/*
 * 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/interp.h>
#include <nw/io.h>
#include <nw/log.h>
#include <nw/ops.h>
#include <nw/routines.h>
#include <nw/stack.h>
#include <nw/types.h>

static int init_io(struct nw_interp *const i, const enum nw_type t)
{
    struct nw_i_sm_get_local *const gl = &i->sm.get_local;
    size_t sz;

    if (nwp_type_sz(t, &sz))
    {
        static const char *const exc = "invalid type";

        i->exception = exc;
#ifdef NW_LOG
        nwp_log("%s: %#x\n", exc, (unsigned)t);
#endif
        return -1;
    }
    else
    {
        struct nw_sm_io io = {0};

        io.buf = &gl->value;
        io.n = sz;
        gl->io = io;
    }

    return 0;
}

static enum nw_state push(struct nw_interp *const i)
{
    struct nw_i_sm_get_local *const gl = &i->sm.get_local;
    const enum nw_state n = nwp_stack_push(i, &gl->io);

    if (n)
        return n;

    nwp_interp_resume(i);
    return NW_AGAIN;
}

static enum nw_state get_local(struct nw_interp *const i)
{
    struct nw_i_sm_get_local *const gl = &i->sm.get_local;
    const struct nw_local_meta *const m = &gl->f.l.meta;
    const enum nw_state n = nwp_stack_read(i, &gl->io, gl->f.l.addr);

    if (n)
        return n;
    else if (init_io(i, m->type))
        return NW_FATAL;

    i->next = push;
    i->push_type = m->type;
    return NW_AGAIN;
}

static enum nw_state prepare_local(struct nw_interp *const i)
{
    const struct nw_local_meta *const m = &i->sm.get_local.f.l.meta;

    if (init_io(i, m->type))
        return NW_FATAL;

    i->next = get_local;
    return NW_AGAIN;
}

static enum nw_state get_param(struct nw_interp *const i)
{
    struct nw_i_sm_get_local *const gl = &i->sm.get_local;
    const struct nw_find_param_out *const o = &gl->f.p.out;
    const enum nw_state n = nwp_stack_read(i, &gl->io, o->addr);

    if (n)
        return n;
    else if (init_io(i, o->type))
        return NW_FATAL;

    i->next = push;
    i->push_type = o->type;
    return NW_AGAIN;
}

static enum nw_state prepare_param(struct nw_interp *const i)
{
    struct nw_i_sm_get_local *const gl = &i->sm.get_local;
    const struct nw_find_param_out *const o = &gl->f.p.out;

    if (init_io(i, o->type))
        return NW_FATAL;

    i->next = get_param;
    return NW_AGAIN;
}

static enum nw_state get_index(struct nw_interp *const i)
{
    struct nw_i_sm_get_local *const gl = &i->sm.get_local;
    struct nw_sm_leb128 *const l = &gl->leb128;
    const struct nw_io_cfg *const cfg = &i->cfg.io;
    const struct nw_frame *const fr = &i->fr;
    const struct nw_fn *const fn = &fr->fn;
    const enum nw_state n = nwp_varuint32(cfg, l, &gl->index, cfg->user);
    nw_varuint32 index;

    if (n)
        return n;
    else if (gl->index < fn->param_count)
        nwp_find_param(i, &gl->f.p, gl->index, prepare_param, NULL);
    else if ((index = gl->index - fn->param_count) >= fr->local_count)
    {
        static const char *const exc = "invalid local index";

        i->exception = exc;
#ifdef NW_LOG
        nwp_log("%s: %lu\n", exc, (unsigned long)gl->index);
#endif
        return NW_FATAL;
    }
    else
        nwp_find_local(i, &gl->f.l, index, prepare_local, NULL);

    return NW_AGAIN;
}

void nwp_op_get_local(struct nw_interp *const i)
{
    static const struct nw_i_sm_get_local gl;

    i->sm.get_local = gl;
    i->next = get_index;
}