#include <amd64/gdt.h>
#include <amd64/proc.h>
#include <aux/elf.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/rw_spin_lock.h>
#include <sync/spin_lock.h>
#include <sys/debug.h>

/* 0 is kpproc */
static atomic_int pids = 1;

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

  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);

  rid = procgroup_get_sys_rid (proc->procgroup);
  struct proc_resource* kstk_r =
      proc_create_resource_mem (proc->procgroup, rid, KSTACK_SIZE / PAGE_SIZE, 0, false);
  if (kstk_r == NULL) {
    procgroup_detach (proc->procgroup, proc);
    free (proc);
    return NULL;
  }

  proc->pdata.kernel_stack = kstk_r->u.mem.paddr + (uintptr_t)hhdm->offset + KSTACK_SIZE;

  rid = procgroup_get_sys_rid (proc->procgroup);
  struct proc_resource* ustk_r =
      proc_create_resource_mem (proc->procgroup, rid, USTACK_SIZE / PAGE_SIZE, 0, false);
  if (ustk_r == NULL) {
    kstk_r->ops.cleanup (kstk_r);
    free (kstk_r);
    procgroup_detach (proc->procgroup, proc);
    free (proc);
    return NULL;
  }

  proc->pdata.user_stack = ustk_r->u.mem.paddr;

  proc_map (proc, proc->pdata.user_stack, PROC_USTACK_TOP - USTACK_SIZE, USTACK_SIZE / PAGE_SIZE,
            MM_PG_USER | MM_PG_PRESENT | MM_PG_RW);

  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, size_t stack_size,
                         uintptr_t entry) {
  struct limine_hhdm_response* hhdm = limine_hhdm_request.response;
  spin_lock_ctx_t ctxprt;
  int rid;

  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 vstack_bottom = vstack_top - stack_size;

  uintptr_t pstack_bottom = mm_v2p (&proc->procgroup->pd, vstack_bottom, MM_PD_LOCK);
  if (pstack_bottom == 0) {
    procgroup_detach (proc->procgroup, proc);
    free (proc);
    return NULL;
  }

  rid = procgroup_get_sys_rid (proc->procgroup);
  struct proc_resource* kstk_r =
      proc_create_resource_mem (proc->procgroup, rid, KSTACK_SIZE / PAGE_SIZE, 0, false);
  if (kstk_r == NULL) {
    procgroup_detach (proc->procgroup, proc);
    free (proc);
    return NULL;
  }

  proc->pdata.kernel_stack = kstk_r->u.mem.paddr + (uintptr_t)hhdm->offset + KSTACK_SIZE;

  proc->pdata.user_stack = pstack_bottom + stack_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;

  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);

  procgroup_detach (proc->procgroup, proc);

  /* clean virtual address space */
  /* if (atomic_fetch_sub (&proc->pd->refs, 1) == 1) { */
  /*   DEBUG ("PID %d Free virtual address space\n", proc->pid); */
  /*   struct list_node_link *mapping_link, *mapping_link_tmp; */
  /*   spin_lock (&proc->pd->lock, &ctxprpd); */

  /*   list_foreach (proc->mappings, mapping_link, mapping_link_tmp) { */
  /*     struct proc_mapping* mapping = */
  /*         list_entry (mapping_link, struct proc_mapping, proc_mappings_link); */

  /*     list_remove (proc->mappings, mapping_link); */
  /*     free (mapping); */
  /*   } */

  /*   pmm_free (proc->pd->cr3_paddr, 1); */
  /*   spin_unlock (&proc->pd->lock, &ctxprpd); */
  /*   free (proc->pd); */
  /* } */

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