#include "jwt.h"
#include <random>

#include "utils.h"

std::string http::auth::jwt::secretKey;

void http::auth::jwt::generateSecretKey() {
    secretKey.clear();

    std::random_device rd;
    std::mt19937 generator(rd());
    std::uniform_int_distribution<> distribution('!', '~');
    for (size_t i = 0; i < 32; ++i) {
        secretKey += static_cast<char>(distribution(generator));
    }
}

// payload, signature
static std::pair<std::string, std::string> parseJwtFromCookie(const std::string& input) {
    std::string val1, val2;
    size_t dotPos = input.find('.');

    // Если точка найдена
    if (dotPos != std::string::npos) {
        val1 = input.substr(0, dotPos);

        // Если в val1 есть еще точки, нужно найти последнюю точку
        size_t lastDotPos = val1.find_last_of('.');
        if (lastDotPos != std::string::npos) {
            val1 = val1.substr(0, lastDotPos + 1);
        }

        val2 = input.substr(dotPos + 1);
    } else {
        // Точка не найдена, val1 - вся строка
        val1 = input;
    }

    return std::make_pair(http::utils::b64Decode(val1), val2);
}

http::auth::jwt::Jwt http::auth::jwt::Jwt::fromCookies(const std::string &cookie) {
    auto pc = utils::parseCookies(cookie);
    Jwt t;
    if (pc.find("auth") != pc.end()) {
        auto tmp = parseJwtFromCookie(pc.at("auth"));
        t.payload = tmp.first;
        t.signature = tmp.second;
    }

    return t;
}

http::auth::jwt::Jwt http::auth::jwt::Jwt::fromUser(const std::string &user) {
    Jwt t;
    t.payload = user;
    return t;
}

bool http::auth::jwt::Jwt::isValid() {
    if (payload.empty() || signature.empty()) {
        return false;
    }

    auto realSignature = utils::sha256(this->payload + secretKey);
    return signature == realSignature;
}

std::string http::auth::jwt::Jwt::getUsername() {
    return payload;
}

std::string http::auth::jwt::Jwt::asCookie() {
    signature = utils::sha256(this->payload + secretKey);
    auto val = utils::b64Encode(payload) + "." + signature;
    return "auth=" + val + ";Path=/; Max-Age=86400; HttpOnly; SameSite=Lax";
}

http::auth::jwt::Jwt::~Jwt() = default;