#include <mutex>
#include "devoptab_fsa.h"

off_t
__wut_fsa_seek(struct _reent *r,
               void *fd,
               off_t pos,
               int whence)
{
   FSError status;
   FSAStat fsStat;
   uint64_t offset;
   __wut_fsa_file_t *file;
   __wut_fsa_device_t *deviceData;

   if (!fd) {
      r->_errno = EINVAL;
      return -1;
   }

   file       = (__wut_fsa_file_t *)fd;

   deviceData = (__wut_fsa_device_t *)r->deviceData;

   std::scoped_lock lock(file->mutex);

   // Find the offset to see from
   switch (whence) {
      case SEEK_SET: { // Set absolute position; start offset is 0
         offset = 0;
         break;
      }
      case SEEK_CUR: { // Set position relative to the current position
         offset = file->offset;
         break;
      }
      case SEEK_END: { // Set position relative to the end of the file
         status = FSAGetStatFile(deviceData->clientHandle, file->fd, &fsStat);
         if (status < 0) {
            WUT_DEBUG_REPORT("FSAGetStatFile(0x%08X, 0x%08X, %p) (%s) failed: %s\n",
                             deviceData->clientHandle, file->fd, &fsStat, file->fullPath, FSAGetStatusStr(status));
            r->_errno = __wut_fsa_translate_error(status);
            return -1;
         }
         offset = fsStat.size;
         break;
      }
      default: { // An invalid option was provided
         r->_errno = EINVAL;
         return -1;
      }
   }

   if (pos < 0 && (off_t)offset < -pos) {
      // Don't allow seek to before the beginning of the file
      r->_errno = EINVAL;
      return -1;
   } else if (offset + pos > UINT32_MAX) {
      // Check for overflow
      r->_errno = EINVAL;
      return -1;
   }

   if ((uint32_t)(offset + pos) == file->offset) {
      return file->offset;
   }

   uint32_t old_pos = file->offset;
   file->offset     = offset + pos;

   status           = FSASetPosFile(deviceData->clientHandle, file->fd, file->offset);
   if (status < 0) {
      WUT_DEBUG_REPORT("FSASetPosFile(0x%08X, 0x%08X, 0x%08X) (%s) failed: %s\n",
                       deviceData->clientHandle, file->fd, file->offset, file->fullPath, FSAGetStatusStr(status));
      file->offset = old_pos;
      r->_errno    = __wut_fsa_translate_error(status);
      return -1;
   }

   return file->offset;
}