/*
 * nanowasm, a tiny WebAssembly/Wasm interpreter
 * Copyright (C) 2023-2025  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 <nanowasm/nw.h>
#include <nw/global.h>
#include <nw/io.h>
#include <nw/interp.h>
#include <nw/stack.h>
#include <nw/log.h>
#include <nw/ops.h>
#include <nw/routines.h>

static enum nw_state set_global(struct nw_interp *const i)
{
    struct nw_i_sm_get_global *const g = &i->sm.get_global;
    const enum nw_state n = nwp_global_store(i, &g->io, g->index);

    if (n)
        return n;

    nwp_interp_resume(i);
    return NW_AGAIN;
}

static enum nw_state pop(struct nw_interp *const i)
{
    struct nw_i_sm_get_global *const g = &i->sm.get_global;
    const enum nw_state n = nwp_stack_pop(i, &g->io);

    if (n)
        return n;
    else
    {
        struct nw_sm_io io = {0};

        io.buf = &g->gl;
        io.n = sizeof g->gl;
        g->io = io;
        i->next = set_global;
    }

    return NW_AGAIN;
}

static enum nw_state read_global(struct nw_interp *const i)
{
    struct nw_i_sm_get_global *const g = &i->sm.get_global;
    struct nw_global *const gl = &g->gl;
    const enum nw_state n = nwp_global_load(i, &g->io, g->index);
    size_t sz;

    if (n)
        return n;
    else if (!gl->mutability)
    {
        static const char *const exc = "cannot set non-mutable global";

        i->exception = exc;
#ifdef NW_LOG
        nwp_log("%s, index: %lu\n", exc, (unsigned long)g->index);
#endif
        return NW_FATAL;
    }
    else if (nwp_type_sz(gl->type, &sz))
    {
        static const char *const exc = "invalid global type";

        i->exception = exc;
#ifdef NW_LOG
        nwp_log("%s: %#x\n", exc, (unsigned)gl->type);
#endif
        return NW_FATAL;
    }
    else
    {
        struct nw_sm_io io = {0};

        io.buf = &gl->value;
        io.n = sz;
        g->io = io;
        i->next = pop;
        i->push_type = gl->type;
    }

    return NW_AGAIN;
}

static enum nw_state get_index(struct nw_interp *const i)
{
    struct nw_i_sm_get_global *const g = &i->sm.get_global;
    struct nw_sm_leb128 *const l = &g->leb128;
    const struct nw_io_cfg *const cfg = &i->cfg.io;
    const enum nw_state n = nwp_varuint32(cfg, l, &g->index, cfg->user);

    if (n)
        return n;
    else
    {
        struct nw_sm_io io = {0};

        io.buf = &g->gl;
        io.n = sizeof g->gl;
        g->io = io;
        i->next = read_global;
    }

    return NW_AGAIN;
}

void nwp_op_set_global(struct nw_interp *const i)
{
    static const struct nw_i_sm_set_global g;

    i->sm.set_global = g;
    i->next = get_index;
}