convert a lot of js to typescript and use a single graduation DB

25 files changed, 827 insertions, 851 deletions

diff --git a/doc/graduation.md b/doc/graduation.md
index 2466c44..9edc289 100644
--- a/doc/graduation.md
+++ b/doc/graduation.md
@@ -1,37 +1,10 @@
 # Graduation
 
-## Tables
+## Table
 
-There exist three different tables to hold all graduation information of a student.
-One global submission table called `Submit` writable by all students and two individual ones per student.
-The separation is needed for the different required permissions to access the stored data.
-All individual tables use the following naming scheme `${StudentId}${Purpose}`.
-
-The section containing the student's tables is only available to teachers and the student.
-
-### Submit Table
-
-The submit table is writable by all students and is used to track observation requests from students.
-It is configured to require approval to publish entries.
-This ensures that entries are only readable by the submitter and the teachers.
-Entries are simply never approved.
-
-### Public Table
-
-The public table tracks all graduation changes known by the student.
-The included information are sufficient to render a student's profile.
-
-Changes can be submitted by any teacher.
-Each change is valid until a subsequent change renders it obsolete.
-
-Changes include points and level changes.
-
-### Shadow Table
-
-The shadow table tracks **all** graduation changes for a student.
-
-Changes can be submitted by any teacher.
-Each change is valid until a subsequent change renders it obsolete.
+There exist a single table called `Graduation` to hold all graduation information.
+A single table is used to reduce the amount of requests required to load the data.
+It is important that only teachers are allowed to read from the table.
 
 ## Graduation Changes
 
@@ -62,11 +35,12 @@ The author of the change and the creation time are tracked by Moodle.
 ### Data format
 
 Each stored change is represented as JSON and has the following fields:
-(Fields marked by `-` are considered private and not stored in the public table.)
+(Fields marked by `?` are optional.)
 
+* `studentId` - the id of the student
 * `change` - the type of the change
-* `-reason` - the type of the change
-* `context` - arbitrary data used to handle the type of change
+* `?reason` - the type of the change
+* `?context` - arbitrary data used to handle the type of change
 
 ### Changes
 
diff --git a/src/cockpit.js b/src/cockpit.js
index 9dea658..67619d8 100644
--- a/src/cockpit.js
+++ b/src/cockpit.js
@@ -1,28 +1,24 @@
 // import {
 	// fetchSubjectsMock as fetchSubjects,
 	// fetchProgressMock as fetchProgress,
-// } from "../../js/mock.js";
+// } from "../../js/mock.ts";
 
 import {
 	OBSERVATION_TYPES,
 	LEVEL_NAMES,
 	GraduationChange,
 	fetchGraduation,
-	fetchPublicGraduation,
 	submitGraduationChange
-} from "./graduation-ENV.js";
+} from "./graduation-ENV.ts";
 
-import { fetchStudent, fetchStudents, Student } from "./student-ENV.js";
+import { fetchStudent, fetchStudents } from "./student-ENV.ts";
 import { 
-	isTeacher as getIsTeacher,
 	getName,
-	getUserId,
 	DATE_FMT,
 	DATETIME_FMT,
 } from "./utils-ENV.js";
 import { initSelection } from "./selection.js";
 
-let isTeacher;
 let name;
 let student;
 
@@ -81,8 +77,7 @@ function pointClickHandler(color) {
 			change = GraduationChange.newRedPointChange(textarea.value, coach);
 			break;
 		default:
-			alert("Invalid color");
-			break;
+			throw new Error("Invalid color");
 		}
 		submitGraduationChange(student, change);
 		textareaDiv.style.display = "none";
@@ -102,11 +97,7 @@ function pointClickHandler(color) {
 }
 
 async function fetchAndUpdateStudentInfo() {
-	if (isTeacher)
-		student.graduation = await fetchGraduation(student);
-	else
-		student.graduation = await fetchPublicGraduation(student);
-
+	student.graduation = await fetchGraduation(student);
 	updateStudentInfo();
 }
 
@@ -135,14 +126,12 @@ function updateStudentInfo() {
 		document.getElementById("student-info-points-orange").innerHTML = student.graduation.orange;
 		document.getElementById("student-info-points-red").innerHTML = student.graduation.red;
 
-		if (isTeacher) {
-			document.getElementById("student-info-green").addEventListener('click',
-				() => pointClickHandler("green"));
-			document.getElementById("student-info-orange").addEventListener('click',
-				() => pointClickHandler("orange"));
-			document.getElementById("student-info-red").addEventListener('click',
-				() => pointClickHandler("red"));
-		}
+		document.getElementById("student-info-green").addEventListener('click',
+			() => pointClickHandler("green"));
+		document.getElementById("student-info-orange").addEventListener('click',
+			() => pointClickHandler("orange"));
+		document.getElementById("student-info-red").addEventListener('click',
+			() => pointClickHandler("red"));
 
 		renderGraduationLevel(student.graduation);
 
@@ -174,7 +163,7 @@ function renderObservationStatus(graduation, node) {
 	node.innerHTML = "";
 
 	let status;
-	if (isTeacher || graduation.isObserved() || graduation.observationRequested) {
+	if (graduation.isObserved() || graduation.observationRequested) {
 		status = document.createElement("span");
 		status.classList.add("student-observation-status");
 		if (graduation.isObserved()) {
@@ -233,7 +222,6 @@ function renderObservationStatus(graduation, node) {
 // }
 
 async function updateStudentGraduation() {
-	if (!isTeacher) return;
 	console.assert(student.graduation, "Student has no graduation");
 	const graduation = student.graduation;
 
@@ -258,7 +246,7 @@ async function updateStudentGraduation() {
 					changeTr.style.background = "orange";
 				break;
 				default:
-					alert(`unexpected change: ${change.change}`);
+					console.error(`unexpected change: ${change.change}`);
 				}
 				continue;
 			}
@@ -339,27 +327,16 @@ async function updateStudentGraduation() {
 }
 
 async function initCockpit() {
-	if (isTeacher) {
-		initStudentSelection();
-		const params = new URLSearchParams(location.search);
-		const userId = params.get("userToLoad");
-		if (userId) {
-			student = await fetchStudent(userId);
-			await loadStudent(student);
-		}
-	} else {
-		// Remove all elements only suitable for teachers
-		for(const elem of document.querySelectorAll("[data-availability=if-lehrer]")) {
-			elem.remove();
-		}
-
-		const student = await Student.fetchById(getUserId());
+	initStudentSelection();
+	const params = new URLSearchParams(location.search);
+	const userId = params.get("userToLoad");
+	if (userId) {
+		student = await fetchStudent(userId);
 		await loadStudent(student);
 	}
 }
 
 window.onload = function() {
-	isTeacher = getIsTeacher();
 	DEFAULT_STUDENT_ICON = document.getElementById("student-info-icon").src;
 	name = getName();
 	initCockpit();
diff --git a/src/database-mock.ts b/src/database-mock.ts
new file mode 100644
index 0000000..24cb08f
--- /dev/null
+++ b/src/database-mock.ts
@@ -0,0 +1,30 @@
+interface DatabaseParams {
+	[key: string]: string;
+}
+
+interface DatabaseEntry {
+	[key: string]: string;
+}
+
+class DB {
+	async fetchEntries(params?: DatabaseParams) {
+		console.log(`Mock DB fetch entries: ${params}`);
+		return [];
+	}
+
+	async saveEntry(json: string) {
+		console.log(`Mock DB save entry ${json}`);
+		return; 
+	}
+
+}
+
+async function getGraduationDb() {
+	return new DB();
+}
+
+export {
+	DB,
+	DatabaseEntry, DatabaseParams,
+	getGraduationDb,
+};
diff --git a/src/database.js b/src/database-prod.ts
index e929896..6a55f25 100644
--- a/src/database.js
+++ b/src/database-prod.ts
@@ -21,67 +21,62 @@ const DB_TEMPLATE_LIST_FOOTER = `
 </table>
 `;
 
