/*
 * Copyright (C) 2025 Johnny Richard <johnny@johnnyrichard.com>
 *
 * SPDX-License-Identifier: LGPL-3.0-or-later
 *
 * This file is part of obe.
 *
 * obe is free software: you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation, either version 3 of the License, or (at your option)
 * any later version.
 *
 * obe is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
 * details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with obe. If not, see <https://www.gnu.org/licenses/>.
 */
#include <assert.h>
#include <obe/arena.h>
#include <stdlib.h>
#include <string.h>

void*
obe_arena_alloc(obe_arena_t* arena, size_t size)
{
    if (arena->end == NULL) {
        assert(arena->begin == NULL);
        size_t capacity = OBE_ARENA_REGION_DEFAULT_CAPACITY;
        if (capacity < OBE_ARENA_PADDING(size))
            capacity = size + OBE_ARENA_PADDING(size);
        arena->end = obe_arena_region_new(capacity);
        arena->begin = arena->end;
    }

    while (arena->end->offset + size > arena->end->capacity &&
           arena->end->next != NULL) {
        arena->end = arena->end->next;
    }

    if (arena->end->offset + size > arena->end->capacity) {
        assert(arena->end->next == NULL);
        size_t capacity = OBE_ARENA_REGION_DEFAULT_CAPACITY;
        if (capacity < size)
            capacity = size + OBE_ARENA_PADDING(size);
        arena->end->next = obe_arena_region_new(capacity);
        arena->end = arena->end->next;
    }

    void* ptr = arena->end->data + arena->end->offset;
    arena->end->offset += size + OBE_ARENA_PADDING(size);
    return ptr;
}

void*
obe_arena_realloc(obe_arena_t* arena,
                  void* old_ptr,
                  size_t old_size,
                  size_t new_size)
{
    if (new_size <= old_size)
        return old_ptr;
    void* new_ptr = obe_arena_alloc(arena, new_size);
    return memcpy(new_ptr, old_ptr, old_size);
}

void
obe_arena_release(obe_arena_t* arena)
{
    for (obe_arena_region_t* r = arena->begin; r != NULL; r = r->next) {
        r->offset = 0;
    }
    arena->end = arena->begin;
}

void
obe_arena_free(obe_arena_t* arena)
{
    obe_arena_region_t* r = arena->begin;
    while (r) {
        obe_arena_region_t* r_tmp = r;
        r = r->next;
        obe_arena_region_free(r_tmp);
    }
    arena->begin = NULL;
    arena->end = NULL;
}

obe_arena_region_t*
obe_arena_region_new(size_t capacity)
{
    size_t size = sizeof(obe_arena_region_t) + sizeof(uint8_t) * capacity;
    obe_arena_region_t* r = (obe_arena_region_t*)malloc(size);
    assert(r);
    r->next = NULL;
    r->offset = 0;
    r->capacity = capacity;
    r->data = (uint8_t*)(r + 1);
    return r;
}

void
obe_arena_region_free(obe_arena_region_t* r)
{
    free(r);
}

char*
obe_arena_strdup(obe_arena_t* arena, char* s)
{
    size_t slen = strlen(s);
    char* d = obe_arena_alloc(arena, sizeof(char) * (slen + 1));
    assert(d);

    for (size_t i = 0; i <= slen; ++i)
        d[i] = s[i];

    return d;
}