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 };