-let studentDbs = populateStudentDbs();
+let graduationDb = findGraduationDb();
 
 const ID_QUERY_PARAM_REGEX = /[?&]id=(\d+)/
 
-async function populateStudentDbs() {
+async function findGraduationDb() {
+	let graduationDbId = localStorage.getItem("gruaduationDbId");
+	if (graduationDbId !== null) {
+		return new DB(Number(graduationDbId));
+	}
+
 	const courseUrl = `https://lernplattform.bycs.de/course/view.php?id=${getCourseId()}`;
 	const courseRes = await fetch(courseUrl);
 	const courseDoc = new DOMParser().parseFromString(await courseRes.text(), 'text/html');
 
-	let dbs = new Map();
-	for (const link of courseDoc.querySelectorAll("div.activityname a.aalink")) {
-		if (link.textContent.trim() === "Submit  Datenbank") {
-			const dbId = link.href.match(ID_QUERY_PARAM_REGEX)[1]
-			dbs.set("submit", new DB(dbId));
-			continue;
-		}
-
-		const match = link.textContent.match(/(\d+)(Shadow|Public|Submit)/);
-		if (!match) continue;
-		const studentId = match[1];
-		const dbType = match[2];
-		const dbId = link.href.match(ID_QUERY_PARAM_REGEX)[1]
-
-		if (!dbs.has(studentId)) {
-			dbs.set(studentId, {});
+	for (const a of courseDoc.querySelectorAll("div.activityname a.aalink")) {
+		if (a.textContent.trim() === "Graduation  Datenbank") {
+			const anchor = (a as HTMLAnchorElement);
+			const match = anchor.href.match(ID_QUERY_PARAM_REGEX);
+			if (match === null) continue;
+			const dbId = match[1];
+			localStorage.setItem("graduationDbId", dbId);
+			return new DB(Number(dbId))
 		}
-
-		dbs.get(studentId)[dbType.toLowerCase()] = new DB(dbId);
 	}
+	console.assert(false, "Graduation DB not found");
+}
 
-	return dbs;
+interface DatabaseParams {
+	[key: string]: string;
 }
 
-async function getSubmitDb() {
-	const dbs = await studentDbs;
-	return dbs.get("submit");
+interface DatabaseEntry {
+	[key: string]: string;
 }
 
 class DB {
-	constructor(id) {
+	id: number;
+
+	constructor(id: number) {
 		this.id = id;
 	}
 
-	async fetchEntries(params) {
+	async fetchEntries(params?: DatabaseParams) {
 		return loadFromDatabaseActivity(this.id, params)
 	}
 
-	async saveEntry(json) {
+	async saveEntry(json: string) {
 		return addEntryToDatabaseActivity(this.id, json);
 	}
 
-	static async getStudentDbs(student) {
-		const dbs = await studentDbs;
-		return dbs.get(student.id);
-	}
 }
 
-async function loadFromDatabaseActivity(id, params) {
+async function loadFromDatabaseActivity(id: string | number, params?: DatabaseParams) {
 	let dbUrl = `${window.location.origin}/mod/data/view.php?id=${id}&mode=list&perpage=1000`;
 	// TODO(muhq): Why does this not include entries?
-	if (params) {
+	if (typeof params !== "undefined") {
 		dbUrl += "&filter=1&advanced=1";
 		for (const param in params) {
 			dbUrl += `&${param}=${encodeURIComponent(params[param])}`
@@ -90,38 +85,37 @@ async function loadFromDatabaseActivity(id, params) {
 
 	const dbRes = await fetch(encodeURI(dbUrl));
 	const dbDoc = new DOMParser().parseFromString(await dbRes.text(), 'text/html');
-	let data = [];
+	let data: any[] = [];
 	dbDoc.querySelectorAll('.db-row').forEach(row => {
-		let entry = {};
-		row.querySelectorAll('.db-cell').forEach(field => {
-			const key = field.dataset.key;
+		let entry: DatabaseEntry = {};
+		row.querySelectorAll<HTMLElement>('.db-cell').forEach(field => {
+			const key = field.dataset.key!;
 			let value;
 			// Moodle includes the full date in the title attribute of the included span
 			if (key === "date") {
-				value = field.querySelector("span").title;
+				value = field.querySelector("span")?.title;
 			} else {
 				value = field.innerText.trim();
 			}
-			entry[key] = value;
+			entry[key] = value!;
 		});
 		data.push(entry);
 	});
 	return data;
 }
 
-async function loadFromStudentDatabase(student, type) {
-	const dbs = await DB.getStudentDbs(student);
-	const db = dbs[type];
-	return await db.fetchEntries()
+async function getGraduationDb() {
+	return (await graduationDb)!;
 }
 
-async function addEntryToDatabaseActivity(id, json) {
+async function addEntryToDatabaseActivity(id: number, json: string) {
+	// TODO(muhq): do not fetch the form
 	const url = `/mod/data/edit.php?id=${id}`;
 	const editRes = await fetch(url);
 	const editDoc = new DOMParser().parseFromString(await editRes.text(), 'text/html');
-	const form = editDoc.querySelector('div[role="main"] > form');
+	const form = editDoc.querySelector<HTMLFormElement>('div[role="main"] > form');
 
-	const formData = new FormData(form);
+	const formData = new FormData(form!);
 
 	for (const key of formData.keys()) {
 		if (key.startsWith("field_")) {
@@ -139,22 +133,8 @@ async function addEntryToDatabaseActivity(id, json) {
 	});
 }
 
