configurability, improve precision, tests of daily XP subtraction

src/main/java/net/discordjug/javabot/data/config/guild/HelpConfig.java

@@ -116,7 +116,17 @@ public class HelpConfig extends GuildConfigItem {
 	private double thankExperience = 3;
 
 	/**
-	 * The amount that should be subtracted from every Help Account each day.
+	 * The minimum total amount of XP that should be subtracted from every Help Account each day.
+	 */
+	private int minDailyExperienceSubtraction = 1;
+
+	/**
+	 * The maximum total amount of XP that should be subtracted from every Help Account each day.
+	 */
+	private int maxDailyExperienceSubtraction = 50;
+
+	/**
+	 * The percentage of XP that should be subtracted from every Help Account each day.
 	 */
 	private double dailyExperienceSubtraction = 5;
 

src/main/java/net/discordjug/javabot/data/h2db/DbHelper.java

@@ -99,7 +99,13 @@ private static boolean shouldInitSchema(String jdbcUrl) {
 		return shouldInitSchema;
 	}
 
-	private static void initializeSchema(HikariDataSource dataSource) throws IOException, SQLException {
+	/**
+	 * Initializes the schema of the database by running all SQL statements from the schema.sql script.
+	 * @param dataSource the {@link DataSource} to connect to the DB
+	 * @throws IOException if an error happened while loading the schema.sql
+	 * @throws SQLException if any SQL error happened
+	 */
+	public static void initializeSchema(DataSource dataSource) throws IOException, SQLException {
 		try (InputStream is = DbHelper.class.getClassLoader().getResourceAsStream("database/schema.sql")) {
 			if (is == null) throw new IOException("Could not load schema.sql.");
 			List<String> queries = Arrays.stream(new String(is.readAllBytes()).split(";"))

src/main/java/net/discordjug/javabot/systems/help/HelpExperienceJob.java

@@ -2,6 +2,7 @@
 
 import lombok.RequiredArgsConstructor;
 import net.discordjug.javabot.data.config.BotConfig;
+import net.discordjug.javabot.data.config.guild.HelpConfig;
 import net.discordjug.javabot.data.h2db.DbHelper;
 import net.discordjug.javabot.systems.help.dao.HelpAccountRepository;
 import net.discordjug.javabot.util.ExceptionLogger;
@@ -31,9 +32,12 @@ public class HelpExperienceJob {
 	public void execute() {
 		asyncPool.execute(() -> {
 			try {
+				// just get the config for the first guild the bot is in, as it's not designed to work in multiple guilds anyway
+				HelpConfig helpConfig = botConfig.get(jda.getGuilds().get(0)).getHelpConfig();
 				helpAccountRepository.removeExperienceFromAllAccounts(
-						// just get the config for the first guild the bot is in, as it's not designed to work in multiple guilds anyway
-						botConfig.get(jda.getGuilds().get(0)).getHelpConfig().getDailyExperienceSubtraction(), 1, 50);
+						helpConfig.getDailyExperienceSubtraction(),
+						helpConfig.getMinDailyExperienceSubtraction(),
+						helpConfig.getMaxDailyExperienceSubtraction());
 			} catch (DataAccessException e) {
 				ExceptionLogger.capture(e, DbHelper.class.getSimpleName());
 			}

src/main/java/net/discordjug/javabot/systems/help/dao/HelpAccountRepository.java

@@ -2,7 +2,6 @@
 
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
-import net.discordjug.javabot.data.config.BotConfig;
 import net.discordjug.javabot.systems.help.model.HelpAccount;
 
 import org.jetbrains.annotations.NotNull;
@@ -26,7 +25,6 @@
 @Repository
 public class HelpAccountRepository {
 	private final JdbcTemplate jdbcTemplate;
-	private final BotConfig botConfig;
 
 	/**
 	 * Inserts a new {@link HelpAccount}.
@@ -105,7 +103,7 @@ public int getTotalAccounts() throws DataAccessException {
 	 * @throws DataAccessException If an error occurs.
 	 */
 	public void removeExperienceFromAllAccounts(double change, int min, int max) throws DataAccessException {
-		long rows = jdbcTemplate.execute("UPDATE help_account SET experience = GREATEST(experience - LEAST(GREATEST(experience * (? / 100), ?), ?), 0)",new CallableStatementCallback<Long>() {
+		long rows = jdbcTemplate.execute("UPDATE help_account SET experience = GREATEST(experience - LEAST(GREATEST((experience * ?) / 100, ?), ?), 0)",new CallableStatementCallback<Long>() {
 
 			@Override
 			public Long doInCallableStatement(CallableStatement cs) throws SQLException, DataAccessException {

src/test/java/net/discordjug/javabot/systems/help/HelpExperienceSubtractionTest.java

