<?php

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
namespace CloudObjects\SDK;

use ML\IRI\IRI;
use ML\JsonLD\Node;
use CloudObjects\SDK\NodeReader;
use Webmozart\Assert\Assert;

/**
 * A CloudObject encapsulates an object node for an object stored in CloudObjects Core
 * with convenience methods to access properties.
 */
class CloudObject {

    private $coid;
    private $node;
    private $reader = null;
    private $retriever = null;

    public function __construct(IRI $coid, Node $node) {
        Assert::eq((string)$coid, $node->getId(), "COID and Node ID must match.");

        $this->coid = $coid;
        $this->node = $node;
    }

    /**
     * Specify a custom NodeReader to use for this CloudObject.
     * If not set, a default NodeReader will be used.
     */
    public function setReader(NodeReader $reader) : self {
        $this->reader = $reader;

        return $this;
    }

    private function getReader() : NodeReader {
        if (!$this->reader) {
            $this->reader = new NodeReader;
        }
        return $this->reader;
    }

    /**
     * Specify an ObjectRetriever to use for retrieval
     * of related objects.
     */
    public function setObjectRetriever(ObjectRetriever $retriever) : self {
        $this->retriever = $retriever;

        return $this;
    }

    /**
     * Get the COID of this object.
     */
    public function getCOID() : IRI {
        return $this->coid;
    }

    /**
     * Get the object node encapsulated in this CloudObject.
     */
    public function getAsNode() : Node {
        return $this->node;
    }

    /**
     * Get the value of a property as a string.
     * If the property has multiple values, only the first is returned.
     */
    public function getString($property, string $default = null) : ?string {
        return $this->getReader()->getFirstValueString($this->node, $property, $default);
    }

    /**
     * Get the value of a property as an integer.
     * If the property has multiple values, only the first is returned.
     */
    public function getInt($property, int $default = null) : ?int {
        return $this->getReader()->getFirstValueInt($this->node, $property, $default);
    }

    /**
     * Get the value of a property as a float.
     * If the property has multiple values, only the first is returned.
     */
    public function getFloat($property, float $default = null) : ?float {
        return $this->getReader()->getFirstValueFloat($this->node, $property, $default);
    }

    /**
     * Get the value of a property as a boolean.
     * If the property has multiple values, only the first is returned.
     */
    public function getBool($property, bool $default = null) : ?bool {
        return $this->getReader()->getFirstValueBool($this->node, $property, $default);
    }

    /**
     * Get the value of a property as an IRI.
     * If the property has multiple values, only the first is returned.
     */
    public function getIRI($property, IRI $default = null) : ?IRI {
        return $this->getReader()->getFirstValueIRI($this->node, $property, $default);
    }

    /**
     * Get the value of a property as a Node.
     * If the property has multiple values, only the first is returned.
     */
    public function getNode($property, Node $default = null) : ?Node {
        return $this->getReader()->getFirstValueNode($this->node, $property, $default);
    }

    /**
     * Get the value of a property and, if it's a COID, retrieve the corresponding CloudObject.
     */
    public function getCloudObject($property) : ?CloudObject {
        Assert::notNull($this->retriever, "No ObjectRetriever set for CloudObject. Cannot retrieve related object.");

        $coid = $this->getReader()->getFirstValueIRI($this->node, $property);

        if (!($coid instanceof IRI)) {
            return null;
        }

        return $this->retriever->getCloudObject($coid);
    }


    /**
     * Get the value of a property and, if it's a COID, retrieve the corresponding object node.
     */
    public function getObjectNode($property) : ?Node {
        Assert::notNull($this->retriever, "No ObjectRetriever set for CloudObject. Cannot retrieve related object.");

        $coid = $this->getReader()->getFirstValueIRI($this->node, $property);

        if (!($coid instanceof IRI)) {
            return null;
        }

        return $this->retriever->getObjectNode($coid);
    }    

}