import os

// tfolder will contain all the temporary files/subfolders made by
// the different tests. It would be removed in testsuite_end(), so
// individual os tests do not need to clean up after themselves.
const tfolder = os.join_path(os.vtmp_dir(), 'os_tests')
const utf16le_stdout_source_code = '
module main

import os

fn main() {
    payload := [u8(`O`), 0, `K`, 0, u8(10), 0]
    mut out := os.stdout()
    out.write(payload) or { panic(err) }
}
'

// os.args has to be *already initialized* with the program's argc/argv at this point
// thus it can be used for other consts too:
const args_at_start = os.args.clone()

fn testsuite_begin() {
    eprintln('testsuite_begin, tfolder = ${tfolder}')
    os.rmdir_all(tfolder) or {}
    assert !os.is_dir(tfolder)
    os.mkdir_all(tfolder) or { panic(err) }
    os.chdir(tfolder) or {}
    assert os.is_dir(tfolder)
    // println('args_at_start: ${args_at_start}')
    assert args_at_start.len > 0
    assert args_at_start == os.args
}

fn testsuite_end() {
    os.chdir(os.wd_at_startup) or {}
    os.rmdir_all(tfolder) or {}
    // assert !os.is_dir(tfolder)
    // eprintln('testsuite_end  , tfolder = ${tfolder} removed.')
}

fn test_open_file() {
    filename := './test1.txt'
    hello := 'hello world!'
    os.open_file(filename, 'r+', 0o666) or {
        assert err.msg() == 'No such file or directory'
        os.File{}
    }
    mut file := os.open_file(filename, 'w+', 0o666) or { panic(err) }
    file.write_string(hello) or { panic(err) }
    file.close()
    assert u64(hello.len) == os.file_size(filename)
    read_hello := os.read_file(filename) or { panic('error reading file ' + filename) }
    assert hello == read_hello
    os.rm(filename) or { panic(err) }
}

fn test_read_file_from_virtual_filesystem() {
    $if linux {
        mounts := os.read_file('/proc/mounts')!

        // it is not empty, contains some mounting such as root filesystem: /dev/x / ext4 rw 0 0
        assert mounts.len > 20
        assert mounts.contains('/')
        assert mounts.contains(' ')
    }
}

fn test_read_binary_from_virtual_filesystem() {
    $if linux {
        mounts_raw := os.read_bytes('/proc/mounts')!
        mounts := mounts_raw.bytestr()

        // it is not empty, contains some mounting such as root filesystem: /dev/x / ext4 rw 0 0
        assert mounts.len > 20
        assert mounts.contains('/')
        assert mounts.contains(' ')
    }
}

fn test_open_file_binary() {
    filename := './test1.dat'
    hello := 'hello \n world!'
    os.open_file(filename, 'r+', 0o666) or {
        assert err.msg() == 'No such file or directory'
        os.File{}
    }
    mut file := os.open_file(filename, 'wb+', 0o666) or { panic(err) }
    bytes := hello.bytes()
    unsafe { file.write_ptr(bytes.data, bytes.len) }
    file.close()
    assert u64(hello.len) == os.file_size(filename)
    read_hello := os.read_bytes(filename) or { panic('error reading file ' + filename) }
    assert bytes == read_hello
    os.rm(filename) or { panic(err) }
}

// fn test_file_get_line() {
//     filename := './fgetline.txt'
//     os.write_file(filename, 'line 1\nline 2')
//     mut f := os.open_file(filename, 'r', 0) or {
//         assert false
//         return
//     }
//     line1 := f.get_line() or {
//         ''
//     }
//     line2 := f.get_line() or {
//         ''
//     }
//     f.close()
//     //
//     eprintln('line1: ${line1} ${line1.bytes()}')
//     eprintln('line2: ${line2} ${line2.bytes()}')
//     assert line1 == 'line 1\n'
//     assert line2 == 'line 2'
// }

fn create_file(fpath string) ! {
    mut f := os.create(fpath)!
    f.close()
}

fn create_and_write_to_file(fpath string, content string) ! {
    mut f := os.create(fpath)!
    f.write_string(content)!
    f.close()
}

fn test_create_file() {
    filename := './test1.txt'
    hello := 'hello world!'
    create_and_write_to_file(filename, hello)!
    assert u64(hello.len) == os.file_size(filename)
    os.rm(filename) or { panic(err) }
}

fn test_is_file() {
    // Setup
    work_dir := os.join_path_single(tfolder, 'is_file_test')
    os.mkdir_all(work_dir) or { panic(err) }
    tfile := os.join_path_single(work_dir, 'tmp_file')
    // Test things that shouldn't be a file
    assert os.is_file(work_dir) == false
    assert os.is_file('non-existent_file.tmp') == false
    // Test file
    tfile_content := 'temporary file'
    os.write_file(tfile, tfile_content) or { panic(err) }
    assert os.is_file(tfile)
    // Test dir symlinks
    $if windows {
        assert true
    } $else {
        dsymlink := os.join_path_single(work_dir, 'dir_symlink')
        os.symlink(work_dir, dsymlink) or { panic(err) }
        assert os.is_file(dsymlink) == false
    }
    // Test file symlinks
    $if windows {
        assert true
    } $else {
        fsymlink := os.join_path_single(work_dir, 'file_symlink')
        os.symlink(tfile, fsymlink) or { panic(err) }
        assert os.is_file(fsymlink)
    }
}

fn test_write_and_read_string_to_file() {
    filename := './test1.txt'
    hello := 'hello world!'
    os.write_file(filename, hello) or { panic(err) }
    assert u64(hello.len) == os.file_size(filename)
    read_hello := os.read_file(filename) or { panic('error reading file ' + filename) }
    assert hello == read_hello
    os.rm(filename) or { panic(err) }
}

