<?php
/**
 * Generic Object.
 *
 * @package Activitypub
 */

namespace Activitypub\Activity;

use function Activitypub\camel_to_snake_case;
use function Activitypub\snake_to_camel_case;

/**
 * Generic Object.
 *
 * This class is used to create Generic Objects.
 * It is used to create objects that might be unknown by the plugin but
 * conform to the ActivityStreams vocabulary.
 *
 * Provides generic magic methods for getting, setting, and adding properties
 * through __call(). Specific property documentation is in the classes where
 * the properties are actually defined.
 *
 * @since 5.3.0
 */
#[\AllowDynamicProperties]
class Generic_Object {
	/**
	 * The JSON-LD context for the object.
	 *
	 * @var array
	 */
	const JSON_LD_CONTEXT = array(
		'https://www.w3.org/ns/activitystreams',
	);

	/**
	 * The object's unique global identifier
	 *
	 * @see https://www.w3.org/TR/activitypub/#obj-id
	 *
	 * @var string
	 */
	protected $id;

	/**
	 * Magic function, to transform the object to string.
	 *
	 * @return string The object id.
	 */
	public function __toString() {
		return $this->to_string();
	}

	/**
	 * Function to transform the object to string.
	 *
	 * @return string The object id.
	 */
	public function to_string() {
		return $this->get_id();
	}

	/**
	 * Magic function to implement getter and setter.
	 *
	 * @param string $method The method name.
	 * @param string $params The method params.
	 *
	 * @return mixed
	 */
	public function __call( $method, $params ) {
		$var = \strtolower( \substr( $method, 4 ) );

		if ( \strncasecmp( $method, 'get', 3 ) === 0 ) {
			if ( ! $this->has( $var ) ) {
				return null;
			}

			return $this->$var;
		}

		if ( \strncasecmp( $method, 'set', 3 ) === 0 ) {
			return $this->set( $var, $params[0] );
		}

		if ( \strncasecmp( $method, 'add', 3 ) === 0 ) {
			return $this->add( $var, $params[0] );
		}

		return null;
	}

	/**
	 * Generic getter.
	 *
	 * @param string $key The key to get.
	 *
	 * @return mixed The value.
	 */
	public function get( $key ) {
		return call_user_func( array( $this, 'get_' . $key ) );
	}

	/**
	 * Generic setter.
	 *
	 * @param string $key   The key to set.
	 * @param string $value The value to set.
	 *
	 * @return mixed The value.
	 */
	public function set( $key, $value ) {
		$this->$key = $value;

		return $this;
	}

	/**
	 * Generic adder.
	 *
	 * @param string $key   The key to set.
	 * @param mixed  $value The value to add.
	 *
	 * @return mixed|void The value.
	 */
	public function add( $key, $value ) {
		if ( empty( $value ) ) {
			return;
		}

		if ( ! isset( $this->$key ) ) {
			$this->$key = array();
		}

		if ( is_string( $this->$key ) ) {
			$this->$key = array( $this->$key );
		}

		$attributes = $this->$key;

		if ( is_array( $value ) ) {
			$attributes = array_merge( $attributes, $value );
		} else {
			$attributes[] = $value;
		}

		$this->$key = array_unique( $attributes );

		return $this->$key;
	}

	/**
	 * Check if the object has a key
	 *
	 * @param string $key The key to check.
	 *
	 * @return boolean True if the object has the key.
	 */
	public function has( $key ) {
		return property_exists( $this, $key );
	}

	/**
	 * Convert JSON input to an array.
	 *
	 * @param string $json The JSON string.
	 *
	 * @return static|\WP_Error An Object built from the JSON string or WP_Error when it's not a JSON string.
	 */
	public static function init_from_json( $json ) {
		$array = \json_decode( $json, true );

		if ( ! is_array( $array ) ) {
			return new \WP_Error( 'invalid_json', __( 'Invalid JSON', 'activitypub' ), array( 'status' => 400 ) );
		}

		return self::init_from_array( $array );
	}

	/**
	 * Convert input array to a Base_Object.
	 *
	 * @param array $data The object array.
	 *
	 * @return static|\WP_Error An Object built from the input array or WP_Error when it's not an array.
	 */
	public static function init_from_array( $data ) {
		if ( ! is_array( $data ) ) {
			return new \WP_Error( 'invalid_array', __( 'Invalid array', 'activitypub' ), array( 'status' => 400 ) );
		}

		$object = new static();
		$object->from_array( $data );

		return $object;
	}

	/**
	 * Convert JSON input to an array and pre-fill the object.
	 *
	 * @param array $data The array.
	 */
	public function from_array( $data ) {
		foreach ( $data as $key => $value ) {
			if ( null !== $value ) {
				// Convert camelCase to snake_case if not prefixed with '_'.
				if ( ! \str_starts_with( $key, '_' ) ) {
					$key = camel_to_snake_case( $key );
				}

				call_user_func( array( $this, 'set_' . $key ), $value );
			}
		}
	}

	/**
	 * Convert JSON input to an array and pre-fill the object.
	 *
	 * @param string $json The JSON string.
	 */
	public function from_json( $json ) {
		$array = \json_decode( $json, true );

