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package name.didier.david.test4j.utils;

import java.io.IOException;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;

/**
 * Utilities dealing with JSON.
 *
 * @author ddidier
 */
public final class JsonUtils {

    /** Serialize JSON. */
    private static final ObjectMapper MAPPER = new ObjectMapper();
    /** Serialize JSON with pretty print. */
    private static final ObjectMapper MAPPER_PP = new ObjectMapper().enable(SerializationFeature.INDENT_OUTPUT);

    /** Default constructor. */
    private JsonUtils() {
        super();
    }

    /**
     * Join the elements and replace all custom quotes with double quotes. Useful to embed JSON strings in code since
     * Java doesn't support hereDoc. For example:
     *
     *      * json('_', "{_id_: 123, _name_: _a cool name_}"
     *
     * OR
     *
     * json('_',
     *   "{",
     *   "  _id_: 123,",
     *   "  _name_: _a cool name_",
     *   "}")
     * 
     *
     * @param doubleQuotes the character to replace with single quote.
     * @param elements the strings to join.
     * @return the JSON string.
     */
    public static String json(char doubleQuotes, CharSequence... elements) {
        return String.join("\n", elements).replace(doubleQuotes, '"');
    }

    /**
     * Join the elements and replace all simple quotes with double quotes. Useful to embed JSON strings in code since
     * Java doesn't support hereDoc. For example:
     *
     *      * json("{'id': 123, 'name': 'a cool name'}"
     *
     * OR
     *
     * json(
     *   "{",
     *   "  'id': 123,",
     *   "  'name': 'a cool name'",
     *   "}")
     * 
     *
     * @param elements the strings to join.
     * @return the JSON string.
     */
    public static String json(CharSequence... elements) {
        return json('\'', elements);
    }

    // -----------------------------------------------------------------------------------------------------------------

    /**
     * Normalize the given JSON string.
     *
     * @param json the JSON to normalize.
     * @return the normalized JSON string.
     */
    public static String normalize(String json) {
        return parseJson(json, MAPPER);
    }

    /**
     * Normalize the given JSON string resulting of {@link #json(CharSequence...)}.
     *
     * @param elements the JSON to join then normalize.
     * @return the normalized JSON string.
     */
    public static String normalizeJson(CharSequence... elements) {
        return normalize(json(elements));
    }

    /**
     * Normalize and pretty print the given JSON string.
     *
     * @param json the JSON to pretty print.
     * @return the pretty printed JSON string.
     */
    public static String prettyPrint(String json) {
        return parseJson(json, MAPPER_PP);
    }

    /**
     * Normalize and pretty print the given JSON string resulting of {@link #json(CharSequence...)}.
     *
     * @param elements the JSON to join then normalize.
     * @return the pretty printed JSON string.
     */
    public static String prettyPrintJson(CharSequence... elements) {
        return prettyPrint(json(elements));
    }

    /**
     * Normalize the given JSON string.
     *
     * @param json the JSON to normalize.
     * @param mapper the JSON parser.
     * @return the normalized JSON string.
     */
    private static String parseJson(String json, ObjectMapper mapper) {
        try {
            return mapper.writeValueAsString(mapper.readValue(json, Object.class));
        } catch (IOException e) {
            throw new RuntimeException("Error while parsing JSON", e);
        }
    }
}