// test_write_and_read_bytes checks for regressions made in the functions
// read_bytes, read_bytes_at and write_bytes.

fn test_write_and_read_bytes() {
    file_name := './byte_reader_writer.tst'
    payload := [u8(`I`), `D`, `D`, `Q`, `D`]
    mut file_write := os.create(os.real_path(file_name)) or {
        eprintln('failed to create file ${file_name}')
        return
    }
    // We use the standard write_bytes function to write the payload and
    // compare the length of the array with the file size (have to match).
    unsafe { file_write.write_ptr(payload.data, 5) }
    file_write.close()
    assert u64(payload.len) == os.file_size(file_name)
    mut file_read := os.open(os.real_path(file_name)) or {
        eprintln('failed to open file ${file_name}')
        return
    }
    // We only need to test read_bytes because this function calls
    // read_bytes_at with second parameter zeroed (size, 0).
    rbytes := file_read.read_bytes(5)
    // eprintln('rbytes: ${rbytes}')
    // eprintln('payload: ${payload}')
    assert rbytes == payload
    // check that trying to read data from EOF doesn't error and returns 0
    mut a := []u8{len: 5}
    nread := file_read.read_bytes_into(5, mut a) or {
        n := if err is os.Eof {
            int(0)
        } else {
            eprintln(err)
            int(-1)
        }
        n
    }
    assert nread == 0
    file_read.close()
    // We finally delete the test file.
    os.rm(file_name) or { panic(err) }
}

fn test_ls() {
    if x := os.ls('') {
        assert false
    } else {
        assert true
    }
    if x := os.ls('.') {
        assert x.len > 0
    } else {
        assert false
    }
}

fn create_tree() ! {
    os.mkdir_all('myfolder/f1/f2/f3')!
    os.mkdir_all('myfolder/a1/a2/a3', mode: 0o700)!
    f3 := os.real_path('myfolder/f1/f2/f3')
    assert os.is_dir(f3)
    create_file('myfolder/f1/f2/f3/.hfile1')!
    create_file('myfolder/f1/f2/f3/a.txt')!
    create_file('myfolder/f1/f2/f3/b.txt')!
    create_file('myfolder/f1/f2/f3/c.txt')!
    create_file('myfolder/f1/f2/f3/d.md')!
    create_file('myfolder/f1/0.txt')!
    create_file('myfolder/another.md')!
    create_file('myfolder/a1/a2/a3/x.txt')!
    create_file('myfolder/a1/a2/a3/y.txt')!
    create_file('myfolder/a1/a2/a3/z.txt')!
    create_file('myfolder/a1/1.txt')!
    create_file('myfolder/a1/.hfile2')!
    create_file('myfolder/xyz.ini')!
}

fn remove_tree() {
    os.rmdir_all('myfolder') or {}
}

fn normalise_paths(paths []string) []string {
    mut res := paths.map(it.replace(os.path_separator, '/'))
    res.sort()
    return res
}

fn test_walk_ext() {
    create_tree()!
    defer {
        remove_tree()
    }
    all := os.walk_ext('.', '')
    assert all.len > 10
    top := normalise_paths(os.walk_ext('myfolder', '.txt'))
    assert top == [
        'myfolder/a1/1.txt',
        'myfolder/a1/a2/a3/x.txt',
        'myfolder/a1/a2/a3/y.txt',
        'myfolder/a1/a2/a3/z.txt',
        'myfolder/f1/0.txt',
        'myfolder/f1/f2/f3/a.txt',
        'myfolder/f1/f2/f3/b.txt',
        'myfolder/f1/f2/f3/c.txt',
    ]
    subfolder_txts := normalise_paths(os.walk_ext('myfolder/a1/a2', '.txt'))
    assert subfolder_txts == [
        'myfolder/a1/a2/a3/x.txt',
        'myfolder/a1/a2/a3/y.txt',
        'myfolder/a1/a2/a3/z.txt',
    ]
    mut mds := normalise_paths(os.walk_ext('myfolder', '.md'))
    assert mds == ['myfolder/another.md', 'myfolder/f1/f2/f3/d.md']

    all_with_hidden := os.walk_ext('.', '', hidden: true)
    assert all_with_hidden.len > all.len
    hidden := normalise_paths(all_with_hidden.filter(it !in all))
    assert hidden == ['./myfolder/a1/.hfile2', './myfolder/f1/f2/f3/.hfile1']
}

fn test_walk_with_context() {
    create_tree()!
    defer {
        remove_tree()
    }
    mut res := []string{}
    os.walk_with_context('myfolder', &res, fn (ctx voidptr, fpath string) {
        mut res := unsafe { &[]string(ctx) }
        res << fpath
    })
    res = normalise_paths(res)
    assert 'myfolder/f1/f2/f3/b.txt' in res
    assert 'myfolder/another.md' in res
}

fn test_create_and_delete_folder() {
    folder := './test1'
    os.mkdir(folder) or { panic(err) }
    assert os.is_dir(folder)
    folder_contents := os.ls(folder) or { panic(err) }
    assert folder_contents.len == 0
    os.rmdir(folder) or { panic(err) }
    folder_exists := os.is_dir(folder)
    assert folder_exists == false
}

fn walk_callback(file string) {
    if file == '.' || file == '..' {
        return
    }
    assert file == 'test_walk' + os.path_separator + 'test1'
}

fn test_walk() {
    folder := 'test_walk'
    os.mkdir(folder) or { panic(err) }
    file1 := folder + os.path_separator + 'test1'
    os.write_file(file1, 'test-1') or { panic(err) }
    os.walk(folder, walk_callback)
    os.rm(file1) or { panic(err) }
    os.rmdir(folder) or { panic(err) }
}

