#include "kapi/cpu.hpp"

#include "kapi/acpi.hpp"
#include "kapi/devices.hpp"
#include "kapi/devices/cpu.hpp"
#include "kapi/memory.hpp"
#include "kapi/system.hpp"

#include "arch/cpu/initialization.hpp"
#include "arch/devices/local_apic.hpp"

#include <kstd/memory>
#include <kstd/print>

#include <acpi/acpi.hpp>

#include <atomic>
#include <ranges>
#include <utility>

namespace kapi::cpu
{

  namespace
  {
    constexpr auto candidate_flags = ::acpi::processor_local_apic::flags::processor_enabled  //
                                     | ::acpi::processor_local_apic::flags::online_capable;
  }

  auto init() -> void
  {
    auto static constinit is_initialized = std::atomic_flag{};

    if (is_initialized.test_and_set())
    {
      system::panic("[x86_64] CPU has already been initialized.");
    }

    arch::cpu::initialize_descriptors();
    arch::cpu::initialize_legacy_interrupts();
  }

  auto halt() -> void
  {
    asm volatile("1: hlt\njmp 1b");
    __builtin_unreachable();
  }

  auto discover_topology() -> bool
  {
    auto static const cpu_major = kapi::devices::allocate_major_number();
    auto static const core_major = kapi::devices::allocate_major_number();
    auto static const interrupt_controller_major = kapi::devices::allocate_major_number();

    auto madt = kapi::acpi::get_table<::acpi::madt_table_signature>();
    if (!madt)
    {
      kstd::println("[x86_64:PLT] Failed to find ACPI APIC table");
      return false;
    }

    auto lapic_entries = *madt | std::views::filter([](auto const & entry) {
      return entry.type() == ::acpi::madt_entry::types::processor_local_apic;
    }) | std::views::transform([](auto const & entry) {
      return static_cast<::acpi::processor_local_apic const &>(entry);
    }) | std::views::filter([](auto const & entry) {
      return static_cast<bool>(entry.active_flags() & candidate_flags);
    });

    auto bsp_found = false;
    auto core_count = 0uz;
    auto local_apic_address = memory::physical_address{madt->local_interrupt_controller_address()};
    auto cpu_bus = kstd::make_unique<devices::cpu>(cpu_major, 0);

    for (auto const & apic : lapic_entries)
    {
      auto is_bsp = !bsp_found;
      bsp_found = true;
      auto core = kstd::make_unique<devices::cpu::core>(core_major, core_count, apic.processor_id(), is_bsp);
      core->add_child(kstd::make_unique<arch::devices::local_apic>(interrupt_controller_major, core_count,
                                                                   apic.apic_id(), local_apic_address, is_bsp));
      cpu_bus->add_child(std::move(core));
      ++core_count;
    }

    devices::get_root_bus().add_child(std::move(cpu_bus));

    kstd::println("[x86_64:PLT] Found {} CPU cores", core_count);
    return core_count > 0;
  }

}  // namespace kapi::cpu