#include "startup_ap.h"

#include "../arch/core_interrupt.h"
#include "../arch/gdt.h"
#include "../arch/lapic.h"
#include "../arch/pit.h"
#include "../debug/assert.h"
#include "../debug/output.h"
#include "../utils/size.h"
#include "../utils/string.h"

namespace ApplicationProcessor {

// Make sure that the RELOCATED_SETUP is in low memory (< 1 MiB)
static_assert((RELOCATED_SETUP & ~0x000ff000) == 0,
              "Not a valid 1 MB address for RELOCATED_SETUP!");

/*! \brief Temporary Global Descriptor Table
 *
 * Blue print, to be copied into real mode code
 */
constinit GDT::SegmentDescriptor ap_gdt[] = {
    // nullptr-Deskriptor
    {},

    // XXX: Can't we just use GDT::protected_mode?
    // code segment
    GDT::SegmentDescriptor::Segment(0, UINT32_MAX, true, 0, GDT::SIZE_32BIT),

    // data segment
    GDT::SegmentDescriptor::Segment(0, UINT32_MAX, false, 0, GDT::SIZE_32BIT),
};

void relocateSetupCode() {
  // Relocated setup code
  memcpy(reinterpret_cast<void*>(RELOCATED_SETUP), &___SETUP_AP_START__,
         &___SETUP_AP_END__ - &___SETUP_AP_START__);

  // Adjust GDT:
  // Calculate offset for real mode GDT and GDT descriptor
  uintptr_t ap_gdt_offset = reinterpret_cast<uintptr_t>(&setup_ap_gdt) -
                            reinterpret_cast<uintptr_t>(&___SETUP_AP_START__);
  uintptr_t ap_gdtd_offset = reinterpret_cast<uintptr_t>(&setup_ap_gdtd) -
                             reinterpret_cast<uintptr_t>(&___SETUP_AP_START__);

  // Copy blue print of real mode GDT to the relocated memory
  void* relocated_ap_gdt =
      reinterpret_cast<void*>(RELOCATED_SETUP + ap_gdt_offset);
  memcpy(relocated_ap_gdt, &ap_gdt, sizeof(ap_gdt));

  // Calculate GDT descriptor for relocated address
  GDT::Pointer* relocated_ap_gdtd =
      reinterpret_cast<GDT::Pointer*>(RELOCATED_SETUP + ap_gdtd_offset);
  relocated_ap_gdtd->set(relocated_ap_gdt, size(ap_gdt));
}

void boot(void) {
  assert(!Core::Interrupt::isEnabled() &&
         "Interrupts should not be enabled before APs have booted!");

  // Relocate setup code
  relocateSetupCode();

  // Calculate Init-IPI vector based on address of relocated setup_ap()
  uint8_t vector = RELOCATED_SETUP >> 12;

  // Send Init-IPI to all APs
  LAPIC::IPI::sendInit();

  // wait at least 10ms
  PIT::delay(10000);

  // Send Startup-IPI twice
  DBG_VERBOSE << "Sending STARTUP IPI #1" << endl;
  LAPIC::IPI::sendStartup(vector);
  // wait at least 200us
  PIT::delay(200);

  DBG_VERBOSE << "Sending STARTUP IPI #2" << endl;
  LAPIC::IPI::sendStartup(vector);
}
}  // namespace ApplicationProcessor