import { z } from "zod";
import { Store } from "./store.ts";
import { QueriedFor, QueriedOfField, StoredFor, Table } from "./typing.ts";

export class Entry<T extends Table<T>, S extends keyof T> {
	public readonly store;
	public readonly schema;
	public readonly id;

	public constructor(store: Store<T>, schema: S, id: string) {
		this.store = store;
		this.schema = schema;
		this.id = id;
	}

	public async get<F extends keyof T[S]>(field: F): Promise<QueriedOfField<T, S, F>> {
		if (!await this.store.entry_exists(this.schema, this.id)) throw new Error("Accessing a deleted entry");
		const str = (value: unknown) => z.string().parse(value);
		const content = await this.store.read_field(this.schema, this.id, field);
		const kind = this.store.nodes.table[this.schema][field];
		if (kind === "string") return z.string().parse(content) as QueriedFor<T, T[S][F]>;
		if (kind === "number") return z.number().parse(content) as QueriedFor<T, T[S][F]>;
		if (kind === "boolean") return z.boolean().parse(content) as QueriedFor<T, T[S][F]>;
		if (kind[0] === "maybe") {
			if (content === null) return null as QueriedFor<T, T[S][F]>;
			else return new Entry(this.store, kind[1], str(content)) as QueriedFor<T, T[S][F]>;
		}
		if (kind[0] === "one") return new Entry(this.store, kind[1], str(content)) as QueriedFor<T, T[S][F]>;
		if (kind[0] === "many") return new Collection(this.store, kind[1], str(content)) as QueriedFor<T, T[S][F]>;
		throw new Error("Unreachable");
	}

	public async set<F extends keyof T[S]>(field: F, value: QueriedFor<T, T[S][F]>) {
		let raw: string | number | boolean | null;
		if (value instanceof Collection) raw = value.id;
		else if (value instanceof Entry) raw = value.id;
		else raw = value;
		await this.store.write_field(this.schema, this.id, field, raw as StoredFor<T, T[S][F]>);
	}

	public async delete() {
		const schema = this.store.nodes.table[this.schema];
		for (const field in schema) {
			const kind = schema[field];
			if (Array.isArray(kind) && kind[0] === "many") {
				// deno-lint-ignore no-explicit-any
				const collection = await this.get(field) as Collection<T, any>;
				for await (const value of collection) this.store.remove_relation(collection.id, value.id);
				await this.store.delete_relations(collection.id);
			}
			await this.store.delete_field(this.schema, this.id, field);
		}
		await this.store.delete_entry(this.schema, this.id);
	}
}

export class Collection<T extends Table<T>, S extends keyof T> {
	public readonly store;
	public readonly schema;
	public readonly id;

	public constructor(store: Store<T>, schema: S, collection_id: string) {
		this.store = store;
		this.schema = schema;
		this.id = collection_id;
	}

	public async *[Symbol.asyncIterator]() {
		for await (const id_ of this.store.list_relations(this.id)) {
			const id = z.string().parse(id_);
			const entry = new Entry(this.store, this.schema, id);
			if (await this.store.entry_exists(this.schema, id)) yield entry;
			else await this.remove(entry);
		}
	}

	public async add(entry: Entry<T, S>) {
		await this.store.add_relation(this.id, entry.id);
	}

	public async remove(entry: Entry<T, S>) {
		await this.store.remove_relation(this.id, entry.id);
	}
}