		$this->from_array( $array );
	}

	/**
	 * Convert Object to an array.
	 *
	 * It tries to get the object attributes if they exist
	 * and falls back to the getters. Empty values are ignored.
	 *
	 * By default, `bto` and `bcc` (the blind audience fields) are stripped
	 * from the output per ActivityPub Section 6, so every serialization path
	 * is safe for emission. Internal callers that need to persist the blind
	 * audience (e.g., outbox/inbox storage) can opt in by passing
	 * `$include_blind_audience = true`.
	 *
	 * @param bool $include_json_ld_context Whether to include the JSON-LD context. Default true.
	 * @param bool $include_blind_audience  Whether to keep `bto` and `bcc` in the output. Default false.
	 *
	 * @return array An array built from the Object.
	 */
	public function to_array( $include_json_ld_context = true, $include_blind_audience = false ) {
		$array = array();
		$vars  = get_object_vars( $this );

		foreach ( $vars as $key => $value ) {
			if ( \is_wp_error( $value ) ) {
				continue;
			}

			// Ignore all _prefixed keys.
			if ( '_' === substr( $key, 0, 1 ) ) {
				continue;
			}

			// If value is empty, try to get it from a getter.
			if ( ! $value ) {
				$value = call_user_func( array( $this, 'get_' . $key ) );
			}

			if ( is_object( $value ) ) {
				$value = $value->to_array( false, $include_blind_audience );
			}

			if ( is_array( $value ) && $this->is_namespaced( $key ) ) {
				foreach ( $value as $sub_key => $sub_value ) {
					$array[ snake_to_camel_case( $key ) . ':' . snake_to_camel_case( $sub_key ) ] = $sub_value;
				}
			} elseif ( isset( $value ) ) {
				$array[ snake_to_camel_case( $key ) ] = $value;
			}
		}

		if ( $include_json_ld_context ) {
			// Get JsonLD context and move it to '@context' at the top.
			$array = array_merge( array( '@context' => $this->get_json_ld_context() ), $array );
		}

		$class = new \ReflectionClass( $this );
		$class = strtolower( $class->getShortName() );

		/**
		 * Filter the array of the ActivityPub object.
		 *
		 * @param array          $array  The array of the ActivityPub object.
		 * @param string         $class  The class of the ActivityPub object.
		 * @param string         $id     The ID of the ActivityPub object.
		 * @param Generic_Object $object The ActivityPub object.
		 *
		 * @return array The filtered array of the ActivityPub object.
		 */
		$array = \apply_filters( 'activitypub_activity_object_array', $array, $class, $this->id, $this );

		/**
		 * Filter the array of the ActivityPub object by class.
		 *
		 * @param array          $array  The array of the ActivityPub object.
		 * @param string         $id     The ID of the ActivityPub object.
		 * @param Generic_Object $object The ActivityPub object.
		 *
		 * @return array The filtered array of the ActivityPub object.
		 */
		$array = \apply_filters( "activitypub_activity_{$class}_object_array", $array, $this->id, $this );

		if ( ! $include_blind_audience ) {
			/*
			 * Strip `bto` and `bcc` from the serialized array per ActivityPub Section 6.
			 * Callers that need the blind audience either read it from the object via
			 * `get_bto()` / `get_bcc()` or opt in with `$include_blind_audience = true`.
			 */
			unset( $array['bto'], $array['bcc'] );
			if ( isset( $array['object'] ) && \is_array( $array['object'] ) ) {
				unset( $array['object']['bto'], $array['object']['bcc'] );
			}
		}

		return $array;
	}

	/**
	 * Convert Object to JSON.
	 *
	 * @param bool $include_json_ld_context Whether to include the JSON-LD context. Default true.
	 * @param bool $include_blind_audience  Whether to keep `bto` and `bcc` in the output. Default false.
	 *
	 * @return string The JSON string.
	 */
	public function to_json( $include_json_ld_context = true, $include_blind_audience = false ) {
		$array   = $this->to_array( $include_json_ld_context, $include_blind_audience );
		$options = \JSON_HEX_TAG | \JSON_HEX_AMP | \JSON_HEX_QUOT | \JSON_UNESCAPED_SLASHES;

		/**
		 * Options to be passed to json_encode().
		 *
		 * @param int $options The current options flags.
		 */
		$options = \apply_filters( 'activitypub_json_encode_options', $options );

		return \wp_json_encode( $array, $options );
	}

	/**
	 * Returns the keys of the object vars.
	 *
	 * @return array The keys of the object vars.
	 */
	public function get_object_var_keys() {
		return \array_keys( \get_object_vars( $this ) );
	}

	/**
	 * Returns the JSON-LD context of this object.
	 *
	 * @return array $context A compacted JSON-LD context for the ActivityPub object.
	 */
	public function get_json_ld_context() {
		return static::JSON_LD_CONTEXT;
	}

	/**
	 * Checks if an attribute is in a namespace.
	 *
	 * @param string $attribute The attribute to check.
	 *
	 * @return bool Whether the attribute is namespaced.
	 */
	private function is_namespaced( $attribute ) {
		$namespaces = array();

		foreach ( static::JSON_LD_CONTEXT as $context ) {
			if ( is_array( $context ) ) {
				$namespaces = \array_merge( $namespaces, $context );
			}
		}

		return isset( $namespaces[ $attribute ] ) && \wp_http_validate_url( $namespaces[ $attribute ] );
	}
}