-async function addEntryToStudentDatabase(student, type, json) {
-	let db;
-	// global submit database
-	if (type === "submit") {
-		db = await getSubmitDb();
-	// individuell databases
-	} else {
-		const dbs = await DB.getStudentDbs(student);
-		db = dbs[type];
-	}
-	await db.saveEntry(json);
-}
-
 export {
 	DB,
-	getSubmitDb,
-	loadFromDatabaseActivity, loadFromStudentDatabase,
-	addEntryToDatabaseActivity, addEntryToStudentDatabase,
+	DatabaseEntry, DatabaseParams,
+	getGraduationDb,
 };
diff --git a/src/graduation-common.js b/src/graduation-common.js
deleted file mode 100644
index 0c28465..0000000
--- a/src/graduation-common.js
+++ /dev/null
@@ -1,396 +0,0 @@
-import { getSubmitDb, loadFromStudentDatabase, addEntryToStudentDatabase } from "./database.js"
-
-import NeulingPng from "../assets/Neuling.png";
-import EntdeckerPng from "../assets/Entdecker.png";
-import NavigatorPng from "../assets/Navigator.png";
-import PioneerPng from "../assets/Pioneer.png";
-
-const LEVEL_NAMES = ["Neuling", "Entdecker", "Navigator", "Pionieer"];
-
-const LEVEL_IMAGES = [
-	new URL(NeulingPng),
-	new URL(EntdeckerPng),
-	new URL(NavigatorPng),
-	new URL(PioneerPng),
-];
-
-class GraduationChange {
-	constructor(date, change, reason, coach, context) {
-		this.date = date;
-		this.change = change;
-		this.reason = reason;
-		this.coach = coach;
-		this.context = context;
-	}
-
-	isPublic() {
-		return [
-			"Grün", "Orange", "Rot",
-			"ObservationStart", "ObservationEnd",
-			"LevelChange"
-		].includes(this.change);
-	}
-
-	publicDBFields () {
-		return {
-			"change": this.change,
-			"date": this.date,
-		};
-	}
-
-	dbFields () {
-		return {
-			// We include the date in the json because Moodle reports the timeadded
-			// locale dependent.
-			"date": this.date,
-			"change": this.change,
-			"reason": this.reason,
-			"context": this.context,
-		};
-	}
-
-	static fromDBEntry(e) {
-		const {coach, json} = e;
-		const change = JSON.parse(json);
-		return new GraduationChange(new Date(change.date), change.change, change.reason, coach, change.context);
-	}
-
-	static newObservationRequest() {
-		return new GraduationChange(new Date(), "ObservationRequest", "", "", "");
-	}
-
-	static newObservationStart() {
-		return new GraduationChange(new Date(), "ObservationStart", "", "", "");
-	}
-
-	static newObservationEnd(reason, success) {
-		return new GraduationChange(new Date(), "ObservationEnd", reason, "", JSON.stringify(success));
-	}
-
-	static newObservationChange(observation) {
-		return new GraduationChange(observation.date, "Observation", "", "", JSON.stringify(observation.status));
-	}
-
-	static newGreenPointChange(reason, coach) {
-		return new GraduationChange(new Date(), "Grün", reason, coach, "");
-	}
-
-	static newOrangePointChange(reason, coach) {
-		return new GraduationChange(new Date(), "Orange", reason, coach, "");
-	}
-
-	static newRedPointChange(reason, coach) {
-		return new GraduationChange(new Date(), "Rot", reason, coach, "");
-	}
-}
-
-class Graduation {
-	constructor(student, green, orange, red, level, stickers, observationRequested, observation, pastObservations, changes) {
-		this.student = student;
-		this.green = green;
-		this.orange = orange;
-		this.red = red;
-		this.level = level;
-		this.stickers = stickers;
-		this.observationRequested = observationRequested;
-		this.observation = observation;
-		this.pastObservations = pastObservations;
-		this.changes = changes;
-
-		student.graduation = this;
-	}
-
-	static from(student, changes) {
-		let green = 0;
-		let orange = 0;
-		let red = 0;
-		let level = 1;
-		let openObservationRequest = null;
-		let observationPeriod = null;
-		let pastObservations = [];
-		let stickers = [];
-
-		// The parsing logic assumes that changes are ordered chronologically
-		changes.sort((a, b) => a.date - b.date);
-
-		for (const change of changes) {
-			switch (change.change) {
-			case "Grün":
-				green++;
-				break;
-
-			case "Orange":
-				orange++;
-				break;
-
-			case "Rot":
-				red++;
-				break;
-
-			case "ObservationRequest":
-				openObservationRequest = change.date;
-				break;
-
-			case "ObservationStart":
-				console.assert(openObservationRequest, "No request for observation start");
-				observationPeriod = new ObservationPeriod(change.date);
-				openObservationRequest = null;
-				break;
-
-			case "ObservationEnd":
-				console.assert(observationPeriod, "No active observation period");
-				observationPeriod.finishPeriod(change.context.success);
-				if (change.context.success) {
-					level++;
-				}
-				pastObservations.push(observationPeriod);
-				observationPeriod = null;
-				break;
-
-			case "Observation":
-				console.assert(observationPeriod, "No active observation period");
-				const observation = Observation.fromChange(change);
-				observationPeriod.addObservation(observation);
-				break;
-
-			case "LevelChange":
-				level = change.context.level;
-				break;
-
-			default:
-				alert(`Unexpected change: ${change}`);
-			}
-		}
-		return new Graduation(student, green, orange, red, level,
-			stickers,
-			openObservationRequest, observationPeriod, pastObservations,
-			changes);
-	}
-
-	addChange(change) {
-		// TODO(muhq): Implement incremental addition
-		let changes = this.changes;
-		changes.push(change);
-		// This updates the student.graduation reference as well
-		Graduation.from(this.student, changes);
-	}
-
-	/**
-	 * Request observation
-	 */
-	async requestObservation() {
-		const request = GraduationChange.newObservationRequest();
-		this.observationRequested = request.date;
-		await addEntryToStudentDatabase(this.student, "submit", JSON.stringify(request.publicDBFields()));
-	}
-
-	/**
-	 * Start an observation
-	 */
-	async startObservation() {
-		if (!this.observationRequested) {
-			console.assert(this.observationRequested, "No observation requested");
-			return;
-		}
-		this.observationRequested = null;
-		this.observation = new ObservationPeriod(new Date());
-		return submitGraduationChange(this.student, GraduationChange.newObservationStart());
-	}
-
-	/**
-	 * End an observation
-	 */
-	async endObservation(reason, success) {
-		if (!this.observation) {
-			console.assert(this.observation, "No active observation");
-			return;
-		}
-		this.observation.end = new Date();
-		this.pastObservations.push(this.observation);
-		this.observation = null;
-		return submitGraduationChange(this.student, GraduationChange.newObservationEnd(reason, success));
-	}
-
-	/**
-	 * Return if the student is in observation.
-	 */
-	isObserved() {
-		return Boolean(this.observation);
-	}
-
-	/**
-	 * Return the URI of the icon representing the graduation level.
-	 */
-	getIcon() {
-		return LEVEL_IMAGES[this.level - 1];
-	}
-
-	/**
-	 * Return the name of the current graduation level.
-	 * @return {String} The name of the current level.
-	 */
-	getLevelName() {
-		return LEVEL_NAMES[this.level - 1];
-	}
-}
-
-class ObservationPeriod {
-	constructor(start) {
-		this.start = start;
-		this.observations = [];
-	}
-
-	finishPeriod(success) {
-		this.end = new Date();
-		this.success = success;
-	}
-
-	ended() {
-		return Boolean(this.end);
-	}
-
-	ready() {
-		if (this.observations.length < 10)
-			return false;
-
-		// at least 10 observation on different days
-		let days = new Map();
-		for (const observation of this.observations) {
-			const d = observation.date;
-			days.set(`${d.getFullYear()}${d.getMonth()}${d.getDate()}`, true);
-		}
-		return days.size >= 10;
-	}
-
-	getObservationsSums() {
-		let sums = Array(OBSERVATION_TYPES.length).fill().map(() => ({"yes":0, "no":0}));
-		for (const observation of this.observations) {
-			for (let i = 0; i < sums.length; i++) {
-				if (observation.status[i]) {
-					if (observation.status[i] === "yes")
-						sums[i].yes++;
-					else
-						sums[i].no++;
-				}
-			}
-		}
-		return sums;
-	}
-
-	addObservation(observation) {
-		this.observations.push(observation);
-	}
-}
-
-const OBSERVATION_TYPES = [
-	"Arbeitet konzentriert an Aufgaben",
-	"Arbeitet zunehmend selbstständig",
-	"Führt das Logbuch zuverlässig",
-	"Bringt Material mit",
-	"Hält Regeln ein",
-	"Geht verantwortungsvoll mit Materialien und LernRaum um",
-	"Nimmt Rückmeldungen an und setzt sie um",
-];
-
-class Observation {
-	constructor(date, status) {
-		console.assert(status.length == OBSERVATION_TYPES.length, "invalid observation status");
-		this.date = date;
-		this.status = status;
-	}
-
-	static fromChange(change) {
-		return new Observation(change.date, JSON.parse(change.context))
-	}
-}
-
-function changesFromDbEntries(entries) {
-	let changes = [];
-	for (const e of entries) {
-		const gradChange = GraduationChange.fromDBEntry(e);
-		changes.push(gradChange);
-	}
-	return changes;
-}
-
-async function fetchGraduationChangesFromDb(student, type) {
-	const data = await loadFromStudentDatabase(student, type);
-	return changesFromDbEntries(data);
-}
-
-const submitEntriesPromise = async function() {
-	const db = await getSubmitDb();
-	const entries = await db.fetchEntries();
-	return changesFromDbEntries(entries);
-}();
-
-async function addSubmittedChanges(student, changes) {
-	let submitEntries = await submitEntriesPromise;
-	for (const e of submitEntries.filter( (c) => c.coach === student.name )) {
-		changes.push(e);
-	}
-	return changes;
-}
-
-async function fetchGraduationChanges(student) {
-	let changes = await fetchGraduationChangesFromDb(student, "shadow");
-	return addSubmittedChanges(student, changes);
-}
-
-async function fetchPublicGraduationChanges(student) {
-	let changes = await fetchGraduationChangesFromDb(student, "public");
-	return addSubmittedChanges(student, changes);
-}
-
-async function fetchGraduation(student) {
-	const changes = await fetchGraduationChanges(student);
-	return Graduation.from(student, changes);
-}
-
-async function fetchPublicGraduation(student) {
-	const changes = await fetchPublicGraduationChanges(student);
-	return Graduation.from(student, changes);
-}
-
-async function submitGraduationChange(student, change) {
-	student.graduation.addChange(change);
-
-	// Submit changes concurrently
-	let promises = [];
-
-	if (change.isPublic()) {
-		promises.push(
-			// TODO(muhq): strip non public fields from changes
-			addEntryToStudentDatabase(student, "public", JSON.stringify(change.publicDBFields()))
-		);
-	}
-
-	promises.push(
-		addEntryToStudentDatabase(student, "shadow", JSON.stringify(change.dbFields()))
