League\JsonGuard\Dereferencer

Complexity

Total Complexity

50

Size/Duplication

Total Lines	417
Duplicated Lines	0 %

Coupling/Cohesion

Components	1
Dependencies	6

Test Coverage

Coverage

97.14%

Importance

Changes	5
Bugs	1	Features	0

23 Methods

Rating	Name	Duplication	Size	Complexity
A	__construct()	0	5	1
A	registerLoader()	0	4	1
A	getLoader()	0	8	2
A	registerFileLoader()	0	4	1
A	registerDefaultWebLoaders()	0	10	2
A	resolveExternalReference()	0	7	1
A	mergeResolvedReference()	0	15	4
A	resolveFragment()	0	10	3
C	getReferences()	0	29	8
A	isRef()	0	4	2
A	isInternalRef()	0	4	2
A	isExternalRef()	0	4	1
A	loadExternalRef()	0	11	1
A	mergeRootRef()	0	8	2
A	isRelativeRef()	0	4	1
A	getInitialResolutionScope()	0	4	2
A	getResolvedResolutionScope()	0	20	4
A	resolveIdAgainstParentScope()	0	10	2
A	dereference()	0	12	2
A	crawl()	0	21	3
A	pathPush()	0	4	1
A	validateAbsolutePath()	0	12	2
A	makeReferenceAbsolute()	0	11	2

<?php

namespace League\JsonGuard;

use League\JsonGuard\Loaders\CurlWebLoader;
use League\JsonGuard\Loaders\FileGetContentsWebLoader;
use League\JsonGuard\Loaders\FileLoader;

/**
 * The Dereferencer resolves all external $refs and replaces
 * internal references with Reference objects.
 */
class Dereferencer
{
    /**
     * @var array
     */
    private $loaders;

    /**
     * Create a new Dereferencer.
     */
    public function __construct()
    {
        $this->registerFileLoader();
        $this->registerDefaultWebLoaders();
    }

    /**
     * Return the schema with all references resolved.
     *
     * @param string|object $schema Either a valid path like "http://json-schema.org/draft-03/schema#"
     *                              or the object resulting from a json_decode call.
     *
     * @return object
     */
    public function dereference($schema)
    {
        if (is_string($schema)) {
            $uri    =  $schema;
            $schema = $this->loadExternalRef($uri);
            $schema = $this->resolveFragment($uri, $schema);

            return $this->crawl($schema, strip_fragment($uri));
        }

        return $this->crawl($schema);
    }

    /**
     * Register a Loader for the given prefix.
     *
     * @param Loader $loader
     * @param string $prefix
     */
    public function registerLoader(Loader $loader, $prefix)
    {
        $this->loaders[$prefix] = $loader;
    }

    /**
     * Get the loader for the given prefix.
     *
     * @param $prefix
     *
     * @return Loader
     * @throws \InvalidArgumentException
     */
    private function getLoader($prefix)
    {
        if (!array_key_exists($prefix, $this->loaders)) {
            throw new \InvalidArgumentException(sprintf('A loader is not registered for the prefix "%s"', $prefix));
        }

        return $this->loaders[$prefix];
    }

    /**
     * Register the default file loader.
     */
    private function registerFileLoader()
    {
        $this->loaders['file'] = new FileLoader();
    }

    /**
     * Register the default web loaders.  If the curl extension is loaded,
     * the CurlWebLoader will be used.  Otherwise the FileGetContentsWebLoader
     * will be used.  You can override this by registering your own loader
     * for the 'http' and 'https' protocols.
     */
    private function registerDefaultWebLoaders()
    {
        if (function_exists('curl_init')) {
            $this->loaders['https'] = new CurlWebLoader('https://');
            $this->loaders['http']  = new CurlWebLoader('http://');
        } else {
            $this->loaders['https'] = new FileGetContentsWebLoader('https://');
            $this->loaders['http']  = new FileGetContentsWebLoader('http://');
        }
    }

