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 newLevelChange(level: number, reason?: string, coach?: string) {
		const ctx = { level: level };
		return new GraduationChange(new Date(), -1, "LevelChange", reason || "", coach || "", ctx);
	}

	static newGreenPointChange(mandatory: boolean, reason?: string, coach?: string) {
		const ctx = { mandatory: mandatory };
		return new GraduationChange(new Date(), -1, "Grün", reason || "", coach || "", ctx);
	}

	static newOrangePointChange(mandatory: boolean, reason?: string, coach?: string) {
		const ctx = { mandatory: mandatory };
		return new GraduationChange(new Date(), -1, "Orange", reason || "", coach || "", ctx);
	}

	static newRedPointChange(mandatory: boolean, reason?: string, coach?: string) {
		const ctx = { mandatory: mandatory };
		return new GraduationChange(new Date(), -1, "Rot", reason || "", coach || "", ctx);
	}
}

class Graduation {
	student: Student;
	green: number;
	orange: number;
	red: number;
	mandatory: number;
	level: number;
	changes: Array<GraduationChange>;

	constructor(
		student: Student,
		green: number,
		orange: number,
		red: number,
		mandatory: number,
		level: number,
		changes: Array<GraduationChange>,
	) {
		this.student = student;
		this.green = green;
		this.orange = orange;
		this.red = red;
		this.level = level;
		this.mandatory = mandatory;
		this.changes = changes;

		student.graduation = this;
	}

	static from(student: Student, changes: Array<GraduationChange>) {
		let green = 0;
		let orange = 0;
		let red = 0;
		let mandatory = 0;
		let level = 1;

		// 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 "LevelChange":
					level = Number(change.context.level);
					break;

				default:
					throw new Error(`Unexpected change: ${change}`);
			}

			if (change.context.mandatory) {
				mandatory++;
			}
		}
		return new Graduation(student, green, orange, red, mandatory, level, 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);
	}

	/**
	 * 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];
	}

	/**
	 * Return the combined value of all points.
	 */
	getNettoPoints(): number {
		return this.green - this.orange - this.red;
	}
}

async function submitGraduationChange(graduation: Graduation, change: GraduationChange) {
	graduation.addChange(change);
	const db = await getGraduationDb();
	return db.saveEntry(JSON.stringify(change.dbFields()));
}

export { LEVEL_NAMES, LEVEL_IMAGES, GraduationChange, Graduation, submitGraduationChange };