#include <multiboot2.h>
#include <stdint.h>
#include <stddef.h>
#include "gdt.h"
#include "idt.h"
#include "pic.h"
#include "port_io.h"
#include "pmm.h"
#include "paging.h"
#include "kmalloc.h"
#include "driver.h"

void offset_print(const char *str)
{
    while (*str) {
        outb(0xE9, *str);
        str++;
    }
}

void print_hex(uint32_t val)
{
    const char *hex = "0123456789ABCDEF";
    outb(0xE9, '0');
    outb(0xE9, 'x');
    for (int i = 28; i >= 0; i -= 4) {
        outb(0xE9, hex[(val >> i) & 0xF]);
    }
    outb(0xE9, '\n');
}

void kernel_main(uint32_t magic, uint32_t addr) {
    if (magic != MULTIBOOT2_BOOTLOADER_MAGIC) {
        offset_print("Invalid magic number: ");
        print_hex(magic);
        return;
    }
    
    offset_print("Booting...\n");

    init_gdt();
    offset_print("GDT initialized\n");
    
    init_idt();
    offset_print("IDT initialized\n");

    init_pic();
    offset_print("PIC initialized\n");
    
    init_pmm(addr);
    offset_print("PMM initialized\n");

    init_paging();
    offset_print("Paging initialized\n");

    /* Test paging: allocate a page and write to it */
    void *test_page = paging_alloc_page();
    if (test_page) {
        offset_print("Allocated virtual page at: ");
        print_hex((uint32_t)test_page);
        *((volatile uint32_t *)test_page) = 0xDEADBEEF;
        offset_print("Virtual page write/read OK\n");
        paging_free_page(test_page);
    } else {
        offset_print("FAILED to allocate virtual page\n");
    }

    init_kmalloc();
    offset_print("Memory allocator initialized\n");

    init_drivers();
    offset_print("Drivers initialized\n");

    /* Test kmalloc/kfree */
    uint32_t *test_alloc = (uint32_t *)kmalloc(64);
    if (test_alloc) {
        *test_alloc = 42;
        offset_print("kmalloc(64) = ");
        print_hex((uint32_t)test_alloc);
        kfree(test_alloc);
        offset_print("kfree OK\n");
    } else {
        offset_print("FAILED to kmalloc\n");
    }

    /* Enable interrupts */
    asm volatile("sti");
    offset_print("Interrupts enabled\n");

    offset_print("Hello, world\n");
}