fn test_cp() {
    old_file_name := 'cp_example.txt'
    new_file_name := 'cp_new_example.txt'
    os.write_file(old_file_name, 'Test data 1 2 3, V is awesome #$%^[]!~⭐')!
    os.cp(old_file_name, new_file_name)!
    old_file := os.read_file(old_file_name)!
    new_file := os.read_file(new_file_name)!
    assert old_file == new_file
    os.rm(old_file_name)!
    os.rm(new_file_name)!
}

fn test_cp_to_folder() {
    file_name := 'cp_to_folder_example.txt'
    folder := 'test_cp_to_folder'
    os.mkdir(folder)!
    os.write_file(file_name, 'Test data 1 2 3, V is awesome #$%^[]!~⭐')!
    os.cp(file_name, folder)!
    new_file_path := os.join_path_single(folder, file_name)
    old_file := os.read_file(file_name)!
    new_file := os.read_file(new_file_path)!
    assert old_file == new_file
    os.rm(file_name)!
    os.rm(new_file_path)!
    os.rmdir(folder)!
}

fn test_cp_fail_if_exists() {
    file_name := 'cp_fail_if_exists_example.txt'
    folder := 'test_cp_fail_if_exists'
    os.mkdir(folder)!
    os.write_file(file_name, 'Test data 1 2 3, V is awesome #$%^[]!~⭐')!
    os.cp(file_name, folder)!
    new_file_path := os.join_path_single(folder, file_name)
    if _ := os.cp(file_name, folder, fail_if_exists: true) {
        assert false
    } else {
        assert err.str().starts_with('cp: failed to '), 'cp err: ${err}'
    }
    os.rm(file_name)!
    os.rm(new_file_path)!
    os.rmdir(folder)!
}

fn test_mv() {
    work_dir := os.join_path_single(tfolder, 'mv_test')
    os.mkdir_all(work_dir) or { panic(err) }
    // Setup test files
    tfile1 := os.join_path_single(work_dir, 'file')
    tfile2 := os.join_path_single(work_dir, 'file.test')
    tfile3 := os.join_path_single(work_dir, 'file.3')
    tfile_content := 'temporary file'
    os.write_file(tfile1, tfile_content) or { panic(err) }
    os.write_file(tfile2, tfile_content) or { panic(err) }
    // Setup test dirs
    tdir1 := os.join_path_single(work_dir, 'dir')
    tdir2 := os.join_path_single(work_dir, 'dir2')
    tdir3 := os.join_path_single(work_dir, 'dir3')
    os.mkdir(tdir1) or { panic(err) }
    os.mkdir(tdir2) or { panic(err) }
    // Move file with no extension to dir
    os.mv(tfile1, tdir1) or { panic(err) }
    mut expected := os.join_path_single(tdir1, 'file')
    assert os.exists(expected)
    assert !os.is_dir(expected)
    // Move dir with contents to other dir
    os.mv(tdir1, tdir2) or { panic(err) }
    expected = os.join_path_single(tdir2, 'dir')
    assert os.exists(expected)
    assert os.is_dir(expected)
    expected = os.join_path(tdir2, 'dir', 'file')
    assert os.exists(expected)
    assert !os.is_dir(expected)
    // Move dir with contents to other dir (by renaming)
    os.mv(os.join_path_single(tdir2, 'dir'), tdir3) or { panic(err) }
    expected = tdir3
    assert os.exists(expected)
    assert os.is_dir(expected)
    assert os.is_dir_empty(tdir2)
    // Move file with extension to dir
    os.mv(tfile2, tdir2) or { panic(err) }
    expected = os.join_path_single(tdir2, 'file.test')
    assert os.exists(expected)
    assert !os.is_dir(expected)
    // Move file to dir (by renaming)
    os.mv(os.join_path_single(tdir2, 'file.test'), tfile3) or { panic(err) }
    expected = tfile3
    assert os.exists(expected)
    assert !os.is_dir(expected)
}

fn test_is_dir_empty() {
    // Test that is_dir_empty returns true on
    // non-existent directories ***as stated in it's doc string***
    assert os.is_dir_empty('dir that does not exist at all')
}

fn test_cp_all() {
    // fileX -> dir/fileX
    // Note: clean up of the files happens inside the cleanup_leftovers function
    os.write_file('ex1.txt', 'wow!') or { panic(err) }
    os.mkdir('ex') or { panic(err) }
    os.cp_all('ex1.txt', 'ex', false) or { panic(err) }
    old := os.read_file('ex1.txt') or { panic(err) }
    new := os.read_file('ex/ex1.txt') or { panic(err) }
    assert old == new
    os.mkdir('ex/ex2') or { panic(err) }
    os.write_file('ex2.txt', 'great!') or { panic(err) }
    os.cp_all('ex2.txt', 'ex/ex2', false) or { panic(err) }
    old2 := os.read_file('ex2.txt') or { panic(err) }
    new2 := os.read_file('ex/ex2/ex2.txt') or { panic(err) }
    assert old2 == new2
    // recurring on dir -> local dir
    os.cp_all('ex', './', true) or { panic(err) }
    // regression test for executive runs with overwrite := true
    os.cp_all('ex', './', true) or { panic(err) }
    os.cp_all('ex', 'nonexisting', true) or { panic(err) }
    assert os.exists(os.join_path_single('nonexisting', 'ex1.txt'))
}

