/*
 * This file is a part of EpnTAPClient.
 * This program aims to provide EPN-TAP support for software clients, like CASSIS spectrum analyzer.
 * See draft specifications: https://voparis-confluence.obspm.fr/pages/viewpage.action?pageId=559861
 * Copyright (C) 2016 Institut de Recherche en Astrophysique et Planétologie.
 *
 * This program is free software: you can
 * redistribute it and/or modify it under the terms of the GNU General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or (at your option) any later
 * version. This program is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 * PURPOSE. See the GNU General Public License for more details. You should have received a copy of
 * the GNU General Public License along with this program. If not, see
 * <http://www.gnu.org/licenses/>.
 */

package eu.omp.irap.vespa.epntapclient;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

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

import eu.omp.irap.vespa.votable.utils.CantSendQueryException;
import eu.omp.irap.vespa.votable.utils.Network;
import eu.omp.irap.vespa.votable.utils.StringJoiner;

/**
 * @author N. Jourdane
 */
public class RequestCtrl {

	/** The URL of the resolver used for the `target name` field. */
	private static final String RESOLVER_URL = "http://voparis-registry.obspm.fr/ssodnet/1/autocomplete";

	/** The text in the query to replaced by the actual table name. */
	protected static final String TABLE_NAME_KEYWORD = "#tablename#";

	/** The query template to get granules. */
	private static final String QUERY = "SELECT DISTINCT TOP %s %s FROM " + TABLE_NAME_KEYWORD
			+ "%s";

	/** The parameters fields for the request. */
	protected Map<String, Object> parameters = new HashMap<>();

	/** The maximum number of rows returned by the query. */
	private int nbMaxResult;


	/** Constructor of RequestCtrl. */
	public RequestCtrl() {
		nbMaxResult = 20;
	}

	/**
	 * Constructor of RequestCtrl.
	 *
	 * @param nbMaxResult The maximum number of rows returned by the query.
	 */
	public RequestCtrl(int nbMaxResult) {
		this.nbMaxResult = nbMaxResult;
	}

	/**
	 * Build an ADQL from the table name, the parameter values and the max results.
	 *
	 * @param tableName The names of the tables, to put in the FROM keyword.
	 * @return The query.
	 */
	public String buildQuery(List<String> columnNames) {
		StringJoiner addJoin = new StringJoiner(" AND ");
		for (Map.Entry<String, Object> param : parameters.entrySet()) {
			if (param.getValue() instanceof ArrayList) {
				StringJoiner orJoin = new StringJoiner(" OR ");
				@SuppressWarnings("unchecked")
				List<String> possibleValues = (List<String>) param.getValue();
				for (String possibleValue : possibleValues) {
					orJoin.add(param.getKey() + " LIKE '" + possibleValue + "'");
				}
				addJoin.add("(" + orJoin + ")");
			} else if (param.getValue() instanceof String) {
				addJoin.add(param.getKey() + " LIKE '" + param.getValue() + "'");
			} else {
				addJoin.add(param.getKey() + " = " + param.getValue().toString());
			}
		}
		String where = addJoin.isEmpty() ? "" : " WHERE " + addJoin;
		return String.format(QUERY, nbMaxResult, StringJoiner.join(columnNames), where);
	}

	/**
	 * The method used to get target names propositions by asking to the resolver.
	 *
	 * @param begining The beginning of the target_name.
	 * @return An array of Strings corresponding to the target names got.
	 * @throws CantSendQueryException Can not read the JSON file.
	 */
	public static String[] getTargetNames(String begining) throws CantSendQueryException {
		Map<String, String> params = new HashMap<>();
		params.put("q", "\"" + begining + "\"");

		String query = Network.buildGetRequest(RESOLVER_URL, params);
		JsonObject root = Network.readJson(query);
		int count = Integer.parseInt(root.get("count").toString());
		String[] targetNames = new String[count];
		JsonArray hits = root.getAsJsonArray("hits");
		for (int i = 0; i < count; i++) {
			JsonObject elmt = hits.get(i).getAsJsonObject();
			targetNames[i] = elmt.get("name").toString().replace("\"", "");
		}
		return targetNames;
	}

	/**
	 * Update a parameter in the query. If the parameter do not exists yet, create it.
	 *
	 * @param paramName The name of the parameter.
	 * @param paramValue The value of the parameter.
	 */
	public void updateParameter(String paramName, Object paramValue) {
		parameters.put(paramName, paramValue);
	}

	/**
	 * Remove a parameter from the query.
	 *
	 * @param paramName The name of the parameter to remove.
	 */
	public void removeParameter(String paramName) {
		parameters.remove(paramName);
	}

	/**
	 * Get the parameters.
	 *
	 * @return A map of couple <parameter name, parameter value>.
	 */
	public Map<String, Object> getParameters() {
		return parameters;
	}

	/**
	 * @return The maximum number of rows returned by the query.
	 */
	public int getNbMaxResult() {
		return nbMaxResult;
	}

	/**
	 * Set the maximum number of rows returned by the query.
	 *
	 * @param nbRows The number of rows.
	 */
	public void setNbMaxResult(int nbRows) {
		nbMaxResult = nbRows;
	}

}