<?php declare(strict_types=1);


namespace Komma\KMS\Core;


use Illuminate\Database\Eloquent\Builder;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;
use Illuminate\Database\Eloquent\Relations\BelongsToMany;
use Komma\KMS\Sites\HasSiteInterface;
use Komma\KMS\Sites\HasSitesInterface;

trait CanSaveSlugsTrait
{
    /**
     * Generates a unique slug for the model, and saves it at the model.
     *
     * @param Model $model
     * @return Model
     */
    protected function saveSlugForModel(Model $model): Model {
        if(!is_a($model,HasSlugInterface::class)) return $model;

        /** @var HasSlugInterface $model */
        $suggestedSlug = $model->suggestSlug();
        $collection = $this->retrieveCollectionForCreatingSlug($model);
        while($collection->where('slug', '=', $suggestedSlug)->count() !== 0) {
            $suggestedSlug = create_unique_slug($collection, $suggestedSlug);
        }
        $model->slug = $suggestedSlug;
        $model->save();

        return $model;
    }

    /**
     * @param Model $model
     * @return Builder[]|\Illuminate\Database\Eloquent\Collection
     */
    private function retrieveCollectionForCreatingSlug(Model $model)
    {
        if(config('app.multipleSites') === false) {
            if(is_a($model, AbstractTranslationModel::class) === false) {
                return $model->where('id', '!=', $model->id)->get();
            } else {
                /** @var $model AbstractTranslationModel */
                return $model->where('id', '!=', $model->id)->whereHas('language', function(Builder $query) use($model) {
                    $query->where('id', '=', $model->language->id);
                })->get();
            }
        } else {
            if(is_a($model, AbstractTranslationModel::class) === false) {
                if(is_a($model, HasSiteInterface::class)) {
                    return $this->modelsHavingSameSiteAsGivenModel($model)->get();
                } else if(is_a($model, HasSitesInterface::class)) {
                    return $this->modelsHavingSameSitesAsGivenModel($model)->get();
                }
            } else {
                return $this->translationModelsHavingTheSameLanguageAndSite($model)->get();
            }
        }
        throw new \InvalidArgumentException('The given Model ('.get_class($model).') does not support slug saving.');
    }

    /**
     * @param HasSiteInterface $model
     * @return Builder
     */
    private function modelsHavingSameSiteAsGivenModel(HasSiteInterface $model)
    {
        $site = $model->site()->first(['id']);
        return $collectionQuery = $model::whereHas('site', function(BelongsTo $query) use($site) {
            $query->where('id', '=', $site->id);
        })->where('id', '!=', $model->id);
    }

    /**
     * @param HasSitesInterface $model
     * @return Builder
     */
    private function modelsHavingSameSitesAsGivenModel(HasSitesInterface $model)
    {
        $sites = $model->sites()->get(['id']);
        $siteIds = $sites->pluck('id')->toArray();
        return $collectionQuery = $model::whereHas('sites', function(BelongsTo $query) use($siteIds) {
            $query->whereIn('id', $siteIds);
        })->where('id', '!=', $model->id);
    }

    /**
     * Returns a query builder that yields the translation models of the same class as the given instance.
     * They will belong to the same site(s) as the given instance's translatable.
     * They will also have the same language as the given instance.
     *
     * @param AbstractTranslationModel $model
     * @return Builder|\Illuminate\Database\Eloquent\Collection|AbstractTranslationModel
     */
    private function translationModelsHavingTheSameLanguageAndSite(AbstractTranslationModel $model) {
        $queryBuilder = $model;

        //Only get results excluding the current model
        $queryBuilder = $queryBuilder->where('id', '!=', $model->id);

        //Only get translations that have the same language as the given one.
        $queryBuilder = $queryBuilder->whereHas('language', function(Builder $query) use($model) {
            $query->where('id', '=', $model->language->id);
        });

        $translatable = $model->translatable()->first(); //Gets the abstractTranslatable model (page for example) for the given translation.
        if(is_a($translatable, HasSiteInterface::class)) {
            /** @var AbstractTranslatableModel|HasSiteInterface $translatable */
            $translatable = $translatable->load('site');
            if($translatable->site) { //We can only take the site into account if there is one
                $queryBuilder = $queryBuilder->whereHas('translatable', function (Builder $query) use ($translatable) {
                    $query->whereHas('site', function (Builder $query) use ($translatable) {
                        $query->where('id', '=', $translatable->site->id);
                    });
                });
            }
        } else if(is_a($model->translatable()->getRelated(), HasSitesInterface::class)) {
            //Get all AbstractTranslationModels (e.g PageTranslations) that have a translatable (e.g Page) that has a same site as the AbstractTranslationModels (e.g PageTranslation)
            /** @var AbstractTranslatableModel|HasSitesInterface $translatable */
            $translatable = $translatable->load('sites');
            if($translatable->sites->count() > 0) { //We can only take sites into account when there are any
                $queryBuilder = $queryBuilder->whereHas('translatable', function (Builder $query) use ($translatable) {
                    $query->whereHas('sites', function (Builder $query) use ($translatable) {
                        $query->whereIn('sites.id', $translatable->sites->pluck('id')->toArray());
                    });
                });
            }
        }

        return $queryBuilder;
    }
}