fn test_realpath_of_empty_string_works() {
    assert os.real_path('') == ''
}

fn test_realpath_non_existing() {
    non_existing_path := 'sdyfuisd_non_existing_file'
    rpath := os.real_path(non_existing_path)
    $if windows {
        // on windows, the workdir is prepended, so the result is absolute:
        assert rpath.len > non_existing_path.len
    }
    $if !windows {
        // on unix, the workdir is NOT prepended for now, so the result remains the same.
        // TODO: the windows behaviour seems saner, think about normalising the unix case to do the same.
        assert os.real_path(non_existing_path) == non_existing_path
    }
}

fn test_realpath_existing() {
    existing_file_name := 'existing_file.txt'
    existing_file := os.join_path_single(tfolder, existing_file_name)
    os.rm(existing_file) or {}
    os.write_file(existing_file, 'abc') or {}
    assert os.exists(existing_file)
    rpath := os.real_path(existing_file)
    assert os.is_abs_path(rpath)
    assert rpath.ends_with(existing_file_name)
    $if windows {
        assert !rpath.starts_with('UNC\\')
        assert !rpath.starts_with('\\\\?\\')
    }
    os.rm(existing_file) or {}
}

fn test_realpath_removes_dots() {
    examples_folder := os.join_path(@VEXEROOT, 'vlib', 'v', '..', '..', 'cmd', '.', '..',
        'examples')
    real_path_of_examples_folder := os.real_path(examples_folder)
    assert real_path_of_examples_folder.len < examples_folder.len
    assert !real_path_of_examples_folder.contains('..')
}

fn test_realpath_absolutizes_existing_relative_paths() {
    old_wd := os.getwd()
    defer {
        os.chdir(old_wd) or { panic(err) }
    }
    os.chdir(@VEXEROOT) or { panic(err) }
    examples_folder := os.join_path('vlib', 'v', '..', '..', 'cmd', '.', '..', 'examples')
    real_path_of_examples_folder := os.real_path(examples_folder)
    assert os.is_abs_path(real_path_of_examples_folder)
}

// TODO: think much more about whether this is desirable:

fn test_realpath_does_not_absolutize_non_existing_relative_paths() {
    relative_path := os.join_path('one', 'nonexisting_folder', '..', 'something')
    $if !windows {
        assert os.real_path(relative_path).contains('..')
        assert os.real_path(relative_path) == relative_path
    }
}

fn handle_privilege_error(err IError) ! {
    if err.msg().contains('required privilege is not held by the client') {
        eprintln('skipping ${@METHOD} on windows, since the user is not administrator, err:\n    ${err}')
        return err
    }
    panic(err)
}

fn test_realpath_absolutepath_symlink() ! {
    file_name := 'tolink_file.txt'
    symlink_name := 'symlink.txt'
    create_file(file_name)!
    os.symlink(file_name, symlink_name) or { handle_privilege_error(err) or { return } }
    rpath := os.real_path(symlink_name)
    println(rpath)
    assert os.is_abs_path(rpath)
    assert rpath.ends_with(file_name)
    $if windows {
        assert !rpath.starts_with('UNC\\')
        assert !rpath.starts_with('\\\\?\\')
    }
    os.rm(symlink_name) or {}
    os.rm(file_name) or {}
}

fn test_make_symlink_check_is_link_and_remove_symlink() {
    folder := 'tfolder'
    symlink := 'tsymlink'
    // windows creates a directory symlink, so delete it with rmdir()
    $if windows {
        os.rmdir(symlink) or {}
    } $else {
        os.rm(symlink) or {}
    }
    os.rmdir(folder) or {}
    os.mkdir(folder) or { panic(err) }
    folder_contents := os.ls(folder) or { panic(err) }
    assert folder_contents.len == 0
    os.symlink(folder, symlink) or { handle_privilege_error(err) or { return } }
    assert os.is_link(symlink)
    $if windows {
        os.rmdir(symlink) or { panic(err) }
    } $else {
        os.rm(symlink) or { panic(err) }
    }
    os.rmdir(folder) or { panic(err) }
    folder_exists := os.is_dir(folder)
    assert folder_exists == false
    symlink_exists := os.is_link(symlink)
    assert symlink_exists == false
}

fn test_make_symlink_check_is_link_and_remove_symlink_with_file() {
    file := 'tfile'
    symlink := 'tsymlink'
    os.rm(symlink) or {}
    os.rm(file) or {}
    create_file(file)!
    os.symlink(file, symlink) or { handle_privilege_error(err) or { return } }
    assert os.is_link(symlink)
    os.rm(symlink) or { panic(err) }
    os.rm(file) or { panic(err) }
    symlink_exists := os.is_link(symlink)
    assert symlink_exists == false
}

fn test_make_hardlink_check_is_link_and_remove_hardlink_with_file() {
    file := 'tfile'
    symlink := 'tsymlink'
    os.rm(symlink) or {}
    os.rm(file) or {}
    create_file(file)!
    os.link(file, symlink) or { panic(err) }
    assert os.exists(symlink)
    os.rm(symlink) or { panic(err) }
    os.rm(file) or { panic(err) }
    symlink_exists := os.is_link(symlink)
    assert symlink_exists == false
}

