy entities on remote store and construct result map
        $this->initialize();

        $list = [];
        
        foreach ($sources as $sourceCollection => $sourceEntities) {
            $uids = array_keys($sourceEntities);

            $mutations = $this->mailService->entityCopy($target->collection(), $sourceCollection, ...$uids);

            foreach ($uids as $uid) {
                $mutatedUid = $mutations[$uid] ?? null;
                $list[(string)$sourceEntities[$uid]] = [
                    'disposition' => $mutatedUid !== null ? 'copied' : 'error',
                    'destination' => $target,
                    'mutation' => $mutatedUid !== null ? new EntityIdentifier($this->provider(), $this->identifier(), $target->collection(), $mutatedUid) : null,
                ];
            }
        }

        return $list;
    }

    /**
     * Resolve the native name of the first collection flagged with the given role.
     */
    private function resolveRoleCollection(CollectionRoles $role): ?string
    {
        $filter = $this->collectionListFilter();
        $filter->condition('role', $role->value);

        $collections = $this->mailService->collectionList(null, $filter, null);

        return $collections === [] ? null : (string) array_key_first($collections);
    }

    /**
     * Resolve the native name of the collection flagged with the Sent role.
     */
    private function resolveSentCollection(): ?string
    {
        return $this->resolveRoleCollection(CollectionRoles::Sent);
    }

    /**
     * Resolve the native name of the collection soft-deleted messages and collections are moved to.
     */
    private function resolveDeleteDestination(): string
    {
        $destination = trim((string) ($this->auxiliary['deleteDestination'] ?? ''));

        if ($destination === '') {
            return $this->resolveRoleCollection(CollectionRoles::Trash)
                ?? throw new \RuntimeException('No Trash collection configured or found for deletion');
        }

        $role = CollectionRoles::tryFrom(strtolower($destination));
        if ($role !== null && $role !== CollectionRoles::None) {
            return $this->resolveRoleCollection($role) ?? $destination;
        }

        return $destination;
    }

    private function groupEntitiesByCollection(EntityIdentifier ...$identifiers): array
    {
        $list = [];
        foreach ($identifiers as $identifier) {
            if ($identifier->provider() !== $this->provider() || $identifier->service() !== $this->identifier()) {
                throw new \InvalidArgumentException('Entity identifier does not belong to this service: ' . $identifier);
            }
            $list[$identifier->collection()][$identifier->entity()] = $identifier;
        }
        return $list;
    }

    /**
     * Convert canonical message flags to IMAP system flags.
     *
     * @return string[]
     */
    private function messageFlags(MessagePropertiesMutableInterface $properties): array
    {
        $flags = [];
        foreach ($properties->getFlags() as $flag => $enabled) {
            if ($enabled !== true) {
                continue;
            }

            $flags[] = match (strtolower((string)$flag)) {
                'seen' => '\\Seen',
                'flagged' => '\\Flagged',
                'answered' => '\\Answered',
                'draft' => '\\Draft',
                'deleted' => '\\Deleted',
                default => (string)$flag,
            };
        }

        return array_values(array_unique($flags));
    }

    /**
     * Convert message properties into the native IMAP append payload.
     *
     * @return array{0: string, 1: string[]}
     */
    private function messagePayload(MessagePropertiesMutableInterface $properties, array $options = []): array
    {
        $flags = $this->messageFlags($properties);
        if (isset($options['flags']) && is_array($options['flags'])) {
            $flags = array_values(array_unique([...$flags, ...$options['flags']]));
        }

        return [(new MessageBuilder())->build($properties), $flags];
    }

    protected function initialize(): void
    {
        if (!isset($this->mailService)) {
            $this->mailService = new LiveMailService($this);
        }
    }
}