/*
  StarForth — Steady-State Virtual Machine Runtime

  Copyright (c) 2023–2025 Robert A. James
  All rights reserved.

  This file is part of the StarForth project.

  Licensed under the StarForth License, Version 1.0 (the "License");
  you may not use this file except in compliance with the License.

  You may obtain a copy of the License at:
      https://github.com/star.4th@proton.me/StarForth/LICENSE.txt

  This software is provided "AS IS", WITHOUT WARRANTY OF ANY KIND,
  express or implied, including but not limited to the warranties of
  merchantability, fitness for a particular purpose, and noninfringement.

 See the License for the specific language governing permissions and
 limitations under the License.

 */

/**
 * session.c - Per-VM session bookkeeping (FABRIC-3.md §H.12 steps 2-3)
 *
 * Slot table sized from stadium_max_vm_count() at session_boot_init() time,
 * mirroring stadium.c's own StadiumVMQuota table (kmalloc'd to a
 * budget-computed count, not a fixed compile-time array -- population isn't
 * knowable in advance, same reasoning stadium.c's own history already
 * settled). No callers yet; wiring into the boot sequence and into
 * stadium_birth_hera()/capsule_birth.c's admission path are later
 * §H.12 steps.
 *
 * session_set_pinned()/session_is_pinned() (step 3) are the pin-authority
 * choke point -- see their own doc comments in session.h for the
 * authoritative-session-mirrored-Stadium-bit split.
 */

#ifdef __STARKERNEL__

#include "starkernel/session.h"
#include "starkernel/vm/stadium.h"
#include "starkernel/kmalloc.h"

static Session *g_sessions        = (Session *)0;
static size_t   g_session_slots   = 0; /* capacity, from stadium_max_vm_count() */
static size_t   g_session_count   = 0; /* slots actually in use, 0..g_session_slots */

int session_boot_init(void)
{
    size_t max_vm_count = stadium_max_vm_count();
    Session *slots;
    size_t i;

    if (max_vm_count == 0) return -1; /* Stadium not yet initialized */

    slots = (Session *)kmalloc(max_vm_count * sizeof(Session));
    if (!slots) return -1;

    for (i = 0; i < max_vm_count; i++) {
        uint8_t *raw = (uint8_t *)&slots[i];
        size_t   j;
        for (j = 0; j < sizeof(Session); j++) raw[j] = 0;
        slots[i].vm_id  = vm_uuid_none();
        slots[i].parent = vm_uuid_none();
    }

    g_sessions      = slots;
    g_session_slots = max_vm_count;
    g_session_count = 0;
    return 0;
}

Session *session_find(VMUuid vm_id)
{
    size_t i;

    if (!g_sessions) return (Session *)0;

    for (i = 0; i < g_session_slots; i++) {
        if (!vm_uuid_is_none(g_sessions[i].vm_id) &&
            vm_uuid_equal(g_sessions[i].vm_id, vm_id)) {
            return &g_sessions[i];
        }
    }
    return (Session *)0;
}

Session *session_register(VMUuid vm_id, VMUuid parent, const char *name)
{
    size_t i;
    Session *slot = (Session *)0;

    if (!g_sessions) return (Session *)0;
    if (session_find(vm_id)) return (Session *)0; /* already registered */

    for (i = 0; i < g_session_slots; i++) {
        if (vm_uuid_is_none(g_sessions[i].vm_id)) {
            slot = &g_sessions[i];
            break;
        }
    }
    if (!slot) return (Session *)0; /* table full */

    slot->vm_id       = vm_id;
    slot->parent      = parent;
    slot->pinned      = 0;
    slot->stadium_cell = SESSION_STADIUM_CELL_NONE;

    {
        size_t j = 0;
        if (name) {
            for (; j < SESSION_NAME_BUF - 1u && name[j]; j++) slot->name[j] = name[j];
        }
        slot->name[j] = '\0';
    }

    {
        uint8_t *raw = (uint8_t *)&slot->identity;
        size_t   j;
        for (j = 0; j < sizeof(VMIdentity); j++) raw[j] = 0;
    }

    g_session_count++;
    return slot;
}

void session_set_pinned(VMUuid vm_id, int pinned)
{
    Session *s = session_find(vm_id);
    StadiumCell *cells;

    if (!s) return;
    s->pinned = pinned ? 1 : 0;

    if (s->stadium_cell == SESSION_STADIUM_CELL_NONE) return;
    if (s->stadium_cell >= stadium_cell_count()) return;

    cells = stadium_cells();
    if (!cells) return;

    if (pinned) {
        cells[s->stadium_cell].header.flags |= STADIUM_FLAG_PIN;
    } else {
        cells[s->stadium_cell].header.flags &= (uint8_t)~STADIUM_FLAG_PIN;
    }
}

int session_is_pinned(VMUuid vm_id)
{
    Session *s = session_find(vm_id);
    if (!s) return 0;
    return s->pinned;
}

#endif /* __STARKERNEL__ */