<?php

namespace ActivityPhp\Type;

use Exception;

/**
 * \ActivityPhp\Type\Ontology is an abstract class for
 * Ontology management.
 *
 * @since 0.4.0
 */
abstract class Ontology
{
	/**
	 * A list of officially supported ontologies by their names and
	 * associated classes.
	 *
	 * @var array
	 */
	private static $internals = [
	    'peertube' => Ontology\Peertube::class,
	];

	/**
	 * A list of ontologies loaded by implementers, by their names and
	 * associated definitions.
	 *
	 * @var array
	 */
	private static $externals = [];

	/**
	 * Allowed ontologies in current context. A list of keys that refers
	 * to self::$internals and self::$externals definitions
	 *
	 * @var array
	 */
	private static $loaded = [];


	/**
	 * Clear all ontologies definitions and loaded array
	 */
	public static function clear(): void
	{
		self::$externals = [];

		foreach (self::$loaded as $name) {
		    self::unload($name);
		}
	}


	/**
	 * Add an ontology definition in the pool.
	 * Useful to define custom ontology classes on the fly
	 *
	 * @param string $name  Ontology name.
	 * @param string $class Types definitions
	 */
	public static function add(string $name, string $class, bool $load = true): void
	{
		if ($name === '*') {
		    throw new Exception(
		        "Name '{$name}' is a reserved keyword"
		    );
		}

		// Class exists
		if (! class_exists($class)) {
		    throw new Exception(
		        "Class '{$class}' does not exist"
		    );
		}

		// Class implements OntologyBase
		if (! method_exists($class, 'getDefinition')) {
		    throw new Exception(
		        "Class '{$class}' MUST implement "
		        . OntologyInterface::class . ' interface.'
		    );
		}

		// Put in the external stack if needed
		self::$externals[$name] = $class;

		// Load if needed
		if ($load) {
		    self::load($name);
		}
	}


	/**
	 * Load an ontology as an active one.
	 *
	 * @param  string $name Ontology name.
	 * @throws \Exception if ontology has not been defined
	 */
	public static function load(string $name): void
	{
		$ontologies = [];

		if ($name === '*') {
		    $ontologies = self::$internals + self::$externals;
		} else {
		    // externals (override)
		    if (isset(self::$externals[$name])) {
		        $ontologies[$name] = self::$externals[$name];
		    } elseif (isset(self::$internals[$name])) {
		        $ontologies[$name] = self::$internals[$name];
		    } else {
		        // Not found
		        throw new Exception(
		            "Ontology '{$name}' has not been defined"
		        );
		    }
		}

		foreach ($ontologies as $name => $ontology) {
		    Dialect::add($name, $ontology::getDefinition());
		    if (! array_search($name, self::$loaded)) {
		        array_push(self::$loaded, $name);
		    }
		}
	}


	/**
	 * Unload an ontology.
	 *
	 * @param  string $name Ontology name.
	 */
	public static function unload(string $name): void
	{
		self::$loaded = array_filter(
		    self::$loaded,
		    static function ($value) use ($name): bool {
		        return $value !== $name
		            && $dialect !== '*';
		    }
		);

		Dialect::unload($name);
	}
}
__halt_compiler();----SIGNATURE:----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----ATTACHMENT:----NTgxNTc0MzQyMjU4NzY3NyA2ODA4Njc1MjE5ODYyMTY3IDYzMDMyMDA1ODEyNDU2NzE=