-	);
-
-	await Promise.all(promises);
-}
-
-async function submitObservation(student, observation) {
-	console.assert(student.graduation.observation, "no active observation");
-	student.graduation.observation.addObservation(observation);
-	await submitGraduationChange(student, GraduationChange.newObservationChange(observation));
-}
-
-export {
-	LEVEL_NAMES,
-	LEVEL_IMAGES,
-	GraduationChange,
-	Graduation,
-	fetchGraduation,
-	fetchPublicGraduation,
-	fetchGraduationChanges,
-	fetchPublicGraduationChanges,
-	submitGraduationChange,
-	submitObservation,
-
-	OBSERVATION_TYPES,
-	Observation,
-	ObservationPeriod,
-};
diff --git a/src/graduation-common.ts b/src/graduation-common.ts
new file mode 100644
index 0000000..61600d3
--- /dev/null
+++ b/src/graduation-common.ts
@@ -0,0 +1,347 @@
+import { getGraduationDb, DatabaseEntry } from "./database-ENV.ts"
+import type { Student } from "./student-common.ts"
+
+import NeulingPng from "../assets/Neuling.png";
+import EntdeckerPng from "../assets/Entdecker.png";
+import NavigatorPng from "../assets/Navigator.png";
+import PioneerPng from "../assets/Pioneer.png";
+
+const LEVEL_NAMES = ["Neuling", "Entdecker", "Navigator", "Pionieer"];
+
+const LEVEL_IMAGES = [
+	new URL(NeulingPng),
+	new URL(EntdeckerPng),
+	new URL(NavigatorPng),
+	new URL(PioneerPng),
+];
+
+class GraduationChange {
+	date: Date;
+	studentId: number;
+	change: string;
+	reason: string;
+	coach: string;
+	context: any;
+
+	constructor(date: Date, studentId: number, change: string, reason: string, coach: string, context: any) {
+		this.date = date;
+		this.studentId = studentId;
+		this.change = change;
+		this.reason = reason;
+		this.coach = coach;
+		this.context = context;
+	}
+
+	dbFields () {
+		return {
+			"studentId": this.studentId,
+			"change": this.change,
+			"reason": this.reason,
+			"context": this.context,
+		};
+	}
+
+	static fromDBEntry(e: DatabaseEntry) {
+		const {date, coach, json} = e;
+		const change = JSON.parse(json);
+		return new GraduationChange(new Date(date), change.change, change.student, change.reason, coach, change.context);
+	}
+
+	static newObservationRequest() {
+		return new GraduationChange(new Date(), -1, "ObservationRequest", "", "", "");
+	}
+
+	static newObservationStart() {
+		return new GraduationChange(new Date(), -1, "ObservationStart", "", "", "");
+	}
+
+	static newObservationEnd(reason: string, success: boolean) {
+		return new GraduationChange(new Date(), -1, "ObservationEnd", reason, "", JSON.stringify(success));
+	}
+
+	static newObservationChange(observation: Observation) {
+		return new GraduationChange(observation.date, -1, "Observation", "", "", JSON.stringify(observation.status));
+	}
+
+	static newGreenPointChange(reason: string, coach: string) {
+		return new GraduationChange(new Date(), -1, "Grün", reason, coach, "");
+	}
+
+	static newOrangePointChange(reason: string, coach: string) {
+		return new GraduationChange(new Date(), -1, "Orange", reason, coach, "");
+	}
+
+	static newRedPointChange(reason: string, coach: string) {
+		return new GraduationChange(new Date(), -1, "Rot", reason, coach, "");
+	}
+}
+
+class Graduation {
+	student: Student;
+	green: number;
+	orange: number;
+	red: number;
+	level: number;
+	observationRequested: Date | null;
+	observation: ObservationPeriod | null;
+	pastObservations: Array<ObservationPeriod>;
+	changes: Array<GraduationChange>;
+
+	constructor(student: Student, green: number, orange: number, red: number, level: number,  observationRequested: Date | null, observation: ObservationPeriod | null, pastObservations: Array<ObservationPeriod>, changes: Array<GraduationChange>) {
+		this.student = student;
+		this.green = green;
+		this.orange = orange;
+		this.red = red;
+		this.level = level;
+		this.observationRequested = observationRequested;
+		this.observation = observation;
+		this.pastObservations = pastObservations;
+		this.changes = changes;
+
+		student.graduation = this;
+	}
+
+	static from(student: Student, changes: Array<GraduationChange>) {
+		let green = 0;
+		let orange = 0;
+		let red = 0;
+		let level = 1;
+		let openObservationRequest = null;
+		let observationPeriod = null;
+		let pastObservations = [];
+
+		// The parsing logic assumes that changes are ordered chronologically
+		changes.sort((a, b) => a.date.valueOf() - b.date.valueOf());
+
+		for (const change of changes) {
+			switch (change.change) {
+			case "Grün":
+				green++;
+				break;
+
+			case "Orange":
+				orange++;
+				break;
+
+			case "Rot":
+				red++;
+				break;
+
+			case "ObservationRequest":
+				openObservationRequest = change.date;
+				break;
+
+			case "ObservationStart":
+				console.assert(openObservationRequest === null,
+					"No request for observation start");
+
+				observationPeriod = new ObservationPeriod(change.date);
+				openObservationRequest = null;
+				break;
+
+			case "ObservationEnd":
+				if (observationPeriod === null) {
+					console.error("No active observation period");
+					continue;
+				}
+				observationPeriod.finishPeriod(change.context.success);
+				if (change.context.success) {
+					level++;
+				}
+				pastObservations.push(observationPeriod);
+				observationPeriod = null;
+				break;
+
+			case "Observation":
+				if (observationPeriod === null) {
+					console.error("No active observation period");
+					continue;
+				}
+				const observation = Observation.fromChange(change);
+				observationPeriod.addObservation(observation);
+				break;
+
+			case "LevelChange":
+				level = change.context.level;
+				break;
+
+			default:
+				throw new Error(`Unexpected change: ${change}`);
+			}
+		}
+		return new Graduation(student, green, orange, red, level,
+			openObservationRequest, observationPeriod, pastObservations,
+			changes);
+	}
+
+	addChange(change: GraduationChange) {
+		change.studentId = this.student.id;
+		// TODO(muhq): Implement incremental addition
+		let changes = this.changes;
+		changes.push(change);
+		// This updates the student.graduation reference as well
+		Graduation.from(this.student, changes);
+	}
+
+	/**
+	 * Request observation
+	 */
+	async requestObservation() {
+		const request = GraduationChange.newObservationRequest();
+		this.observationRequested = request.date;
+		const db = await getGraduationDb();
+		await db.saveEntry(JSON.stringify(request.dbFields()));
+	}
+
+	/**
+	 * Start an observation
+	 */
+	async startObservation() {
+		if (this.observationRequested === null) {
+			console.error("No observation requested");
+			return;
+		}
+		this.observationRequested = null;
+		this.observation = new ObservationPeriod(new Date());
+		return submitGraduationChange(this, GraduationChange.newObservationStart());
+	}
+
+	/**
+	 * End an observation
+	 */
+	async endObservation(reason: string, success: boolean) {
+		if (this.observation === null) {
+			console.error("No active observation");
+			return;
+		}
+		this.observation.end = new Date();
+		this.pastObservations.push(this.observation);
+		this.observation = null;
+		return submitGraduationChange(this, GraduationChange.newObservationEnd(reason, success));
+	}
+
+	/**
+	 * Return if the student is in observation.
+	 */
+	isObserved() {
+		return Boolean(this.observation);
+	}
+
+	/**
+	 * Return the URI of the icon representing the graduation level.
+	 */
+	getIcon() {
+		return LEVEL_IMAGES[this.level - 1];
+	}
+
+	/**
+	 * Return the name of the current graduation level.
+	 */
+	getLevelName() {
+		return LEVEL_NAMES[this.level - 1];
+	}
+}
+
+class ObservationPeriod {
+	start: Date;
+	end: Date | null;
+	observations: Array<Observation>;
+	success = false;
+
+	constructor(start: Date) {
+		this.start = start;
+		this.end = null;
+		this.observations = [];
+	}
+
+	finishPeriod(success: boolean) {
+		this.end = new Date();
+		this.success = success;
+	}
+
+	ended() {
+		return Boolean(this.end);
+	}
+
+	ready() {
+		if (this.observations.length < 10)
+			return false;
+
+		// at least 10 observation on different days
+		let days = new Map();
+		for (const observation of this.observations) {
+			const d = observation.date;
+			days.set(`${d.getFullYear()}${d.getMonth()}${d.getDate()}`, true);
+		}
+		return days.size >= 10;
+	}
+
+	getObservationsSums() {
+		let sums = Array(OBSERVATION_TYPES.length).fill(null).map(() => ({"yes":0, "no":0}));
+		for (const observation of this.observations) {
+			for (let i = 0; i < sums.length; i++) {
+				if (observation.status[i]) {
+					if (observation.status[i] === "yes")
+						sums[i].yes++;
+					else
+						sums[i].no++;
+				}
+			}
+		}
+		return sums;
+	}
+
+	addObservation(observation: Observation) {
+		this.observations.push(observation);
+	}
+}
+
+const OBSERVATION_TYPES = [
+	"Arbeitet konzentriert an Aufgaben",
+	"Arbeitet zunehmend selbstständig",
+	"Führt das Logbuch zuverlässig",
+	"Bringt Material mit",
+	"Hält Regeln ein",
+	"Geht verantwortungsvoll mit Materialien und LernRaum um",
+	"Nimmt Rückmeldungen an und setzt sie um",
+];
+
+class Observation {
+	date: Date;
+	status: Array<string>;
+
+	constructor(date: Date, status: Array<string>) {
+		console.assert(status.length == OBSERVATION_TYPES.length, "invalid observation status");
+		this.date = date;
+		this.status = status;
+	}
+
+	static fromChange(change: GraduationChange) {
+		return new Observation(change.date, JSON.parse(change.context))
+	}
+}
+
+async function submitGraduationChange(graduation: Graduation, change: GraduationChange) {
+	graduation.addChange(change);
+	const db = await getGraduationDb();
+	return db.saveEntry(JSON.stringify(change.dbFields()));
+}
+
+async function submitObservation(graduation: Graduation, observation: Observation) {
+	if(graduation.observation === null) throw new Error("no active observation");
+	graduation.observation.addObservation(observation);
+	await submitGraduationChange(graduation, GraduationChange.newObservationChange(observation));
+}
+
+export {
+	LEVEL_NAMES,
+	LEVEL_IMAGES,
+	GraduationChange,
+	Graduation,
+	submitGraduationChange,
+	submitObservation,
+
+	OBSERVATION_TYPES,
+	Observation,
+	ObservationPeriod,
+};
diff --git a/src/graduation-mock.js b/src/graduation-mock.ts
index 1c84433..84a7143 100644
--- a/src/graduation-mock.js
+++ b/src/graduation-mock.ts
@@ -6,21 +6,19 @@ import {
 	OBSERVATION_TYPES,
 	Observation,
 	ObservationPeriod,
-} from "./graduation-common.js";
+} from "./graduation-common.ts";
 
