#include <amd64/gdt.h>
#include <amd64/intr.h>
#include <amd64/mm.h>
#include <amd64/msr-index.h>
#include <amd64/msr.h>
#include <libk/list.h>
#include <libk/string.h>
#include <m/status.h>
#include <m/syscall_defs.h>
#include <mm/liballoc.h>
#include <proc/proc.h>
#include <proc/reschedule.h>
#include <sys/debug.h>
#include <sys/smp.h>
#include <syscall/syscall.h>

extern void amd64_syscall_entry (void);

uintptr_t amd64_syscall_dispatch (void* stack_ptr) {
  amd64_load_kernel_cr3 ();
  struct saved_regs* regs = stack_ptr;

  spin_lock (&thiscpu->lock);
  struct proc* caller = thiscpu->proc_current;
  int caller_pid = caller->pid;
  spin_lock (&caller->lock);

  memcpy (&caller->pdata.regs, regs, sizeof (struct saved_regs));

  spin_unlock (&caller->lock);
  spin_unlock (&thiscpu->lock);

  int syscall_num = regs->rax;
  syscall_handler_func_t func = syscall_find_handler (syscall_num);

  if (func == NULL) {
    return -ST_SYSCALL_NOT_FOUND;
  }

  struct reschedule_ctx rctx = {.reschedule = false, .cpu = NULL};

  uintptr_t r =
      func (caller, regs, &rctx, regs->rdi, regs->rsi, regs->rdx, regs->r10, regs->r8, regs->r9);

  caller = proc_find_pid (caller_pid);

  if (caller != NULL) {
    spin_lock (&caller->lock);
    caller->pdata.regs.rax = r;
    spin_unlock (&caller->lock);
  }

  if (rctx.reschedule)
    cpu_request_sched (rctx.cpu);

  return r;
}

void syscall_init (void) {
  amd64_wrmsr (MSR_STAR, ((uint64_t)GDT_KCODE << 32) | ((uint64_t)(GDT_KDATA | 0x03) << 48));
  amd64_wrmsr (MSR_LSTAR, (uint64_t)&amd64_syscall_entry);
  amd64_wrmsr (MSR_SYSCALL_MASK, (1ULL << 9));
  amd64_wrmsr (MSR_EFER, amd64_rdmsr (MSR_EFER) | EFER_SCE);
}