/*
 * Copyright (c) 2017 Lev Walkin <vlm@lionet.info>.
 * All rights reserved.
 * Redistribution and modifications are permitted subject to BSD license.
 */
#include <osmocom/tcap/asn_internal.h>
#include <osmocom/tcap/ANY.h>
#include <errno.h>

struct _callback_arg {
    uint8_t *buffer;
    size_t offset;
    size_t size;
};

static int ANY__consume_bytes(const void *buffer, size_t size, void *key) {
    struct _callback_arg *arg = (struct _callback_arg *)key;

    if((arg->offset + size) >= arg->size) {
        size_t nsize = (arg->size ? arg->size << 2 : 16) + size;
        void *p = REALLOC(arg->buffer, nsize);
        if(!p) return -1;
        arg->buffer = (uint8_t *)p;
        arg->size = nsize;
    }

    memcpy(arg->buffer + arg->offset, buffer, size);
    arg->offset += size;
    assert(arg->offset < arg->size);

    return 0;
}

int
ANY_fromType(ANY_t *st, asn_TYPE_descriptor_t *td, void *sptr) {
    struct _callback_arg arg;
    asn_enc_rval_t erval = {0,0,0};

    if(!st || !td) {
        errno = EINVAL;
        return -1;
    }

    if(!sptr) {
        if(st->buf) FREEMEM(st->buf);
        st->size = 0;
        return 0;
    }

    arg.offset = arg.size = 0;
    arg.buffer = 0;

    erval = der_encode(td, sptr, ANY__consume_bytes, &arg);
    if(erval.encoded == -1) {
        if(arg.buffer) FREEMEM(arg.buffer);
        return -1;
    }
    assert((size_t)erval.encoded == arg.offset);

    if(st->buf) FREEMEM(st->buf);
    st->buf = arg.buffer;
    st->size = arg.offset;

    return 0;
}

ANY_t *
ANY_new_fromType(asn_TYPE_descriptor_t *td, void *sptr) {
    ANY_t tmp;
    ANY_t *st;

    if(!td || !sptr) {
        errno = EINVAL;
        return 0;
    }

    memset(&tmp, 0, sizeof(tmp));

    if(ANY_fromType(&tmp, td, sptr)) return 0;

    st = (ANY_t *)CALLOC(1, sizeof(ANY_t));
    if(st) {
        *st = tmp;
        return st;
    } else {
        FREEMEM(tmp.buf);
        return 0;
    }
}

int
ANY_to_type(ANY_t *st, asn_TYPE_descriptor_t *td, void **struct_ptr) {
    asn_dec_rval_t rval;
    void *newst = 0;

    if(!st || !td || !struct_ptr) {
        errno = EINVAL;
        return -1;
    }

    if(st->buf == 0) {
        /* Nothing to convert, make it empty. */
        *struct_ptr = (void *)0;
        return 0;
    }

    rval = ber_decode(0, td, (void **)&newst, st->buf, st->size);
    if(rval.code == RC_OK) {
        *struct_ptr = newst;
        return 0;
    } else {
        /* Remove possibly partially decoded data. */
        ASN_STRUCT_FREE(*td, newst);
        return -1;
    }
}
