/*
 * 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 <nanowasm/nw.h>
#include <nw/interp.h>
#include <nw/io.h>
#include <nw/log.h>
#include <nw/routines.h>

static enum nw_state entry_loop(struct nw_mod *m);

static enum nw_state get_index(struct nw_mod *const m)
{
    nw_varuint32 index;
    const struct nw_io_cfg *const cfg = &m->cfg.io;
    struct nw_sm_exp *const e = &m->sm.export;
    struct nw_sm_leb128 *const l = &e->leb128;
    const enum nw_state n = nwp_varuint32(cfg, l, &index);

    if (n)
        return n;

    e->entry_i++;
    m->next = entry_loop;
    return NW_AGAIN;
}

static enum nw_state get_kind(struct nw_mod *const m)
{
    uint8_t kind;
    const struct nw_io_cfg *const cfg = &m->cfg.io;
    struct nw_sm_io io = {.buf = &kind, .n = sizeof kind};
    const enum nw_state n = nwp_io_read(cfg, &io);

    if (n)
        return n;

    /* TODO: check kind */
    m->next = get_index;
    return NW_AGAIN;
}

static enum nw_state get_name(struct nw_mod *const m)
{
    uint8_t b;
    struct nw_sm_exp *const e = &m->sm.export;
    const struct nw_io_cfg *const cfg = &m->cfg.io;
    struct nw_sm_io io = {.buf = &b, .n = sizeof b};
    const enum nw_state n = nwp_io_read(cfg, &io);

    if (n)
        return n;
    else if (++e->len_i >= e->field_len)
    {
        e->len_i = 0;
        m->next = get_kind;
    }

    return NW_AGAIN;
}

static enum nw_state get_len(struct nw_mod *const m)
{
    const struct nw_io_cfg *const cfg = &m->cfg.io;
    struct nw_sm_exp *const e = &m->sm.export;
    struct nw_sm_leb128 *const l = &e->leb128;
    const enum nw_state n = nwp_varuint32(cfg, l, &e->field_len);

    if (n)
        return n;
    else if (!e->field_len)
    {
        LOG("%s: invalid field length\n", __func__);
        return NW_FATAL;
    }

    m->next = get_name;
    return NW_AGAIN;
}

static enum nw_state entry_loop(struct nw_mod *const m)
{
    const struct nw_sm_exp *const e = &m->sm.export;

    m->next = e->entry_i < e->count ? get_len : nwp_section_exit;
    return NW_AGAIN;
}

static enum nw_state get_count(struct nw_mod *const m)
{
    const struct nw_io_cfg *const cfg = &m->cfg.io;
    struct nw_sm_exp *const e = &m->sm.export;
    struct nw_sm_leb128 *const l = &e->leb128;
    const enum nw_state n = nwp_varuint32(cfg, l, &e->count);

    if (n)
        return n;

    m->next = entry_loop;
    return NW_AGAIN;
}

void nwp_section_export(struct nw_mod *const m)
{
    m->next = get_count;
    m->sm.export = (const struct nw_sm_exp){0};
}