// fn test_fork() {
// pid := os.fork()
// if pid == 0 {
// println('Child')
// }
// else {
// println('Parent')
// }
// }
// fn test_wait() {
// pid := os.fork()
// if pid == 0 {
// println('Child')
// exit(0)
// }
// else {
// cpid := os.wait()
// println('Parent')
// println(cpid)
// }
// }

fn test_symlink() {
    os.mkdir('symlink') or { panic(err) }
    os.symlink('symlink', 'symlink2') or { handle_privilege_error(err) or { return } }
    assert os.exists('symlink2')
    // cleanup
    os.rmdir('symlink') or { panic(err) }
    $if windows {
        os.rmdir('symlink2') or { panic(err) }
    } $else {
        os.rm('symlink2') or { panic(err) }
    }
}

fn test_readlink() {
    $if windows {
        eprintln('skipping ${@METHOD} on windows, api not supported')
        return
    }
    os.symlink('some_target_string', 'some_symlink')!
    defer { os.rm('some_symlink') or { panic(err) } }
    assert os.readlink('some_symlink')! == 'some_target_string'
}

fn test_exists_symlink_dangling() {
    $if msvc {
        eprintln('skipping ${@METHOD} on windows + msvc; TODO: investigate why os.lstat/1 behaves differently than for gcc/clang')
        return
    }
    os.symlink('nonexistent', 'dangling_symlink') or { handle_privilege_error(err) or { return } }
    // sanity check that the symlink truly does exist.  the lack of error alone is the check.
    // (on linux, `.get_filetype() == os.FileType.symbolic_link` is true, but on windows, a dangling symlink is reported as a regular file.)
    os.lstat('dangling_symlink')!
    // the exists function says false in this scenario... on linux and linux-like systems.
    // it says true on windows!
    $if windows {
        assert os.exists('dangling_symlink') == true
    } $else {
        assert os.exists('dangling_symlink') == false
    }
}

fn test_is_executable_writable_readable() {
    file_name := 'rwxfile.exe'
    create_file(file_name)!
    $if !windows {
        os.chmod(file_name, 0o600) or {} // mark as readable && writable, but NOT executable
        assert os.is_writable(file_name)
        assert os.is_readable(file_name)
        assert !os.is_executable(file_name)
        os.chmod(file_name, 0o700) or {} // mark as executable too
        assert os.is_executable(file_name)
    } $else {
        assert os.is_writable(file_name)
        assert os.is_readable(file_name)
        assert os.is_executable(file_name)
        for ext in ['exe', 'com', 'bat', 'cmd'] {
            mut executable_file_name := 'executable.${ext}'
            create_file(executable_file_name)!
            assert os.is_executable(executable_file_name)
            os.rm(executable_file_name) or { panic(err) }
        }
    }
    // We finally delete the test file.
    os.rm(file_name) or { panic(err) }
}

fn test_file_ext() {
    assert os.file_ext('') == ''
    assert os.file_ext('file.v') == '.v'
    assert os.file_ext('file.js.v') == '.v'
    assert os.file_ext('file.ext1.ext2.ext3') == '.ext3'
    assert os.file_ext('.ignore_me.v') == '.v'
    assert os.file_ext('file') == ''
    assert os.file_ext('.git') == ''
    assert os.file_ext('file.') == ''
    assert os.file_ext('.') == ''
    assert os.file_ext('..') == ''
    assert os.file_ext('file...') == ''
    assert os.file_ext('.file.') == ''
    assert os.file_ext('..file..') == ''
    assert os.file_ext('./.git') == ''
    assert os.file_ext('./.git/') == ''
    assert os.file_ext('\\.git') == ''
    assert os.file_ext('\\.git\\') == ''
}

fn test_rmdir_all() {
    mut dirs := ['some/dir', 'some/.hidden/directory']
    $if windows {
        for mut d in dirs {
            d = d.replace('/', '\\')
        }
    }
    for d in dirs {
        os.mkdir_all(d) or { panic(err) }
        assert os.is_dir(d)
    }
    os.rmdir_all('some') or { assert false }
    assert !os.exists('some')
}

fn test_rmdir_not_exist() ! {
    dir := 'non_existing_dir'
    assert !os.exists(dir)
    os.rmdir(dir) or {
        // 0x00000002 is both ENOENT in POSIX and ERROR_FILE_NOT_FOUND in Win32 API
        assert err.code() == 0x00000002
    }
    assert !os.exists(dir)
}

fn test_dir() {
    assert os.dir('') == '.'
    assert os.dir('\\') == '\\'
    assert os.dir('C:\\a\\b\\c') == 'C:\\a\\b'
    assert os.dir('C:\\a\\b\\') == 'C:\\a\\b'
    assert os.dir('C:/a/b/c') == 'C:/a/b'
    assert os.dir('C:/a/b/') == 'C:/a/b'
    assert os.dir('/') == '/'
    assert os.dir('/abc') == '/'
    assert os.dir('/var/tmp/foo') == '/var/tmp'
    assert os.dir('/var/tmp/') == '/var/tmp'
    assert os.dir('os') == '.'
}

fn test_base() {
    assert os.base('') == '.'
    assert os.base('v\\vlib\\os') == 'os'
    assert os.base('v\\vlib\\os\\') == 'os'
    assert os.base('v/vlib/os') == 'os'
    assert os.base('v/vlib/os/') == 'os'
    assert os.base('v/vlib/os') == 'os'
    assert os.base('v/vlib/os/') == 'os'
    assert os.base('v\\vlib\\os') == 'os'
    assert os.base('v\\vlib\\os\\') == 'os'
    assert os.base('filename') == 'filename'
}

fn test_file_name() {
    assert os.file_name('') == ''
    assert os.file_name('v\\vlib\\os\\os.v') == 'os.v'
    assert os.file_name('v\\vlib\\os\\') == ''
    assert os.file_name('v\\vlib\\os') == 'os'
    assert os.file_name('v/vlib/os/os.v') == 'os.v'
    assert os.file_name('v/vlib/os/') == ''
    assert os.file_name('v/vlib/os') == 'os'
    assert os.file_name('filename') == 'filename'
}

fn test_split_path() {
    mut dir := ''
    mut filename := ''
    mut ext := ''

