#include "VfsSyscall.h"
#include "kstring.h"
#include "assert.h"
#include "Dirent.h"
#include "Inode.h"
#include "Dentry.h"
#include "Superblock.h"
#include "File.h"
#include "FileDescriptor.h"
#include "FileSystemType.h"
#include "FileSystemInfo.h"
#include "VirtualFileSystem.h"
#include "MinixFSType.h"
#include "PathWalker.h"
#include "VfsMount.h"
#include "kprintf.h"
#ifndef EXE2MINIXFS
#include "Thread.h"
#endif

#define SEPARATOR '/'
#define CHAR_DOT '.'

FileDescriptor* VfsSyscall::getFileDescriptor(uint32 fd)
{
  return global_fd_list.getFileDescriptor(fd);
}


int32 VfsSyscall::mkdir(const char* pathname, int32)
{
  debug(VFSSYSCALL, "(mkdir) Path: %s\n", pathname);
  FileSystemInfo *fs_info = getcwd();

  Path target_path;
  Path parent_dir_path;
  int32 path_walk_status = PathWalker::pathWalk(pathname, fs_info, target_path, &parent_dir_path);

  if((path_walk_status == PW_ENOTFOUND) && parent_dir_path.dentry_)
  {
    ustl::string new_dir_name = PathWalker::lastPathSegment(pathname, true);

    Inode* parent_dir_inode = parent_dir_path.dentry_->getInode();
    Superblock* parent_dir_sb = parent_dir_inode->getSuperblock();

    if (parent_dir_inode->getType() != I_DIR)
    {
      debug(VFSSYSCALL, "(mkdir) Error: This path is not a directory\n");
      return -1;
    }

    debug(VFSSYSCALL, "(mkdir) Creating new directory Inode in superblock %p of type %s\n", parent_dir_sb, parent_dir_sb->getFSType()->getFSName());
    Inode* new_dir_inode = parent_dir_sb->createInode(I_DIR);

    debug(VFSSYSCALL, "(mkdir) Creating new dentry: %s in parent dir %s\n", new_dir_name.c_str(), parent_dir_path.dentry_->getName());
    Dentry* new_dir_dentry = new Dentry(new_dir_inode, parent_dir_path.dentry_, new_dir_name);
    new_dir_inode->mkdir(new_dir_dentry);

    return 0;
  }
  else if (path_walk_status == PW_SUCCESS)
  {
    debug(VFSSYSCALL, "(mkdir) Error: The pathname already exists\n");
  }
  else if (path_walk_status == PW_EINVALID)
  {
    debug(VFSSYSCALL, "(mkdir) Error: Invalid pathname\n");
  }
  else if ((path_walk_status == PW_ENOTFOUND) && !parent_dir_path.dentry_)
  {
    debug(VFSSYSCALL, "(mkdir) Error: Parent directory not found\n\n");
  }

  return -1;
}

static const char* readdirPrefix(uint32 inode_type)
{
    switch (inode_type)
    {
    case I_DIR:
        return "[D] ";
    case I_FILE:
        return "[F] ";
    case I_LNK:
        return "[L] ";
    default:
        return "";
    }
}

Dirent* VfsSyscall::readdir(const char* pathname, char* buffer, size_t size)
{
  FileSystemInfo *fs_info = getcwd();

  Path target_path;
  if (PathWalker::pathWalk(pathname, fs_info, target_path) != PW_SUCCESS)
  {
    debug(VFSSYSCALL, "(readdir) ERROR: Path doesn't exist\n");
    kprintf("Error: %s not found\n", pathname);
    return 0;
  }

  if (target_path.dentry_->getInode()->getType() != I_DIR)
  {
    debug(VFSSYSCALL, "(readdir) ERROR: This path is not a directory\n");
    kprintf("Error: %s is not a directory\n", pathname);
    return nullptr;
  }

  debug(VFSSYSCALL, "(readdir) listing dir %s:\n", target_path.dentry_->getName());
  size_t it = 0;
  for (Dentry* sub_dentry : target_path.dentry_->d_child_)
  {
    uint32 inode_type = sub_dentry->getInode()->getType();
    const char* prefix = readdirPrefix(inode_type);
    const char* name = sub_dentry->getName();

    if(buffer)
    {
      auto len_name = strlen(name);
      if(it + len_name + 1 >= size)
      {
        debug(VFSSYSCALL, "Buffer is too small for all elements -> return it as it is\n");
        buffer[it] = 0;
        return 0;
      }

      memcpy(buffer + it, name, len_name);
      it += len_name;
      buffer[it++] = '\n';
    }
    else
    {
      kprintf("%s%s\n", prefix, name);
    }
  }

  if(buffer)
  {
    buffer[it] = 0;
  }

  return 0;
}

int32 VfsSyscall::chdir(const char* pathname)
{
  debug(VFSSYSCALL, "(chdir) Changing working directory to: %s\n", pathname);

  FileSystemInfo *fs_info = getcwd();

  Path target_path;
  if (PathWalker::pathWalk(pathname, fs_info, target_path) != PW_SUCCESS)
  {
    debug(VFSSYSCALL, "(chdir) Error: The directory does not exist.\n");
    return -1;
  }

