/*
 * This file is part of onkostar-plugin-dnpm
 *
 * Copyright (C) 2023-2026 the original author or authors.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package dev.dnpm.oshelper.atc.services;

import static java.util.stream.Collectors.groupingBy;

import dev.dnpm.oshelper.atc.AgentCode;
import java.util.Comparator;
import java.util.List;
import java.util.Objects;
import java.util.Optional;
import java.util.function.Function;
import java.util.stream.Collectors;
import org.jspecify.annotations.NullMarked;

/**
 * Common interface for agent code services
 *
 * @author Paul-Christian Volkmer
 * @since 2.0.0
 */
public interface AgentCodeService {

  /**
   * Filters the provided list of AgentCodes to include only the latest available versions for each
   * unique code name and, if required, code. If the input list is empty or null, an empty list will
   * be returned.
   *
   * @param agentCodes A list of {@link AgentCode} objects to be filtered. Each object in the list
   *     should contain information about the agent's code, name, system, and version.
   * @param classifier A function that returns a string value to be used as a key for grouping agent
   *     codes.
   * @return A list of {@link AgentCode} objects representing the latest available versions of
   *     unique agent codes. If no valid inputs are provided, an empty list is returned.
   */
  @NullMarked
  static List<AgentCode> latestAgentCodeVersions(
      List<AgentCode> agentCodes, Function<AgentCode, String> classifier) {
    return latestAvailable(agentCodes, classifier);
  }

  /**
   * Function that extracts the name of an {@link AgentCode} object. This function is used as a
   * classifier for grouping agent codes by their name.
   */
  Function<AgentCode, String> byCodeOnly = AgentCode::getName;

  /**
   * Function that extracts the name and code of an {@link AgentCode} object. This function is used
   * as a classifier for grouping agent codes by their name and code.
   */
  Function<AgentCode, String> byNameAndCode =
      (agentCode -> String.format("%s_%s", agentCode.getCode(), agentCode.getName()));

  @NullMarked
  private static List<AgentCode> latestAvailable(
      List<AgentCode> agentCodes, Function<AgentCode, String> classifier) {
    return agentCodes.stream().collect(groupingBy(classifier)).values().stream()
        .map(
            list ->
                list.stream()
                    .sorted(Comparator.comparing(AgentCode::getCode))
                    .max(
                        (ac1, ac2) -> {
                          if (null == ac1.getVersion()) {
                            return -1;
                          } else if (null == ac2.getVersion()) {
                            return 1;
                          }
                          return ac1.getVersion().compareTo(ac2.getVersion());
                        })
                    .orElse(null))
        .filter(Objects::nonNull)
        .distinct()
        .collect(Collectors.toList());
  }

  /**
   * Queries source for agents with name and code starting with query string. If size is zero, all
   * available results will be returned.
   *
   * @param query The query string
   * @param size Maximal amount of responses
   * @return A list with agent codes
   */
  List<AgentCode> findAgentCodes(String query, int size);

  /**
   * Queries source for agents with code matching code string.
   *
   * @param code The code string
   * @return An optional agent code if found
   */
  Optional<AgentCode> getAgentCode(String code);
}