#if !defined(INCLUDED_FS_FILESYSTEM_H)
#define INCLUDED_FS_FILESYSTEM_H

#include "string/string.h"
#include "os/path.h"

#include <map>

inline unsigned int path_get_depth(const char* path)
{
  unsigned int depth = 0;
  while(path != 0 && path[0] != '\0')
  {
    path = strchr(path, '/');
    if(path != 0)
    {
      ++path;
    }
    ++depth;
  }
  return depth;
}

/// \brief A generic unix-style file-system which maps paths to files and directories.
/// Provides average O(log n) find and insert methods.
/// \param file_type The data type which represents a file.
template<typename file_type>
class GenericFileSystem
{
  class Path
  {
    CopiedString m_path;
    unsigned int m_depth;
  public:
    Path(const char* path)
      : m_path(path), m_depth(path_get_depth(c_str()))
    {
    }
    Path(const char* start, const char* finish)
      : m_path(start, finish), m_depth(path_get_depth(c_str()))
    {
    }
    bool operator<(const Path& other) const
    {
      return string_less_nocase(c_str(), other.c_str());
    }
    unsigned int depth() const
    {
      return m_depth;
    }
    const char* c_str() const
    {
      return m_path.c_str();
    }
  };

  class Entry
  {
    file_type* m_file;
  public:
    Entry(file_type* file)
      : m_file(file)
    {
    }
    file_type* file() const
    {
      return m_file;
    }
    bool is_directory() const
    {
      return file() == 0;
    }
  };

  typedef std::map<Path, Entry> Entries;
  Entries m_entries;

public:
  typedef typename Entries::iterator iterator;
  typedef typename Entries::value_type value_type;

  iterator begin()
  {
    return m_entries.begin();
  }
  iterator end()
  {
    return m_entries.end();
  }

  /// \brief Adds the file \p entry at \p path.
  /// Creates all directories below \p path if they do not exist.
  /// O(log n) on average.
  void insert(const Path& path, const Entry& entry)
  {
    {
      const char* end = path_remove_directory(path.c_str());
      while(end[0] != '\0')
      {
        Path dir(path.c_str(), end);
        m_entries.insert(value_type(dir, Entry(0)));
        end = path_remove_directory(end);
      }
    }

    m_entries.insert(value_type(path, entry));
  }

  /// \brief Returns the file at \p path or end() if not found.
  iterator find(const Path& path)
  {
    return m_entries.find(path);
  }

  iterator begin(const char* root)
  {
    if(root[0] == '\0')
    {
      return m_entries.begin();
    }
    iterator i = m_entries.find(root);
    if(i == m_entries.end())
    {
      return i;
    }
    return ++i;
  }

  /// \brief Performs a depth-first traversal of the file-system subtree rooted at \p root.
  /// Traverses the entire tree if \p root is "".
  /// Calls \p visitor.file() with the path to each file relative to the filesystem root.
  /// Calls \p visitor.directory() with the path to each directory relative to the filesystem root.
  template<typename visitor_type>
  void traverse(visitor_type visitor, const char* root)
  {
    unsigned int start_depth = path_get_depth(root);
    unsigned int skip_depth = 0;
    for(iterator i = begin(root); i != end() && i->first.depth() > start_depth; ++i)
    {
      if(i->first.depth() == skip_depth)
      {
        skip_depth = 0;
      }
      if(skip_depth == 0)
      {
        if(!i->second.is_directory())
        {
          visitor.file(i->first.c_str());
        }
        else if(visitor.directory(i->first.c_str(), i->first.depth() - start_depth))
        {
          skip_depth = i->first.depth();
        }
      }
    }
  }
};

#endif