/*
 * nanowasm, a tiny WebAssembly/Wasm interpreter
 * Copyright (C) 2023-2024  Xavier Del Campo Romero
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 */

#include <nw/log.h>
#include <nw/ops.h>
#include <nanowasm/nw.h>
#include <nw/types.h>
#include <nw/interp.h>
#include <stdint.h>
#include <stddef.h>
#include <stdio.h>

static int store(struct nw_interp *const i, const varuint32 flags,
    const varuint32 offset)
{
    enum {ALIGN = 2};

    if (flags != ALIGN)
    {
        LOG("%s: expected 32-bit alignment (%d), got %lu\n",
            __func__, ALIGN, (unsigned long)flags);
        i->exception = "unaligned access";
        return -1;
    }

    int32_t value, addr;

    if (interp_stack_pop(i, &value, sizeof value))
    {
        LOG("%s: inter_stack_pop value failed\n", __func__);
        return -1;
    }
    else if (interp_stack_pop(i, &addr, sizeof addr))
    {
        LOG("%s: inter_stack_pop addr failed\n", __func__);
        return -1;
    }
    else if (offset > SIZE_MAX - addr)
    {
        static const char exc[] = "offset address overflow";

        LOG("%s: %s\n", __func__, exc);
        i->exception = exc;
        return -1;
    }

    const int32_t value_le = htoni32(value);

    if (interp_heap_store(i, offset + addr, &value_le, sizeof value_le))
    {
        LOG("%s: interp_heap_store failed\n", __func__);
        return -1;
    }

    return 0;
#if 0
    stack_i -= sizeof addr;

    if (max < addr || offset >= max - addr)
    {
        LOG("%s: heap overflow\n", __func__);
        i->exception = "heap overflow";
        return -1;
    }

    const size_t raddr = offset + addr;

    if (raddr % sizeof addr)
    {
        LOG("%s: unaligned memory address\n", __func__);
        i->exception = "unaligned access";
        return -1;
    }
    else if (stack_i < sizeof (uint32_t))
    {
        LOG("%s: stack underflow (value)\n", __func__);
        i->exception = "stack underflow";
        return -1;
    }

    const int32_t value = htoni32(*stackptr);
    void *dst = &((char *)i->cfg.heap.buf)[raddr];

    *(int32_t *)dst = value;
    stack_i -= sizeof addr;
    i->stack_i = stack_i;
    return 0;
#endif
}

static int op(struct nw_interp *const i, FILE *const f)
{
    varuint32 flags, offset;

    if (varuint32_read(f, &flags))
    {
        LOG("%s: varint32_read flags failed\n", __func__);
        return -1;
    }
    else if (varuint32_read(f, &offset))
    {
        LOG("%s: varint32_read offset failed\n", __func__);
        return -1;
    }
    else if (i && store(i, flags, offset))
    {
        LOG("%s: store failed\n", __func__);
        return -1;
    }

    return 0;
}

int op_i32_store(struct nw_interp *const i)
{
    return op(i, i->f);
}

int check_i32_store(FILE *const f)
{
    return op(NULL, f);
}