<?php

namespace Nest\Model;

use Nest\Database\Query\DeleteQuery;
use Nest\Database\Query\InsertQuery;
use Nest\Database\Query\Raw;
use Nest\Database\Query\SelectQuery;
use Nest\Database\Exceptions\NotCurrentTransactionException;
use Nest\Database\Exceptions\Query\MissingConditionValueException;
use Nest\Database\Exceptions\UnknownDatabaseException;
use Nest\Model\Query\EntityQuery;
use function Nest\Utils\array_first_or_val;
use function Nest\Utils\str_snake_singularize;

class ArrayInstance extends ReadableArrayBlueprint
{
	/**
	 * Create an array field instance from an array field definition.
	 * @param ArrayBlueprint $array
	 */
	public function __construct(ArrayBlueprint $array)
	{
		parent::__construct($array->entityClass, $array->name);

		// Copy all fields.
		$this->type = $array->type;
		$this->table = $array->table;
		$this->foreignKeyName = $array->foreignKeyName;
		$this->foreignValueName = $array->foreignValueName;
	}

	/**
	 * Get current table / foreign key / foreign value state.
	 * @param string $fromTable Table from which to get values.
	 * @return array{string, string, string} Table, Foreign key, Foreign value.
	 */
	public function getState(string $fromTable): array
	{
		return [
			$table = $this->getTable() ?? "{$fromTable}_{$this->name}",
			$foreignKey = $this->getForeignKeyName() ?? "$table.".str_snake_singularize($fromTable)."_id",
			$foreignValue = $this->getForeignValueName() ?? "$table.".str_snake_singularize($this->name),
		];
	}

	/**
	 * Extract a column name from a fully qualified name.
	 * @return string The column name.
	 */
	private function getColumnName(string $fullyQualifiedName): string
	{
		return substr($fullyQualifiedName, strrpos($fullyQualifiedName, ".") + 1);
	}

	/**
	 * Setup inline loading for the current array field in an entity query.
	 * @param EntityQuery $baseQuery The entity query to alter.
	 * @param string $prefix Prefix to add to the name of the properties.
	 * @return Raw Generated select subquery.
	 * @throws MissingConditionValueException
	 */
	public function genSelect(EntityQuery $baseQuery, string $prefix = ""): Raw
	{
		// Get all auto values for undefined tables or keys.
		[$table, $foreignKey, $foreignValue] = $this->getState($baseQuery->getTableName());

		// Build subquery SELECT SQL.
		$sql = ((new SelectQuery($baseQuery->getDatabase(), $table))
			->select($foreignValue)
			->whereColumn("{$baseQuery->getTableName()}.".$baseQuery->getPrimaryKeyName(), "=", $foreignKey))->build();

		// Return the raw SELECT of a JSON array.
		return new Raw(
			"ARRAY_TO_JSON(ARRAY($sql->sql)) AS $prefix$this->name",
			$sql->bindings,
		);
	}

	/**
	 * @param Entity $entity Entity for which to save.
	 * @param array $value Array to save.
	 * @return void
	 * @throws MissingConditionValueException
	 * @throws UnknownDatabaseException
	 * @throws NotCurrentTransactionException
	 */
	public function save(Entity $entity, array $value): void
	{
		// Start a transaction for the whole save.
		$transaction = $entity->getDatabase()->startTransaction();

		// Get all auto values for undefined tables or keys.
		[$table, $foreignKey, $foreignValue] = $this->getState($entity->getTableName());

		// Get entity primary key value.
		$entityKey = $entity->{array_first_or_val($entity->getPrimaryFields())};

		// Delete existing values.
		((new DeleteQuery($entity->getDatabase(), $table))
			->where($foreignKey, "=", $entityKey))
			->execute();

		// Get actual columns names.
		$foreignKey = $this->getColumnName($foreignKey);
		$foreignValue = $this->getColumnName($foreignValue);

		// Insert new ones.
		((new InsertQuery($entity->getDatabase(), $table)))
			// Insert all values of the array.
			->values(...array_map(fn (mixed $val) => ([
				$foreignKey => $entityKey,
				$foreignValue => $val,
			]), $value))
			->execute();

		// Commit transaction.
		$transaction->commit();
	}
}