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

static int get_i32(struct nw_interp *const i, const void *const src)
{
    return interp_stack_push(i, src, sizeof (int32_t));
}

static int get_i64(struct nw_interp *const i, const void *const src)
{
    return interp_stack_push(i, src, sizeof (int64_t));
}

static int get_f32(struct nw_interp *const i, const void *const src)
{
    return interp_stack_push(i, src, sizeof (float));
}

static int get_f64(struct nw_interp *const i, const void *const src)
{
    return interp_stack_push(i, src, sizeof (double));
}

static int get_global(struct nw_interp *const i, const varuint32 global_index)
{
    struct nw_gframe *gfr;
    varuint32 idx;

    for (idx = global_index, gfr = i->gfp; gfr; gfr = gfr->next)
        if (idx == global_index)
            break;

    if (!gfr)
    {
        LOG("%s: cannot access global variable %lu\n", __func__,
            (unsigned long)global_index);
        i->exception = "global variable index out of bounds";
        return -1;
    }

    static int (*const get[])(struct nw_interp *, const void *) =
    {
        [VALUE_TYPE_I32] = get_i32,
        [VALUE_TYPE_I64] = get_i64,
        [VALUE_TYPE_F32] = get_f32,
        [VALUE_TYPE_F64] = get_f64,
    };

    if (get[gfr->type](i, gfr + 1))
    {
        LOG("%s: get type %s failed\n", __func__, value_type_tostr(gfr->type));
        return -1;
    }

    return 0;
}

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

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

    return 0;
}

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

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