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Welcome to the Stark Infra Java SDK! This tool is made for Java developers who want to easily integrate with our API. This SDK version is compatible with the Stark Infra API v2.
There is a newer version: 0.11.2
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package com.starkinfra.utils;

import com.google.gson.Gson;
import com.google.gson.JsonArray;
import com.google.gson.JsonObject;

import com.starkinfra.User;
import com.starkinfra.Settings;
import com.starkbank.ellipticcurve.Ecdsa;
import com.starkbank.ellipticcurve.PublicKey;
import com.starkbank.ellipticcurve.Signature;
import com.starkinfra.error.InvalidSignatureError;
import com.starkbank.ellipticcurve.utils.ByteString;

import java.lang.reflect.Type;
import java.util.HashMap;

public final class Parse{

    /**
     * Create single notification Event from a content string
     * 
     * Create a single Event object received from event listening at subscribed user endpoint.
     * If the provided digital signature does not check out with the Stark public key, a
     * com.starkinfra.error.InvalidSignatureError will be raised.
     * 

     * Parameters:
     * @param content [string]: response content from request received at user endpoint (not parsed)
     * @param signature [string]: base-64 digital signature received at response header "Digital-Signature"
     * 

     * Return:
     * @return Event object with updated attributes
     * @throws Exception error in the request
     */
    public static T parse(Resource.ClassData resource, String content, String signature) throws Exception {
        return Parse.parseAndVerify(resource, content, signature, Settings.user);
    }

    /**
     * Create single notification Event from a content string
     * 

     * Create a single Event object received from event listening at subscribed user endpoint.
     * If the provided digital signature does not check out with the Stark public key, a
     * com.starkinfra.error.InvalidSignatureError will be raised.
     * 

     * Parameters:
     * @param content [string]: response content from request received at user endpoint (not parsed)
     * @param signature [string]: base-64 digital signature received at response header "Digital-Signature"
     * @param user [Organization/Project object, default null]: Organization or Project object. Not necessary if starkinfra.Settings.user was set before function call
     * 
     * Return:
     * @return Event object with updated attributes
     * @throws Exception error in the request
     */
    public static  T parseAndVerify(Resource.ClassData resource, String content, String signature, User user) throws Exception {
        String verifiedContent = verify(content, signature, user);

        Gson gson = GsonEvent.getInstance();
        JsonObject contentJson = gson.fromJson(verifiedContent, JsonObject.class);
        JsonObject jsonObject = contentJson.getAsJsonObject();

        if (Api.getLastName(resource).equals("event")){
            jsonObject = contentJson.get(Api.getLastName(resource)).getAsJsonObject();
        }

        return gson.fromJson(jsonObject, (Type) resource.cls);
    }

    public static  String verify (String content, String signature, User user) throws Exception {
        Signature signatureObject;
        try {
            signatureObject = Signature.fromBase64(new ByteString(signature.getBytes()));
        } catch (Error | RuntimeException e) {
            throw new InvalidSignatureError("The provided signature is not valid");
        }

        if (verifySignature(user, content, signatureObject, false)) {
            return content;
        }
        if (verifySignature(user, content, signatureObject, true)) {
            return content;
        }

        throw new InvalidSignatureError("The provided signature and content do not match the Stark Infra public key");
    }

    private static boolean verifySignature(User user, String content, Signature signature, boolean refresh) throws Exception {
        PublicKey publicKey = Cache.starkPublicKey;
        if (publicKey == null || refresh) {
            publicKey = getStarkPublicKey(user);
            Cache.starkPublicKey = publicKey;
        }
        return Ecdsa.verify(content, signature, publicKey);
    }

    private static PublicKey getStarkPublicKey(User user) throws Exception {
        HashMap query = new HashMap<>();
        query.put("limit", "1");
        String content = Response.fetch(
                "/public-key",
                "GET",
                null,
                query,
                user
        ).content();
        JsonObject contentJson = new Gson().fromJson(content, JsonObject.class);
        JsonArray publicKeys = contentJson.get("publicKeys").getAsJsonArray();
        return PublicKey.fromPem(
                publicKeys.get(0).getAsJsonObject().get("content").getAsString()
        );
    }
}

abstract class Cache {
    public static PublicKey starkPublicKey = null;
}