@@ -0,0 +1,132 @@
+package net.discordjug.javabot.systems.help;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.io.IOException;
+import java.sql.SQLException;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.jdbc.DataSourceBuilder;
+import org.springframework.jdbc.core.JdbcTemplate;
+
+import com.zaxxer.hikari.HikariDataSource;
+
+import net.discordjug.javabot.data.h2db.DbHelper;
+import net.discordjug.javabot.systems.help.dao.HelpAccountRepository;
+import net.discordjug.javabot.systems.help.model.HelpAccount;
+
+/**
+ * Tests functionality of automated experience subtraction.
+ */
+public class HelpExperienceSubtractionTest {
+
+	private HikariDataSource dataSource;
+	private HelpAccountRepository repo;
+
+	@BeforeEach
+	void setUp() throws IOException, SQLException {
+		dataSource = DataSourceBuilder.create()
+				.type(HikariDataSource.class)
+				.url("jdbc:h2:mem:test")
+				.username("test")
+				.password("")
+				.build();
+
+		DbHelper.initializeSchema(dataSource);
+
+		JdbcTemplate template = new JdbcTemplate(dataSource);
+		repo = new HelpAccountRepository(template);
+	}
+
+	@AfterEach
+	void cleanUp() {
+		dataSource.close();
+	}
+
+	/**
+	 * If a user has less XP than the minimum experience subtraction, the user should lose all XP.
+	 */
+	@Test
+	void testUserHasLessThanMinimum() {
+		repo.insert(new HelpAccount(1, 1));
+		repo.removeExperienceFromAllAccounts(50, 2, 10);
+		assertEquals(0, repo.getByUserId(1).get().getExperience());
+	}
+
+	/**
+	 * If the XP to subtract is less than the minimum, the minimum XP should be subtracted.
+	 */
+	@Test
+	void testSubtractMinimum() {
+		repo.insert(new HelpAccount(1, 6));//6XP
+		//would remove 50% i.e. 3XP
+		//the minimum is 4XP hence it should subtract 4XP
+		repo.removeExperienceFromAllAccounts(50, 4, 10);
+		assertEquals(2, repo.getByUserId(1).get().getExperience());
+	}
+
+	@Test
+	void testSubtractMaximum() {
+		repo.insert(new HelpAccount(1, 100));
+		//tries to subtract 50% which is 50XP
+		//but maximum is 10XP hence it should subtract 10XP
+		repo.removeExperienceFromAllAccounts(50, 1, 10);
+		assertEquals(90, repo.getByUserId(1).get().getExperience());
+	}
+
+	@Test
+	void testFraction() {
+		repo.insert(new HelpAccount(1, 100));
+		//subtract 10% i.e. 10XP
+		//should be inside [1,50] hence neither minimum nor maximum is active
+		repo.removeExperienceFromAllAccounts(10, 1, 50);
+		assertEquals(90, repo.getByUserId(1).get().getExperience());
+		//subtract 10% i.e. 9XP
+		//should be inside [1,50] hence neither minimum nor maximum is active
+		repo.removeExperienceFromAllAccounts(10, 1, 50);
+		assertEquals(81, repo.getByUserId(1).get().getExperience());
+	}
+
+	@Test
+	void testXPHalfLife() {
+		int startXP = 1_000;
+		int half = startXP/2;
+		repo.insert(new HelpAccount(1, startXP));
+		for (int i = 0; i < 55; i++) {
+			repo.removeExperienceFromAllAccounts(1.25, 0, 1_000);
+			double actualXP = repo.getByUserId(1).get().getExperience();
+			assertTrue(actualXP > half, "In iteration "+i+", XP have decayed by more than 50%, user has "+actualXP+"XP after iteration");
+		}
+		repo.removeExperienceFromAllAccounts(1.25, 0, 1_000);
+		double actualXP = repo.getByUserId(1).get().getExperience();
+		assertFalse(actualXP > half, "After all iterations, XP have not decayed by more than 50%, user has "+actualXP+"XP at the end");
+	}
+
+	@Test
+	void testMultipleUsers() {
+		repo.insert(new HelpAccount(79, 79));//below min
+		repo.insert(new HelpAccount(80, 80));//exactly min
+		repo.insert(new HelpAccount(100, 100));//within bounds
+		repo.insert(new HelpAccount(2_000, 2_000));//within bounds
+		repo.insert(new HelpAccount(3_999, 3_999));//close to upper bound
+		repo.insert(new HelpAccount(4_000, 4_000));//exactly upper bound
+		repo.insert(new HelpAccount(4_001, 4_001));//exceeds upper bound
+		repo.insert(new HelpAccount(10_000, 10_000));//significantly exceeds upper bound
+
+		repo.removeExperienceFromAllAccounts(1.25, 1, 50);
+
+		double delta = 0.0001;//required precision
+		assertEquals(78, repo.getByUserId(79).get().getExperience(), delta);
+		assertEquals(79, repo.getByUserId(80).get().getExperience(), delta);
+		assertEquals(98.75, repo.getByUserId(100).get().getExperience(), delta);
+		assertEquals(1975, repo.getByUserId(2_000).get().getExperience(), delta);
+		assertEquals(3949.0125, repo.getByUserId(3_999).get().getExperience(), delta);
+		assertEquals(3950, repo.getByUserId(4_000).get().getExperience(), delta);
+		assertEquals(3951, repo.getByUserId(4_001).get().getExperience(), delta);
+		assertEquals(9_950, repo.getByUserId(10_000).get().getExperience(), delta);
+	}
+}