#include <jni.h>
#include <string>
#include <vector>

long fib(long n)
{
    if (n < 3)
        return 1;
    return fib(n-1) + fib(n-2);
}

std::string toUpper(std::string str)
{
    std::string result = str;

    for(char &c : result)
    {
        if (c >= 'a' && c <= 'z')
            c = c - 'a' + 'A';
    }

    return result;
}


extern "C"
{
    JNIEXPORT jstring JNICALL
    Java_com_example_adam_lab3_MainActivity_stringFromJNI(
            JNIEnv *env,
            jobject /* this */) {
        std::string hello = "Hello from C++";
        return env->NewStringUTF(hello.c_str());
    };

    JNIEXPORT jlong JNICALL Java_com_example_adam_lab3_MainActivity_fib
            (JNIEnv *env, jclass jc, jlong n)
    {
        return fib(n);
    };

    JNIEXPORT jstring JNICALL Java_com_example_adam_lab3_MainActivity_toUpper
            (JNIEnv *env, jclass jc, jstring jStr)
    {
        if(!jStr)
            return env->NewStringUTF("");

        std::vector<char> charsCode;
        const jchar *chars = env->GetStringChars(jStr, NULL);
        jsize len = env->GetStringLength(jStr);
        jsize i;

        for( i=0;i<len; i++){
            int code = (int)chars[i];
            charsCode.push_back( code );
        }
        env->ReleaseStringChars(jStr, chars);

        return env->NewStringUTF(toUpper(std::string(charsCode.begin(), charsCode.end())).c_str());
    };
}