Add Avro to JSON data format conversion

src/core/operations/AvroToJSON.mjs

@@ -0,0 +1,79 @@
+/**
+ * @author jarrodconnolly [jarrod@nestedquotes.ca]
+ * @copyright Crown Copyright 2019
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation.mjs";
+import OperationError from "../errors/OperationError.mjs";
+import avro from "avsc";
+
+/**
+ * Avro to JSON operation
+ */
+class AvroToJSON extends Operation {
+
+    /**
+     * AvroToJSON constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Avro to JSON";
+        this.module = "Avro";
+        this.description = "Converts Avro encoded data into JSON.";
+        this.infoURL = "https://avro.apache.org/docs/current/spec.html";
+        this.inputType = "ArrayBuffer";
+        this.outputType = "JSON";
+        this.args = [{
+            name: "Force Valid JSON",
+            type: "boolean",
+            value: true
+        }];
+    }
+
+    /**
+     * @param {ArrayBuffer} input
+     * @param {Object[]} args
+     * @returns {JSON}
+     */
+    run(input, args) {
+        const self = this;
+        if (input.byteLength <= 0) {
+            throw new OperationError("Please provide an input.");
+        }
+
+        const forceJSON = args[0];
+
+        return new Promise((resolve, reject) => {
+            const result = [];
+            const inpArray = new Uint8Array(input);
+            const decoder = new avro.streams.BlockDecoder();
+
+            decoder
+                .on("data", function (obj) {
+                    result.push(obj);
+                })
+                .on("error", function () {
+                    reject(new OperationError("Error parsing Avro file."));
+                })
+                .on("end", function () {
+                    if (forceJSON) {
+                        self.presentType = "JSON";
+                        self.outputType = "JSON";
+                        resolve(result.length === 1 ? result[0] : result);
+                    } else {
+                        self.presentType = "string";
+                        self.outputType = "string";
+                        const data = result.reduce((result, current) => result + JSON.stringify(current) + "\n", "");
+                        resolve(data);
+                    }
+                });
+
+            decoder.write(inpArray);
+            decoder.end();
+        });
+    }
+}
+
+export default AvroToJSON;