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/*
 * Copyright (c) 2021 the original author or 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.github.pustike.web;

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

/**
 * Binds the value(s) of a HTTP header to a resource method parameter,
 * resource class field, or resource class bean property. A default value
 * can be specified using the {@link DefaultValue} annotation.
 *
 * The type {@code T} of the annotated parameter, field or property
 * must either:
 * 
 * Be a primitive type
 * Have a constructor that accepts a single {@code String} argument
 * Have a static method named {@code valueOf} or {@code fromString} that accepts a single
 * {@code String} argument (see, for example, {@link Integer#valueOf(String)})
 * Have a registered source to target type converter in {@link io.github.pustike.json.TypeConverter}
 * Be {@code List}, {@code Set} or {@code SortedSet}, where {@code T} satisfies 2, 3 or 4 above.
 * The resulting collection is read-only.
 * 
 *
 * If the type is not one of the collection types listed in 5 above and the
 * header parameter is represented by multiple values then the first value (lexically)
 * of the parameter is used.
 *
 * Because injection occurs at object creation time, use of this annotation
 * on resource class fields and bean properties is only supported for the
 * default per-request resource class lifecycle. Resource classes using
 * other lifecycles should only use this annotation on resource method
 * parameters.
 *
 * @see DefaultValue
 */
@Target({ElementType.PARAMETER, ElementType.METHOD, ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface HeaderParam {

    /**
     * Defines the name of the HTTP header whose value will be used to initialize the value
     * of the annotated method argument, class field or bean property. Case insensitive.
     * @return name of the HTTP header
     */
    String value();
}