package it.cavallium.dbengine.client;

import it.cavallium.dbengine.database.LLIndexRequest;
import it.cavallium.dbengine.database.LLSoftUpdateDocument;
import it.cavallium.dbengine.database.LLUpdateDocument;
import it.cavallium.dbengine.database.LLTerm;
import it.cavallium.dbengine.database.LLUpdateFields;
import it.cavallium.dbengine.database.LLUtils;
import java.util.Set;
import org.jetbrains.annotations.NotNull;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
import reactor.util.function.Tuple2;

public abstract class Indicizer<T, U> {

	/**
	 * Transform a value to an IndexRequest.
	 */
	public abstract @NotNull Mono<? extends LLIndexRequest> toIndexRequest(@NotNull T key, @NotNull U value);

	public final @NotNull Mono<LLUpdateDocument> toDocument(@NotNull T key, @NotNull U value) {
		return toIndexRequest(key, value).map(req -> {
			if (req instanceof LLUpdateFields updateFields) {
				return new LLUpdateDocument(updateFields.items());
			} else if (req instanceof LLUpdateDocument updateDocument) {
				return updateDocument;
			} else if (req instanceof LLSoftUpdateDocument softUpdateDocument) {
				return new LLUpdateDocument(softUpdateDocument.items());
			} else {
				throw new UnsupportedOperationException("Unexpected request type: " + req);
			}
		});
	}

	public abstract @NotNull LLTerm toIndex(@NotNull T key);

	public abstract @NotNull String getKeyFieldName();

	public abstract @NotNull T getKey(String key);

	public abstract IndicizerAnalyzers getPerFieldAnalyzer();

	public abstract IndicizerSimilarities getPerFieldSimilarity();

	public Flux<Tuple2<String, Set<String>>> getMoreLikeThisDocumentFields(T key, U value) {
		return Flux.empty();
	}
}