<?php

namespace Nest\Model;

use Nest\Database\Query\Raw;
use Nest\Database\Exceptions\UnknownDatabaseException;
use Nest\Model\Query\EntityQuery;
use function Nest\Utils\array_first;
use function Nest\Utils\array_first_or_val;
use function Nest\Utils\str_snake_singularize;

class EntityPropertyInstance extends ReadableEntityPropertyBlueprint
{
	/**
	 * Goal entity instance.
	 * @var Entity
	 */
	private Entity $entity;

	/**
	 * Create an entity property instance from an entity property definition.
	 * @param EntityPropertyBlueprint $entityProperty The entity property to copy from.
	 */
	public function __construct(EntityPropertyBlueprint $entityProperty)
	{
		// Copy all fields.
		$this->class = $entityProperty->class;
		$this->multiple = $entityProperty->multiple;
		$this->allowInline = $entityProperty->allowInline;
		$this->mode = $entityProperty->mode;
		$this->localKey = $entityProperty->localKey;
		$this->relatedKey = $entityProperty->relatedKey;
		$this->pivotTable = $entityProperty->pivotTable;
		$this->pivotLocalKey = $entityProperty->pivotLocalKey;
		$this->pivotRelatedKey = $entityProperty->pivotRelatedKey;
		$this->eagerLoad = $entityProperty->eagerLoad;

		// Initialize goal entity.
		$this->entity = new ($this->getClass())();
	}

	/**
	 * Create a new related entity.
	 * @return Entity A new related entity instance.
	 */
	public function newEntity(): Entity
	{
		return $this->entity->new();
	}

	/**
	 * Determine if the property can be inline loaded.
	 * @return bool True if the property can be inline loaded.
	 */
	public function canInlineLoad(): bool
	{
		return !$this->isMultiple() && $this->isInlineAllowed();
	}

	/**
	 * Build a query to retrieve relations for the given entities.
	 * @param Entity[] $entities Entities for which to retrieve relations.
	 * @return EntityQuery Built entities query.
	 * @throws UnknownDatabaseException
	 */
	public function queryFor(array $entities): EntityQuery
	{
		// Initialize query.
		$query = $this->entity->query();

		if (empty($entities))
			// No entities, return a simple query without conditions.
			return $query;

		// Get a reference entity.
		$referenceEntity = array_first($entities);
		// Entity primary key.
		$entityPrimaryKey = array_first_or_val($referenceEntity->getPrimaryFields());

		// Get keys from entities list.
		$entitiesKeys = array_column($entities, $entityPrimaryKey);

		switch ($this->getMode())
		{ // Build query depending on the relation mode.
			case EntityPropertyMode::LOCAL:
				$query
					->select(new Raw("\"{$referenceEntity->getTableName()}\".\"$entityPrimaryKey\" AS \"__reference_key\""))
					// Generate SELECT for the related entity.
					->select(...$this->entity->sqlSelectFields())
					->innerJoin($referenceEntity->getTableName())->on(
						"{$this->entity->getTableName()}.".(
							$this->getRelatedKey() ?? array_first_or_val($this->entity->getPrimaryFields())
						),
						"=",
						"{$referenceEntity->getTableName()}.".(
							$this->getLocalKey() ?? str_snake_singularize($this->entity->getTableName())."_id"
						),
					)->whereIn(
						"{$referenceEntity->getTableName()}.$entityPrimaryKey", $entitiesKeys
					);
				break;
			case EntityPropertyMode::RELATED:
				$query
					->select(new Raw("\"{$this->entity->getTableName()}\".\"".(
							$this->getRelatedKey() ?? str_snake_singularize($referenceEntity->getTableName())."_id"
						)."\" AS \"__reference_key\""))
					// Generate SELECT for the related entity.
					->select(...$this->entity->sqlSelectFields())
					->whereIn(
						"{$this->entity->getTableName()}.".(
							$this->getRelatedKey() ?? str_snake_singularize($referenceEntity->getTableName())."_id"
						)."",
						$entitiesKeys
					);
				break;
			case EntityPropertyMode::PIVOT:
				$query
					->select(new Raw("\"{$this->entity->getTableName()}\".\"".(
							$this->getPivotLocalKey() ?? str_snake_singularize($referenceEntity->getTableName())."_id"
						)."\" AS \"__reference_key\""))
					// Generate SELECT for the related entity.
					->select(...$this->entity->sqlSelectFields())
					->innerJoin($this->getPivotTable())->on(
						"{$query->getTableName()}.".(
							$this->getRelatedKey() ?? $query->getPrimaryKeyName()
						),
						"=",
						"{$this->getPivotTable()}.".(
							$this->getPivotLocalKey() ?? str_snake_singularize($query->getTableName())."_id"
						),
					)
					->whereIn(
						"{$this->getPivotTable()}.".(
							$this->getPivotLocalKey() ?? str_snake_singularize($referenceEntity->getTableName())."_id"
						),
						$entitiesKeys
					);
				break;
		}

		return $query;
	}

	/**
	 * Setup inline loading for the current property in an entity query.
	 * @param EntityQuery $query The entity query to alter.
	 * @return void
	 */
	public function setupInlineLoading(EntityQuery $query): void
	{
		switch ($this->getMode())
		{ // Add join depending on the relation mode.
			case EntityPropertyMode::LOCAL:
				$query
					->leftJoin($this->entity->getTableName())->on(
						"{$query->getTableName()}.".(
							$this->getLocalKey() ?? str_snake_singularize($this->entity->getTableName())."_id"
						),
						"=",
						"{$this->entity->getTableName()}.".(
							$this->getRelatedKey() ?? array_first_or_val($this->entity->getPrimaryFields())
						),
					);
				break;
			case EntityPropertyMode::RELATED:
				$query
					->leftJoin($this->entity->getTableName())->on(
						"{$query->getTableName()}.".(
							$this->getLocalKey() ?? $query->getPrimaryKeyName()
						),
						"=",
						"{$this->entity->getTableName()}.".(
							$this->getRelatedKey() ?? str_snake_singularize($query->getTableName())."_id"
						),
					);
				break;
			case EntityPropertyMode::PIVOT:
				$query
					->leftJoin($this->getPivotTable())->on(
						"{$query->getTableName()}.".(
							$this->getLocalKey() ?? $query->getPrimaryKeyName()
						),
						"=",
						"{$this->getPivotTable()}.".(
							$this->getPivotLocalKey() ?? str_snake_singularize($query->getTableName())."_id"
						),
					)
					->leftJoin($this->entity->getTableName())->on(
						"{$this->getPivotTable()}.".(
							$this->getPivotRelatedKey() ?? str_snake_singularize($this->entity->getTableName())."_id"
						),
						"=",
						"{$this->entity->getTableName()}.".(
							$this->getRelatedKey() ?? array_first_or_val($this->entity->getPrimaryFields())
						),
					);
				break;
		}
	}
}