#include <aux/compiler.h>
#include <device/device.h>
#include <fs/path.h>
#include <fs/vfs.h>
#include <libk/assert.h>
#include <libk/fieldlengthof.h>
#include <libk/fieldsizeof.h>
#include <libk/std.h>
#include <limine/requests.h>
#include <m/status.h>
#include <m/syscall_defs.h>
#include <mm/pmm.h>
#include <proc/mail.h>
#include <proc/mutex.h>
#include <proc/proc.h>
#include <proc/procgroup.h>
#include <proc/resource.h>
#include <sync/spin_lock.h>
#include <sys/debug.h>
#include <sys/mm.h>
#include <sys/proc.h>
#include <syscall/syscall.h>

#define DEFINE_SYSCALL(name)                                                                       \
  uintptr_t name (struct proc* UNUSED proc, void* UNUSED regs, bool* UNUSED reschedule,            \
                  struct cpu** UNUSED reschedule_cpu, uintptr_t UNUSED a1, uintptr_t UNUSED a2,    \
                  uintptr_t UNUSED a3, uintptr_t UNUSED a4, uintptr_t UNUSED a5,                   \
                  uintptr_t UNUSED a6)

#define SYSRESULT(x) ((uintptr_t)(x))

static void* sys_get_user_buffer (struct proc* proc, uintptr_t uvaddr, size_t size) {
  struct limine_hhdm_response* hhdm = limine_hhdm_request.response;

  spin_lock (&proc->procgroup->lock);

  if (!mm_validate_buffer (&proc->procgroup->pd, (uintptr_t)uvaddr, size)) {
    spin_unlock (&proc->procgroup->lock);
    return NULL;
  }

  uintptr_t out_paddr = mm_v2p (&proc->procgroup->pd, uvaddr);

  spin_unlock (&proc->procgroup->lock);

  uintptr_t out_kvaddr = (uintptr_t)hhdm->offset + out_paddr;

  return (void*)out_kvaddr;
}

/* int quit (void) */
DEFINE_SYSCALL (sys_quit) {
  if (proc_kill (proc, reschedule_cpu) == PROC_NEED_RESCHEDULE)
    *reschedule = true;

  return SYSRESULT (ST_OK);
}

/* int test (void) */
DEFINE_SYSCALL (sys_test) {
  char c = (char)a1;
  DEBUG ("test syscall from %d! %c\n", proc->pid, c);
  return SYSRESULT (ST_OK);
}

/* int map (uintptr_t vaddr, size_t pages, uint32_t flags) */
DEFINE_SYSCALL (sys_map) {
  uintptr_t vaddr = a1;
  size_t pages = (size_t)a2;
  uint32_t flags = (uint32_t)a3;

  if (vaddr % PAGE_SIZE != 0)
    return SYSRESULT (-ST_UNALIGNED);

  return SYSRESULT (procgroup_map (proc->procgroup, vaddr, pages, flags, NULL));
}

/* int unmap (uintptr_t vaddr, size_t pages) */
DEFINE_SYSCALL (sys_unmap) {
  uintptr_t vaddr = a1;
  size_t pages = (size_t)a2;

  if (vaddr % PAGE_SIZE != 0)
    return SYSRESULT (-ST_UNALIGNED);

  return SYSRESULT (procgroup_unmap (proc->procgroup, vaddr, pages));
}

/* int clone (uintptr_t vstack_top, void* entry, void* argument_ptr) */
DEFINE_SYSCALL (sys_clone) {
  uintptr_t vstack_top = a1;
  uintptr_t entry = a2;
  uintptr_t argument_ptr = a3;

  struct proc* new = proc_clone (proc, vstack_top, entry, argument_ptr);

  if (new == NULL) {
    return SYSRESULT (-ST_OOM_ERROR);
  }

  int pid = new->pid;

  if (proc_register (new, reschedule_cpu) == PROC_NEED_RESCHEDULE)
    *reschedule = true;

  return SYSRESULT (pid);
}

/* void* argument_ptr (void) */
DEFINE_SYSCALL (sys_argument_ptr) { return proc->uvaddr_argument; }

/* int sched (void) */
DEFINE_SYSCALL (sys_sched) {
  *reschedule = true;
  return SYSRESULT (ST_OK);
}

