package eu.dnetlib.dhp.provision.update;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;

import eu.dnetlib.dhp.provision.scholix.ScholixCollectedFrom;
import eu.dnetlib.dhp.provision.scholix.ScholixEntityId;
import eu.dnetlib.dhp.provision.scholix.ScholixIdentifier;
import eu.dnetlib.dhp.provision.scholix.ScholixResource;
import eu.dnetlib.dhp.utils.DHPUtils;

public class CrossRefParserJSON {

	private static final List<ScholixCollectedFrom> collectedFrom = generateCrossrefCollectedFrom("complete");

	public static ScholixResource parseRecord(final String record) {
		if (record == null)
			return null;
		JsonElement jElement = new JsonParser().parse(record);
		JsonElement source = null;
		if (jElement.getAsJsonObject().has("_source")) {
			source = jElement.getAsJsonObject().get("_source");
			if (source == null || !source.isJsonObject())
				return null;
		} else if (jElement.getAsJsonObject().has("DOI")) {
			source = jElement;
		} else {
			return null;
		}

		final JsonObject message = source.getAsJsonObject();
		ScholixResource currentObject = new ScholixResource();

		if (message.get("DOI") != null) {
			final String doi = message.get("DOI").getAsString();
			currentObject.setIdentifier(Collections.singletonList(new ScholixIdentifier(doi, "doi")));
		}

		if ((!message.get("created").isJsonNull())
			&& (message.getAsJsonObject("created").get("date-time") != null)) {
			currentObject
				.setPublicationDate(
					message.getAsJsonObject("created").get("date-time").getAsString());
		}

		if (message.get("title") != null
			&& !message.get("title").isJsonNull()
			&& message.get("title").isJsonArray()) {

			JsonArray array = message.get("title").getAsJsonArray();
			currentObject.setTitle(array.get(0).getAsString());
		}
		if (message.get("author") != null && !message.get("author").isJsonNull()) {
			JsonArray author = message.getAsJsonArray("author");
			List<ScholixEntityId> authorList = new ArrayList<>();
			for (JsonElement anAuthor : author) {
				JsonObject currentAuth = anAuthor.getAsJsonObject();

				String family = "";
				String given = "";
				if (currentAuth != null
					&& currentAuth.get("family") != null
					&& !currentAuth.get("family").isJsonNull()) {
					family = currentAuth.get("family").getAsString();
				}
				if (currentAuth != null
					&& currentAuth.get("given") != null
					&& !currentAuth.get("given").isJsonNull()) {
					given = currentAuth.get("given").getAsString();
				}
				authorList.add(new ScholixEntityId(String.format("%s %s", family, given), null));
			}
			currentObject.setCreator(authorList);
		}
		if (message.get("publisher") != null && !message.get("publisher").isJsonNull()) {
			currentObject
				.setPublisher(
					Collections
						.singletonList(
							new ScholixEntityId(message.get("publisher").getAsString(), null)));
		}
		currentObject.setCollectedFrom(collectedFrom);
		currentObject.setObjectType("publication");
		currentObject
			.setDnetIdentifier(
				generateId(message.get("DOI").getAsString(), "doi", "publication"));

		return currentObject;
	}

	private static List<ScholixCollectedFrom> generateCrossrefCollectedFrom(
		final String completionStatus) {
		final ScholixEntityId scholixEntityId = new ScholixEntityId(
			"Crossref",
			Collections
				.singletonList(
					new ScholixIdentifier("dli_________::crossref", "dnet_identifier")));
		return Collections
			.singletonList(
				new ScholixCollectedFrom(scholixEntityId, "resolved", completionStatus));
	}

	private static String generateId(
		final String pid, final String pidType, final String entityType) {
		String type;
		switch (entityType) {
			case "publication":
				type = "50|";
				break;
			case "dataset":
				type = "60|";
				break;
			case "unknown":
				type = "70|";
				break;
			default:
				throw new IllegalArgumentException("unexpected value " + entityType);
		}
		return type
			+ DHPUtils
				.md5(
					String.format("%s::%s", pid.toLowerCase().trim(), pidType.toLowerCase().trim()));
	}
}