[ADF-4647] download service (#4836)

* split download api into separate service

* move tests and fix code

* break dependency for thumbnail service

* update tests

* test fixes

* fix code

* fix unit tests

lib/core/services/download.service.ts

@@ -0,0 +1,89 @@
+/*!
+ * @license
+ * Copyright 2019 Alfresco Software, Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { Injectable } from '@angular/core';
+
+@Injectable({
+    providedIn: 'root'
+})
+export class DownloadService {
+    private saveData: Function;
+
+    constructor() {
+        this.saveData = (function() {
+            const a = document.createElement('a');
+            document.body.appendChild(a);
+            a.style.display = 'none';
+
+            return function(fileData, format, fileName) {
+                let blob = null;
+
+                if (format === 'blob' || format === 'data') {
+                    blob = new Blob([fileData], { type: 'octet/stream' });
+                }
+
+                if (format === 'object' || format === 'json') {
+                    const json = JSON.stringify(fileData);
+                    blob = new Blob([json], { type: 'octet/stream' });
+                }
+
+                if (blob) {
+                    if (
+                        typeof window.navigator !== 'undefined' &&
+                        window.navigator.msSaveOrOpenBlob
+                    ) {
+                        navigator.msSaveOrOpenBlob(blob, fileName);
+                    } else {
+                        const url = window.URL.createObjectURL(blob);
+                        a.href = url;
+                        a.download = fileName;
+                        a.click();
+
+                        window.URL.revokeObjectURL(url);
+                    }
+                }
+            };
+        })();
+    }
+
+    /**
+     * Invokes content download for a Blob with a file name.
+     * @param blob Content to download.
+     * @param fileName Name of the resulting file.
+     */
+    downloadBlob(blob: Blob, fileName: string): void {
+        this.saveData(blob, 'blob', fileName);
+    }
+
+    /**
+     * Invokes content download for a data array with a file name.
+     * @param data Data to download.
+     * @param fileName Name of the resulting file.
+     */
+    downloadData(data: any, fileName: string): void {
+        this.saveData(data, 'data', fileName);
+    }
+
+    /**
+     * Invokes content download for a JSON object with a file name.
+     * @param json JSON object to download.
+     * @param fileName Name of the resulting file.
+     */
+    downloadJSON(json: any, fileName: string): void {
+        this.saveData(json, 'json', fileName);
+    }
+}