/* int mutex_create (int mutex_rid) */
DEFINE_SYSCALL (sys_mutex_create) {
  int mutex_rid = (int)a1;

  struct proc_resource* mutex_resource = proc_create_resource_mutex (proc->procgroup, mutex_rid);

  if (mutex_resource == NULL)
    return SYSRESULT (-ST_OOM_ERROR);

  return SYSRESULT (mutex_resource->rid);
}

/* int mutex_delete (int mutex_rid) */
DEFINE_SYSCALL (sys_mutex_delete) {
  int mutex_rid = (int)a1;

  struct proc_resource* mutex_resource = proc_find_resource (proc->procgroup, mutex_rid);

  if (mutex_resource == NULL)
    return SYSRESULT (-ST_NOT_FOUND);

  if (proc_delete_resource (mutex_resource, reschedule_cpu) == PROC_NEED_RESCHEDULE)
    *reschedule = true;

  return SYSRESULT (ST_OK);
}

/* int mutex_lock (int mutex_rid) */
DEFINE_SYSCALL (sys_mutex_lock) {
  int mutex_rid = (int)a1;

  struct proc_resource* mutex_resource = proc_find_resource (proc->procgroup, mutex_rid);

  if (mutex_resource == NULL)
    return SYSRESULT (-ST_NOT_FOUND);

  if (proc_mutex_lock (proc, &mutex_resource->u.mutex, reschedule_cpu) == PROC_NEED_RESCHEDULE)
    *reschedule = true;

  return SYSRESULT (ST_OK);
}

/* int mutex_unlock (int mutex_rid) */
DEFINE_SYSCALL (sys_mutex_unlock) {
  int mutex_rid = (int)a1;

  struct proc_resource* mutex_resource = proc_find_resource (proc->procgroup, mutex_rid);

  if (mutex_resource == NULL)
    return SYSRESULT (-ST_NOT_FOUND);

  if (proc_mutex_unlock (proc, &mutex_resource->u.mutex, reschedule_cpu) == PROC_NEED_RESCHEDULE)
    *reschedule = true;

  return SYSRESULT (ST_OK);
}

/* int mail_send (int pgid, void* mesg, size_t mesg_size) */
DEFINE_SYSCALL (sys_mail_send) {
  int pgid = (int)a1;
  uintptr_t uvaddr_mesg = a2;
  size_t mesg_size = (size_t)a3;

  void* mesg = sys_get_user_buffer (proc, uvaddr_mesg, mesg_size);

  if (mesg == NULL)
    return SYSRESULT (-ST_BAD_ADDRESS_SPACE);

  struct procgroup* procgroup = procgroup_find (pgid);

  if (procgroup == NULL)
    return SYSRESULT (-ST_NOT_FOUND);

  struct proc_resource* mail_resource = proc_find_resource (procgroup, 1);

  if (mail_resource == NULL)
    return SYSRESULT (-ST_NOT_FOUND);

  if (proc_mail_send (proc, &mail_resource->u.mail, reschedule_cpu, mesg, mesg_size) ==
      PROC_NEED_RESCHEDULE) {
    *reschedule = true;
  }

  return SYSRESULT (ST_OK);
}

/* int mail_receive (void* recv_mesg, size_t mesg_size) */
DEFINE_SYSCALL (sys_mail_receive) {
  uintptr_t uvaddr_mesg = a1;
  size_t mesg_size = (size_t)a2;

  void* mesg = sys_get_user_buffer (proc, uvaddr_mesg, mesg_size);

  if (mesg == NULL)
    return SYSRESULT (-ST_BAD_ADDRESS_SPACE);

  struct proc_resource* mail_resource = proc_find_resource (proc->procgroup, 1);

  if (mail_resource == NULL)
    return SYSRESULT (-ST_NOT_FOUND);

  if (proc_mail_receive (proc, &mail_resource->u.mail, reschedule_cpu, mesg, mesg_size) ==
      PROC_NEED_RESCHEDULE) {
    *reschedule = true;
  }

  return SYSRESULT (ST_OK);
}

/* int device_do (int device_id, int cmd, void* a1, void* a2, void* a3, void* a4) */
DEFINE_SYSCALL (sys_device_do) {
  struct limine_hhdm_response* hhdm = limine_hhdm_request.response;

  int device_id = (int)a1;
  int cmd = (int)a2;
  uintptr_t ua1 = a3, ka1 = 0;
  uintptr_t ua2 = a4, ka2 = 0;
  uintptr_t ua3 = a5, ka3 = 0;
  uintptr_t ua4 = a6, ka4 = 0;
  uintptr_t out_paddr;

  if (!(cmd >= 0 && cmd < (int)fieldlengthof (struct device, ops)))
    return SYSRESULT (-ST_BAD_DEVICE_OP);

  spin_lock (&proc->procgroup->lock);

