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package com.hashicorp.nomad.javasdk;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.hashicorp.nomad.apimodel.Job;

import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

import static com.fasterxml.jackson.databind.PropertyNamingStrategy.UPPER_CAMEL_CASE;

/**
 * Serialises Nomad API model types to JSON, and vice versa.
 * 
 * You are encourage to use the {@code toString()} and {@code fromJson()} on the classes in
 * the {@code com.hashicorp.nomad.apimodel} package directly, rather than using this class.
 */
public abstract class NomadJson {

    static final ObjectMapper OBJECT_MAPPER = new ObjectMapper()
            .setPropertyNamingStrategy(UPPER_CAMEL_CASE)
            .disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);

    static {
        OBJECT_MAPPER.setConfig(
                OBJECT_MAPPER.getSerializationConfig()
                        .with(new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"))
        );
    }

    /**
     * Reads a JSON job spec.
     *
     * @param jobSpec a JSON-formatted job spec
     * @throws IOException if there the JSON ends unexpectedly
     */
    public static Job readJobSpec(String jobSpec) throws IOException {
        return OBJECT_MAPPER.readValue(jobSpec, JobSpec.class).job;
    }

    /**
     * Writes a JSON job spec.
     *
     * @param job the job to render as a JSON job spec
     * @throws JsonProcessingException if there is a problem with the JSON
     */
    public static String asJobSpec(Job job) throws JsonProcessingException {
        return OBJECT_MAPPER.writeValueAsString(new JobSpec(job));
    }

    /**
     * Serializes a Nomad API object to JSON.
     * 

     * You are encourage to use the {@code toString()} method on objects of the classes in
     * the {@code com.hashicorp.nomad.apimodel} package directly, rather than using this method.
     *
     * @param value the value to serialize
     */
    public static String serialize(Object value) {
        try {
            return OBJECT_MAPPER.writeValueAsString(value);
        } catch (JsonProcessingException e) {
            throw new RequestSerializationException("Unable to serialize request entity: " + e, e);
        }
    }

    /**
     * Deserializes a Nomad API object from a JSON object.
     * 

     * You are encourage to use the {@code fromJson()} method on the classes in
     * the {@code com.hashicorp.nomad.apimodel} package directly, rather than using this method.
     *
     * @param    the type of the object
     * @param json  the JSON representation of the object
     * @param clazz the class of the object
     * @throws IOException if the JSON can't be deserialized
     */
    public static  T deserialize(String json, Class clazz) throws IOException {
        return deserialize(json, OBJECT_MAPPER.constructType(clazz));
    }

    /**
     * Deserializes a list of Nomad API objects from a JSON array.
     * 
     * You are encourage to use the {@code fromJsonArray()} method on the classes in
     * the {@code com.hashicorp.nomad.apimodel} package directly, rather than using this method.
     *
     * @param    the type of the object
     * @param json  the JSON representation of the list
     * @param clazz the class of the list elements
     * @throws IOException if the JSON can't be deserialized
     */
    public static  List deserializeList(String json, Class clazz) throws IOException {
        return deserialize(json, OBJECT_MAPPER.getTypeFactory().constructCollectionType(List.class, clazz));
    }

    static  T deserialize(String json, JavaType javaType) throws IOException {
        return OBJECT_MAPPER.readValue(json, javaType);
    }

    static  JsonParser parserFor(JavaType valueType) {
        return new JsonParser(valueType);
    }

    static  JsonParser parserFor(Class clazz) {
        return parserFor(OBJECT_MAPPER.constructType(clazz));
    }

    static  JsonParser> parserForListOf(Class elementType) {
        return parserFor(OBJECT_MAPPER.getTypeFactory().constructCollectionType(List.class, elementType));
    }

    static  ValueExtractor> parserForSortedListOf(
            final Class elementType, final Comparator comparator) {
        final JsonParser> parser = parserForListOf(elementType);
        return new ValueExtractor>() {
            @Override
            public List extractValue(String json) throws ResponseParsingException {
                List list = parser.extractValue(json);
                Collections.sort(list, comparator);
                return list;
            }
        };
    }

    /**
     * A Job wrapper to produce or parse the
     * JSON job spec representation.
     */
    private static class JobSpec {
        @JsonProperty("Job")
        public final Job job; // Checkstyle suppress VisibilityModifier

        @JsonCreator
        JobSpec(@JsonProperty("Job") Job job) {
            this.job = job;
        }
    }
}