/*
 * Copyright (c) 2025 Ian Marco Moffett and the Osmora Team.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of Hyra nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPKERNE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LKERNS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * PKERNSIBILITY OF SUCH DAMAGE.
 */

#include <sys/types.h>
#include <sys/cdefs.h>
#include <kern/panic.h>
#include <os/trace.h>
#include <vm/phys.h>
#include <lib/limine.h>

#define dtrace(fmt, ...) trace("phys: " fmt, ##__VA_ARGS__)

#define MEM_GIB 0x40000000
#define MEM_MIB 0x100000

/* Aliases for portability */
#define MEM_USABLE              (LIMINE_MEMMAP_USABLE)
#define MEM_RESERVED            (LIMINE_MEMMAP_RESERVED)
#define MEM_ACPI_RECLAIMABLE    (LIMINE_MEMMAP_ACPI_RECLAIMABLE)
#define MEM_ACPI_NVS            (LIMINE_MEMMAP_ACPI_NVS)
#define MEM_BAD                 (LIMINE_MEMMAP_BAD_MEMORY)
#define MEM_BOOTLOADER          (LIMINE_MEMMAP_BOOTLOADER_RECLAIMABLE)
#define MEM_KERNEL              (LIMINE_MEMMAP_KERNEL_AND_MODULES)
#define MEM_FRAMEBUFFER         (LIMINE_MEMMAP_FRAMEBUFFER)

#define MEM_ENTRY(INDEX) (memmap_resp->entries[(INDEX)])
#define MEM_ENTRY_COUNT  (memmap_resp->entry_count)

typedef struct limine_memmap_entry mementry_t;

/* Memory statistics */
static size_t total_mem = 0;
static size_t free_mem = 0;
static size_t reserved_mem = 0;
static uintptr_t highest_usable = 0;

/*
 * Request a memor map from the bootloader
 */
static struct limine_memmap_response *memmap_resp;
static volatile struct limine_memmap_request memmap_req = {
    .id = LIMINE_MEMMAP_REQUEST,
    .revision = 0
};

/*
 * Print memory size related stats
 */
static void
vm_printstat(const char *name, size_t size)
{
    if (size >= MEM_GIB) {
        dtrace("%s %d GiB\n", name, size / MEM_GIB);
    } else {
        dtrace("%s %d MiB\n", name, size / MEM_MIB);
    }
}

/*
 * Probe for usable memory
 */
static void
vm_probe(void)
{
    mementry_t *entry;

    for (size_t i = 0; i < MEM_ENTRY_COUNT; ++i) {
        entry = MEM_ENTRY(i);

        if (entry->type != MEM_USABLE) {
            total_mem += entry->length;
            reserved_mem += entry->length;
            continue;
        }

        total_mem += entry->length;
        free_mem += entry->length;

        if ((entry->base + entry->length) > highest_usable) {
            highest_usable = entry->base + entry->length;
        }
    }

    vm_printstat("memory installed", total_mem);
    vm_printstat("memory usable", free_mem);
    vm_printstat("memory reserved", reserved_mem);
    dtrace("usable top @ %p\n", highest_usable);
}

void
vm_phys_init(void)
{
    memmap_resp = memmap_req.response;
    if (__unlikely(memmap_resp == NULL)) {
        panic("vm: unable to get memory map\n");
    }

    dtrace("checking memory resources...\n");
    vm_probe();
}