 import {
 	fetchGraduationMock as fetchGraduation,
-	fetchPublicGraduationMock as fetchPublicGraduation,
 	submitGraduationChangeMock as submitGraduationChange,
 	submitObservationMock as submitObservation
-} from "./mock.js";
+} from "./mock.ts";
 
 export {
 	LEVEL_NAMES,
 	GraduationChange,
 	Graduation,
 	fetchGraduation,
-	fetchPublicGraduation,
 	submitGraduationChange,
 	submitObservation,
 
diff --git a/src/graduation-prod.js b/src/graduation-prod.js
deleted file mode 100644
index 0e86956..0000000
--- a/src/graduation-prod.js
+++ /dev/null
@@ -1,15 +0,0 @@
-export {
-	LEVEL_NAMES,
-	GraduationChange,
-	Graduation,
-	fetchGraduation,
-	fetchPublicGraduation,
-	fetchGraduationChanges,
-	fetchPublicGraduationChanges,
-	submitGraduationChange,
-	submitObservation,
-
-	OBSERVATION_TYPES,
-	Observation,
-	ObservationPeriod,
-} from "./graduation-common.js";
diff --git a/src/graduation-prod.ts b/src/graduation-prod.ts
new file mode 100644
index 0000000..975fd0f
--- /dev/null
+++ b/src/graduation-prod.ts
@@ -0,0 +1,43 @@
+import { getGraduationDb } from "./database-ENV.ts"
+import { Graduation, GraduationChange } from "./graduation-common.ts";
+import type { Student } from "./student-common.ts";
+
+const _graduationChangesPromise = async function() {
+	const db = await getGraduationDb();
+	let changes = new Map();
+	let entries = await db.fetchEntries();
+	for (const e of entries) {
+		const gradChange = GraduationChange.fromDBEntry(e);
+		const studentChanges = changes.get(gradChange.studentId);
+		if (studentChanges === null) {
+			changes.set(gradChange.studentId, [gradChange]);
+		} else {
+			studentChanges.push(gradChange);
+		}
+	}
+	return changes;
+}();
+
+const graduations: Map<number, Graduation> = new Map();
+
+export async function fetchGraduation(student: Student): Promise<Graduation> {
+	if (!graduations.has(student.id)) {
+		const studentChanges = (await _graduationChangesPromise).get(student.id) ?? [];
+		const graduation = Graduation.from(student, studentChanges);
+		graduations.set(student.id, graduation);
+		return graduation;
+	}
+	return graduations.get(student.id)!;
+}
+
+export {
+	LEVEL_NAMES,
+	GraduationChange,
+	Graduation,
+	submitGraduationChange,
+	submitObservation,
+
+	OBSERVATION_TYPES,
+	Observation,
+	ObservationPeriod,
+} from "./graduation-common.ts";
diff --git a/src/group-fetch.ts b/src/group-fetch.ts
new file mode 100644
index 0000000..de0991d
--- /dev/null
+++ b/src/group-fetch.ts
@@ -0,0 +1,18 @@
+import { fetchStudents } from "./student-ENV.ts";
+import { Group, buildGroups, _groups } from "./group.ts";
+
+/**
+ * Fetch all Groups and return them as a map.
+ */
+async function fetchGroups() {
+	if (_groups.size) {
+		return _groups;
+	}
+
+	// Fetch all students and build the groups from them
+	const students = await fetchStudents();
+	buildGroups(students);
+	return _groups;
+}
+
+export { Group, buildGroups, fetchGroups };
diff --git a/src/group.js b/src/group.js
deleted file mode 100644
index d52707b..0000000
--- a/src/group.js
+++ /dev/null
@@ -1,57 +0,0 @@
-import { getCourseParticipantsUrl } from "./utils-ENV.js";
-import { fetchStudents } from "./student-ENV.js";
-
-/**
- * Class to represent a Group of Students.
- */
-class Group {
-	constructor(name, students) {
-		this.name = name;
-		if (!students) {
-			this.students = [];
-		}
-	}
-
-	setStudents(students) {
-		this.students = students;
-	}
-
-	addStudent(student) {
-		this.students.push(student);
-	}
-
-	async getStudents() {
-		return this.students;
-	}
-}
-
-const groups = new Map();
-
-function buildGroups(students) {
-	for (const student of students) {
-		let group = groups.get(student.group);
-
-		if (!group) {
-			group = new Group(student.group);
-			groups.set(student.group, group);
-		}
-
-		group.addStudent(student);
-	}
-}
-
-/**
- * Fetch all Groups and return them as a map.
- */
-async function fetchGroups() {
-	if (groups.size) {
-		return groups;
-	}
-
-	// Fetch all students and build the groups from them
-	const students = await fetchStudents();
-	buildGroups(students);
-	return groups;
-}
-
-export { Group, buildGroups, fetchGroups };
diff --git a/src/group.ts b/src/group.ts
new file mode 100644
index 0000000..e840ffd
--- /dev/null
+++ b/src/group.ts
@@ -0,0 +1,45 @@
+import type { Student } from "./student-common.ts";
+
+/**
+ * Class to represent a Group of Students.
+ */
+class Group {
+	name: string;
+	students: Array<Student> = [];
+
+	constructor(name: string, students?: Array<Student>) {
+		this.name = name;
+		if (typeof students !== "undefined") {
+			this.students = students;
+		}
+	}
+
+	setStudents(students: Array<Student>) {
+		this.students = students;
+	}
+
+	addStudent(student: Student) {
+		this.students.push(student);
+	}
+
+	async getStudents() {
+		return this.students;
+	}
+}
+
+const groups = new Map();
+
+function buildGroups(students: Array<Student>) {
+	for (const student of students) {
+		let group = groups.get(student.group);
+
+		if (!group) {
+			group = new Group(student.group);
+			groups.set(student.group, group);
+		}
+
+		group.addStudent(student);
+	}
+}
+
+export { Group, buildGroups, groups as _groups };
diff --git a/src/mass-graduation.js b/src/mass-graduation.js
index 0a69cd1..b9240f0 100644
--- a/src/mass-graduation.js
+++ b/src/mass-graduation.js
@@ -4,9 +4,9 @@ import {
 	submitGraduationChange,
 	Observation,
 	submitObservation
-} from "./graduation-ENV.js";
+} from "./graduation-ENV.ts";
 