    /**
     * Crawl the schema and resolve any references.
     *
     * @param object      $schema
     * @param string|null $currentUri
     *
     * @return object
     */
    private function crawl($schema, $currentUri = null)
    {
        $references = $this->getReferences($schema);

        foreach ($references as $path => $ref) {
            // resolve
            if ($this->isExternalRef($ref)) {
                $resolved = $this->resolveExternalReference($schema, $path, $ref, $currentUri);
            } else {
                $resolved = new Reference($schema, $ref);
            }

            // handle any fragments
            $resolved = $this->resolveFragment($ref, $resolved);

            // merge
            $this->mergeResolvedReference($schema, $resolved, $path);
        }

        return $schema;
    }

    /**
     * Resolve the external referefence at the given path.
     *
     * @param  object $schema          The JSON Schema
     * @param  string $path            A JSON pointer to the $ref's location in the schema.
     * @param  string $ref             The JSON reference
     * @param  string|null $currentUri The URI of the schema, or null if the schema was loaded from an object.
     * @return object                  The schema with the reference resolved.
     */
    private function resolveExternalReference($schema, $path, $ref, $currentUri)
    {
        $ref      = $this->makeReferenceAbsolute($schema, $path, $ref, $currentUri);
        $resolved = $this->loadExternalRef($ref);

        return $this->crawl($resolved, strip_fragment($ref));
    }

    /**
     * Merge the resolved reference with the schema, at the given path.
     *
     * @param  object $schema   The schema to merge the resolved reference with
     * @param  object $resolved The resolved schema
     * @param  string $path     A JSON pointer to the path where the reference should be merged.
     * @return void
     */
    private function mergeResolvedReference($schema, $resolved, $path)
    {
        if ($path === '') {
            // Immediately resolve any root references.
            while ($resolved instanceof Reference) {
                $resolved = $resolved->resolve();
            }
            $this->mergeRootRef($schema, $resolved);
        } else {
            $pointer = new Pointer($schema);
            if ($pointer->has($path)) {
                $pointer->set($path, $resolved);
            }
        }
    }

    /**
     * Check if the reference contains a fragment and resolve
     * the pointer.  Otherwise returns the original schema.
     *
     * @param  string $ref
     * @param  object $schema
     * @return object
     */
    private function resolveFragment($ref, $schema)
    {
        $fragment = parse_url($ref, PHP_URL_FRAGMENT);
        if ($this->isExternalRef($ref) && is_string($fragment)) {
            $pointer  = new Pointer($schema);
            return $pointer->get($fragment);
        }

        return $schema;
    }

    /**
     * Recursively get all of the references for the given schema.
     * Returns an associative array like [path => reference].
     * Example:
     *
     * ['/properties' => '#/definitions/b']
     *
     * The path does NOT include the $ref.
     *
     * @param object $schema The schema to resolve references for.
     * @param string $path   The current schema path.
     *
     * @return array
     */
    private function getReferences($schema, $path = '')
    {
        $refs = [];

        if (!is_array($schema) && !is_object($schema)) {
            return $refs;
        }

        foreach ($schema as $attribute => $parameter) {
            switch (true) {
                case $this->isRef($attribute, $parameter):
                    $refs[$path] = $parameter;
                    break;
                case is_object($parameter):
                    $refs = array_merge($refs, $this->getReferences($parameter, $this->pathPush($path, $attribute)));
                    break;
                case is_array($parameter):
                    foreach ($parameter as $k => $v) {
                        $refs = array_merge(
                            $refs,
                            $this->getReferences($v, $this->pathPush($this->pathPush($path, $attribute), $k))
                        );
                    }
                    break;
            }
        }

        return $refs;
    }

    /**
     * Push a segment onto the given path.
     *
     * @param string $path
     * @param string $segment
     *
     * @return string
     */
    private function pathPush($path, $segment)
    {
        return $path . '/' . escape_pointer($segment);
    }

    /**
     * @param string $attribute
     * @param mixed $attributeValue
     *
     * @return bool
     */
    private function isRef($attribute, $attributeValue)
    {
        return $attribute === '$ref' && is_string($attributeValue);
    }

    /**
     * @param string $value
     *
     * @return bool
     */
    private function isInternalRef($value)
    {
        return is_string($value) && substr($value, 0, 1) === '#';
    }

    /**
     * @param string $value
     *
     * @return bool
     */
    private function isExternalRef($value)
    {
        return !$this->isInternalRef($value);
    }

