/**
 * @file Directory.cpp
 * @author apio (cloudapio.eu)
 * @brief A C++-friendly API for directory access.
 *
 * @copyright Copyright (c) 2023, the Luna authors.
 *
 */

#include <errno.h>
#include <fcntl.h>
#include <luna/CString.h>
#include <os/Directory.h>
#include <os/FileSystem.h>
#include <sys/syscall.h>
#include <unistd.h>

static bool should_skip_entry(const char* name, os::Directory::Filter filter)
{
    if (filter == os::Directory::Filter::None) return false;

    if (filter == os::Directory::Filter::Hidden) return *name == '.';

    if (filter == os::Directory::Filter::ParentAndBase) return !strcmp(name, ".") || !strcmp(name, "..");

    unreachable();
}

namespace os
{

    Result<SharedPtr<Directory>> Directory::open(const Path& path)
    {
        auto dir = TRY(adopt_shared_if_nonnull(new (std::nothrow) Directory({})));

        long rc = syscall(SYS_openat, path.dirfd(), path.name().chars(), O_RDONLY | O_DIRECTORY, 0);
        int fd = TRY(Result<int>::from_syscall(rc));

        DIR* dp = fdopendir(fd);
        if (!dp)
        {
            close(fd);
            return err(errno);
        }

        dir->m_dirp = dp;

        return dir;
    }

    Result<String> Directory::next(Filter filter)
    {
        errno = 0;

        struct dirent* ent;
        do {
            ent = readdir(m_dirp);
        } while (ent && should_skip_entry(ent->d_name, filter));

        if (!ent && errno) return err(errno);

        if (!ent) return String {};

        return String::from_cstring(ent->d_name);
    }

    Result<Vector<String>> Directory::list_names(Filter filter)
    {
        Vector<String> result;

        rewind();

        String entry {};
        while ((entry = TRY(next(filter))), !entry.is_empty()) TRY(result.try_append(move(entry)));

        return result;
    }

    Result<Vector<Directory::Entry>> Directory::list(Filter filter)
    {
        Vector<Directory::Entry> result;

        rewind();

        String name {};
        while ((name = TRY(next(filter))), !name.is_empty())
        {
            struct stat st;
            TRY(FileSystem::stat({ dirfd(m_dirp), name.chars() }, st, false));

            Directory::Entry entry {
                .name = move(name),
                .mode = st.st_mode,
                .size = (usize)st.st_size,
                .mtime = st.st_mtime,
            };

            TRY(result.try_append(move(entry)));
        }

        return result;
    }

    void Directory::rewind()
    {
        rewinddir(m_dirp);
    }

    Directory::~Directory()
    {
        if (m_dirp) closedir(m_dirp);
    }

    Directory::Directory(Badge<Directory>)
    {
    }
}