  out_paddr = mm_v2p (&proc->procgroup->pd, ua1);
  if (out_paddr != 0)
    ka1 = (uintptr_t)hhdm->offset + out_paddr;

  out_paddr = mm_v2p (&proc->procgroup->pd, ua2);
  if (out_paddr != 0)
    ka2 = (uintptr_t)hhdm->offset + out_paddr;

  out_paddr = mm_v2p (&proc->procgroup->pd, ua3);
  if (out_paddr != 0)
    ka3 = (uintptr_t)hhdm->offset + out_paddr;

  out_paddr = mm_v2p (&proc->procgroup->pd, ua4);
  if (out_paddr != 0)
    ka4 = (uintptr_t)hhdm->offset + out_paddr;

  spin_unlock (&proc->procgroup->lock);

  struct device* device = device_find (device_id);

  if (device == NULL)
    return SYSRESULT (-ST_NOT_FOUND);

  struct device_op_ctx op_ctx = {
      .proc = proc,
      .reschedule = reschedule,
      .reschedule_cpu = reschedule_cpu,
  };

  spin_lock (&device->lock);

  int ret = device->ops[cmd](device, &op_ctx, (void*)ka1, (void*)ka2, (void*)ka3, (void*)ka4);

  spin_unlock (&device->lock);

  return SYSRESULT (ret);
}

/* int exec (char* path) */
DEFINE_SYSCALL (sys_exec) {
  uintptr_t uvaddr_path = a1;

  struct limine_hhdm_response* hhdm = limine_hhdm_request.response;

  uintptr_t out_paddr;

  spin_lock (&proc->procgroup->lock);
  out_paddr = mm_v2p (&proc->procgroup->pd, uvaddr_path);
  spin_unlock (&proc->procgroup->lock);

  if (out_paddr == 0)
    return SYSRESULT (-ST_BAD_ADDRESS_SPACE);

  const char* path = (const char*)((uintptr_t)hhdm->offset + out_paddr);

  char mountpoint[fieldsizeof (struct vfs_mountpoint, key)];
  const char* subpath = NULL;

  if (!path_parse (path, mountpoint, &subpath))
    return SYSRESULT (-ST_BAD_PATH);

  struct proc* new = proc_from_file (proc->procgroup, mountpoint, subpath);

  if (new == NULL)
    return SYSRESULT (-ST_EXEC_ERROR);

  int pid = new->pid;
  new->exec_pid = proc->pid;

  if (proc_register (new, reschedule_cpu) == PROC_NEED_RESCHEDULE)
    *reschedule = true;

  return SYSRESULT (pid);
}

/* int open (char* path) */
DEFINE_SYSCALL (sys_open) {
  uintptr_t uvaddr_path = a1;

  struct limine_hhdm_response* hhdm = limine_hhdm_request.response;

  uintptr_t out_paddr;

  spin_lock (&proc->procgroup->lock);
  out_paddr = mm_v2p (&proc->procgroup->pd, uvaddr_path);
  spin_unlock (&proc->procgroup->lock);

  if (out_paddr == 0)
    return SYSRESULT (-ST_BAD_ADDRESS_SPACE);

  const char* path = (const char*)((uintptr_t)hhdm->offset + out_paddr);

  char mountpoint[fieldsizeof (struct vfs_mountpoint, key)];
  const char* subpath = NULL;

  if (!path_parse (path, mountpoint, &subpath))
    return SYSRESULT (-ST_BAD_PATH);

  return SYSRESULT (vfs_open (proc->procgroup, mountpoint, subpath));
}

/* int close (char* path) */
DEFINE_SYSCALL (sys_close) {
  uintptr_t uvaddr_path = a1;

  struct limine_hhdm_response* hhdm = limine_hhdm_request.response;

  uintptr_t out_paddr;

  spin_lock (&proc->procgroup->lock);
  out_paddr = mm_v2p (&proc->procgroup->pd, uvaddr_path);
  spin_unlock (&proc->procgroup->lock);

  if (out_paddr == 0)
    return SYSRESULT (-ST_BAD_ADDRESS_SPACE);

  const char* path = (const char*)((uintptr_t)hhdm->offset + out_paddr);

  char mountpoint[fieldsizeof (struct vfs_mountpoint, key)];
  const char* subpath = NULL;

  if (!path_parse (path, mountpoint, &subpath))
    return SYSRESULT (-ST_BAD_PATH);

  return SYSRESULT (vfs_close (proc->procgroup, mountpoint, subpath));
}

/* int read (char* path, size_t off, uint8_t* buffer, size_t size) */
DEFINE_SYSCALL (sys_read) {
  uintptr_t uvaddr_path = a1;
  size_t off = (size_t)a2;
  uintptr_t uvaddr_buffer = a3;
  size_t size = (size_t)a4;