    dir, filename, ext = os.split_path('')
    assert [dir, filename, ext] == ['.', '', '']

    dir, filename, ext = os.split_path('a')
    assert [dir, filename, ext] == ['.', 'a', '']

    dir, filename, ext = os.split_path('.')
    assert [dir, filename, ext] == ['.', '', '']

    dir, filename, ext = os.split_path('..')
    assert [dir, filename, ext] == ['..', '', '']

    dir, filename, ext = os.split_path('\\')
    assert [dir, filename, ext] == ['\\', '', '']

    dir, filename, ext = os.split_path('\\x.c.v')
    assert [dir, filename, ext] == ['\\', 'x.c', '.v']

    dir, filename, ext = os.split_path('.\\x.c.v')
    assert [dir, filename, ext] == ['.', 'x.c', '.v']

    dir, filename, ext = os.split_path('x.c.v')
    assert [dir, filename, ext] == ['.', 'x.c', '.v']

    dir, filename, ext = os.split_path('..\\x.c.v')
    assert [dir, filename, ext] == ['..', 'x.c', '.v']

    dir, filename, ext = os.split_path('\\lib\\x.c.v')
    assert [dir, filename, ext] == ['\\lib', 'x.c', '.v']

    dir, filename, ext = os.split_path('\\lib\\x.c.v\\')
    assert [dir, filename, ext] == ['\\lib\\x.c.v', '', '']

    dir, filename, ext = os.split_path('\\lib\\x.c.')
    assert [dir, filename, ext] == ['\\lib', 'x.c.', '']

    dir, filename, ext = os.split_path('C:\\lib\\x.c.')
    assert [dir, filename, ext] == ['C:\\lib', 'x.c.', '']

    dir, filename, ext = os.split_path('/')
    assert [dir, filename, ext] == ['/', '', '']

    dir, filename, ext = os.split_path('/x.c.v')
    assert [dir, filename, ext] == ['/', 'x.c', '.v']

    dir, filename, ext = os.split_path('./x.c.v')
    assert [dir, filename, ext] == ['.', 'x.c', '.v']

    dir, filename, ext = os.split_path('../x.c.v')
    assert [dir, filename, ext] == ['..', 'x.c', '.v']

    dir, filename, ext = os.split_path('/lib/x.c.v')
    assert [dir, filename, ext] == ['/lib', 'x.c', '.v']

    dir, filename, ext = os.split_path('/lib/x.c.v/')
    assert [dir, filename, ext] == ['/lib/x.c.v', '', '']

    dir, filename, ext = os.split_path('/lib/../x.c.v/')
    assert [dir, filename, ext] == ['/lib/../x.c.v', '', '']

    dir, filename, ext = os.split_path('/lib/x.c.')
    assert [dir, filename, ext] == ['/lib', 'x.c.', '']
}

fn test_uname() {
    u := os.uname()
    assert u.sysname.len > 0
    assert u.nodename.len > 0
    assert u.release.len > 0
    assert u.version.len > 0
    assert u.machine.len > 0
}

// tests for write_file_array and read_file_array[T]:
const maxn = 3

struct IntPoint {
    x int
    y int
}

fn test_write_file_array_bytes() {
    fpath := './abytes.bin'
    mut arr := []u8{len: maxn}
    for i in 0 .. maxn {
        arr[i] = 65 + u8(i)
    }
    os.write_file_array(fpath, arr) or { panic(err) }
    rarr := os.read_bytes(fpath) or { panic(err) }
    assert arr == rarr
    // eprintln(arr.str())
    // eprintln(rarr.str())
}

fn test_write_bytes() {
    fpath := './wbytes.bin'
    for arr in [[u8(65), 66, 67, 68, 69, 70], [u8(3), 2, 1], []u8{}] {
        os.write_bytes(fpath, arr)!
        rarr := os.read_bytes(fpath)!
        assert arr == rarr
    }
}

fn test_write_file_array_structs() {
    fpath := './astructs.bin'
    mut arr := []IntPoint{len: maxn}
    for i in 0 .. maxn {
        arr[i] = IntPoint{65 + i, 65 + i + 10}
    }
    os.write_file_array(fpath, arr) or { panic(err) }
    rarr := os.read_file_array[IntPoint](fpath)
    assert rarr == arr
    assert rarr.len == maxn
    // eprintln( rarr.str().replace('\n', ' ').replace('},', '},\n'))
}

fn test_stdout_capture() {
    /*
    mut cmd := os.Command{
    path:'cat'
    redirect_stdout: true
}
cmd.start()
for !cmd.eof {
    line := cmd.read_line()
    println('line="${line}"')
}
cmd.close()
    */
}

fn test_posix_set_bit() {
    $if windows {
        assert true
    } $else {
        fpath := 'permtest'
        create_file(fpath)!
        os.chmod(fpath, 0o0777) or { panic(err) }
        c_fpath := &char(fpath.str)
        mut s := C.stat{}
        unsafe {
            C.stat(c_fpath, &s)
        }
        // Take the permissions part of the mode
        mut mode := u32(s.st_mode) & 0o0777
        assert mode == 0o0777
        // `chmod u-r`
        os.posix_set_permission_bit(fpath, os.s_irusr, false)
        unsafe {
            C.stat(c_fpath, &s)
        }
        mode = u32(s.st_mode) & 0o0777
        assert mode == 0o0377
        // `chmod u+r`
        os.posix_set_permission_bit(fpath, os.s_irusr, true)
        unsafe {
            C.stat(c_fpath, &s)
        }
        mode = u32(s.st_mode) & 0o0777
        assert mode == 0o0777
        // Note: setting the sticky bit is platform dependent
        // `chmod -s -g -t`
        os.posix_set_permission_bit(fpath, os.s_isuid, false)
        os.posix_set_permission_bit(fpath, os.s_isgid, false)
        os.posix_set_permission_bit(fpath, os.s_isvtx, false)
        unsafe {
            C.stat(c_fpath, &s)
        }
        mode = u32(s.st_mode) & 0o0777
        assert mode == 0o0777
        // `chmod g-w o-w`
        os.posix_set_permission_bit(fpath, os.s_iwgrp, false)
        os.posix_set_permission_bit(fpath, os.s_iwoth, false)
        unsafe {
            C.stat(c_fpath, &s)
        }
        mode = u32(s.st_mode) & 0o7777
        assert mode == 0o0755
        os.rm(fpath) or {}
    }
}

