cz.jalasoft.util.configuration.ConfigutrationInterfaceValidator Maven / Gradle / Ivy

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package cz.jalasoft.util.configuration;

import cz.jalasoft.util.configuration.annotation.Key;
import cz.jalasoft.util.configuration.annotation.KeyPrefix;
import cz.jalasoft.util.configuration.exception.InvalidPretenderTypeException;
import cz.jalasoft.util.configuration.exception.InvalidPropertyMethod;

import java.lang.reflect.Method;

import static java.util.Arrays.*;

/**
 * @author Honza Lastovicka ([email protected])
 * @since 2016-07-26.
 */
final class ConfigutrationInterfaceValidator {

    private final ConverterRegistry converterRegistry;

    ConfigutrationInterfaceValidator(ConverterRegistry converterRegistry) {
        this.converterRegistry = converterRegistry;
    }

    void validate(Class type) {
        assertInterface(type);
        assertKeyPrefixAnnotationIfPresent(type);
        assertDeclaredMethods(type);
    }

    private void assertInterface(Class type) {
        if (!type.isInterface()) {
            throw new InvalidPretenderTypeException(type, "Type is not an interface.");
        }
    }

    private void assertKeyPrefixAnnotationIfPresent(Class type) {
        if (!type.isAnnotationPresent(KeyPrefix.class)) {
            return;
        }

        KeyPrefix prefixAnnotation = type.getAnnotation(KeyPrefix.class);
        String prefix = prefixAnnotation.value();

        if (prefix.isEmpty()) {
            throw new InvalidPretenderTypeException(type, "Key prefix must not be empty.");
        }
    }

    private void assertDeclaredMethods(Class type) {
        Method[] declaredMethods = type.getDeclaredMethods();
        stream(declaredMethods)
                .forEach(this::assertDeclaredMethod);
    }

    private void assertDeclaredMethod(Method method) {
        assertZeroArguments(method);
        assertReturnValue(method);
        assertKeyAnnotationIfPresent(method);
    }

    private void assertZeroArguments(Method method) {
        int paramsCount = method.getParameterCount();

        if (paramsCount == 0) {
            return;
        }
        if (paramsCount > 0) {
            throw new InvalidPropertyMethod(method, "Number of arguments is " + paramsCount + ". Must be zero.");
        }
    }

    private void assertReturnValue(Method method) {
        Class returnType = method.getReturnType();

        if (returnType.equals(Void.class)) {
            throw new InvalidPropertyMethod(method, "Return type must not br Void.");
        }
    }

    private void assertKeyAnnotationIfPresent(Method method) {
        if (!method.isAnnotationPresent(Key.class)) {
            return;
        }

        Key annotation = method.getAnnotation(Key.class);
        String key = annotation.value();
        if (key.isEmpty()) {
            throw new InvalidPropertyMethod(method, "Method has annotation @Key whose value is an empty string. Provide non empty key.");
        }
    }
}