/*
 * 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 enum nw_state set_local(struct nw_interp *const i)
{
    struct nw_i_sm_set_local *const sl = &i->sm.set_local;
    const enum nw_state n = nwp_stack_write(i, &sl->io, sl->f.l.addr);

    if (n)
        return n;

    i->next = sl->next;
    return NW_AGAIN;
}

static int init_io(struct nw_interp *const i, const enum nw_type t)
{
    struct nw_i_sm_set_local *const sl = &i->sm.set_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 = &sl->out.value;
        io.n = sz;
        sl->io = io;
    }

    return 0;
}

static enum nw_state pop(struct nw_interp *const i, const enum nw_type t,
    enum nw_state (*const next)(struct nw_interp *))
{
    struct nw_i_sm_set_local *const sl = &i->sm.set_local;
    const enum nw_state n = nwp_stack_pop(i, &sl->io);

    if (n)
        return n;
    else if (init_io(i, t))
        return NW_FATAL;

    sl->out.type = t;
    i->next = next;
    return NW_AGAIN;
}

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

    return pop(i, m->type, set_local);
}

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

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

    i->next = pop_local;
    return NW_AGAIN;
}

static enum nw_state set_param(struct nw_interp *const i)
{
    struct nw_i_sm_set_local *const sl = &i->sm.set_local;
    const enum nw_state n = nwp_stack_write(i, &sl->io, sl->f.p.out.addr);

    if (n)
        return n;

    i->next = sl->next;
    return NW_AGAIN;
}

static enum nw_state pop_param(struct nw_interp *const i)
{
    const struct nw_find_param_out *const o = &i->sm.set_local.f.p.out;

    return pop(i, o->type, set_param);
}

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

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

    i->next = pop_param;
    return NW_AGAIN;
}

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

    if (n)
        return n;
    else if (sl->index < fn->param_count)
        nwp_find_param(i, &sl->f.p, sl->index, prepare_param, NULL);
    else if ((index = sl->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)sl->index);
#endif
        return NW_FATAL;
    }
    else
        nwp_find_local(i, &sl->f.l, index, prepare_local, NULL);

    return NW_AGAIN;
}

void nwp_set_local(struct nw_interp *const i,
    enum nw_state (*const next)(struct nw_interp *))
{
    const struct nw_i_sm_set_local sl = {0};
    struct nw_i_sm_set_local *const p = &i->sm.set_local;

    *p = sl;
    p->next = next;
    i->next = get_index;
}