Rework currencies

api/pom.xml

@@ -20,6 +20,12 @@
             <artifactId>annotations</artifactId>
             <version>${jetbrains.annotations.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>${junit.version}</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
 </project>

api/src/main/java/me/lokka30/treasury/api/economy/currency/Currency.java

@@ -12,69 +12,227 @@
 
 package me.lokka30.treasury.api.economy.currency;
 
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-
 import java.util.Locale;
+import java.util.Objects;
 import java.util.UUID;
+import java.util.function.BiFunction;
+import java.util.function.Function;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 /**
- * @author lokka30, Geolykt
- * @since v1.0.0
  * One of Treasury's core features is multi-currency support.
  * This allows economy providers and plugins to use different
  * currencies for different transactions, e.g. a daily reward
  * plugin can award players 'Tokens', but a job plugin
  * can award players 'Dollars'. Facilitates great customisability.
+ *
+ * @author lokka30, Geolykt, MrIvanPlays
+ * @since v1.0.0
  */
-@SuppressWarnings("unused")
-public interface Currency {
+public class Currency {
+
+    /**
+     * Creates a new currency with random {@link UUID} {@code currencyId} and a {@code startingBalance} handler of
+     * always returning 0.
+     *
+     * @param currencyChar          a way to identify the currency via a character e.g. '$' for a dollar. can be null.
+     * @param roundedDigits         to which digit shall we round balances. can specify -1 for no rounding.
+     * @param conversionCoefficient coefficient at which this currency is going to be converted to other currencies.
+     * @param balanceFormatter      a function, giving a human-readable format of a balance.
+     * @param names                 acceptable names of the currency. primary name shall be the first specified.
+     * @return new currency instance
+     */
+    @NotNull
+    public static Currency of(
+            @Nullable Character currencyChar,
+            int roundedDigits,
+            double conversionCoefficient,
+            @NotNull BiFunction<Double, Locale, String> balanceFormatter,
+            @NotNull String @NotNull... names
+    ) {
+        return new Currency(
+                null,
+                currencyChar,
+                roundedDigits,
+                conversionCoefficient,
+                null,
+                balanceFormatter,
+                names
+        );
+    }
+
+    /**
+     * Creates a new currency.
+     *
+     * @param currencyId            the currency id.
+     * @param currencyChar          a way to identify the currency via a character e.g. '$' for a dollar. can be null.
+     * @param roundedDigits         to which digit shall we round balances. can specify -1 for no rounding.
+     * @param conversionCoefficient coefficient at which this currency is going to be converted to other currencies.
+     * @param startingBalance       a function, giving a starting balance for the inputted player uuid, which can be null.
+     * @param balanceFormatter      a function, giving a human-readable format of a balance.
+     * @param names                 acceptable names of the currency. primary name shall be the first specified.
+     * @return new currency instance
+     */
+    @NotNull
+    public static Currency of(
+            @NotNull UUID currencyId,
+            @Nullable Character currencyChar,
+            int roundedDigits,
+            double conversionCoefficient,
+            @Nullable Function<UUID, Double> startingBalance,
+            @NotNull BiFunction<Double, Locale, String> balanceFormatter,
+            @NotNull String @NotNull... names
+    ) {
+        Objects.requireNonNull(currencyId, "currencyId");
+        return new Currency(
+                currencyId,
+                currencyChar,
+                roundedDigits,
+                conversionCoefficient,
+                startingBalance,
+                balanceFormatter,
+                names
+        );
+    }
+
+    private final UUID currencyId;
+    private final Character currencyChar;
+    private final String[] names;
+    private final int roundedDigits;
+    private double conversionCoefficient;
+    private final Function<UUID, Double> startingBalance;
+    private final BiFunction<Double, Locale, String> balanceFormatter;
+
+    private Currency(@Nullable UUID currencyId,
+                     @Nullable Character currencyChar,
+                     int roundedDigits,
+                     double conversionCoefficient,
+                     @Nullable Function<UUID, Double> startingBalance,
+                     @NotNull BiFunction<Double, Locale, String> balanceFormatter,
+                     @NotNull String @NotNull... names
+    ) {
+        if (names.length < 1) {
+            throw new IllegalArgumentException("Empty array specified for currency name.");
+        }
+        this.balanceFormatter = Objects.requireNonNull(balanceFormatter, "balanceFormatter");
+        this.names = Objects.requireNonNull(names, "names");
+        this.currencyId = currencyId == null ? UUID.randomUUID() : currencyId;
+        this.currencyChar = currencyChar;
+        this.roundedDigits = roundedDigits;
+        this.conversionCoefficient = conversionCoefficient;
+        this.startingBalance = startingBalance == null ? ($) -> 0d : startingBalance;
+    }
 
