package hhn.temp.project.provider;

import hhn.temp.project.Task;
import hhn.temp.project.TaskState;

import java.sql.*;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

public class SimpleDatabaseManager<E> implements DatabaseManager<E> {

  private Connection connection;

  private enum QueryMode {
    SELECT, INSERT, DELETE, UPDATE
  }

  private int taskStateToInt(TaskState taskState) {
    return (taskState == TaskState.FINISHED) ? 1 : 0;
  }

  private TaskState intToTaskState(int i) {
    if (i < 0 || i > 1) {
      throw new IllegalArgumentException("Integer may only bet 0 or 1");
    }

    return (i == 1) ? TaskState.FINISHED : TaskState.IN_PROGRESS;
  }

  private String getQuery(QueryMode query) {
    String queryString = null;

    switch (query) {
      case INSERT -> queryString = "INSERT INTO Task (taskid, name, description, workerid, taskstate) VALUES (?, ?, ?, ?, ?)";
      case UPDATE -> queryString = "UPDATE Task SET name = ?, description = ?, taskstate = ? WHERE taskid = ?";
      case DELETE -> queryString = "DELETE FROM Task WHERE taskid = ?";
      case SELECT -> queryString = "SELECT * FROM Task WHERE workerid = ?";
    }

    return queryString;
  }

  public void clearDatabase() throws SQLException {
    try (Statement statement = connection.createStatement()) {
      statement.executeUpdate("TRUNCATE TABLE Task;");
    }
  }

  @Override
  public void saveObjects(Collection<E> objects) throws SQLException {
    for (E obj : objects) {
      saveObject(obj);
    }
  }


  @Override
  public Collection<E> getObjects() throws SQLException {
    return null;
  }

  @Override
  public void saveObject(E object) throws SQLException {
    String query = getQuery(QueryMode.INSERT);

    if (object instanceof Task task) {
      PreparedStatement ps = connection.prepareStatement(query);
      ps.setInt(1, task.getTaskId());
      ps.setString(2, task.getName());
      ps.setString(3, task.getDescription());
      ps.setInt(4, task.getWorkerId());
      ps.setInt(5, taskStateToInt(task.getTaskState()));

      ps.executeUpdate();
    }
  }

  @Override
  public E getObject(int taskId) throws SQLException {
    String query = getQuery(QueryMode.SELECT);
    Task task = null;

    PreparedStatement ps = connection.prepareStatement(query);
    ps.setInt(1, taskId);

    ResultSet resultSet = ps.executeQuery();

    if (resultSet.next()) {

      task = new Task(
              resultSet.getInt("taskid"),
              resultSet.getInt("workerid"),
              resultSet.getString("name"),
              resultSet.getString("description")
      );
      task.setTaskState(intToTaskState(resultSet.getInt("taskstate")));
    }

    return (E) task;
  }

  @Override
  public void deleteObject(int taskId) throws SQLException {
    String query = getQuery(QueryMode.DELETE);

    try (PreparedStatement ps = connection.prepareStatement(query)) {
      ps.setInt(1, taskId);
      ps.executeUpdate();
    }
  }

  @Override
  public E updateObject(int taskId, E object) throws SQLException {
    String query = getQuery(QueryMode.UPDATE);

    if (object instanceof Task task) {

      if (taskId != task.getTaskId()) {
        throw new IllegalArgumentException("Task ID does not equals Task ID from Task!");
      }

      PreparedStatement ps = connection.prepareStatement(query);
      ps.setString(1, task.getName());
      ps.setString(2, task.getDescription());
      ps.setInt(3, taskStateToInt(task.getTaskState()));
      ps.setInt(4, task.getTaskId());

      int updated = ps.executeUpdate();

      if (updated == 0) {
        return null;
      }

      return (E) task;
    }

    return null;
  }

  @Override
  public void connect() throws SQLException {
    connection = DriverManager.getConnection("jdbc:mysql://sql7.freesqldatabase.com/sql7810540?user=sql7810540&password=mXdJCFtDZz");
  }

  @Override
  public void close() throws SQLException {
    if (connection != null) {
      connection.close();
    }
  }
}