import { Item_Unresolvable } from '@efforting.tech/errors';

export class Abstract_Resolver {
	resolve(item) {
		const result = this.resolve_handler(item);
		if (!result?.handler) {
			throw new Item_Unresolvable({ resolver: this, item });
		}
		// TO DOC: Spreading result into the resulting context means there are some reserved keys we need to be mindful of to avoid clobbering them
		return result.handler({ resolver: this, item, ...result });
	}
}

export class Chained_Resolver extends Abstract_Resolver {
	constructor(chain_links) {
		super();
		Object.assign(this, { chain_links });
	}

	resolve_handler(item) {
		const { chain_links } = this;
		for (const link of chain_links) {
			const result = link.resolve_handler(item);
			if (result?.handler) {
				return result;
			}
		}
	}
}

export class Predicate_Resolver extends Abstract_Resolver {
	constructor(rules=[]) {
		// NOTE: Rules should be iterable as [predicate, handler] pairs
		super();
		Object.assign(this, { rules });
	}

	resolve_handler(item) {
		const { rules } = this;
		for (const [predicate, handler] of rules) {
			const predicate_result = predicate(item);
			if (predicate_result !== undefined) {
				return { handler, predicate_result };
			}
		}
	}
}

export class RegExp_Resolver extends Predicate_Resolver {
	constructor(rules=[]) {
		// NOTE: Rules should be iterable as [predicate, handler] pairs
		super();
		Object.assign(this, { rules: rules.map(([pattern, handler]) => {

			const wrapped_handler = handler;	//TODO
			const predicate = ((str) => str.match(pattern));

			return [predicate, wrapped_handler];
		})});
	}


}

export class Mapping_Resolver extends Abstract_Resolver {
	constructor(rules=new Map(), key_function=null) {
		super();
		Object.assign(this, { rules, key_function });
	}

	resolve_handler(item) {
		const { key_function, rules } = this;
		const key = key_function ? key_function(item) : item;
		return rules.get(key);
	}

}