#include <amd64/apic.h>
#include <libk/std.h>
#include <limine/requests.h>
#include <sys/debug.h>
#include <sys/mm.h>
#include <uacpi/acpi.h>
#include <uacpi/status.h>
#include <uacpi/tables.h>
#include <uacpi/uacpi.h>

#define IOAPICS_MAX                 24
#define INTERRUPT_SRC_OVERRIDES_MAX 24

static struct acpi_madt_ioapic apics[IOAPICS_MAX];
/* clang-format off */
static struct acpi_madt_interrupt_source_override intr_src_overrides[INTERRUPT_SRC_OVERRIDES_MAX];
/* clang-format on */
static size_t ioapic_entries = 0;
static size_t intr_src_override_entries = 0;

extern void amd64_spin (void);

static uint32_t amd64_ioapic_read (uintptr_t vaddr, uint32_t reg) {
  *(volatile uint32_t*)vaddr = reg;
  return *(volatile uint32_t*)(vaddr + 0x10);
}

static void amd64_ioapic_write (uintptr_t vaddr, uint32_t reg, uint32_t value) {
  *(volatile uint32_t*)vaddr = reg;
  *(volatile uint32_t*)(vaddr + 0x10) = value;
}

static struct acpi_madt_ioapic* amd64_ioapic_find (uint8_t irq) {
  struct acpi_madt_ioapic* apic = NULL;
  struct limine_hhdm_response* hhdm = limine_hhdm_request.response;

  for (size_t i = 0; i < ioapic_entries; i++) {
    apic = &apics[i];
    uint32_t version = amd64_ioapic_read (
        (uintptr_t)hhdm->offset + (uintptr_t)apic->address, 1);
    uint32_t max = (version >> 16);

    if ((apic->gsi_base <= irq) && ((apic->gsi_base + max) > irq))
      break;
  }

  return apic;
}

void amd64_ioapic_route_irq (uint8_t vec, uint8_t irq, uint64_t flags,
                             uint64_t lapic_id) {
  struct acpi_madt_ioapic* apic;
  struct acpi_madt_interrupt_source_override* override;
  bool found_override = false;
  struct limine_hhdm_response* hhdm = limine_hhdm_request.response;

  for (size_t i = 0; i < intr_src_override_entries; i++) {
    override = &intr_src_overrides[i];
    if (override->source == irq) {
      found_override = true;
      break;
    }
  }

  uint64_t calc_flags = (lapic_id << 56) | (flags) | (vec & 0xFF);

  if (found_override) {
    uint8_t polarity = ((override->flags & 0x03) == 0x03) ? 1 : 0;
    uint8_t mode = (((override->flags >> 2) & 0x03) == 0x03) ? 1 : 0;
    calc_flags = (lapic_id << 56) | (mode << 15) | (polarity << 14) |
        (vec & 0xFF) | flags;
  }

  apic = amd64_ioapic_find (irq);

  if (apic == NULL)
    return;

  uint32_t irq_reg = ((irq - apic->gsi_base) * 2) + 0x10;

  amd64_ioapic_write ((uintptr_t)hhdm->offset + (uintptr_t)apic->address,
                      irq_reg, (uint32_t)calc_flags);

  amd64_ioapic_write ((uintptr_t)hhdm->offset + (uintptr_t)apic->address,
                      irq_reg + 1, (uint32_t)(calc_flags >> 32));
}

void amd64_ioapic_mask (uint8_t irq) {
  struct acpi_madt_ioapic* apic;
  struct limine_hhdm_response* hhdm = limine_hhdm_request.response;

  apic = amd64_ioapic_find (irq);

  if (apic == NULL)
    return;

  uint32_t irq_reg = ((irq - apic->gsi_base) * 2) + 0x10;

  uint32_t value = amd64_ioapic_read (
      (uintptr_t)hhdm->offset + (uintptr_t)apic->address, irq_reg);
  amd64_ioapic_write ((uintptr_t)hhdm->offset + (uintptr_t)apic->address,
                      irq_reg, value | (1 << 16));
}

void amd64_ioapic_unmask (uint8_t irq) {
  struct acpi_madt_ioapic* apic;
  struct limine_hhdm_response* hhdm = limine_hhdm_request.response;

  apic = amd64_ioapic_find (irq);

  if (apic == NULL)
    return;

  uint32_t irq_reg = ((irq - apic->gsi_base) * 2) + 0x10;

  uint32_t value = amd64_ioapic_read (
      (uintptr_t)hhdm->offset + (uintptr_t)apic->address, irq_reg);
  amd64_ioapic_write ((uintptr_t)hhdm->offset + (uintptr_t)apic->address,
                      irq_reg, value & ~(1 << 16));
}

void amd64_ioapic_init (void) {
  struct limine_hhdm_response* hhdm = limine_hhdm_request.response;

  struct uacpi_table apic_table;
  uacpi_status status =
      uacpi_table_find_by_signature (ACPI_MADT_SIGNATURE, &apic_table);
  if (status != UACPI_STATUS_OK) {
    DEBUG ("Could not find MADT table!\n");
    amd64_spin ();
  }

  struct acpi_madt* apic = (struct acpi_madt*)apic_table.virt_addr;
  struct acpi_entry_hdr* current = (struct acpi_entry_hdr*)apic->entries;

  for (;;) {
    if ((uintptr_t)current >= ((uintptr_t)apic->entries + apic->hdr.length -
                               sizeof (struct acpi_madt)))
      break;

    switch (current->type) {
    case ACPI_MADT_ENTRY_TYPE_IOAPIC: {
      struct acpi_madt_ioapic* ioapic = (struct acpi_madt_ioapic*)current;
      mm_map_kernel_page ((uintptr_t)ioapic->address,
                          (uintptr_t)hhdm->offset + (uintptr_t)ioapic->address,
                          MM_PG_USER | MM_PG_RW);
      apics[ioapic_entries++] = *ioapic;
    } break;
    case ACPI_MADT_ENTRY_TYPE_INTERRUPT_SOURCE_OVERRIDE: {
      struct acpi_madt_interrupt_source_override* override =
          (struct acpi_madt_interrupt_source_override*)current;
      intr_src_overrides[intr_src_override_entries++] = *override;
    } break;
    }

    current = (struct acpi_entry_hdr*)((uintptr_t)current + current->length);
  }
}