/*
 * Copyright 2017-2020 original authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package io.micronaut.context.annotation;

import io.micronaut.context.condition.Condition;
import io.micronaut.context.condition.TrueCondition;
import io.micronaut.core.annotation.InstantiatedMember;

import java.lang.annotation.Annotation;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Repeatable;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

Expresses a requirement for a bean or Configuration. 
Author:
Graeme Rocher
Since:
1.0/**
 * Expresses a requirement for a bean or {@link Configuration}.
 *
 * @author Graeme Rocher
 * @since 1.0
 */
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.PACKAGE, ElementType.TYPE, ElementType.ANNOTATION_TYPE, ElementType.METHOD})
@Repeatable(Requirements.class)
public @interface Requires {

    
Expresses that the configuration will only load within the given environments.
Returns:
The names of the environments this configuration will load in/**
     * Expresses that the configuration will only load within the given environments.
     *
     * @return The names of the environments this configuration will load in
     */
    String[] env() default {};

    
Expresses that the configuration will not load within the given environments.
Returns:
The names of the environments this configuration will not load in/**
     * Expresses that the configuration will not load within the given environments.
     *
     * @return The names of the environments this configuration will not load in
     */
    String[] notEnv() default {};

    
Expresses that the given property should be set for the bean to load.
Returns:
The property that should be set./**
     * Expresses that the given property should be set for the bean to load.
     *
     * @return The property that should be set.
     */
    String property() default "";

    
Constraint a property to not equal the given value.
Returns:
The value to not equal/**
     * Constraint a property to not equal the given value.
     *
     * @return The value to not equal
     */
    String notEquals() default "";

    
One ore more custom condition classes.
Returns:
The condition classes/**
     * One ore more custom condition classes.
     *
     * @return The condition classes
     */
    @InstantiatedMember
    Class<? extends Condition> condition() default TrueCondition.class;

    
Used to express an SDK requirement. Typically used in combination with version() to specify a minimum version requirement. 
Returns:
The SDK required/**
     * Used to express an SDK requirement. Typically used in combination with {@link #version()} to specify a minimum
     * version requirement.
     *
     * @return The SDK required
     */
    Sdk sdk() default Sdk.MICRONAUT;

    
Expresses the configurations that should be present for the bean or configuration to load.
Returns:
The configurations/**
     * Expresses the configurations that should be present for the bean or configuration to load.
     *
     * @return The configurations
     */
    String configuration() default "";

    
Used in combination with property() to express the required value of the property. 
Returns:
The required value/**
     * Used in combination with {@link #property()} to express the required value of the property.
     *
     * @return The required value
     */
    String value() default "";

    
Returns:
The default value if no value is specified/**
     * @return The default value if no value is specified
     */
    String defaultValue() default "";

    
Used in combination with property() to express the required pattern of the property. The pattern will be evaluated with String.matches(String). 
Returns:
The required pattern/**
     * Used in combination with {@link #property()} to express the required pattern of the property. The
     * pattern will be evaluated with {@link String#matches(String)}.
     *
     * @return The required pattern
     */
    String pattern() default "";

    
Used in combination with sdk(), configuration(), classes() or beans() to express a minimum version of the SDK, configuration or classes. 
Returns:
The minimum version/**
     * Used in combination with {@link #sdk()}, {@link #configuration()}, {@link #classes()} or {@link #beans()} to
     * express a minimum version of the SDK, configuration or classes.
     *
     * @return The minimum version
     */
    String version() default "";

    
Expresses the given classes that should be present on the classpath for the bean or configuration to load.
Returns:
The classes/**
     * Expresses the given classes that should be present on the classpath for the bean or configuration to load.
     *
     * @return The classes
     */
    Class[] classes() default {};

    
Expresses that the configuration requires entities annotated with the given annotations to be available to the
application via package scanning.
Returns:
The classes/**
     * Expresses that the configuration requires entities annotated with the given annotations to be available to the
     * application via package scanning.
     *
     * @return The classes
     */
    Class<? extends Annotation>[] entities() default {};


    
Expresses that beans of the given types should be available for the bean or configuration to load.
Returns:
The beans/**
     * Expresses that beans of the given types should be available for the bean or configuration to load.
     *
     * @return The beans
     */
    Class[] beans() default {};

    
Expresses the given classes that should be missing from the classpath for the bean or configuration to load.
Returns:
The classes/**
     * Expresses the given classes that should be missing from the classpath for the bean or configuration to load.
     *
     * @return The classes
     */
    Class[] missing() default {};

    
Expresses the given class names should be missing from the classpath for the bean configuration to load.
Returns:
The names of the classes that should be missing/**
     * Expresses the given class names should be missing from the classpath for the bean configuration to load.
     *
     * @return The names of the classes that should be missing
     */
    @AliasFor(member = "missing")
    String[] missingClasses() default {};

    
Expresses the given beans that should be missing from the classpath for the bean or configuration to load.
Returns:
The classes/**
     * Expresses the given beans that should be missing from the classpath for the bean or configuration to load.
     *
     * @return The classes
     */
    Class[] missingBeans() default {};

    
Expresses the given configurations that should be missing from the classpath for the bean or configuration to
load.
Returns:
The classes/**
     * Expresses the given configurations that should be missing from the classpath for the bean or configuration to
     * load.
     *
     * @return The classes
     */
    String[] missingConfigurations() default {};

    
Expresses that the bean or configuration will only be configured if the given property is missing.
Returns:
The property or properties that should be missing/**
     * Expresses that the bean or configuration will only be configured if the given property is missing.
     *
     * @return The property or properties that should be missing
     */
    String missingProperty() default "";

    
Expresses the given resources should exist for the bean configuration to load. Resources can be anything that ResourceResolver can read, eg: 
 file:/path/to/file.txt
 classpath:com/mycompany/file.txt

Returns:
The file paths/**
     * Expresses the given resources should exist for the bean configuration to load.
     * Resources can be anything that {@link io.micronaut.core.io.ResourceResolver} can read, eg:
     * <pre>
     *  file:/path/to/file.txt
     *  classpath:com/mycompany/file.txt
     * </pre>
     *
     * @return The file paths
     */
    String[] resources() default {};

    
Expresses the current operating system must be one in the given list.
Returns:
The os families/**
     * Expresses the current operating system must be one in the given list.
     *
     * @return The os families
     */
    Family[] os() default {};

    
Expresses the current operating system must not be one in the given list.
Returns:
The os families/**
     * Expresses the current operating system must not be one in the given list.
     *
     * @return The os families
     */
    Family[] notOs() default {};

    
Used to express a required SDK version.
/**
     * Used to express a required SDK version.
     */
    enum Sdk {
        JAVA,
        GROOVY,
        KOTLIN,
        MICRONAUT
    }

    
Used to express an operation system family.
/**
     * Used to express an operation system family.
     */
    enum Family {
        LINUX, MAC_OS, WINDOWS, SOLARIS, OTHER
    }
}