-import { fetchGroups } from "./group.js";
+import { fetchGroups } from "./group-fetch.ts";
 import { initSelection } from "./selection.js";
 import { getName, DATETIME_FMT, datetimeStringNow } from "./utils-ENV.js";
 
diff --git a/src/mock.js b/src/mock.js
deleted file mode 100644
index 33d1a1a..0000000
--- a/src/mock.js
+++ /dev/null
@@ -1,104 +0,0 @@
-import { Graduation, GraduationChange } from "./graduation-common.js";
-import { Student } from "./student-common.js";
-import { buildGroups } from "./group.js";
-
-const students = [
-	new Student(1, 'foo bar', 'test'),
-	new Student(2, 'maxi mustermensch', 'test'),
-	new Student(3, 'b b b', '5a')
-];
-
-// Build the groups from our mock students
-buildGroups(students);
-
-function fetchStudentsMock() {
-	return new Promise((resolve) => { resolve(students); });
-}
-
-function fetchSubjectsMock() {
-	return new Promise((resolve) => {
-		resolve(['Mathe', 'Deutsch', 'Englisch']);
-	});
-}
-
-function fetchProgressMock(subject) {
-	return new Promise((resolve) => {
-		if (subject === "Mathe") {
-			resolve([40, 10, 3]);
-		} else if (subject === "Deutsch") {
-			resolve([10, 2, 0]);
-		} else if (subject === "Englisch") {
-			resolve([50, 25, 10]);
-		} else {
-			resolve([0, 0, 0]);
-		}
-	});
-}
-
-const graduationChanges = {};
-for (const s of students) {
-	switch (s.name) {
-	case "foo bar":
-		graduationChanges[s.name] = [
-			GraduationChange.newGreenPointChange("Gute Arbeit", "Florian Fischer"),
-			GraduationChange.newOrangePointChange("", "Florian Fischer"),
-		];
-		break;
-	case "maxi mustermensch":
-		graduationChanges[s.name] = [
-			GraduationChange.newGreenPointChange("", "Florian Fischer"),
-			GraduationChange.newGreenPointChange("", "Florian Fischer"),
-			new GraduationChange(new Date(), "ObservationStart", "", "Florian Fischer", ""),
-		];
-		break;
-	case "b b b":
-		graduationChanges[s.name] = [
-			GraduationChange.newRedPointChange("", "Florian Fischer"),
-		];
-	}
-	// Build the student's graduation
-	Graduation.from(s, graduationChanges[s.name]);
-}
-
-function fetchGraduationMock(s) {
-	return new Promise((resolve) => {
-		const changes =  graduationChanges[s.name];
-		if (!changes) {
-			resolve(null);
-		} else {
-			resolve(Graduation.from(s, changes));
-		}
-	});
-}
-
-function fetchPublicGraduationMock(s) {
-	return new Promise((resolve) => {
-		const changes =  graduationChanges[s.name];
-		if (!changes) {
-			resolve(null);
-		} else {
-			resolve(Graduation.from(s, changes.filter((change) => change.isPublic())));
-		}
-	});
-}
-
-function submitGraduationChangeMock(s, c) {
-	console.assert(s.graduation, "no graduation");
-	s.graduation.addChange(c);
-}
-
-function submitObservationMock(s, o) {
-	console.assert(s.graduation, "no graduation");
-	console.assert(s.graduation.observation, "no observation period");
-	s.graduation.observation.addObservation(o);
-}
-
-export {
-	fetchStudentsMock,
-	fetchSubjectsMock,
-	fetchProgressMock,
-	fetchGraduationMock,
-	fetchPublicGraduationMock,
-	submitGraduationChangeMock,
-	submitObservationMock,
-};
diff --git a/src/mock.ts b/src/mock.ts
new file mode 100644
index 0000000..220b1e3
--- /dev/null
+++ b/src/mock.ts
@@ -0,0 +1,81 @@
+import { Graduation, GraduationChange, Observation } from "./graduation-common.ts";
+import { Student } from "./student-common.ts";
+import { buildGroups } from "./group.ts";
+
+const students = [
+	new Student(1, 'foo bar', 'test'),
+	new Student(2, 'maxi mustermensch', 'test'),
+	new Student(3, 'b b b', '5a')
+];
+
+// Build the groups from our mock students
+buildGroups(students);
+
+async function fetchStudentsMock(_id?: number, _name?: string, _group?: string) {
+	return students;
+}
+
+async function fetchSubjectsMock() {
+	return ['Mathe', 'Deutsch', 'Englisch'];
+}
+
+function fetchProgressMock(subject: string) {
+	return new Promise((resolve) => {
+		if (subject === "Mathe") {
+			resolve([40, 10, 3]);
+		} else if (subject === "Deutsch") {
+			resolve([10, 2, 0]);
+		} else if (subject === "Englisch") {
+			resolve([50, 25, 10]);
+		} else {
+			resolve([0, 0, 0]);
+		}
+	});
+}
+
+const graduations = new Map();
+for (const s of students) {
+	switch (s.name) {
+	case "foo bar":
+		graduations.set(s, Graduation.from(s, [
+			GraduationChange.newGreenPointChange("Gute Arbeit", "Florian Fischer"),
+			GraduationChange.newOrangePointChange("", "Florian Fischer"),
+		]));
+		break;
+	case "maxi mustermensch":
+		graduations.set(s, Graduation.from(s, [
+			GraduationChange.newGreenPointChange("", "Florian Fischer"),
+			GraduationChange.newGreenPointChange("", "Florian Fischer"),
+			new GraduationChange(new Date(), s.id, "ObservationStart", "", "Florian Fischer", ""),
+		]));
+		break;
+	case "b b b":
+		graduations.set(s, Graduation.from(s, [
+			GraduationChange.newRedPointChange("", "Florian Fischer"),
+		]));
+	}
+}
+
+async function fetchGraduationMock(s: Student) {
+	return graduations.get(s);
+}
+
+function submitGraduationChangeMock(s: Student, c: GraduationChange) {
+	if (s.graduation === null) throw new Error("no graduation");
+	s.graduation.addChange(c);
+}
+
+function submitObservationMock(s: Student, o: Observation) {
+	if (s.graduation === null) throw new Error("no graduation");
+	if (s.graduation.observation === null) throw new Error("no observation period");
+	s.graduation.observation.addObservation(o);
+}
+
+export {
+	fetchStudentsMock,
+	fetchSubjectsMock,
+	fetchProgressMock,
+	fetchGraduationMock,
+	submitGraduationChangeMock,
+	submitObservationMock,
+};
diff --git a/src/student-common.js b/src/student-common.js
deleted file mode 100644
index 2dfa35d..0000000
--- a/src/student-common.js
+++ /dev/null
@@ -1,115 +0,0 @@
-import { getCourseId, getUserIconUrl, getCourseParticipantsUrl } from "./utils-ENV.js";
-import { fetchGraduation } from "./graduation-common.js";
-/**
- * Class to represent Students.
- */
-class Student {
-	graduation = null;
-
-	constructor(id, name, group) {
-		this.id = id;
-		this.name = name;
-		this.group = group;
-	}
-
-	async getIconUrl() {
-		return await getUserIconUrl(this.id);
-	}
-
-	getGroup() {
-		return this.group;
-	}
-
-	async getGraduation() {
-		if(!this.graduation) {
-			// fetchGraduation(this) sets this.graduation
-			await fetchGraduation(this);
-		}
-		return this.graduation;
-	}
-
-	static async fetchById(id) {
-		let name = "";
-		let group = "";
-
-		const res = await fetch(`/user/view.php?id=${id}&course=${getCourseId()}`);
-		const doc = new DOMParser().parseFromString(await res.text(), "text/html");
-
-		name = doc.querySelector("div.page-header-headings > h2").textContent;
-
-		const cards = doc.querySelectorAll("div.card-body dl");
-		for (const card of cards) {
-			if (card.querySelector("dt").textContent !== "Gruppe")
-				continue;
-			group = card.querySelector("dd > a").textContent;
-			break;
-		}
-
-		return new Student(id, name, group);
-	}
-}
-
-// Cache the fetched students.
-let students = [];
-
-const idRegex = /id=(\d+)/;
-async function _fetchStudents() {
-	const res = await fetch(getCourseParticipantsUrl());
-	const doc = new DOMParser().parseFromString(await res.text(), "text/html");
-	const table = doc.querySelector("tbody");
-	let fetchedStudents = [];
-	table.querySelectorAll("tr").forEach(row => {
-		if (row.classList.contains("emptyrow"))
-			return;
-
-		const roleCell = row.querySelector(".c4");
-		// TODO(muhq): Is this locale dependent?
-		if (roleCell.innerHTML.includes("Lehrer")) {
-			return;
-		}
-
-		const nameCell = row.querySelector(".c1");
-		let name;
-		if (nameCell.firstChild.firstChild.tagName == "SPAN")
-			name = nameCell.firstChild.firstChild.title;
-		else
-			name = nameCell.innerText;
