/*
 * 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.core.convert;

import io.micronaut.core.annotation.AnnotationMetadataProvider;
import io.micronaut.core.type.Argument;
import io.micronaut.core.type.TypeVariableResolver;
import io.micronaut.core.util.ArgumentUtils;
import io.micronaut.core.util.ArrayUtils;

import edu.umd.cs.findbugs.annotations.Nullable;
import java.lang.annotation.Annotation;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.*;

A conversion context is a context object supplied to a TypeConverter that allows more accurate conversion. 
Author:
Graeme Rocher
Since:
1.0/**
 * A conversion context is a context object supplied to a {@link TypeConverter} that allows more accurate conversion.
 *
 * @author Graeme Rocher
 * @since 1.0
 */
public interface ConversionContext extends AnnotationMetadataProvider, TypeVariableResolver, ErrorsContext {

    
The default conversion context.
/**
     * The default conversion context.
     */
    ConversionContext DEFAULT = new ConversionContext() {
    };

    
Constant for Boolean argument.
/**
     * Constant for Boolean argument.
     */
    ArgumentConversionContext<Boolean> BOOLEAN = ConversionContext.of(Argument.BOOLEAN);

    
Constant for Integer argument.
/**
     * Constant for Integer argument.
     */
    ArgumentConversionContext<Integer> INT = ConversionContext.of(Argument.INT);

    
Constant for Long argument.
/**
     * Constant for Long argument.
     */
    ArgumentConversionContext<Long> LONG = ConversionContext.of(Argument.LONG);

    
Constant for String argument.
/**
     * Constant for String argument.
     */
    ArgumentConversionContext<String> STRING = ConversionContext.of(Argument.STRING);

    
Constant for List argument.
/**
     * Constant for List<String> argument.
     */
    ArgumentConversionContext<List<String>> LIST_OF_STRING = ConversionContext.of(Argument.LIST_OF_STRING);

    
Constant for List argument.
/**
     * Constant for List<String> argument.
     */
    ArgumentConversionContext<Map> MAP = ConversionContext.of(Argument.of(Map.class));

    
In the case where the type to be converted contains generic type arguments this map will return the concrete types of those arguments. For example for the Map type two keys will be present called 'K' and 'V' with the actual types of the key and value. 
Returns:
A map of type variables/**
     * In the case where the type to be converted contains generic type arguments this map will return
     * the concrete types of those arguments. For example for the {@link Map} type two keys will be present
     * called 'K' and 'V' with the actual types of the key and value.
     *
     * @return A map of type variables
     */
    @Override
    default Map<String, Argument<?>> getTypeVariables() {
        return Collections.emptyMap();
    }

    
Returns:
The locale to use/**
     * @return The locale to use
     */
    default Locale getLocale() {
        return Locale.getDefault();
    }

    
Returns:
The standard charset used in conversion/**
     * @return The standard charset used in conversion
     */
    default Charset getCharset() {
        return StandardCharsets.UTF_8;
    }

    
Augment this context with data for the given argument.
Params:
argument – The argument
Type parameters:
<T> –      type Generic
Returns:
The conversion context/**
     * Augment this context with data for the given argument.
     *
     * @param <T>      type Generic
     * @param argument The argument
     * @return The conversion context
     */
    @SuppressWarnings("unchecked")
    default <T> ArgumentConversionContext<T> with(Argument<T> argument) {

        ConversionContext childContext = ConversionContext.of(argument);
        ConversionContext thisContext = this;
        return new DefaultArgumentConversionContext(argument, thisContext.getLocale(), thisContext.getCharset()) {
            @Override
            public <T extends Annotation> T synthesize(Class<T> annotationClass) {
                T annotation = childContext.synthesize(annotationClass);
                if (annotation == null) {
                    return thisContext.synthesize(annotationClass);
                }
                return annotation;
            }

            @Override
            public Annotation[] synthesizeAll() {
                return ArrayUtils.concat(childContext.synthesizeAll(), thisContext.synthesizeAll());
            }

            @Override
            public Annotation[] synthesizeDeclared() {
                return ArrayUtils.concat(childContext.synthesizeDeclared(), thisContext.synthesizeDeclared());
            }

            @Override
            public void reject(Exception exception) {
                thisContext.reject(exception);
            }

            @Override
            public void reject(Object value, Exception exception) {
                thisContext.reject(value, exception);
            }

            @Override
            public Iterator<ConversionError> iterator() {
                return thisContext.iterator();
            }

            @Override
            public Optional<ConversionError> getLastError() {
                return thisContext.getLastError();
            }
        };
    }

    
Create a simple ConversionContext for the given generic type variables. 
Params:
typeVariables – The type variables
Returns:
The conversion context/**
     * Create a simple {@link ConversionContext} for the given generic type variables.
     *
     * @param typeVariables The type variables
     * @return The conversion context
     */
    static ConversionContext of(Map<String, Argument<?>> typeVariables) {
        return new ConversionContext() {
            @Override
            public Map<String, Argument<?>> getTypeVariables() {
                return typeVariables;
            }

        };
    }

    
Create a simple ConversionContext for the given generic type variables. 
Params:
argument – The argument
Type parameters:
<T> –      type Generic
Returns:
The conversion context/**
     * Create a simple {@link ConversionContext} for the given generic type variables.
     *
     * @param <T>      type Generic
     * @param argument The argument
     * @return The conversion context
     */
    static <T> ArgumentConversionContext<T> of(Argument<T> argument) {
        return of(argument, null, null);
    }

    
Create a simple ConversionContext for the given generic type variables. 
Params:
argument – The argument
Type parameters:
<T> –      type Generic
Returns:
The conversion context/**
     * Create a simple {@link ConversionContext} for the given generic type variables.
     *
     * @param <T>      type Generic
     * @param argument The argument
     * @return The conversion context
     */
    static <T> ArgumentConversionContext<T> of(Class<T> argument) {
        ArgumentUtils.requireNonNull("argument", argument);
        return of(Argument.of(argument), null, null);
    }

    
Create a simple ConversionContext for the given generic type variables. 
Params:
argument – The argument
locale –   The locale
Type parameters:
<T> –      type Generic
Returns:
The conversion context/**
     * Create a simple {@link ConversionContext} for the given generic type variables.
     *
     * @param <T>      type Generic
     * @param argument The argument
     * @param locale   The locale
     * @return The conversion context
     */
    static <T> ArgumentConversionContext of(Argument<T> argument, @Nullable Locale locale) {
        return of(argument, locale, null);
    }

    
Create a simple ConversionContext for the given generic type variables. 
Params:
argument – The argument
locale –   The locale
charset –  The charset
Type parameters:
<T> –      type Generic
Returns:
The conversion context/**
     * Create a simple {@link ConversionContext} for the given generic type variables.
     *
     * @param <T>      type Generic
     * @param argument The argument
     * @param locale   The locale
     * @param charset  The charset
     * @return The conversion context
     */
    static <T> ArgumentConversionContext<T> of(Argument<T> argument, @Nullable Locale locale, @Nullable Charset charset) {
        ArgumentUtils.requireNonNull("argument", argument);
        Charset finalCharset = charset != null ? charset : StandardCharsets.UTF_8;
        Locale finalLocale = locale != null ? locale : Locale.getDefault();
        return new DefaultArgumentConversionContext<>(argument, finalLocale, finalCharset);
    }
}