#include <limits.h>
#include <stdlib.h>
#include <sys/stat.h>

#ifdef _WIN32
#include <Shlwapi.h>
#include <windows.h>
#endif

#include "filesystem.hpp"

#ifdef _WIN32

#define S_ISDIR( a ) a & _S_IFDIR

using stat_t = struct _stat;

#else

using stat_t = struct stat;

#endif // _WIN32

#ifndef GUI // these functions aren't needed in GUI

bool FSLib::exists( const string &path ) {
    stat_t path_stat;

#ifdef _WIN32
    return _wstat( path.c_str(), &path_stat ) == 0;
#else
    return stat( path.c_str(), &path_stat ) == 0;
#endif
}

string FSLib::canonical( const string &path ) {

#ifdef _WIN32
    auto PATH_MAX = MAX_PATH;
#endif

    char_t *canonical_path = new char_t[PATH_MAX];

#ifdef _WIN32
    auto failed = !PathCanonicalizeW( canonical_path, path.c_str() );
#else
    auto failed = realpath( path.c_str(), canonical_path ) == nullptr;
#endif

    if ( failed ) {
        delete[] canonical_path;
        return string();
    }

    string canonical_string{ canonical_path };
    delete[] canonical_path;
    return canonical_string;
}

#endif // ndef GUI

bool FSLib::isDirectory( const string &path ) {
    stat_t path_stat;

#ifdef _WIN32
    _wstat( path.c_str(), &path_stat );
#else
    stat( path.c_str(), &path_stat );
#endif

    return S_ISDIR( path_stat.st_mode );
}

bool FSLib::rename( const string &file_a, const string &file_b ) {
#ifdef _WIN32
    return MoveFileExW( file_a.c_str(), file_b.c_str(),
                        MOVEFILE_COPY_ALLOWED | MOVEFILE_REPLACE_EXISTING );
#else
    return ::rename( file_a.c_str(), file_b.c_str() ) == 0;
#endif
}

FSLib::Directory::iterator FSLib::Directory::begin() {
    return Iterator( *this );
}

FSLib::Directory::const_iterator FSLib::Directory::begin() const {
    return Iterator( *this );
}

FSLib::Directory::const_iterator FSLib::Directory::cbegin() const {
    return begin();
}

FSLib::Directory::iterator FSLib::Directory::end() {
#ifdef _WIN32
    return Iterator( true );
#else
    return Iterator( *this, nullptr );
#endif
}

FSLib::Directory::const_iterator FSLib::Directory::end() const {
#ifdef _WIN32
    return Iterator( true );
#else
    return Iterator( *this, nullptr );
#endif
}

FSLib::Directory::const_iterator FSLib::Directory::cend() const {
    return end();
}

const char_t *FSLib::Directory::path() const {
    return dir_path.c_str();
}

char_t const *FSLib::Directory::Iterator::operator*() const {
#ifdef _WIN32
    return data.cFileName;
#else
    return current_entry->d_name;
#endif
}

#ifdef _WIN32

FSLib::Directory::Iterator &FSLib::Directory::Iterator::operator++() {
    if ( ended == true )
        return *this;
    // skip . and ..
    if ( FindNextFileW( hFind, &data ) == 0 ) {
        ended = true;
    } else if ( !wcscmp( data.cFileName, L"." ) ||
                !wcscmp( data.cFileName, L".." ) ) {
        return operator++();
    }
    return *this;
}

#else

FSLib::Directory::Iterator &FSLib::Directory::Iterator::operator++() {
    if ( current_entry == nullptr )
        return *this;
    current_entry = readdir( d );
    // skip . and ..
    if ( current_entry != nullptr &&
         ( !strcmp( current_entry->d_name, "." ) ||
           !strcmp( current_entry->d_name, ".." ) ) )
        return operator++();
    return *this;
}

#endif

FSLib::Directory::Iterator FSLib::Directory::Iterator::operator++( int ) {
    Iterator ret( *this );
    operator++();
    return ret;
}

bool FSLib::Directory::Iterator::operator==( const Iterator &i_other ) const {
#ifdef _WIN32
    return i_other.ended == ended;
#else
    return i_other.current_entry == current_entry;
#endif
}

bool FSLib::Directory::Iterator::operator!=( const Iterator &i_other ) const {
    return !( i_other == *this );
}