Resolve "Add support to SmartDataContext API"

Related to #37 (closed)

api/context.php

+<?php
+
+namespace SmartData;
+require_once('../bin/smartdata/SmartAPI.php');
+require_once('../bin/smartdata/Config.php');
+
+use SmartData\Exception\CustomException;
+
+function context($url, $domain, $content) {
+
+    if (substr( $url, 0, 5 ) != "/docs" && substr( $url, 0, 8 ) != "/openapi") {
+        $url = $url . "/$domain";
+        header('Content-Type: application/json');
+    }
+
+    if (substr( $url, 0, 4 ) == "/get") {
+        $url = $url . "/" . $content['smartDataContextId'];
+    }
+
+    $ch = curl_init();
+
+    curl_setopt($ch, CURLOPT_URL,  Config::config()::SMARTDATACONTEXT_API . "$url");
+
+    if (substr( $url, 0, 4 ) != "/get" && substr( $url, 0, 5 ) != "/docs" && substr( $url, 0, 8 ) != "/openapi") {
+        curl_setopt($ch, CURLOPT_POST, true);
+        curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($content));
+        curl_setopt($ch, CURLOPT_HTTPHEADER, array(
+            'Content-Type: application/json'
+        ));
+    }
+
+    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
+
+    $response = curl_exec($ch);
+    $http_status = curl_getinfo($ch, CURLINFO_HTTP_CODE);
+
+    if ($http_status == 0) {
+        # Could not connect to the smartdatacontext API
+        $http_status = 503; # Service Unavailable
+        $response = '{"errors": ["SmartDataContext API not available"]}';
+    }
+
+    http_response_code($http_status);
+    return $response;
+}
+
+try {
+    if (array_key_exists('docs', $_GET)) {
+        echo context("/docs", null, null);
+    } else if (array_key_exists('openapi', $_GET)) {
+        echo context("/openapi", null, null);
+    } else {
+        $content = file_get_contents('php://input');
+        $json = json_decode($content, false, 512, JSON_BIGINT_AS_STRING);
+
+        // Validate certificate usage and domain usage
+        $credentials = null;
+        if(isset($json->credentials))
+            $credentials = Credentials::fromJson($json->credentials);
+        $backend = new Backend($credentials);
+
+        $json = json_decode($content, true, 512, JSON_BIGINT_AS_STRING);
+
+        // Pass the request to the smartdatacontext backend and retrieve result
+        echo context($json['command'], $backend->domainInUse(), $json['request']);    }
+} catch (CustomException $e) {
+    http_response_code($e->getHTTPCodeError());
+    header('X-Message: ' . $e->getMessage(), false);
+    return false;
+} catch (\Exception $e) {
+    http_response_code(HttpStatusCode::BAD_REQUEST);
+    return false;
+}
\ No newline at end of file