     /**
-     * @author lokka30
+     * Gets the {@link UUID} of the currency.
+     *
+     * @return the UUID of the currency
+     * @author lokka30, MrIvanPlays
      * @since v1.0.0
-     * Get the UUID of the currency.
-     * @return the UUID of the currency.
      */
     @NotNull
-    UUID getCurrencyId();
+    public UUID getCurrencyId() {
+        return currencyId;
+    }
 
     /**
-     * @author lokka30
+     * Gets the character which identifies this currency, which may be null.
+     *
+     * @return char identifier. could be null
+     * @author MrIvanPlays
+     * @since v1.0.0
+     */
+    @Nullable
+    public Character getCurrencyCharacter() {
+        return currencyChar;
+    }
+
+    /**
+     * Get the primary name of the currency, e.g. 'dollar' or 'token'.
+     *
+     * @return the name of the currency
+     * @author lokka30, MrIvanPlays
      * @since v1.0.0
-     * Get the name of the currency, e.g. 'dollars' or 'tokens'.
-     * @return the name of the currency.
      */
     @NotNull
-    String getCurrencyName();
+    public String getPrimaryCurrencyName() {
+        return names[0];
+    }
 
     /**
-     * @author lokka30
+     * Get the acceptable currency names. Used for parsing.
+     *
+     * @return acceptable currency names
+     * @author MrIvanPlays
      * @since v1.0.0
+     */
+    @NotNull
+    public String @NotNull [] getCurrencyNames() {
+        return names;
+    }
+
+    /**
      * Some economy providers like to round balances' decimals.
      * Economy providers that do not round any digits should specify `-1`.
+     *
      * @return how many rounded digits the provider uses, or `-1` for none
+     * @author lokka30, MrIvanPlays
+     * @since v1.0.0
      */
-    int getRoundedDigits();
+    public int getRoundedDigits() {
+        return roundedDigits;
+    }
 
     /**
-     * @author lokka30, Geolykt
+     * Get the conversion coefficient of this currency.
+     *
+     * @return conversion coefficient
+     * @author MrIvanPlays
      * @since v1.0.0
+     */
+    public double getConversionCoefficient() {
+        return conversionCoefficient;
+    }
+
+    /**
+     * Sets a new conversion coefficient of this currency.
+     *
+     * @param conversionCoefficient new conversion coefficient
+     * @author MrIvanPlays
+     * @since v1.0.0
+     */
+    protected void setConversionCoefficient(double conversionCoefficient) {
+        this.conversionCoefficient = conversionCoefficient;
+    }
+
+    /**
      * Get the starting balance of the currency.
-     * The player UUID is nullable, it should be specified if the starting balance
-     * concerns a PlayerAccount.
-     * @param playerUUID a UUID of the player account concerned. For global scenarios, specify `null`.
+     * The player {@link UUID} is nullable, it should be specified if the starting balance
+     * concerns a {@link me.lokka30.treasury.api.economy.account.PlayerAccount}.
+     *
+     * @param playerUUID a UUID of the player account created. For global scenarios, specify `null`.
      * @return the starting balance of the currency concerning specified player's UUID.
+     * @author lokka30, Geolykt, MrIvanPlays
+     * @since v1.0.0
      */
-    double getStartingBalance(@Nullable UUID playerUUID);
+    public double getStartingBalance(@Nullable UUID playerUUID) {
+        return startingBalance.apply(playerUUID);
+    }
 
     /**
      * Gets a human-readable format of the balance.
      * For example, '$1.50' or '1.50 dollars' or 'One dollar and fifty cents'.
+     *
      * @param amount to be formatted.
      * @param locale of the formatted balance being requested.
      * @return the human-readable format of the specified amount and locale.
+     * @author lokka30, MrIvanPlays
+     * @since v1.0.0
      */
     @NotNull
-    String formatBalance(double amount, @NotNull Locale locale);
-}
+    public String formatBalance(double amount, @NotNull Locale locale) {
+        Objects.requireNonNull(locale, "locale");
+        return balanceFormatter.apply(amount, locale);
+    }
+}