Christopher Kaliszewski's Completed Assignment

README.md

@@ -1,11 +1,19 @@
+# Assignment Completed
+
+**Author:** Christopher Kaliszewski
+
+**Code Coverage (_using `nyc`_):** 100%
+
+**Test Command:** `npm test .\test\consumer\merge-school-enrollment-info.test.js`
+
 # UnitTestingNode
 
 Here's the assignment task
 
 Create a new function named mergeSchoolInfoToEnrollments
 This function should fetch the schools and the enrollment data and run the enrollment data through a stream
-in one the streams ,we need to add the school information each enrollment. 
+in one the streams ,we need to add the school information each enrollment.
 and then the final stream should write the data to the a file named enrollments_with_schools.json
 
-Also write the unit test for this function. 
+Also write the unit test for this function.
 

api/app.js

@@ -2,18 +2,18 @@ const express = require('express');
 const app = express();
 const fs = require('fs');
 app.get("/students", (req, res) => {
-  var fileContent = fs.readFileSync("students.json");
+  var fileContent = fs.readFileSync('api/students.json');
   res.json(JSON.parse(fileContent.toString()));
 });
 
 app.get("/schools", (req, res) => {
-var fileContent = fs.readFileSync("school.json");
+var fileContent = fs.readFileSync('api/schools.json');
 res.json(JSON.parse(fileContent.toString()));
 });
 
 app.get("/enrollments", (req, res) => {
-  var fileContent = fs.readFileSync("enrollments.json");
+  var fileContent = fs.readFileSync('api/enrollments.json');
   res.json(JSON.parse(fileContent.toString()));
 });
 
-app.listen(3000);
+app.listen(3000);

consumer/index.js

@@ -1,7 +1,7 @@
-
 const produceStudentOutput = require('./produce-student-output');
+const mergeSchoolEnrollmentInfo = require('./merge-school-enrollment-info');
 
-(async function() {
-await produceStudentOutput();
-}
-)();
+(async () => {
+  // await produceStudentOutput();
+  await mergeSchoolEnrollmentInfo();
+})();

consumer/merge-school-enrollment-info.js

@@ -0,0 +1,68 @@
+const StudentApi = require('./student-api');
+const JSONStream = require('jsonstream');
+const { Writable, Transform } = require('stream');
+const pump = require('pump');
+const fs = require('fs');
+
+const buildSchoolLookup = async (schoolStream) => {
+  const schoolLookup = {};
+
+  await new Promise((resolve) => {
+    schoolStream
+      .pipe(JSONStream.parse('*'))
+      .pipe(new Writable({
+        objectMode: true,
+        write(chunk, encoding, callback) {
+          schoolLookup[chunk.id] = chunk;
+          callback();
+        }
+      }));
+
+    schoolStream.on('end', () => {
+      resolve();
+    });
+  });
+
+  return schoolLookup;
+};
+
+module.exports = async function() {
+  const api = new StudentApi();
+  const schoolLookup = await buildSchoolLookup(await api.getSchools());
+  const enrollmentStream = await api.getEnrollments();
+
+  const processEnrollmentStream = new Transform({
+    objectMode: true,
+    transform(chunk, encoding, callback) {
+      const school = schoolLookup[chunk.school_id] || null;
+      this.push({
+        id: chunk.id,
+        student_id: chunk.student_id,
+        school
+      });
+      callback();
+    }
+  });
+
+  const resultFilePath = './merged-enrollments.json';
+
+  try {
+    fs.unlinkSync(resultFilePath);
+  } catch(error) { }
+
+  const fileStream = fs.createWriteStream(resultFilePath);
+
+  return new Promise((resolve, reject) => {
+    pump(
+      enrollmentStream,
+      JSONStream.parse('*'),
+      processEnrollmentStream,
+      JSONStream.stringify(),
+      fileStream,
+      (error) => {
+        if (error) { reject(error); }
+        resolve();
+      }
+    );
+  });
+};