#include <amd64/apic.h>
#include <amd64/init.h>
#include <amd64/mm.h>
#include <amd64/msr-index.h>
#include <amd64/msr.h>
#include <libk/std.h>
#include <libk/string.h>
#include <limine/requests.h>
#include <mm/liballoc.h>
#include <sync/spin_lock.h>
#include <sys/debug.h>
#include <sys/smp.h>

static uint32_t cpu_counter = 0;
static spin_lock_t cpu_counter_lock = SPIN_LOCK_INIT;
static struct cpu cpus[CPUS_MAX];

struct cpu* cpu_make (void) {
  spin_lock (&cpu_counter_lock);
  int id = cpu_counter++;
  spin_unlock (&cpu_counter_lock);

  struct cpu* cpu = &cpus[id];

  memset (cpu, 0, sizeof (*cpu));
  cpu->id = id;

  return cpu_get (id);
}

struct cpu* cpu_get (uint32_t id) {
  if (id >= CPUS_MAX)
    return NULL;

  return &cpus[id];
}

uint32_t cpu_id (void) { return (uint32_t)amd64_rdmsr (MSR_GS_BASE); }

void cpu_assign (uint32_t id) { amd64_wrmsr (MSR_GS_BASE, (uint64_t)id); }

static void amd64_smp_bootstrap (struct limine_mp_info* mp_info) {
  amd64_load_kernel_cr3 ();

  struct cpu* cpu = cpu_make ();
  cpu_assign (cpu->id);

  amd64_init (cpu, true); /* gdt + idt */

  thiscpu->lapic_ticks = amd64_lapic_init (2500);
  amd64_lapic_tick (thiscpu->lapic_ticks);

  DEBUG ("CPU %u is online!\n", thiscpu->id);

  __asm__ volatile ("sti");

  for (;;)
    ;
}

void smp_init (void) {
  thiscpu->lapic_ticks = amd64_lapic_init (2500);

  struct limine_mp_response* mp = limine_mp_request.response;

  for (size_t i = 0; i < mp->cpu_count; i++) {
    if (mp->cpus[i]->lapic_id != thiscpu->id) {
      DEBUG ("Trying CPU %u\n", mp->cpus[i]->lapic_id);
      mp->cpus[i]->goto_address = &amd64_smp_bootstrap;
    }
  }
}