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Hyperledger Fabric Java Chaincode Shim
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/*
Copyright IBM Corp. All Rights Reserved.

SPDX-License-Identifier: Apache-2.0
*/

package org.hyperledger.fabric.shim;

import java.util.HashMap;
import java.util.Map;

import static java.nio.charset.StandardCharsets.UTF_8;

/**
 * Defines methods that all chaincodes must implement.
 */
public interface Chaincode {
    /**
     * Called during an instantiate transaction after the container has been
     * established, allowing the chaincode to initialize its internal data.
     */
    public Response init(ChaincodeStub stub);

    /**
     * Called for every Invoke transaction. The chaincode may change its state
     * variables.
     */
    public Response invoke(ChaincodeStub stub);

    /**
     * Wrapper around protobuf Response, contains status, message and payload. Object returned by
     * call to {@link #init(ChaincodeStub)} and{@link #invoke(ChaincodeStub)}
     */
    class Response {

        private final int statusCode;
        private final String message;
        private final byte[] payload;

        public Response(Status status, String message, byte[] payload) {
            this.statusCode = status.getCode();
            this.message = message;
            this.payload = payload;
        }

        public Response(int statusCode, String message, byte[] payload) {
            this.statusCode = statusCode;
            this.message = message;
            this.payload = payload;
        }

        public Status getStatus() {
            if (Status.hasStatusForCode(statusCode)) {
                return Status.forCode(statusCode);
            } else {
                return null;
            }
        }

        public int getStatusCode() {
            return statusCode;
        }

        public String getMessage() {
            return message;
        }

        public byte[] getPayload() {
            return payload;
        }

        public String getStringPayload() {
            return (payload==null) ? null : new String(payload, UTF_8);
        }

        /**
         * {@link Response} status enum.
         */
        public enum Status {
            SUCCESS(200),
            ERROR_THRESHOLD(400),
            INTERNAL_SERVER_ERROR(500);

            private static final Map codeToStatus = new HashMap<>();
            private final int code;

            private Status(int code) {
                this.code = code;
            }

            public int getCode() {
                return code;
            }

            public static Status forCode(int code) {
                final Status result = codeToStatus.get(code);
                if (result == null) throw new IllegalArgumentException("no status for code " + code);
                return result;
            }

            public static boolean hasStatusForCode(int code) {
                return codeToStatus.containsKey(code);
            }

            static {
                for (Status status : Status.values()) {
                    codeToStatus.put(status.code, status);
                }
            }

        }

    }
}