#include "hash.h"
#include "mbedtls/md.h" // for SHA256

// Logging
static const char* TAG = "HASH";

String get_sha256(String payload) {
    byte shaResult[32];
    mbedtls_md_context_t ctx;
    mbedtls_md_type_t md_type = MBEDTLS_MD_SHA256;
    mbedtls_md_init(&ctx);
    mbedtls_md_setup(&ctx, mbedtls_md_info_from_type(md_type), 0);
    mbedtls_md_starts(&ctx);
    mbedtls_md_update(&ctx, (const unsigned char *) payload.c_str(), payload.length()); 
    mbedtls_md_finish(&ctx, shaResult);
    mbedtls_md_free(&ctx);
    // convert to hex string
    char buffer[sizeof(shaResult)*2 + 1];
    const char hexmap[] = "0123456789abcdef";
    for (int i = 0; i < sizeof(shaResult); i++) {
        buffer[i*2] = hexmap[(shaResult[i] >> 4) & 0x0F];
        buffer[i*2+1] = hexmap[shaResult[i] & 0x0F];
    }
    buffer[sizeof(buffer) - 1] = '\0';
    return String(buffer);
}