/*
 * 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 condition(struct nw_interp *const i)
{
    const struct nw_i_sm_br_if *const b = &i->sm.br_if;

    switch (i->push_type)
    {
        case NW_TYPE_I32:
            return b->condition.i32;

        case NW_TYPE_I64:
            return b->condition.i64.low || b->condition.i64.hi;

        case NW_TYPE_F32:
            return b->condition.f32;

        case NW_TYPE_F64:
            return b->condition.f64;
    }

    return 0;
}

static enum nw_state pop(struct nw_interp *const i)
{
    struct nw_i_sm_br_if *const b = &i->sm.br_if;
    const enum nw_state n = nwp_stack_pop(i, &b->io);

    if (n)
        return n;
    else if (condition(i))
        nwp_break(i, b->relative_depth, 0);
    else
        nwp_interp_resume(i);

    return NW_AGAIN;
}

static enum nw_state get_relative_depth(struct nw_interp *const i)
{
    struct nw_i_sm_br_if *const b = &i->sm.br_if;
    const struct nw_io_cfg *const cfg = &i->cfg.io;
    const enum nw_state n = nwp_varuint32(cfg, &b->leb128,
        &b->relative_depth, cfg->user);
    size_t sz;

    if (n)
        return n;
    else if (nwp_type_sz(i->push_type, &sz))
    {
        static const char *const exc = "invalid type";

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

        io.buf = &b->condition;
        io.n = sz;
        b->io = io;
        i->next = pop;
    }

    return NW_AGAIN;
}

void nwp_op_br_if(struct nw_interp *const i)
{
    static const struct nw_i_sm_br_if b;

    i->next = get_relative_depth;
    i->sm.br_if = b;
}