#ifndef FSLIB_H
#define FSLIB_H

#include <string.h>
#include <string>

#ifdef _WIN32

#include <Windows.h>

#else

#include <dirent.h>

#endif

// set apropriate data types for each operating system
#ifdef _WIN32

using string = std::wstring;
using char_t = wchar_t;

#else

using string = std::string;
using char_t = char;

#endif

// windows version stolen from
// http://www.martinbroadhurst.com/list-the-files-in-a-directory-in-c.html

namespace FSLib {

#ifndef GUI
bool exists( const string &path );
string canonical( const string &path );
#endif

bool isDirectory( const string &path );
bool rename( const string &file_a, const string &file_b );

class Directory {
public:
    Directory( const string &path_ ) : dir_path( path_ ) {
#ifdef _WIN32
        // need to append \\* for windows to search files in directory
        dir_path.append( L"\\*" );
#endif
    }
    Directory() = delete;
    Directory( const Directory &d ) = default;
    Directory( Directory &&d ) = default;

    class Iterator {
    public:
#ifdef _WIN32
        Iterator( const Directory &d_ ) {
            hFind = FindFirstFileW( d_.path(), &data );
            if ( hFind != INVALID_HANDLE_VALUE ) {
                if ( !wcscmp( data.cFileName, L"." ) ||
                     !wcscmp( data.cFileName, L".." ) ) {
                    ++( *this );
                }
            } else {
                ended = true;
            }
        }
        // this is definitely not a good way to create the "end" iterator
        // but it was the only way I thought of with my limited knowledge of
        // windows.h
        Iterator( bool ended_ ) : ended( ended_ ) {}

        ~Iterator() {
            if ( hFind )
                FindClose( hFind );
        }
#else
        Iterator( const Directory &d_ ) : d( opendir( d_.path() ) ) {
            current_entry = readdir( d );
            if ( current_entry != nullptr &&
                 ( !strcmp( current_entry->d_name, "." ) ||
                   !strcmp( current_entry->d_name, ".." ) ) )
                ++( *this );
        }

        Iterator( const Directory &d_, const struct dirent *current_entry_ )
                : d( opendir( d_.path() ) ), current_entry( current_entry_ ) {}

        ~Iterator() {
            closedir( d );
        }
#endif

        Iterator() = delete;

        Iterator( const Iterator &i ) = default;

        Iterator( Iterator &&i ) = default;

        char_t const *operator*() const;

        Iterator &operator++();

        Iterator operator++( int );

        bool operator==( const Iterator &i_other ) const;

        bool operator!=( const Iterator &i_other ) const;

    private:
#ifndef _WIN32
        DIR *d;
        const struct dirent *current_entry;
#else
        HANDLE hFind;
        WIN32_FIND_DATA data;
        bool ended{ false };
#endif
    };

    using iterator = Iterator;
    using const_iterator = Iterator;

    iterator begin();

    const_iterator begin() const;

    const_iterator cbegin() const;

    iterator end();

    const_iterator end() const;

    const_iterator cend() const;

    const char_t *path() const;

private:
    string dir_path;
};
} // namespace FSLib

#endif