#include <kernel/kernel.h>
#include <kernel/multiboot.h>
#include <kernel/serial.h>
#include <kernel/idt.h>
#include <kernel/pic.h>
#include <kernel/pit.h>

kernel_ctx_t ctx = {0};
struct idt_entry idt[256] = {0};
struct idtr idtr = {0};

extern uint32_t isr_stub_table[32];
extern void pit_isr(void);

void exception_handler(int_stack_frame_t r) {
    LOG("Exception 0x%X (0x%X) has occurred\nEAX: 0x%08X\nECX: 0x%08X\nEDX: 0x%08X\nEBX: 0x%08X\nESI: 0x%08X\nEDI: 0x%08X\nEBP: 0x%08X\nESP: 0x%08X\n",
            r.int_no, r.err_code, r.eax, r.ecx, r.edx, r.ebx, r.esi, r.edi, r.ebp, r.esp+24); 
    LOG("\nEIP:     0x%08X\nCS:      0x%08X\nEFLAGS:  0x%08X\n",
            r.eip, r.cs, r.eflags);
}

void sleep(int delay) {
    uint64_t end = ctx.ticks + delay;
    while (ctx.ticks < end)
	cpu_relax;
}

void kernel(multiboot_info_t *info) {
    if (!CHECK_FLAG(info->flags, 6)) goto halt;  // Memory map
    if (!CHECK_FLAG(info->flags, 12)) goto halt; // VBE data 
    ctx.mem_map = (multiboot_memory_map_t *)info->memmapaddress;
    ctx.mem_map_len = info->memmaplength;

    if (serial_port_init(COM1)) ctx.log_method = LOG_COM1;

    LOG("Kernel log being sent to COM1\n");

    for (int i = 0; i < 32; i++) {
        idt_encode_entry(idt, i, isr_stub_table[i], GDT_SEGMENT_SELECTOR(1, 0), TRAP_GATE_32 | INT_RING0 | INT_PRESENT);
    }
    idt_encode_entry(idt, 32, (uint32_t)pit_isr, GDT_SEGMENT_SELECTOR(1, 0), TRAP_GATE_32 | INT_RING0 | INT_PRESENT);
    
    idtr.size = (sizeof(struct idt_entry) * 256) - 1;
    idtr.base = (uint32_t) idt;

    asm volatile ("lidt %0" :: "m"(idtr));
    pic_remap(PIC_1_START, PIC_2_START);
    asm volatile ("sti" ::);

    ctx.ticks = 0;
    pit_init();

halt:
    for (;;) {}
}