  Inode* current_inode = target_path.dentry_->getInode();
  if (current_inode->getType() != I_DIR)
  {
    debug(VFSSYSCALL, "(chdir) Error: This path is not a directory\n");
    return -1;
  }

  fs_info->setPwd(target_path);

  return 0;
}

int32 VfsSyscall::rm(const char* pathname)
{
  debug(VFSSYSCALL, "(rm) Removing: %s\n", pathname);

  FileSystemInfo *fs_info = getcwd();

  Path target_path;
  if (PathWalker::pathWalk(pathname, fs_info, target_path) != PW_SUCCESS)
  {
    debug(VFSSYSCALL, "(rm) target file does not exist.\n");
    return -1;
  }
  debug(VFSSYSCALL, "(rm) current_dentry->getName(): %s \n", target_path.dentry_->getName());
  Inode* current_inode = target_path.dentry_->getInode();
  debug(VFSSYSCALL, "(rm) current_inode: %p\n", current_inode);

  if (current_inode->getType() != I_FILE)
  {
    debug(VFSSYSCALL, "(rm) Target is not a file\n");
    return -1;
  }

  if (current_inode->unlink(target_path.dentry_))
  {
    debug(VFSSYSCALL, "(rm) Error: File unlink failed\n");
    return -1;
  }

  delete target_path.dentry_;
  if (!current_inode->numRefs())
  {
    Superblock* sb = current_inode->getSuperblock();
    debug(VFSSYSCALL, "(rm) No more references to inode left, remove inode %p from the list of sb: %p\n", current_inode, sb);
    sb->deleteInode(current_inode);
  }

  return 0;
}

int32 VfsSyscall::rmdir(const char* pathname)
{
  FileSystemInfo *fs_info = getcwd();

  Path target_dir;
  Path parent_dir_path;
  int32 path_walk_status = PathWalker::pathWalk(pathname, fs_info, target_dir, &parent_dir_path);

  if(path_walk_status != PW_SUCCESS)
  {
    debug(VFSSYSCALL, "(rmdir) Error: The directory does not exist.\n");
    return -1;
  }

  Inode* current_inode = target_dir.dentry_->getInode();

  //if directory is read from a real file system,
  //it can't ever be empty, "." and ".." are still
  //contained; this has to be checked in Inode::rmdir()

  if (current_inode->getType() != I_DIR)
  {
    debug(VFSSYSCALL, "(rmdir) Error: This is not a directory\n");
    return -1;
  }

  if (current_inode->rmdir(target_dir.dentry_))
  {
    debug(VFSSYSCALL, "(rmdir) Error: File system rmdir failed\n");
    return -1;
  }

  delete target_dir.dentry_;
  if (!current_inode->numRefs())
  {
    Superblock* sb = current_inode->getSuperblock();
    debug(VFSSYSCALL, "(rmdir) No more references to inode left, remove inode %p from the list of sb: %p\n", current_inode, sb);
    sb->deleteInode(current_inode);
  }

  return 0;
}

int32 VfsSyscall::close(uint32 fd)
{
  debug(VFSSYSCALL, "(close) Close fd num %u\n", fd);
  FileDescriptor* file_descriptor = getFileDescriptor(fd);

  if (file_descriptor == 0)
  {
    debug(VFSSYSCALL, "(close) Error: the fd does not exist.\n");
    return -1;
  }

  assert(!global_fd_list.remove(file_descriptor));
  file_descriptor->getFile()->closeFd(file_descriptor);

  debug(VFSSYSCALL, "(close) File closed\n");
  return 0;
}

int32 VfsSyscall::open(const char* pathname, uint32 flag)
{
  if(!pathname)
  {
    debug(VFSSYSCALL, "(open) Invalid pathname\n");
    return -1;
  }

  debug(VFSSYSCALL, "(open) Opening file %s\n", pathname);
  if (flag & ~(O_RDONLY | O_WRONLY | O_CREAT | O_RDWR | O_TRUNC | O_APPEND))
  {
    debug(VFSSYSCALL, "(open) Invalid flag parameter\n");
    return -1;
  }
  if(flag & (O_APPEND | O_TRUNC))
  {
    kprintfd("(open) ERROR: Flags not yet implemented\n"); // kprintfd instead of debug so it will be printed even if the debug flag is disabled
    return -1;
  }

  FileSystemInfo *fs_info = getcwd();

  Path target_path;
  Path parent_dir_path;
  int32 path_walk_status = PathWalker::pathWalk(pathname, fs_info, target_path, &parent_dir_path);

  if (path_walk_status == PW_SUCCESS)
  {
    debug(VFSSYSCALL, "(open) Found target file: %s\n", target_path.dentry_->getName());
    Inode* target_inode = target_path.dentry_->getInode();

    if (target_inode->getType() != I_FILE)
    {
      debug(VFSSYSCALL, "(open) Error: This path is not a file\n");
      return -1;
    }