-
-		const profileUrl = nameCell.querySelector("a.aabtn").href;
-		const match = idRegex.exec(profileUrl);
-		const id = match[1];
-
-		const groupCell = row.querySelector(".c5");
-		const group = groupCell.querySelector("a.quickeditlink").textContent;
-
-		fetchedStudents.push(new Student(id, name, group));
-	});
-	return fetchedStudents;
-}
-
-async function fetchStudents(idFilter, nameFilter, groupFilter) {
-	if (!students.size) {
-		const studentsPromise = _fetchStudents()
-		const storedStudents = localStorage.getItem("students");
-		if (storedStudents) {
-			studentsPromise.then((fetched) => localStorage.setItem("students", JSON.stringify(fetched)));
-			for (const o of JSON.parse(storedStudents)) {
-				students.push(new Student(o.id, o.name, o.group));
-			}
-		} else {
-			students = await studentsPromise;
-			localStorage.setItem("students", JSON.stringify(students));
-		}
-	}
-
-	return students.filter((s) => (!idFilter || s.id === idFilter) &&
-		(!nameFilter || s.name.includes(nameFilter)) &&
-		(!groupFilter || s.group.includes(groupFilter)));
-}
-
-async function fetchStudent(idFilter, nameFilter, groupFilter) {
-	const students = await fetchStudents(idFilter, nameFilter, groupFilter);
-	return students[0];
-}
-
-export { Student, fetchStudents, fetchStudent };
diff --git a/src/student-common.ts b/src/student-common.ts
new file mode 100644
index 0000000..a76a816
--- /dev/null
+++ b/src/student-common.ts
@@ -0,0 +1,42 @@
+import type { Graduation } from "./graduation-common.ts";
+/**
+ * Class to represent Students.
+ */
+export class Student {
+	id: number;
+	name: string;
+	group: string;
+	graduation: Graduation | null = null;
+
+	constructor(id: number, name: string, group: string) {
+		this.id = id;
+		this.name = name;
+		this.group = group;
+	}
+
+	getGroup() {
+		return this.group;
+	}
+
+	/**
+	static async fetchById(id: number) {
+		let name = "";
+		let group = "";
+
+		const res = await fetch(`/user/view.php?id=${id}&course=${getCourseId()}`);
+		const doc = new DOMParser().parseFromString(await res.text(), "text/html");
+
+		name = doc.querySelector("div.page-header-headings > h2")!.textContent;
+
+		const cards = doc.querySelectorAll("div.card-body dl");
+		for (const card of cards) {
+			if (card.querySelector("dt")!.textContent !== "Gruppe")
+				continue;
+			group = card.querySelector("dd > a")!.textContent;
+			break;
+		}
+
+		return new Student(id, name, group);
+	}
+	*/
+}
diff --git a/src/student-mock.js b/src/student-mock.js
deleted file mode 100644
index 7c79e12..0000000
--- a/src/student-mock.js
+++ /dev/null
@@ -1,9 +0,0 @@
-import { Student } from "./student-common.js";
-import { fetchStudentsMock as fetchStudents } from "./mock.js";
-
-async function fetchStudent(idFilter, nameFilter, groupFilter) {
-	const students = await fetchStudents(idFilter, nameFilter, groupFilter);
-	return students[0];
-}
-
-export { Student, fetchStudents, fetchStudent };
diff --git a/src/student-mock.ts b/src/student-mock.ts
new file mode 100644
index 0000000..93b45b0
--- /dev/null
+++ b/src/student-mock.ts
@@ -0,0 +1,25 @@
+import type { Graduation } from "./graduation-common.ts";
+import { Student } from "./student-common.ts";
+import { fetchStudentsMock as fetchStudents, fetchGraduationMock } from "./mock.ts";
+
+declare module "./student-common.ts" {
+  interface Student {
+    getGraduation(): Promise<Graduation>;
+    getIconUrl(): Promise<string>;
+  }
+}
+Student.prototype.getGraduation = function () {
+   return fetchGraduationMock(this);
+};
+
+Student.prototype.getIconUrl = async function () {
+   return "";
+};
+
+
+async function fetchStudent(_idFilter?: number, _nameFilter?: string, _groupFilter?: string) {
+	const students = await fetchStudents();
+	return students[0];
+}
+
+export { Student, fetchStudents, fetchStudent };
diff --git a/src/student-prod.js b/src/student-prod.js
deleted file mode 100644
index 9c8d7cb..0000000
--- a/src/student-prod.js
+++ /dev/null
@@ -1,2 +0,0 @@
-import { Student, fetchStudent, fetchStudents } from "./student-common.js";
-export { Student, fetchStudents, fetchStudent };
diff --git a/src/student-prod.ts b/src/student-prod.ts
new file mode 100644
index 0000000..24ac869
--- /dev/null
+++ b/src/student-prod.ts
@@ -0,0 +1,90 @@
+import type { Graduation } from "./graduation-common.ts";
+import { Student } from "./student-common.ts";
+import { getUserIconUrl, getCourseParticipantsUrl } from "./utils-prod.js"
+import { fetchGraduation } from "./graduation-prod.ts";
+
+declare module "./student-common.ts" {
+  interface Student {
+    getGraduation(): Promise<Graduation>;
+    getIconUrl(): Promise<string>;
+  }
+}
+Student.prototype.getGraduation = function () {
+   return fetchGraduation(this);
+};
+
+Student.prototype.getIconUrl = function () {
+   return getUserIconUrl(this.id);
+};
+
+// Cache the fetched students.
+let students: Array<Student> | null = null;
+
+const idRegex = /id=(\d+)/;
+async function _fetchStudents() {
+	const res = await fetch(getCourseParticipantsUrl());
+	const doc = new DOMParser().parseFromString(await res.text(), "text/html");
+	const table = doc.querySelector("tbody")!;
+	const fetchedStudents: Array<Student> = [];
+	table.querySelectorAll("tr").forEach(row => {
+		if (row.classList.contains("emptyrow"))
+			return;
+
+		const roleCell = row.querySelector(".c4")!;
+		// TODO(muhq): Is this locale dependent?
+		if (roleCell.innerHTML.includes("Lehrer")) {
+			return;
+		}
+
+		const nameCell = row.querySelector<HTMLElement>(".c1")!;
+		let name;
+		const c = nameCell.firstChild!.firstChild! as HTMLElement;
+		if (c.tagName == "SPAN")
+			name = c.title;
+		else
+			name = nameCell.innerText;
+
+		const profileUrl = nameCell.querySelector<HTMLAnchorElement>("a.aabtn")!.href;
+		const match = idRegex.exec(profileUrl);
+		if (match === null) {
+			console.error("Profile Regex did not match");
+			return;
+		}
+		const id = match[1];
+
+		const groupCell = row.querySelector(".c5")!;
+		const group = groupCell.querySelector<HTMLElement>("a.quickeditlink")!.textContent;
+
+		fetchedStudents.push(new Student(Number(id), name, group));
+	});
+	return fetchedStudents;
+}
+
+async function fetchStudents(idFilter?: number, nameFilter?: string, groupFilter?: string) {
+	if (students === null) {
+		const studentsPromise = _fetchStudents();
+		const storedStudents = localStorage.getItem("students");
+		if (storedStudents) {
+			studentsPromise.then((fetched) => localStorage.setItem("students", JSON.stringify(fetched)));
+			students = [];
+			for (const o of JSON.parse(storedStudents)) {
+				students.push(new Student(o.id, o.name, o.group));
+			}
+		} else {
+			students = await studentsPromise;
+			localStorage.setItem("students", JSON.stringify(students));
+		}
+	}
+
+	return students.filter((s) => 
+		(typeof idFilter === "undefined" || s.id === idFilter) &&
+		(typeof nameFilter === "undefined" || s.name.includes(nameFilter)) &&
+		(typeof groupFilter === "undefined" || s.group.includes(groupFilter)));
+}
+
+async function fetchStudent(idFilter: number, nameFilter: string, groupFilter: string) {
+	const students = await fetchStudents(idFilter, nameFilter, groupFilter);
+	return students[0];
+}
+
+export { Student, fetchStudents, fetchStudent };
diff --git a/src/untyped.d.ts b/src/untyped.d.ts
new file mode 100644
index 0000000..bae3ce7
--- /dev/null
+++ b/src/untyped.d.ts
@@ -0,0 +1,4 @@
+declare module "*.png" {
+	let data: string;
+	export default data;
+}
diff --git a/src/utils-common.ts b/src/utils-common.ts
index 89a8ddd..f3ad944 100644
--- a/src/utils-common.ts
+++ b/src/utils-common.ts
@@ -13,7 +13,7 @@ export function datetimeStringNow() {
 }
 
