#include "kernel/filesystem/type_registry.hpp"
#include <kernel/devices/storage/management.hpp>
#include <kernel/filesystem/open_file_table.hpp>
#include <kernel/filesystem/vfs.hpp>
#include <kernel/memory.hpp>

#include <kapi/boot_modules.hpp>
#include <kapi/cio.hpp>
#include <kapi/cpu.hpp>
#include <kapi/devices.hpp>
#include <kapi/filesystem.hpp>
#include <kapi/interrupts.hpp>
#include <kapi/memory.hpp>
#include <kapi/system.hpp>

#include <kstd/format>
#include <kstd/print>
#include <kstd/units>
#include <kstd/vector>

#include <cstddef>
#include <string_view>

using namespace kstd::units_literals;

auto run_demo() -> void
{
  // 1) open a file
  kstd::println("attempting to open /entrance/tickets.txt");
  auto fd_1 = kapi::filesystem::open("/entrance/tickets.txt");
  if (fd_1 == -1)
  {
    kapi::system::panic("demo failed");
  }
  else
  {
    kstd::println("--> successfully opened /entrance/tickets.txt with file descriptor {}", fd_1);
  }

  // 2) read from the file
  kstd::vector<std::byte> buffer_1{10};
  auto bytes_read = kapi::filesystem::read(fd_1, buffer_1.data(), buffer_1.size());
  auto buffer_as_str = std::string_view{reinterpret_cast<char *>(buffer_1.data()), static_cast<size_t>(bytes_read)};
  kstd::println("--> read {} bytes from /entrance/tickets.txt: {}", bytes_read, buffer_as_str);
  kstd::println("");

  // 3) show that /entrance/information/info_1.txt is not accessible before mounting
  kstd::println("attempting to open /entrance/information/info_1.txt before mounting");
  auto fd_before_mount = kapi::filesystem::open("/entrance/information/info_1.txt");
  if (fd_before_mount == -1)
  {
    kstd::println("--> as expected the file could not be opened before mounting");
  }

  // 4) mount a new filesystem on top of /entrance
  kstd::println("mount /dev/ram16 to /entrance");
  if (kapi::filesystem::mount("/dev/ram16", "/entrance") == 0)
  {
    kstd::println("--> successfully mounted /dev/ram16 to /entrance");
  }
  else
  {
    kapi::system::panic("demo failed");
  }
  kstd::println("");

  // 5) open a file from the new filesystem
  kstd::println("attempting to open /entrance/information/info_1.txt");
  auto fd_2 = kapi::filesystem::open("/entrance/information/info_1.txt");
  if (fd_2 != -1)
  {
    kstd::println("--> successfully opened /entrance/information/info_1.txt with file descriptor {}", fd_2);
  }
  else
  {
    kapi::system::panic("demo failed");
  }

  // 6) read from the new file
  kstd::vector<std::byte> buffer_2{10};
  bytes_read = kapi::filesystem::read(fd_2, buffer_2.data(), buffer_2.size());
  buffer_as_str = std::string_view{reinterpret_cast<char *>(buffer_2.data()), static_cast<size_t>(bytes_read)};
  kstd::println("--> read {} bytes from /entrance/information/info_1.txt: {} ", bytes_read, buffer_as_str);

  // 7) open device as file
  kstd::println("attempting to open /dev/ram32 as a file");
  auto fd_3 = kapi::filesystem::open("/dev/ram32");
  if (fd_3 != -1)
  {
    kstd::println("--> successfully opened /dev/ram32 as a file with file descriptor {}", fd_3);
  }
  else
  {
    kapi::system::panic("demo failed");
  }

  // 8) read from the device file
  kstd::vector<std::byte> buffer_3{2};
  bytes_read = kapi::filesystem::read(fd_3, buffer_3.data(), buffer_3.size());
  kstd::println("--> read {} bytes from /dev/ram32: {::#04x} ", bytes_read, buffer_3);

  // 9) write to the device file
  auto const default_buffer_value = std::byte{0xAA};
  kstd::vector<std::byte> write_buffer{default_buffer_value, default_buffer_value};
  auto bytes_written = kapi::filesystem::write(fd_3, write_buffer.data(), write_buffer.size());
  kstd::println("--> written {} bytes to /dev/ram32: {::#04x}", bytes_written, write_buffer);

  // 10) do memory dump to show that the write to the device file had an effect
}

auto main() -> int
{
  kapi::cio::init();
  kstd::println("[OS] IO subsystem initialized.");

  kapi::cpu::init();

  kapi::memory::init();
  kernel::memory::init_heap(kapi::memory::heap_base);
  kapi::system::memory_initialized();
  kapi::memory::init_mmio(kapi::memory::mmio_base, 1_GiB / kapi::memory::page::size);
  kstd::println("[OS] Memory subsystem initialized.");

  kapi::devices::init();
  kstd::println("[OS] System root bus initialized.");

  kapi::devices::init_platform_devices();
  kstd::println("[OS] Platform devices initialized.");

  kapi::interrupts::enable();
  kstd::println("[OS] Interrupts enabled.");

  kapi::boot_modules::init();
  kstd::println("[OS] Boot module registry initialized.");

  kernel::devices::storage::management::init();
  kstd::println("[OS] Storage management initialized.");

  kernel::filesystem::open_file_table::init();
  kstd::println("[OS] Global open file table initialized.");

  kernel::filesystem::type_registry::init();
  kstd::println("[OS] Builtin filesystems registered.");

  kernel::filesystem::vfs::init();
  kstd::println("[OS] Virtual filesystem initialized.");

  // TODO BA-FS26 remove demo code?
  // run_demo();

  kapi::system::panic("Returning from kernel main!");
}