// FileName.cxx

#include "dataset_util/FileName.h"
#include <iostream>
#include <unistd.h>
#include "dataset_util/getcwd.h"

using std::ostream;

typedef FileName::Name Name;

//**********************************************************************

// Constructor.

FileName::FileName(Name name) : m_name(name) { }

//**********************************************************************

// Validity.

bool FileName::is_valid() const {
  if ( m_name.size() == 0 ) return false;
  return true;
}

//**********************************************************************

// Is this a full path (/...)?

bool FileName::is_fullpath() const {
  if ( ! is_valid() ) return false;
  return m_name[0] == delimiter();
}

//**********************************************************************

// Is this a relative path (.../...)?

bool FileName::is_relative() const {
  if ( ! is_valid() ) return false;
  return m_name[0] != delimiter();
}

//**********************************************************************

// Return name with full path.

FileName FileName::fullpath() const {
  if ( ! is_valid() ) return FileName();
  if ( is_fullpath() ) {
    return *this;
  }
  Name newname = getcwd() + delimiter() + name();
  return FileName(newname);
}

//**********************************************************************

// Return name with no path.

Name FileName::nopath_name() const {
  // Set position at end of string.
  Name::size_type ipos = m_name.size();
  // Find trailing delimiter..
  while ( ipos >0 && m_name[ipos-1]!=delimiter() ) --ipos;
  return (m_name.substr(ipos));
}

//**********************************************************************

// Return name of directory.

Name FileName::directory_name() const {
  return directory().name();
}

//**********************************************************************

// Return name with full path.

Name FileName::fullpath_name() const {
  return fullpath().name();
}

//**********************************************************************

// Return parent directory.

FileName FileName::directory() const {
  // Set position at end of string.
  Name::size_type ipos = m_name.size();
  // Drop trailing delimiters.
  while ( ipos >0 && m_name[ipos-1]==delimiter() ) --ipos;
  // Find the preceding delimiter.
  while ( ipos >0 && m_name[ipos-1]!=delimiter() ) --ipos;
  // Drop trailing delimiters.
  while ( ipos >0 && m_name[ipos-1]==delimiter() ) --ipos;
  if ( ipos == 0 ) {
    return FileName("");
  }
  return FileName(m_name.substr(0, ipos));
}

//**********************************************************************

// Return the name without any symbolic links.

FileName FileName::unlinked(int maxlink, bool maxerr) const {
  if ( ! is_valid() ) return *this;
  char buf[4096];
  size_t bufsiz = 4096;
  // Check if this is a link.
  int nchar = readlink(m_name.c_str(), buf, bufsiz);
  bool linkerror = false;
  if ( nchar <= 0 ) {
    linkerror = true;
    int err = errno;
    if ( err == ENOTDIR ) linkerror = false;
    if ( err == ENOENT ) linkerror = false;
    if ( err == EINVAL ) linkerror = false;    // Why is this needed?
  }
  buf[nchar] = 0;
  // ..error ==> return invalid name
  if ( linkerror ) {
    return FileName("");
  }
  // This name is a symbolic link.
  if ( nchar > 0 ) {
    // Exit if the maximum # links has been exceeded.
    if ( maxlink <= 0 ) {
      if ( maxerr ) {
        return FileName();
      } else {
        return *this;
      }
    }
    // Otherwise unlink the link name.
    FileName newname(buf);
    // If the link is relative, prepend the path.
    if ( newname.is_relative() && directory().is_valid() ) {
      newname = FileName(directory().name() + string_delimiter()
                         + newname.name());
    }
    return newname.unlinked(maxlink-1, maxerr);
  }
  // This name is not a symbolic link.
  FileName dir = directory();
  // If there is no parent directory, we are done.
  if ( ! dir.is_valid() ) {
    return *this;
  }
  // Otherwise unlink the parent.
  FileName udir = dir.unlinked(maxlink, maxerr);
  if ( ! udir.is_valid() ) {
    return FileName("");
  }
  return FileName(udir.name() + string_delimiter() + nopath_name());
}

//**********************************************************************

// Output stream.

ostream& operator<<(ostream& lhs, const FileName& rhs) {
  if ( rhs.is_valid() ) {
    lhs << rhs.name();
  } else {
    lhs << "Invalid file name";
  }
  return lhs;
}

//**********************************************************************