    File* file = target_inode->open(target_path.dentry_, flag);
    FileDescriptor* fd = file->openFd();
    assert(!global_fd_list.add(fd));

    debug(VFSSYSCALL, "(open) Fd for new open file: %d, flags: %x\n", fd->getFd(), flag);
    return fd->getFd();
  }
  else if ((path_walk_status == PW_ENOTFOUND) && (flag & O_CREAT))
  {
    if (!parent_dir_path.dentry_)
    {
      debug(VFSSYSCALL, "(open) ERROR: unable to create file, directory does not exist\n");
      return -1;
    }

    debug(VFSSYSCALL, "(open) target does not exist, creating new file\n");

    ustl::string new_dentry_name = PathWalker::lastPathSegment(pathname);
    if(new_dentry_name == "") // Path has trailing slashes
    {
      debug(VFSSYSCALL, "(open) Error: last path segment is empty (trailing '/')\n");
      return -1;
    }

    debug(VFSSYSCALL, "(open) new file name: %s\n", new_dentry_name.c_str());

    Inode* parent_dir_inode = parent_dir_path.dentry_->getInode();
    Superblock* parent_dir_sb = parent_dir_inode->getSuperblock();

    if (parent_dir_inode->getType() != I_DIR)
    {
      debug(VFSSYSCALL, "(open) ERROR: This path is not a directory\n");
      return -1;
    }

    debug(VFSSYSCALL, "(open) Creating new file Inode in superblock %p of type %s\n", parent_dir_sb, parent_dir_sb->getFSType()->getFSName());
    Inode* new_file_inode = parent_dir_sb->createInode(I_FILE);
    if (!new_file_inode)
    {
      debug(VFSSYSCALL, "(open) ERROR: Unable to create inode for new file\n");
      return -1;
    }

    debug(VFSSYSCALL, "(open) Creating new dentry: %s in parent dir %s\n", new_dentry_name.c_str(), parent_dir_path.dentry_->getName());
    Dentry* new_file_dentry = new Dentry(new_file_inode, parent_dir_path.dentry_, new_dentry_name);
    new_file_inode->mkfile(new_file_dentry);

    File* file = new_file_inode->open(new_file_dentry, flag);
    FileDescriptor* fd = file->openFd();
    assert(!global_fd_list.add(fd));

    debug(VFSSYSCALL, "(open) Fd for new open file: %d, flags: %x\n", fd->getFd(), flag);
    return fd->getFd();
  }
  else if (path_walk_status == PW_EINVALID)
  {
    debug(VFSSYSCALL, "(open) Error: Invalid pathname\n");
  }
  else
  {
    debug(VFSSYSCALL, "(open) Error: File not found\n");
  }
  return -1;
}

int32 VfsSyscall::read(uint32 fd, char* buffer, uint32 count)
{
  FileDescriptor* file_descriptor = getFileDescriptor(fd);

  if (file_descriptor == 0)
  {
    debug(VFSSYSCALL, "(read) Error: the fd does not exist.\n");
    return -1;
  }

  if (count == 0)
    return 0;

  return file_descriptor->getFile()->read(buffer, count, 0);
}

int32 VfsSyscall::write(uint32 fd, const char *buffer, uint32 count)
{
  FileDescriptor* file_descriptor = getFileDescriptor(fd);

  if (file_descriptor == 0)
  {
    debug(VFSSYSCALL, "(write) Error: the fd does not exist.\n");
    return -1;
  }

  if (count == 0)
    return 0;

  return file_descriptor->getFile()->write(buffer, count, 0);
}

l_off_t VfsSyscall::lseek(uint32 fd, l_off_t offset, uint8 origin)
{
  FileDescriptor* file_descriptor = getFileDescriptor(fd);

  if (file_descriptor == 0)
  {
    debug(VFSSYSCALL, "(lseek) Error: the fd does not exist.\n");
    return -1;
  }

  return file_descriptor->getFile()->lseek(offset, origin);
}

int32 VfsSyscall::flush(uint32 fd)
{
  FileDescriptor* file_descriptor = getFileDescriptor(fd);

  if (file_descriptor == 0)
  {
    debug(VFSSYSCALL, "(read) Error: the fd does not exist.\n");
    return -1;
  }

  return file_descriptor->getFile()->flush();
}

#ifndef EXE2MINIXFS
int32 VfsSyscall::mount(const char *device_name, const char *dir_name, const char *file_system_name, int32 flag)
{
  FileSystemType* type = vfs.getFsType(file_system_name);
  if (!type)
  {
      debug(VFSSYSCALL, "(mount) Unknown file system %s\n", file_system_name);
      return -1;
  }

  return vfs.mount(device_name, dir_name, file_system_name, flag);
}

int32 VfsSyscall::umount(const char *dir_name, int32 flag)
{
  return vfs.umount(dir_name, flag);
}
#endif

uint32 VfsSyscall::getFileSize(uint32 fd)
{
  FileDescriptor* file_descriptor = getFileDescriptor(fd);

  if (file_descriptor == 0)
  {
    debug(VFSSYSCALL, "(read) Error: the fd does not exist.\n");
    return -1;
  }

  return file_descriptor->getFile()->getSize();
}