fn test_exists_in_system_path() {
    assert os.exists_in_system_path('') == false
    $if windows {
        assert os.exists_in_system_path('cmd.exe')
        return
    }
    assert os.exists_in_system_path('ls')
}

fn test_truncate() {
    filename := './test_trunc.txt'
    hello := 'hello world!'
    mut f := os.create(filename)!
    f.write_string(hello)!
    f.close()
    assert u64(hello.len) == os.file_size(filename)
    newlen := u64(40000)
    os.truncate(filename, newlen) or { panic(err) }
    assert newlen == os.file_size(filename)
    os.rm(filename) or { panic(err) }
}

fn test_hostname() {
    hostname := os.hostname() or { '' }
    assert hostname.len > 2
}

// fn test_loginname() {
// loginname := os.loginname() or { '' }
// assert loginname.len > 2
//}

fn test_glob() {
    os.mkdir('test_dir') or { panic(err) }
    for i in 0 .. 4 {
        if i == 3 {
            create_file('test_dir/test0_another')!
            create_file('test_dir/test')!
        } else {
            create_file('test_dir/test' + i.str())!
        }
    }
    files := os.glob('test_dir/t*') or { panic(err) }
    assert files.len == 5
    assert os.base(files[0]) == 'test'

    for i in 0 .. 3 {
        os.rm('test_dir/test' + i.str()) or { panic(err) }
    }
    os.rm('test_dir/test0_another') or { panic(err) }
    os.rm('test_dir/test') or { panic(err) }
    os.rmdir_all('test_dir') or { panic(err) }
}

fn test_utime() {
    filename := './test_utime.txt'
    hello := 'hello world!'
    mut f := os.create(filename) or { panic(err) }
    defer {
        f.close()
        os.rm(filename) or { panic(err) }
    }
    f.write_string(hello) or { panic(err) }
    atime := i64(2_147_483_648)
    mtime := i64(2_306_102_495)
    os.utime(filename, atime, mtime) or { panic(err) }
    assert os.file_last_mod_unix(filename) == mtime
}

fn test_execute() {
    print0script := os.join_path_single(tfolder, 'print0.v')
    // The output of the next command contains a 0 byte in the middle.
    // Nevertheless, the execute function *should* return a string that
    // contains it.
    os.write_file(print0script, 'C.printf(c"start%cMIDDLE%cfinish\nxx", 0, 0)\n')!
    defer {
        os.rm(print0script) or {}
    }
    result := os.execute('${os.quoted_path(@VEXE)} run ${os.quoted_path(print0script)}')
    hexresult := result.output.hex()
    // println('exit_code: ${result.exit_code}')
    // println('output: |${result.output}|')
    // println('output.len: ${result.output.len}')
    // println('output hexresult: ${hexresult}')
    assert result.exit_code == 0
    assert hexresult.contains('7374617274004d4944444c450066696e697368')
    assert hexresult.ends_with('0a7878')
}

fn test_exec_with_args() {
    source_path := os.join_path_single(tfolder, 'exec_args.v')
    output_arg := os.join_path_single(tfolder, 'exec_args')
    exe_path := if os.user_os() == 'windows' {
        output_arg + '.exe'
    } else {
        output_arg
    }
    os.write_file(source_path,
        "import os\n\nfn main() {\n\tprintln(os.args[1..].join('|'))\n\teprintln('stderr-ok')\n}\n")!
    defer {
        os.rm(source_path) or {}
        os.rm(exe_path) or {}
        os.rm(output_arg + '.c') or {}
    }
    compile_result :=
        os.execute('${os.quoted_path(@VEXE)} -o ${os.quoted_path(output_arg)} ${os.quoted_path(source_path)}')
    assert compile_result.exit_code == 0, compile_result.output

    result := os.exec([exe_path, 'one two', 'semi;colon'])
    normalized_output := result.output.replace('\r\n', '\n')
    assert result.exit_code == 0, result.output
    assert normalized_output.contains('one two|semi;colon\n'), result.output
    assert normalized_output.contains('stderr-ok\n'), result.output

    shell_metachar_result := os.exec([exe_path, 'first; echo injected'])
    normalized_shell_metachar_output := shell_metachar_result.output.replace('\r\n', '\n')
    assert shell_metachar_result.exit_code == 0, shell_metachar_result.output
    assert normalized_shell_metachar_output.contains('first; echo injected\n'), shell_metachar_result.output
}

fn test_execute_with_stderr_redirection() {
    result := os.execute('${os.quoted_path(@VEXE)} wrong_command')
    assert result.exit_code == 1
    assert result.output.contains('unknown command `wrong_command`')

    stderr_path := os.join_path_single(tfolder, 'stderr.txt')
    result2 :=
        os.execute('${os.quoted_path(@VEXE)} wrong_command 2> ${os.quoted_path(stderr_path)}')
    assert result2.exit_code == 1
    assert result2.output == ''
    assert os.exists(stderr_path)
}

