#include <fs/ramdiskfs.h>
#include <fs/vfs.h>
#include <libk/fieldsizeof.h>
#include <libk/hash.h>
#include <libk/lengthof.h>
#include <libk/std.h>
#include <libk/string.h>
#include <m/status.h>
#include <mm/liballoc.h>
#include <proc/procgroup.h>
#include <sync/spin_lock.h>
#include <sys/debug.h>

static struct vfs_mount_table mount_table;

static struct vfs_mountpoint* vfs_find_mountpoint (const char* mountpoint) {
  struct hash_node_link* found_link = NULL;
  size_t mountpoint_len = strlen (mountpoint);
  uint32_t hash = hash_fnv32 (mountpoint, strlen (mountpoint));

  spin_lock (&mount_table.lock);
  hash_find (&mount_table, mountpoint, mountpoint_len, hash,
             lengthof (mount_table.mountpoint_buckets), mountpoint_buckets, struct vfs_mountpoint,
             mount_table_link, key, found_link);
  spin_unlock (&mount_table.lock);

  if (found_link == NULL)
    return NULL;

  return hash_entry (found_link, struct vfs_mountpoint, mount_table_link);
}

struct vfs_mountpoint* vfs_create_mountpoint (const char* key, int fs_type) {
  if (strlen_null (key) > fieldsizeof (struct vfs_mountpoint, key))
    return NULL;

  struct vfs_mountpoint* mountpoint = malloc (sizeof (*mountpoint));

  if (mountpoint == NULL)
    return NULL;

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

  memcpy (mountpoint->key, key, strlen_null (key));
  mountpoint->fs_type = fs_type;
  mountpoint->lock = SPIN_LOCK_INIT;

  switch (mountpoint->fs_type) {
  case VFS_RAMDISKFS: {
    mountpoint->driver_ops.mount = &ramdiskfs_mount;
    mountpoint->driver_ops.describe = &ramdiskfs_describe;
    mountpoint->driver_ops.read = &ramdiskfs_read;
  } break;
  default: {
    free (mountpoint);
    return NULL;
  } break;
  }

  bool ok = mountpoint->driver_ops.mount (mountpoint);

  if (!ok) {
    free (mountpoint);
    return NULL;
  }

  uint32_t mp_hash = hash_fnv32 (mountpoint->key, strlen (mountpoint->key));

  spin_lock (&mount_table.lock);

  hash_insert (&mount_table, &mountpoint->mount_table_link, mp_hash,
               lengthof (mount_table.mountpoint_buckets), mountpoint_buckets);

  spin_unlock (&mount_table.lock);

  return mountpoint;
}

int vfs_open (struct procgroup* procgroup, const char* mountpoint, const char* path) {
  (void)path;

  struct vfs_mountpoint* vmp = vfs_find_mountpoint (mountpoint);

  if (vmp == NULL)
    return -ST_NOT_FOUND;

  spin_lock (&vmp->lock);

  vmp->ownerpg = procgroup;
  vmp->locked = true;

  spin_unlock (&vmp->lock);

  return ST_OK;
}

int vfs_close (struct procgroup* procgroup, const char* mountpoint, const char* path) {
  (void)path;

  struct vfs_mountpoint* vmp = vfs_find_mountpoint (mountpoint);

  if (vmp == NULL)
    return -ST_NOT_FOUND;

  spin_lock (&vmp->lock);

  if (procgroup != NULL && vmp->ownerpg != procgroup) {
    spin_unlock (&vmp->lock);
    return -ST_PERMISSION_ERROR;
  }

  vmp->locked = false;
  vmp->ownerpg = NULL;

  spin_unlock (&vmp->lock);

  return ST_OK;
}

int vfs_describe (struct procgroup* procgroup, const char* mountpoint, const char* path,
                  struct fs_desc_buffer* desc) {
  struct vfs_mountpoint* vmp = vfs_find_mountpoint (mountpoint);

  if (vmp == NULL)
    return -ST_NOT_FOUND;

  spin_lock (&vmp->lock);

  if ((procgroup != NULL && vmp->ownerpg != procgroup) && vmp->locked) {
    spin_unlock (&vmp->lock);
    return -ST_PERMISSION_ERROR;
  }

  int ret = vmp->driver_ops.describe (vmp, path, desc);

  spin_unlock (&vmp->lock);

  return ret;
}

int vfs_read (struct procgroup* procgroup, const char* mountpoint, const char* path,
              uint8_t* buffer, size_t off, size_t size) {
  struct vfs_mountpoint* vmp = vfs_find_mountpoint (mountpoint);

  if (vmp == NULL)
    return -ST_NOT_FOUND;

  spin_lock (&vmp->lock);

  if ((procgroup != NULL && vmp->ownerpg != procgroup) && vmp->locked) {
    spin_unlock (&vmp->lock);
    return -ST_PERMISSION_ERROR;
  }

  int ret = vmp->driver_ops.read (vmp, path, buffer, off, size);

  spin_unlock (&vmp->lock);

  return ret;
}

void vfs_procgroup_cleanup (struct procgroup* procgroup) {
  spin_lock (&mount_table.lock);

  for (size_t i = 0; i < lengthof (mount_table.mountpoint_buckets); i++) {
    struct hash_node_link* link = mount_table.mountpoint_buckets[i];
    struct vfs_mountpoint* vmp = hash_entry (link, struct vfs_mountpoint, mount_table_link);

    spin_lock (&vmp->lock);

    if (vmp->ownerpg == procgroup) {
      vmp->locked = false;
      vmp->ownerpg = NULL;
    }

    spin_unlock (&vmp->lock);
  }

  spin_unlock (&mount_table.lock);
}

void vfs_init (void) {
  memset (&mount_table, 0, sizeof (mount_table));

  mount_table.lock = SPIN_LOCK_INIT;
}