Add FilterBuilder

src/main/java/xyz/srnyx/magicmongo/builders/FilterBuilder.java

@@ -0,0 +1,95 @@
+package xyz.srnyx.magicmongo.builders;
+
+import com.mongodb.client.model.Filters;
+
+import org.bson.conversions.Bson;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.function.BinaryOperator;
+
+
+public class FilterBuilder {
+    /**
+     * The {@link Bson filter} to build
+     */
+    @Nullable private Bson filter;
+
+    /**
+     * Creates a new {@link FilterBuilder} instance with no starting {@link #filter}
+     */
+    public FilterBuilder() {}
+
+    /**
+     * Creates a new {@link FilterBuilder} instance with the given {@link #filter}
+     *
+     * @param   filter  the {@link Bson filter} to start with
+     */
+    public FilterBuilder(@Nullable Bson filter) {
+        this.filter = filter;
+    }
+
+    /**
+     * Returns the final/built {@link Bson filter}
+     *
+     * @return                          the final/built {@link Bson filter}
+     *
+     * @throws  IllegalStateException   if the {@link #filter} is null (only ever happens if {@link FilterBuilder the builder} is created with no starting {@link #filter})
+     */
+    @NotNull
+    public Bson build() {
+        if (filter == null) throw new IllegalStateException("filter cannot be null");
+        return filter;
+    }
+
+    /**
+     * Adds a new {@link Bson filter} to the current {@link #filter}
+     *
+     * @param   filterFunction  the {@link BinaryOperator} to apply to the current {@link #filter} with the new {@link Bson filter}
+     * @param   newFilter       the new {@link Bson filter} to add
+     *
+     * @return                  the current {@link FilterBuilder}
+     */
+    @NotNull
+    public FilterBuilder add(@NotNull BinaryOperator<Bson> filterFunction, @NotNull Bson newFilter) {
+        filter = filterFunction.apply(filter, newFilter);
+        return this;
+    }
+
+    /**
+     * Adds a new {@link Bson filter} to the current {@link #filter} using {@link Filters#and(Bson...)}
+     *
+     * @param   newFilter   the new {@link Bson filter} to add
+     *
+     * @return              the current {@link FilterBuilder} instance
+     */
+    @NotNull
+    public FilterBuilder and(@NotNull Bson newFilter) {
+        return add(Filters::and, newFilter);
+    }
+
+    /**
+     * Adds a new {@link Bson filter} to the current {@link #filter} using {@link Filters#or(Bson...)}
+     *
+     * @param   newFilter   the new {@link Bson filter} to add
+     *
+     * @return              the current {@link FilterBuilder} instance
+     */
+    @NotNull
+    public FilterBuilder or(@NotNull Bson newFilter) {
+        return add(Filters::or, newFilter);
+    }
+
+    /**
+     * Adds a new {@link Bson filter} to the current {@link #filter} using {@link Filters#nor(Bson...)}
+     *
+     * @param   newFilter   the new {@link Bson filter} to add
+     *
+     * @return              the current {@link FilterBuilder} instance
+     */
+    @NotNull
+    public FilterBuilder nor(@NotNull Bson newFilter) {
+        return add(Filters::nor, newFilter);
+    }
+}