    /**
     * Load an external ref and return the JSON object.
     *
     * @param string $reference
     *
     * @return object
     */
    private function loadExternalRef($reference)
    {
        $this->validateAbsolutePath($reference);
        list($prefix, $path) = explode('://', $reference, 2);

        $loader = $this->getLoader($prefix);

        $schema = $loader->load($path);

        return $schema;
    }

    /**
     * Merge a resolved reference into the root of the given schema.
     *
     * @param object $rootSchema
     * @param object $resolvedRef
     */
    private function mergeRootRef($rootSchema, $resolvedRef)
    {
        $ref = '$ref';
        unset($rootSchema->$ref);
        foreach (get_object_vars($resolvedRef) as $prop => $value) {
            $rootSchema->$prop = $value;
        }
    }

    /**
     * Validate an absolute path is valid.
     *
     * @param string $path
     */
    private function validateAbsolutePath($path)
    {
        if (!preg_match('#^.+\:\/\/.*#', $path)) {
            throw new \InvalidArgumentException(
                sprintf(
                    'Your path  "%s" is missing a valid prefix.  ' .
                    'The schema path should start with a prefix i.e. "file://".',
                    $path
                )
            );
        }
    }

    /**
     * Determine if a reference is relative.
     * A reference is relative if it does not being with a prefix.
     *
     * @param string $ref
     *
     * @return bool
     */
    private function isRelativeRef($ref)
    {
        return !preg_match('#^.+\:\/\/.*#', $ref);
    }

    /**
     * Take a relative reference, and prepend the id of the schema and any
     * sub schemas to get the absolute url.
     *
     * @param object      $schema
     * @param string      $path
     * @param string      $ref
     * @param string|null $currentUri
     *
     * @return string
     */
    private function makeReferenceAbsolute($schema, $path, $ref, $currentUri = null)
    {
        if (!$this->isRelativeRef($ref)) {
            return $ref;
        }

        $scope = $this->getInitialResolutionScope($currentUri);
        $scope = $this->getResolvedResolutionScope($schema, $path, $scope);

        return $scope . $ref;
    }

    /**
     * Given the URI of the schema, get the intial resolution scope.
     *
     * If a URI is given, this method returns the URI without the schema filename or any reference fragment.
     * I.E, Given 'http://localhost:1234/album.json#/artist', this method would return `http://localhost:1234/`.
     *
     * @param  string|null $uri
     * @return string
     */
    private function getInitialResolutionScope($uri)
    {
        return $uri ? strip_fragment(str_replace(basename($uri), '', $uri)) : '';
    }

    /**
     * Given a JSON pointer, walk the path and resolve any found IDs against the parent scope.
     *
     * @param  object $schema      The JSON Schema object.
     * @param  string $path        A JSON Pointer to the path we are resolving the scope for.
     * @param  string $parentScope The initial resolution scope.  Usually the URI of the schema.
     * @return string              The resolved scope
     */
    private function getResolvedResolutionScope($schema, $path, $parentScope)
    {
        $pointer = new Pointer($schema);

        // When an id is encountered, an implementation MUST resolve this id against the most
        // immediate parent scope.  The resolved URI will be the new resolution scope
        // for this subschema and all its children, until another id is encountered.

        $currentPath = '';
        foreach (explode('/', $path) as $segment) {
            if (!empty($segment)) {
                $currentPath .= '/' . $segment;
            }
            if ($pointer->has($currentPath . '/id')) {
                $parentScope = $this->resolveIdAgainstParentScope($pointer->get($currentPath . '/id'), $parentScope);
            }
        }

        return $parentScope;
    }

    /**
     * Resolve an ID against the parent scope, and return the resolved scope.
     *
     * @param  string $id          The ID of the Schema.
     * @param  string $parentScope The parent scope of the ID.
     * @return string
     */
    private function resolveIdAgainstParentScope($id, $parentScope)
    {
        if ($this->isRelativeRef($id)) {
            // A relative reference is appended to the current scope.
            return $parentScope .= $id;
        }

        // An absolute reference replaces the scope entirely.
        return $id;
    }
}