#include "jwt.h"

#include "json_parser.h"
#include "logger.h"

#define JWT_ALG_FIELD_NAME      "alg"

int 
jwt_get_header_payload_and_sign(const str_t *jwt, 
                                /*out*/ str_t *header, 
                                /*out*/ str_t *header_payload, 
                                /*out*/ str_t *sign)
{
    LOG_TRACE("jwt_get_header_payload_and_sign enter");

    size_t p_start = 0, p_end = 0;

    for (size_t i = 0; i < jwt->len; i++) {
        if (jwt->data[i] == '.') {
            if (p_start == 0) {
                p_start = i + 1;
            } else {
                p_end = i;
                break;
            }
        }
    }

    if (p_start == 0 || p_end == 0) {
        LOG_ERROR("Could not parse jwt. p_start = %zd, p_end = %zd", p_start, p_end);
        return -1;
    }

    header->data = (char*)jwt->data;
    header->len = p_start - 1;

    header_payload->data = (char*)jwt->data;
    header_payload->len = p_end;

    sign->data = (char*)jwt->data + p_end + 1;
    sign->len = jwt->len - p_end - 1;

    LOG_DEBUG("header: %.*s", (int) header->len, header->data);
    LOG_DEBUG("header_payload: %.*s", (int) header_payload->len, header_payload->data);
    LOG_DEBUG("sign: %.*s", (int) sign->len, sign->data);

    LOG_TRACE("jwt_get_header_payload_and_sign exit");

    return 0;
}

int
jwt_get_alg_from_header(const str_t *header, /*out*/ str_t *alg) 
{
    LOG_TRACE("jwt_get_alg_from_header enter");

    Hjson_parser parser = json_parser_create(header->data, header->len);
    if (parser == NULL) {
        goto error;
    }

    if (json_get_string_member(parser, JWT_ALG_FIELD_NAME, alg)) {
        goto error;
    }

    json_parser_free(parser);

    LOG_TRACE("jwt_get_alg_from_header exit");
    return 0;

error:
    json_parser_free(parser);
    LOG_ERROR("jwt_get_alg_from_header exit with error");
    return -1;
}