fn test_execute_with_linefeeds() {
    if os.user_os() == 'windows' {
        return
    }
    result := os.execute('true\n')
    assert result.exit_code == 0
    result2 := os.execute('false\n')
    assert result2.exit_code == 1
}

fn test_execute_with_semicolon_inside_quoted_string_on_windows() {
    if os.user_os() != 'windows' {
        return
    }
    result := os.execute('echo "hello;"')
    assert result.exit_code == 0, result.output
    assert result.output.trim_space() == '"hello;"'
}

fn test_execute_pipe_into_vfmt() {
    producer_script := os.join_path_single(tfolder, 'pipe_into_vfmt.v')
    os.write_file(producer_script, "fn main() {\n\tprint('fn main(){println(1)}\\n')\n}\n")!
    defer {
        os.rm(producer_script) or {}
    }
    result :=
        os.execute('${os.quoted_path(@VEXE)} run ${os.quoted_path(producer_script)} | ${os.quoted_path(@VEXE)} fmt')
    assert result.exit_code == 0, result.output
    assert result.output.replace('\r\n', '\n') == 'fn main() {\n\tprintln(1)\n}\n'
}

fn test_execute_fc_get_output() {
    if os.user_os() != 'windows' {
        return
    }
    result := os.execute('c:\\windows\\system32\\fc.exe /?')
    assert result.output.contains('filename')
    assert result.exit_code == -1
}

fn test_execute_decodes_utf16le_output() {
    if os.user_os() != 'windows' {
        return
    }
    source_path := os.join_path_single(tfolder, 'utf16le_stdout.v')
    os.write_file(source_path, utf16le_stdout_source_code)!
    defer {
        os.rm(source_path) or {}
    }
    result := os.execute('${os.quoted_path(@VEXE)} run ${os.quoted_path(source_path)}')
    assert result.exit_code == 0, result.output
    assert result.output == 'OK\n', result.output
}

fn test_reading_from_proc_cpuinfo() {
    // This test is only for plain linux systems (they have a /proc virtual filesystem).
    $if android {
        assert true
        return
    }
    $if !linux {
        assert true
        return
    }
    info := os.read_file('/proc/cpuinfo')!
    assert info.len > 0
    assert info.contains('processor')
    // dump(info)
    // assert info.ends_with('\n\n') // fails on QEMU for s390x

    info_bytes := os.read_bytes('/proc/cpuinfo')!
    assert info_bytes.len > 0
    assert info.len == info_bytes.len
}

fn test_reading_from_empty_file() {
    empty_file := os.join_path_single(tfolder, 'empty_file.txt')
    os.rm(empty_file) or {}
    assert !os.exists(empty_file)
    os.write_file(empty_file, '')!
    assert os.exists(empty_file)
    content := os.read_file(empty_file)!
    assert content.len == 0
    content_bytes := os.read_bytes(empty_file)!
    assert content_bytes.len == 0
    os.rm(empty_file)!
}

fn move_across_partitions_using_function(f fn (src string, dst string, opts os.MvParams) !) ! {
    bindfs := os.find_abs_path_of_executable('bindfs') or {
        eprintln('skipping test_mv_by_cp, because bindfs was not present')
        return
    }
    // eprintln('>> ${bindfs}')
    pfolder := os.join_path(tfolder, 'parent')
    cfolder := os.join_path(pfolder, 'child')
    mfolder := os.join_path(pfolder, 'mountpoint')
    cdeepfolder := os.join_path(cfolder, 'deep', 'folder')
    os.mkdir_all(mfolder)!
    os.mkdir_all(cfolder)!
    os.mkdir_all(cdeepfolder)!

    original_path := os.join_path(pfolder, 'original.txt')
    target_path := os.join_path(cdeepfolder, 'target.txt')
    os.write_file(original_path, 'text')!
    os.write_file(os.join_path(cdeepfolder, 'x.txt'), 'some text')!
    // os.system('tree ${pfolder}')
    /*
    /tmp/v_1000/v/tests/os_test/parent
    ├── child
    │   └── deep
    │       └── folder
    │           └── x.txt
    ├── mountpoint
    └── original.txt
    */
    os.system('${bindfs} --no-allow-other ${cfolder} ${mfolder}')
    defer {
        os.system('sync; umount ${mfolder}')
    }
    // os.system('tree ${pfolder}')
    /*
    /tmp/v_1000/v/tests/os_test/parent
    ├── child
    │   └── deep
    │       └── folder
    │           └── x.txt
    ├── mountpoint
    │   └── deep
    │       └── folder
    │           └── x.txt
    └── original.txt
    */

    f(original_path, target_path)!

    assert os.exists(target_path)
    assert !os.exists(original_path)
}

fn test_mv_by_cp_across_partitions() {
    move_across_partitions_using_function(os.mv_by_cp)!
}

fn test_mv_across_partitions() {
    move_across_partitions_using_function(os.mv)!
}

fn test_page_size() {
    assert os.page_size() >= 4096 // this is normal and assumed.
}

fn test_mkdir_at_file_dst() {
    f3 := os.join_path('myfolder', 'f1', 'f2', 'f3')
    os.mkdir_all(f3)!
    assert os.is_dir(f3)
    path := os.join_path(f3, 'no_ext_doc')
    os.write_file(path, '')!
    assert os.exists(path) && os.is_file(path)
    os.mkdir_all(path) or {
        assert err.msg() == 'path `${path}` already exists, and is not a folder', err.msg()
        return
    }
    assert false
}

fn test_disk_usage() {
    usage := os.disk_usage('.')!
    assert usage.total > 0
    assert usage.available > 0
    assert usage.used > 0
}