/*
 * 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 loop(struct nw_mod *const m)
{
    struct nw_sm_gl *const gl = &m->sm.global;
    const enum nw_state n = nwp_interp_run(&gl->interp);

    if (n)
        return n;

    m->next = nwp_section_exit;
    return NW_AGAIN;
}

static enum nw_state get_global(struct nw_mod *const m)
{
    struct nw_sm_gl *const gl = &m->sm.global;
    const struct nw_interp_cfg cfg =
    {
        .stack =
        {
            .buf = &gl->value,
            .n = sizeof gl->value
        },

        .m = m,
        .io = m->cfg.io
    };

    if (nwp_interp_start(&cfg, &nwp_interp_initexpr_set, &gl->interp))
    {
        LOG("%s: nw_interp_start failed\n", __func__);
        return NW_FATAL;
    }

    m->next = loop;
    return NW_AGAIN;
}

static enum nw_state get_mutability(struct nw_mod *const m)
{
    nw_varuint1 mutability;
    const struct nw_io_cfg *const cfg = &m->cfg.io;
    struct nw_sm_gl *const gl = &m->sm.global;
    struct nw_sm_leb128 *const l = &gl->leb128;
    const enum nw_state n = nwp_varuint1(cfg, l, &mutability);

    if (n)
        return n;

    m->next = get_global;
    return NW_AGAIN;
}

static int get_type(const nw_varint7 content_type, enum nw_type *const out)
{
    static const struct type
    {
        nw_varint7 key;
        enum nw_type value;
    } list[] =
    {
        {.key = 0x7f, .value = NW_TYPE_I32},
        {.key = 0x7e, .value = NW_TYPE_I64},
        {.key = 0x7d, .value = NW_TYPE_F32},
        {.key = 0x7c, .value = NW_TYPE_F64}
    };

    for (size_t i = 0; i < sizeof list / sizeof *list; i++)
    {
        const struct type *const t = &list[i];

        if (content_type == t->key)
        {
            *out = t->value;
            return 0;
        }
    }

    LOG("%s: invalid type: %#hhx\n", __func__, (char)content_type);
    return -1;
}

static enum nw_state get_content_type(struct nw_mod *const m)
{
    nw_varint7 content_type;
    const struct nw_io_cfg *const cfg = &m->cfg.io;
    struct nw_sm_gl *const gl = &m->sm.global;
    struct nw_sm_leb128 *const l = &gl->leb128;
    const enum nw_state n = nwp_varint7(cfg, l, &content_type);

    if (n)
        return n;
    else if (get_type(content_type, &gl->type))
    {
        LOG("%s: get_type failed\n", __func__);
        return NW_FATAL;
    }

    m->next = get_mutability;
    return NW_AGAIN;
}

static enum nw_state entry_loop(struct nw_mod *const m)
{
    const struct nw_sm_gl *const gl = &m->sm.global;

    m->next = gl->entry_i < m->global_count ?
        get_content_type : 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_gl *const gl = &m->sm.global;
    struct nw_sm_leb128 *const l = &gl->leb128;
    const enum nw_state n = nwp_varuint32(cfg, l, &m->global_count);

    if (n)
        return n;

    m->next = entry_loop;
    return NW_AGAIN;
}

void nwp_section_global(struct nw_mod *const m)
{
    m->next = get_count;
    m->sm.global = (const struct nw_sm_gl){0};
}