#include "vmm.h"
#include <stdlib.h>

typedef void (*constructor)();

extern "C" {
/* .text */
uint32_t begin_text;
uint32_t end_text;

/* .rodata */
uint32_t begin_rodata;
uint32_t end_rodata;

/* .data */
uint32_t begin_constinit;
uint32_t end_constinit;
constructor begin_ctors;
constructor end_ctors;
uint32_t begin_data;
uint32_t end_data;

/* .bss */
uint32_t begin_bss;
uint32_t end_bss;

void kernel_constructors() {
  for (constructor* i = &begin_ctors; i != &end_ctors; ++i) (*i)();
}

void dump_address() {
  printk("text      begin: ", uhex{reinterpret_cast<uint32_t>(&begin_text)},
         " end: ", uhex{reinterpret_cast<uint32_t>(&end_text)}, '\n');

  printk("rodata    begin: ", uhex{reinterpret_cast<uint32_t>(&begin_rodata)},
         " end: ", uhex{reinterpret_cast<uint32_t>(&end_rodata)}, '\n');

  printk("constinit begin: ", uhex{reinterpret_cast<uint32_t>(&begin_constinit)},
         " end: ", uhex{reinterpret_cast<uint32_t>(&end_constinit)}, '\n');

  printk("ctors     begin: ", uhex{reinterpret_cast<uint32_t>(&begin_ctors)},
         " end: ", uhex{reinterpret_cast<uint32_t>(&end_ctors)}, '\n');

  printk("data      begin: ", uhex{reinterpret_cast<uint32_t>(&begin_data)},
         " end: ", uhex{reinterpret_cast<uint32_t>(&end_data)}, '\n');

  printk("bss       begin: ", uhex{reinterpret_cast<uint32_t>(&begin_bss)},
         " end: ", uhex{reinterpret_cast<uint32_t>(&end_bss)}, '\n');
}
}  // extern "C"

/* boot.S page directory and kernel page table */
extern uint32_t kernel_pagedir;
extern uint32_t kernel_ptable0;

constexpr uint32_t to_vma(uint32_t page_dir_address) {
  page_dir_address &= 0xfffff000;
  page_dir_address += 0xc0000000;
  page_dir_address -= 0x00400000;
  return page_dir_address;
}

vmm::vmm(uint32_t* addr) : directory{(addr == nullptr) ? &kernel_pagedir : addr} {
  printk("page directory is at ", uhex{reinterpret_cast<uint32_t>(directory)}, '\n');
  printk("page table 768       ", uhex{reinterpret_cast<uint32_t>(directory[768])}, '\n');
  printk("page table 768 vma   ", uhex{to_vma(reinterpret_cast<uint32_t>(directory[768]))}, '\n');
  printk("kernel_ptable0 is at ", uhex{reinterpret_cast<uint32_t>(&kernel_ptable0)}, '\n');

  uint32_t* page = reinterpret_cast<uint32_t*>(&kernel_ptable0);
  for (size_t i = 0; i < 32; ++i) {
    printk(uhex{page[i] & 0xfffff000}, ' ');
    if (i % 4 == 3) printk('\n');
  }
}

uint32_t vmm::map(uint32_t phys_addr, uint32_t dest) {
  const auto phys_offset = phys_addr % 4096;
  const auto phys_page = phys_addr - phys_offset;

  const auto table = table_id(dest);
  const auto page = page_id(dest - table * 4 * 1024 * 1024);

  printk("phys_addr page: ", uhex{phys_page}, '\n');
  printk("        offset: ", uhex{phys_offset}, '\n');
  printk("         table: ", table, '\n');
  printk("          page: ", page, '\n');

  if (directory[table] == 0) return 0;

  uint32_t* page_table = reinterpret_cast<uint32_t*>(to_vma(reinterpret_cast<uint32_t>(directory[table])));
  if (page_table[page] != 0) return 0;
  page_table[page] = phys_page | 0x003;

  uint32_t cr0;
  asm volatile("mov %%cr0, %0" : "=r"(cr0));
  asm volatile("mov %0, %%cr0" : : "r"(cr0));

  return table * 4 * 1024 * 1024 + page * 4 * 1024 + phys_offset;
}