  uint8_t* buffer = sys_get_user_buffer (proc, uvaddr_buffer, size);

  if (buffer == NULL)
    return SYSRESULT (-ST_BAD_ADDRESS_SPACE);

  struct limine_hhdm_response* hhdm = limine_hhdm_request.response;

  uintptr_t out_paddr;

  spin_lock (&proc->procgroup->lock);
  out_paddr = mm_v2p (&proc->procgroup->pd, uvaddr_path);
  spin_unlock (&proc->procgroup->lock);

  if (out_paddr == 0)
    return SYSRESULT (-ST_BAD_ADDRESS_SPACE);

  const char* path = (const char*)((uintptr_t)hhdm->offset + out_paddr);

  char mountpoint[fieldsizeof (struct vfs_mountpoint, key)];
  const char* subpath = NULL;

  if (!path_parse (path, mountpoint, &subpath))
    return SYSRESULT (-ST_BAD_PATH);

  return SYSRESULT (vfs_read (proc->procgroup, mountpoint, subpath, buffer, off, size));
}

/* int describe (char* path, struct fs_desc_buffer* desc) */
DEFINE_SYSCALL (sys_describe) {
  uintptr_t uvaddr_path = a1;
  uintptr_t uvaddr_desc = a2;

  struct fs_desc_buffer* desc =
      sys_get_user_buffer (proc, uvaddr_desc, sizeof (struct fs_desc_buffer));

  if (desc == NULL)
    return SYSRESULT (-ST_BAD_ADDRESS_SPACE);

  struct limine_hhdm_response* hhdm = limine_hhdm_request.response;

  uintptr_t out_paddr;

  spin_lock (&proc->procgroup->lock);
  out_paddr = mm_v2p (&proc->procgroup->pd, uvaddr_path);
  spin_unlock (&proc->procgroup->lock);

  if (out_paddr == 0)
    return SYSRESULT (-ST_BAD_ADDRESS_SPACE);

  const char* path = (const char*)((uintptr_t)hhdm->offset + out_paddr);

  char mountpoint[fieldsizeof (struct vfs_mountpoint, key)];
  const char* subpath = NULL;

  if (!path_parse (path, mountpoint, &subpath))
    return SYSRESULT (-ST_BAD_PATH);

  return SYSRESULT (vfs_describe (proc->procgroup, mountpoint, subpath, desc));
}

/* int get_procgroup (int pid) */
DEFINE_SYSCALL (sys_get_procgroup) {
  int pid = (int)a1;

  struct proc* target_proc = proc_find_pid (pid);

  return SYSRESULT (target_proc->procgroup->pgid);
}

/* int get_exec_pid (void) */
DEFINE_SYSCALL (sys_get_exec_pid) { return SYSRESULT (proc->exec_pid); }

static syscall_handler_func_t handler_table[] = {
    [SYS_QUIT] = &sys_quit,
    [SYS_TEST] = &sys_test,
    [SYS_MAP] = &sys_map,
    [SYS_UNMAP] = &sys_unmap,
    [SYS_CLONE] = &sys_clone,
    [SYS_ARGUMENT_PTR] = &sys_argument_ptr,
    [SYS_SCHED] = &sys_sched,
    [SYS_MUTEX_CREATE] = &sys_mutex_create,
    [SYS_MUTEX_DELETE] = &sys_mutex_delete,
    [SYS_MUTEX_LOCK] = &sys_mutex_lock,
    [SYS_MUTEX_UNLOCK] = &sys_mutex_unlock,
    [SYS_DEVICE_DO] = &sys_device_do,
    [SYS_EXEC] = &sys_exec,
    [SYS_OPEN] = &sys_open,
    [SYS_CLOSE] = &sys_close,
    [SYS_READ] = &sys_read,
    [SYS_DESCRIBE] = &sys_describe,
    [SYS_MAIL_SEND] = &sys_mail_send,
    [SYS_MAIL_RECEIVE] = &sys_mail_receive,
    [SYS_GET_PROCGROUP] = &sys_get_procgroup,
    [SYS_GET_EXEC_PID] = &sys_get_exec_pid,
};

syscall_handler_func_t syscall_find_handler (int syscall_num) {
  if (!(syscall_num >= 0 &&
        syscall_num < (int)(sizeof (handler_table) / sizeof (handler_table[0])))) {
    return NULL;
  }

  return handler_table[syscall_num];
}