import { DocumentSnapshot, getFirestore, FieldValue } from "firebase-admin/firestore";
import { Change, EventContext } from "firebase-functions";
import * as common from "@shinonomekazan/scrap-conan-online";

export function AkashicInstanceCount(change: Change<DocumentSnapshot>, context: EventContext): Promise<any> | any {
	// playing
	// standby
	// terminated
	let changeCount = 0;
	if (change.after.exists !== true) {
		// delete
		const deletedPlay = change.before.data() as common.GamePlay;
		if (deletedPlay.state === "playing") {
			changeCount = -1;
		}
	} else {
		const updatedPlay = change.after.data() as common.GamePlay;
		if (updatedPlay.state === "playing") {
			const beforeNotPlaying =
				change.before.exists !== true || (change.before.data() as common.GamePlay).state !== "playing";
			if (beforeNotPlaying) {
				changeCount = 1;
			}
		} else if (updatedPlay.state === "terminated" || updatedPlay.state === "completed") {
			const beforePlaying =
				change.before.exists === true && (change.before.data() as common.GamePlay).state === "playing";
			if (beforePlaying) {
				changeCount = -1;
			}
		}
	}
	if (changeCount !== 0) {
		return getFirestore()
			.collection("/properties")
			.doc("akashic")
			.update({
				instanceCount: FieldValue.increment(changeCount),
			});
	}
	return Promise.resolve();
}