/*
 * 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/.
 */

#ifndef NANOWASM_TYPES_H
#define NANOWASM_TYPES_H

#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>

#ifdef __cplusplus
extern "C"
{
#endif

union nw_value
{
    long i32;
    long long i64;
    float f32;
    double f64;
    /* TODO: define {de}serialization between Wasm and host. */
    void *p;
};

enum nw_kind
{
    NW_KIND_FUNCTION,
    NW_KIND_TABLE,
    NW_KIND_MEMORY,
    NW_KIND_GLOBAL
};

struct nw_args
{
    const union nw_value *args;
    size_t n;
};

struct nw_buf
{
    void *buf;
    size_t n;
};

enum nw_state
{
    NW_STATE_AGAIN,
    NW_STATE_RETURNED,
    NW_STATE_EXCEPTION,
    NW_STATE_FATAL
};

struct nw_mod_cfg
{
    const struct nw_import
    {
        enum nw_kind kind;
        const char *module, *field;

        union
        {
            struct
            {
                /* This must follow the format below, whitespace ignored:
                 * [return type]([param type][, ...])
                 * For convenience, the interpreter can do automatic checks on
                 * pointer arguments and/or return values if using '*' as type.
                 * Examples:
                 * "()"
                 * "i32(f32)"
                 * "*(f64, i32, *, i64)"
                 * As per WebAssembly MVP spec, multiple return types are not
                 * supported yet. */
                const char *signature;
                int (*fn)(const struct nw_args *params,
                    union nw_value *ret, void *user);
            } function;
        } u;
    } *imports;

    size_t n_imports;
    const char *path;
    void *user;
};

struct nw_interp_cfg
{
    struct nw_buf stack, heap, global;
    const struct nw_mod *m;
};

struct nw_inst_cfg
{
    struct nw_interp_cfg interp;
};

struct nw_mod
{
    struct nw_sections
    {
        long type, import, function, table, memory, global, export,
            start, element, code, data;
    } sections;

    size_t data_len, heap_len;
    struct nw_mod_cfg cfg;
};

struct nw_inst
{
    struct nw_interp
    {
        const struct nw_mod *m;
        FILE *f;
        const char *exception;
        bool exit;
        int retval;
        struct nw_interp_cfg cfg;
        size_t stack_i, global_i;
        struct nw_frame *fp;
        struct nw_gframe *gfp;
    } interp;

    union nw_inst_state
    {
        long retval;
        const char *exception;
    } state;
};

#define NW_BUF(sz) {.buf = (char [sz]){0}, .n = sz}

#ifdef __cplusplus
}
#endif

#endif