 // TODO(muhq): Cache the retrieved URL
-export async function getUserIconUrl(userId: number) {
+export async function getUserIconUrl(userId: number): Promise<string> {
 	const userRes = await fetch(`https://lernplattform.bycs.de/user/profile.php?id=${userId}`)
 	const userDoc = new DOMParser().parseFromString(await userRes.text(), 'text/html')
 	const userpicture = userDoc.querySelector(".userpicture");
@@ -21,5 +21,5 @@ export async function getUserIconUrl(userId: number) {
 		return "";
 	}
 
-	return (userpicture as HTMLImageElement).src;
+	return (userpicture as HTMLImageElement).src ?? "";
 }
diff --git a/src/utils-mock.js b/src/utils-mock.js
index e64b59d..ab87ddc 100644
--- a/src/utils-mock.js
+++ b/src/utils-mock.js
@@ -1,5 +1,11 @@
-import { fetchStudent } from "./student-ENV.js";
-export { DATE_FMT, DATETIME_FMT, dateStringNow, datetimeStringNow } from "../dist/src/utils-common.js";
+import { fetchStudentsMock } from "./mock.ts";
+export {
+	DATE_FMT,
+	DATETIME_FMT,
+	dateStringNow,
+	datetimeStringNow,
+	getUserIconUrl
+} from "./utils-common.ts";
 
 export function isTeacher() {
 	return !(new URLSearchParams(document.location.search)).has("student");
@@ -11,9 +17,9 @@ export function getFirstAndLastname() {
 
 	const params = new URLSearchParams(document.location.search);
 	if (params.has("firstname"))
-		firstname = params.get("firstname")
+		firstname = params.get("firstname");
 	if (params.has("lastname"))
-		lastname = params.get("lastname")
+		lastname = params.get("lastname");
 
 	return [firstname, lastname];
 }
@@ -23,9 +29,9 @@ export function getName() {
 
 	const params = new URLSearchParams(document.location.search);
 	if (params.has("firstname"))
-		name = params.get("firstname")
+		name = params.get("firstname");
 	if (params.has("lastname"))
-		name += params.get("lastname")
+		name += params.get("lastname");
 
 	return name;
 }
@@ -33,9 +39,16 @@ export function getName() {
 export function getUserId() {
 	const name = getName();
 
-	return fetchStudent(null, name).id;
+	return fetchStudentsMock.filter((s) => s.name === name )[0].id;
 }
 
 export function getCourseId() {
 	return "1337";
 }
+
+export function getCourseParticipantsUrl() {
+	console.error("Try to get mocked participations URL");
+	return "";
+}
+
+
diff --git a/src/utils-prod.js b/src/utils-prod.js
index efcd8e3..f7c89e4 100644
--- a/src/utils-prod.js
+++ b/src/utils-prod.js
@@ -1,4 +1,10 @@
-export { DATE_FMT, DATETIME_FMT, dateStringNow, datetimeStringNow, getUserIconUrl } from "./utils-common.ts";
+export {
+	DATE_FMT,
+	DATETIME_FMT,
+	dateStringNow,
+	datetimeStringNow,
+	getUserIconUrl
+} from "./utils-common.ts";
 
 export function isTeacher() {
 	return Boolean(document.querySelector('.editmode-switch-form'))
@@ -34,3 +40,4 @@ export function getCourseId() {
 export function getCourseParticipantsUrl() {
 	return `https://lernplattform.bycs.de/user/index.php?id=${getCourseId()}&perpage=5000`;
 }
+