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";