import { integer, MilestoneDocument } from "tachi-common";

/**
 * Retrieves the goalID documents in a single array from the
 * nested structure of milestones.
 */
export function GetGoalIDsFromMilestone(milestone: MilestoneDocument) {
	// this sucks - maybe a nicer way to do this, because nested
	// maps are just ugly
	return milestone.milestoneData.map((e) => e.goals.map((e) => e.goalID)).flat(1);
}

/**
 * Work out how many goals need to be achieved for this
 * milestone to be considered completed.
 */
export function CalculateMilestoneOutOf(milestone: MilestoneDocument, goalIDs: string[]): integer {
	if (milestone.criteria.type === "all") {
		return goalIDs.length;
	} else if (milestone.criteria.type === "abs") {
		if (milestone.criteria.value === null) {
			throw new Error(
				`Invalid milestone ${milestone.milestoneID} - abs and null are not compatible.`
			);
		}

		return milestone.criteria.value!;
	} else if (milestone.criteria.type === "proportion") {
		if (milestone.criteria.value === null) {
			throw new Error(
				`Invalid milestone ${milestone.milestoneID} - proportion and null are not compatible.`
			);
		}

		return Math.floor(milestone.criteria.value * goalIDs.length);
	}

	throw new Error(
		`Invalid milestone.criteria.type of ${milestone.criteria.type} -- milestoneID ${milestone.milestoneID}`
	);
}