import type * as Db from "backend/database";
import { AttachmentId, PieceId, RepertoireId, UserId } from "common";
import { Cache, Duration, Effect, Option, pipe } from "effect";
import { client, mapResponse } from "./client";

export interface User {
	readonly userId: UserId;
	readonly username: string;
	readonly admin: boolean;
}

export interface SystemInformation {
	readonly createdBy: Option.Option<User>;
	readonly createdAt: string;
	readonly modifiedBy: Option.Option<User>;
	readonly modifiedAt: Option.Option<string>;
}

export interface Attachment extends SystemInformation {
	readonly attachmentId: AttachmentId;
	readonly pieceId: PieceId;
	readonly sha256: string;
	readonly filename: string;
	readonly mediaType: string;
}

export interface Piece extends SystemInformation {
	readonly pieceId: PieceId;
	readonly name: string;
	readonly composer: Option.Option<string>;
	readonly lyricist: Option.Option<string>;
	readonly arranger: Option.Option<string>;
	readonly attachments: readonly Attachment[];
}

interface DbSystemInformation {
	readonly createdBy: UserId | null;
	readonly createdAt: string;
	readonly modifiedBy: UserId | null;
	readonly modifiedAt: string | null;
}

export const denormalizeSystemInformation = <T extends DbSystemInformation>({
	createdBy,
	modifiedBy,
	modifiedAt,
	...rest
}: T) => pipe(
	Effect.all({
		createdBy: pipe(
			createdBy,
			Effect.fromNullable,
			Effect.flatMap((userId) => Effect.uninterruptible(userCache.get(userId))),
			Effect.optionFromOptional,
		),
		modifiedBy: pipe(
			modifiedBy,
			Effect.fromNullable,
			Effect.flatMap((userId) => Effect.uninterruptible(userCache.get(userId))),
			Effect.optionFromOptional,
		),
	}, { concurrency: "unbounded" }),
	Effect.map((si) => Object.freeze({
		...rest,
		...si,
		modifiedAt: Option.fromNullable(modifiedAt),
	})),
);

export const denormalizePiece = ({
	composer,
	lyricist,
	arranger,
	attachments,
	...rest
}: Db.Piece & { attachments: (Omit<Db.Attachment, "sha256"> & { sha256: string })[] }) => pipe(
	Effect.all({
		attachments: Effect.all(attachments.map(denormalizeSystemInformation), { concurrency: "unbounded" }),
	}, { concurrency: "unbounded" }),
	Effect.map((piece) => Object.freeze({
		...rest,
		...piece,
		composer: Option.fromNullable(composer),
		lyricist: Option.fromNullable(lyricist),
		arranger: Option.fromNullable(arranger),
	})),
	Effect.flatMap(denormalizeSystemInformation),
);

export const denormalizeRepertoire = ({
	entries,
	...rest
}: Db.Repertoire & { entries: PieceId[] }) => pipe(
	Effect.all({
		entries: Effect.all(entries.map((entry) => Effect.uninterruptible(pieceCache.get(entry))), { concurrency: "unbounded" }),
	}, { concurrency: "unbounded" }),
	Effect.map((repertoire) => Object.freeze({
		...rest,
		...repertoire,
	})),
	Effect.flatMap(denormalizeSystemInformation),
);

const UserSemaphore = Effect.unsafeMakeSemaphore(1);
const CacheSemaphore = Effect.unsafeMakeSemaphore(4);
const RepertoireSemaphore = Effect.unsafeMakeSemaphore(1);

export const userLookup = (userId: UserId) => pipe(
	Effect.promise((signal) => client.user({ userId }).get({ fetch: { signal } })),
	Effect.flatMap(mapResponse),
	UserSemaphore.withPermits(1),
);

export const pieceLookup = (pieceId: PieceId) => pipe(
	Effect.promise((signal) => client.piece({ pieceId }).get({ fetch: { signal } })),
	Effect.flatMap(mapResponse),
	Effect.flatMap(denormalizePiece),
	CacheSemaphore.withPermits(1),
);

export const repertoireLookup = (repertoireId: RepertoireId) => pipe(
	Effect.promise((signal) => client.repertoire({ repertoireId }).get({ fetch: { signal } })),
	Effect.flatMap(mapResponse),
	Effect.flatMap(denormalizeRepertoire),
	RepertoireSemaphore.withPermits(1),
);

export const userCache = Effect.runSync(Cache.make({
	capacity: Infinity,
	timeToLive: Duration.days(1),
	lookup: userLookup,
}));

export const pieceCache = Effect.runSync(Cache.make({
	capacity: Infinity,
	timeToLive: Duration.days(1),
	lookup: pieceLookup,
}));

export const repertoireCache = Effect.runSync(Cache.make({
	capacity: Infinity,
	timeToLive: Duration.days(1),
	lookup: repertoireLookup,
}));