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

static enum nw_state get_content_type(struct nw_inst *const i);

static enum nw_state store(struct nw_inst *const inst)
{
    struct nw_inst_sm_gl *const g = &inst->sm.global;
    struct nw_interp *const i = &inst->interp;
    const enum nw_state n = nwp_global_store(i, &g->io, g->entry_i);

    if (n)
        return n;

    inst->next = ++g->entry_i >= g->count ? g->next : get_content_type;
    return NW_AGAIN;
}

static enum nw_state pop(struct nw_inst *const inst)
{
    struct nw_inst_sm_gl *const g = &inst->sm.global;
    struct nw_interp *const i = &inst->interp;
    const enum nw_state n = nwp_stack_pop(i, &g->io);

    if (n)
        return n;
    else
    {
        struct nw_sm_io io = {0};

        io.buf = &g->out;
        io.n = sizeof g->out;
        g->io = io;
        inst->next = store;
    }

    return NW_AGAIN;
}

static enum nw_state loop(struct nw_inst *const i)
{
    struct nw_inst_sm_gl *const g = &i->sm.global;
    const enum nw_state n = nwp_interp_run(&i->interp);
    size_t sz;

    if (n)
        return n;
    else if (nwp_type_sz(g->out.type, &sz))
    {
#ifdef NW_LOG
        static const char *const exc = "invalid type";

        nwp_log("%s: %#x\n", exc, (unsigned)g->out.type);
#endif
        return NW_FATAL;
    }
    else
    {
        struct nw_sm_io io = {0};

        io.buf = &g->out.value;
        io.n = sz;
        g->io = io;
        i->next = pop;
    }

    return NW_AGAIN;
}

static enum nw_state get_mutability(struct nw_inst *const inst)
{
    struct nw_inst_sm_gl *const g = &inst->sm.global;
    struct nw_interp *const i = &inst->interp;
    const struct nw_io_cfg *const cfg = &i->cfg.io;
    struct nw_sm_leb128 *const l = &g->leb128;
    const enum nw_state n = nwp_varuint1(cfg, l, &g->out.mutability, cfg->user);

    if (n)
        return n;

    nwp_interp_resume(i);
    inst->next = loop;
    return NW_AGAIN;
}

static enum nw_state get_content_type(struct nw_inst *const i)
{
    nw_varint7 content_type;
    struct nw_inst_sm_gl *const g = &i->sm.global;
    const struct nw_io_cfg *const cfg = &i->interp.cfg.io;
    struct nw_sm_leb128 *const l = &g->leb128;
    const enum nw_state n = nwp_varint7(cfg, l, &content_type, cfg->user);

    if (n)
        return n;
    else if (nwp_get_type(content_type, &g->out.type))
    {
#ifdef NW_LOG
        static const char *const exc = "invalid type";

        nwp_log("%s: %#x\n", exc, (unsigned)content_type);
#endif
        return NW_FATAL;
    }

    i->next = get_mutability;
    return NW_AGAIN;
}

static enum nw_state get_count(struct nw_inst *const i)
{
    struct nw_inst_sm_gl *const g = &i->sm.global;
    struct nw_sm_leb128 *const l = &g->leb128;
    const struct nw_interp_cfg *const icfg = &i->interp.cfg;
    const struct nw_io_cfg *const cfg = &icfg->io;
    const nw_varuint32 expected = icfg->m->global_count;
    const enum nw_state n = nwp_varuint32(cfg, l, &g->count, cfg->user);

    if (n)
        return n;
    else if (g->count != expected)
    {
#ifdef NW_LOG
        static const char *const exc = "global count mismatch";

        nwp_log("%s, expected %lu, got %lu\n", exc,
            (unsigned long)expected, (unsigned long)g->count);
#endif
        return NW_FATAL;
    }

    i->next = g->count ? get_content_type : g->next;
    return NW_AGAIN;
}

static enum nw_state seek_global(struct nw_inst *const i)
{
    struct nw_inst_sm_gl *const g = &i->sm.global;
    const struct nw_interp_cfg *const icfg = &i->interp.cfg;
    const struct nw_io_cfg *const cfg = &icfg->io;
    const long offset = icfg->m->sections[NW_SECTION_GLOBAL];
    enum nw_state n;

    if (!offset)
    {
        i->next = g->next;
        return NW_AGAIN;
    }
    else if ((n = cfg->seek(offset, cfg->user)))
        return n;

    i->next = get_count;
    return NW_AGAIN;
}

void nwp_init_globals(struct nw_inst *const i,
    enum nw_state (*const next)(struct nw_inst *))
{
    const struct nw_inst_sm_gl gl = {0};
    struct nw_inst_sm_gl *const p = &i->sm.global;

    *p = gl;
    p->next = next;
    i->next = seek_global;
}