#include <amd64/gdt.h>
#include <amd64/proc.h>
#include <aux/elf.h>
#include <libk/align.h>
#include <libk/list.h>
#include <libk/rbtree.h>
#include <libk/std.h>
#include <libk/string.h>
#include <limine/requests.h>
#include <mm/liballoc.h>
#include <mm/pmm.h>
#include <proc/proc.h>
#include <proc/procgroup.h>
#include <proc/resource.h>
#include <sync/spin_lock.h>
#include <sys/debug.h>
#include <sys/proc.h>

static atomic_int pids = 0;

struct proc* proc_from_elf (uint8_t* elf_contents) {
  struct limine_hhdm_response* hhdm = limine_hhdm_request.response;

  struct proc* proc = malloc (sizeof (*proc));
  if (proc == NULL)
    return NULL;

  memset (proc, 0, sizeof (*proc));

  proc->lock = SPIN_LOCK_INIT;
  atomic_store (&proc->state, PROC_READY);
  proc->pid = atomic_fetch_add (&pids, 1);

  proc->procgroup = procgroup_create ();
  if (proc->procgroup == NULL) {
    free (proc);
    return NULL;
  }
  procgroup_attach (proc->procgroup, proc);

  uintptr_t kstack_paddr = pmm_alloc (KSTACK_SIZE / PAGE_SIZE);
  proc->pdata.kernel_stack = kstack_paddr + (uintptr_t)hhdm->offset + KSTACK_SIZE;

  procgroup_map (proc->procgroup, PROC_USTACK_TOP - USTACK_SIZE, USTACK_SIZE / PAGE_SIZE,
                 MM_PG_USER | MM_PG_PRESENT | MM_PG_RW, NULL);

  proc->flags |= PROC_USTK_PREALLOC;

  struct elf_aux aux = proc_load_segments (proc, elf_contents);

  proc->pdata.regs.ss = GDT_UDATA | 0x03;
  proc->pdata.regs.rsp = (uint64_t)PROC_USTACK_TOP;
  proc->pdata.regs.rflags = 0x202;
  proc->pdata.regs.cs = GDT_UCODE | 0x03;
  proc->pdata.regs.rip = aux.entry;

  return proc;
}

struct proc* proc_clone (struct proc* proto, uintptr_t vstack_top, uintptr_t entry) {
  struct limine_hhdm_response* hhdm = limine_hhdm_request.response;
  spin_lock_ctx_t ctxprt;

  struct proc* proc = malloc (sizeof (*proc));
  if (proc == NULL)
    return NULL;

  memset (proc, 0, sizeof (*proc));

  proc->lock = SPIN_LOCK_INIT;
  atomic_store (&proc->state, PROC_READY);
  proc->pid = atomic_fetch_add (&pids, 1);

  spin_lock (&proto->lock, &ctxprt);

  proc->procgroup = proto->procgroup;
  procgroup_attach (proc->procgroup, proc);

  spin_unlock (&proto->lock, &ctxprt);

  uintptr_t kstack_paddr = pmm_alloc (KSTACK_SIZE / PAGE_SIZE);
  proc->pdata.kernel_stack = kstack_paddr + (uintptr_t)hhdm->offset + KSTACK_SIZE;

  proc->pdata.regs.ss = GDT_UDATA | 0x03;
  proc->pdata.regs.rsp = (uint64_t)vstack_top;
  proc->pdata.regs.rflags = 0x202;
  proc->pdata.regs.cs = GDT_UCODE | 0x03;
  proc->pdata.regs.rip = (uint64_t)entry;

  proc_init_tls (proc);

  return proc;
}

void proc_cleanup (struct proc* proc) {
  spin_lock_ctx_t ctxsq, ctxpr;

  spin_lock (&proc->lock, &ctxpr);

  /* clean suspension queue entries */
  struct list_node_link *sq_link, *sq_link_tmp;
  list_foreach (proc->sq_entries, sq_link, sq_link_tmp) {
    struct proc_sq_entry* sq_entry = list_entry (sq_link, struct proc_sq_entry, proc_link);
    struct proc_suspension_q* sq = sq_entry->sq;

    spin_lock (&sq->lock, &ctxsq);

    /* remove from sq's list */
    list_remove (sq->proc_list, &sq_entry->sq_link);

    /* remove from proc's list */
    list_remove (proc->sq_entries, &sq_entry->proc_link);

    spin_unlock (&sq->lock, &ctxsq);

    free (sq_entry);
  }

  spin_unlock (&proc->lock, &ctxpr);

  pmm_free (proc->pdata.kernel_stack, KSTACK_SIZE / PAGE_SIZE);
  procgroup_unmap (proc->procgroup, proc->pdata.tls_vaddr, proc->procgroup->tls.tls_tmpl_pages);

  procgroup_detach (proc->procgroup, proc);

  /* clean the process */
  free (proc);
}

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

  size_t tls_size = proc->procgroup->tls.tls_tmpl_size;

  uintptr_t tls_paddr;
  uint32_t flags = MM_PG_USER | MM_PG_PRESENT | MM_PG_RW;

  uintptr_t tls_vaddr =
      procgroup_map (proc->procgroup, 0, proc->procgroup->tls.tls_tmpl_pages, flags, &tls_paddr);

  uintptr_t k_tls_addr = (uintptr_t)hhdm->offset + tls_paddr;

  uintptr_t ktcb = k_tls_addr + tls_size;
  uintptr_t utcb = tls_vaddr + tls_size;

  memset ((void*)k_tls_addr, 0, tls_size);
  memcpy ((void*)k_tls_addr, (void*)proc->procgroup->tls.tls_tmpl, tls_size);

  *(uintptr_t*)ktcb = utcb;

  proc->pdata.fs_base = utcb;
  proc->pdata.tls_vaddr = tls_vaddr;
}