#![deny(warnings)]

// This test suite is incomplete and doesn't cover all available functionality.
// Contributions to improve test coverage would be highly appreciated!

#[cfg(feature = "stream")]
use inotify::StreamExt;
use inotify::{EventMask, Inotify, WatchMask};
use std::fs::File;
use std::io::{ErrorKind, Write};
#[cfg(feature = "stream")]
use std::mem;
use std::os::fd::AsFd;
use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd};
use std::path::PathBuf;
use tempfile::TempDir;

#[cfg(feature = "stream")]
use futures_util::FutureExt;
#[cfg(feature = "stream")]
use maplit::hashmap;
#[cfg(feature = "stream")]
use rand::{prelude::SliceRandom, thread_rng};
#[cfg(feature = "stream")]
use std::sync::{Arc, Mutex};

#[test]
fn it_should_watch_a_file() {
    let mut testdir = TestDir::new();
    let (path, mut file) = testdir.new_file();

    let mut inotify = Inotify::init().unwrap();
    let watch = inotify.watches().add(&path, WatchMask::MODIFY).unwrap();

    write_to(&mut file);

    let mut buffer = [0; 1024];
    let events = inotify.read_events_blocking(&mut buffer).unwrap();

    let mut num_events = 0;
    for event in events {
        assert_eq!(watch, event.wd);
        num_events += 1;
    }
    assert!(num_events > 0);
}

#[cfg(feature = "stream")]
#[tokio::test]
async fn it_should_watch_a_file_async() {
    let mut testdir = TestDir::new();
    let (path, mut file) = testdir.new_file();

    let inotify = Inotify::init().unwrap();

    // Hold ownership of `watches` for this test, so that the underlying file descriptor has
    // at least one reference to keep it alive, and we can inspect the WatchDescriptors below.
    // Otherwise the `Weak<FdGuard>` contained in the WatchDescriptors will be invalidated
    // when `inotify` is consumed by `into_event_stream()` and the EventStream is dropped
    // during `await`.
    let mut watches = inotify.watches();

    let watch = watches.add(&path, WatchMask::MODIFY).unwrap();

    write_to(&mut file);

    let mut buffer = [0; 1024];

    let events = inotify
        .into_event_stream(&mut buffer[..])
        .unwrap()
        .take(1)
        .collect::<Vec<_>>()
        .await;

    let mut num_events = 0;
    for event in events.into_iter().flatten() {
        assert_eq!(watch, event.wd);
        num_events += 1;
    }
    assert!(num_events > 0);
}

#[cfg(feature = "stream")]
#[tokio::test]
async fn it_should_watch_a_file_from_eventstream_watches() {
    let mut testdir = TestDir::new();
    let (path, mut file) = testdir.new_file();

    let inotify = Inotify::init().unwrap();

    let mut buffer = [0; 1024];

    let stream = inotify.into_event_stream(&mut buffer[..]).unwrap();

    // Hold ownership of `watches` for this test, so that the underlying file descriptor has
    // at least one reference to keep it alive, and we can inspect the WatchDescriptors below.
    // Otherwise the `Weak<FdGuard>` contained in the WatchDescriptors will be invalidated
    // when `stream` is dropped during `await`.
    let mut watches = stream.watches();

    let watch = watches.add(&path, WatchMask::MODIFY).unwrap();
    write_to(&mut file);

    let events = stream.take(1).collect::<Vec<_>>().await;

    let mut num_events = 0;
    for event in events.into_iter().flatten() {
        assert_eq!(watch, event.wd);
        num_events += 1;
    }
    assert!(num_events > 0);
}

#[cfg(feature = "stream")]
#[tokio::test]
async fn it_should_watch_a_file_after_converting_back_from_eventstream() {
    let mut testdir = TestDir::new();
    let (path, mut file) = testdir.new_file();

    let inotify = Inotify::init().unwrap();

    let mut buffer = [0; 1024];
    let stream = inotify.into_event_stream(&mut buffer[..]).unwrap();
    let mut inotify = stream.into_inotify();

    let watch = inotify.watches().add(&path, WatchMask::MODIFY).unwrap();

    write_to(&mut file);

    let events = inotify.read_events_blocking(&mut buffer).unwrap();

    let mut num_events = 0;
    for event in events {
        assert_eq!(watch, event.wd);
        num_events += 1;
    }
    assert!(num_events > 0);
}

#[test]
fn it_should_return_immediately_if_no_events_are_available() {
    let mut inotify = