package com.tangem.domain.cardReader;

import android.content.Context;

import com.google.gson.JsonArray;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;
import com.tangem.util.Util;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;

public class FW {
    private static JsonArray jaFirmwares=null;

    public static boolean needInit() {
        return jaFirmwares == null;
    }

    public static void Init(Context context) {
        try(InputStream is=context.getAssets().open("fw_hashes.json")) {
            try (InputStreamReader reader = new InputStreamReader(is, StandardCharsets.UTF_8)) {
                JsonParser parser = new JsonParser();
                jaFirmwares = parser.parse(reader).getAsJsonArray();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static class VerifyCodeRecord
    {
        public String hashAlg;
        public int blockIndex;
        public int blockCount;
        public byte[] challenge;
        public byte[] digest;
    }

    public static VerifyCodeRecord selectRandomVerifyCodeBlock(String firmwareVersion) throws IOException {

        try {
            for (int i = 0; i < jaFirmwares.size(); i++) {
                JsonObject jsVersion = jaFirmwares.get(i).getAsJsonObject();
                if (jsVersion.get("fw").getAsString().equals(firmwareVersion)) {
                    VerifyCodeRecord result = new VerifyCodeRecord();
                    result.hashAlg = "sha-256";
                    JsonArray jsHashes = jsVersion.get(result.hashAlg).getAsJsonArray();
                    result.challenge = Util.hexToBytes(jsVersion.get("challenge").getAsString());
                    int caseIndex = (Util.byteArrayToInt(Util.generateRandomBytes(4)) & 0xFFFFFF) % jsHashes.size();
                    JsonObject jsRecord = jsHashes.get(caseIndex).getAsJsonObject();
                    result.blockIndex = jsRecord.get("block").getAsInt();
                    result.blockCount = jsRecord.get("count").getAsInt();
                    result.digest = Util.hexToBytes(jsRecord.get("digest").getAsString());
                    return result;
                }
            }
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
        return null;
    }
}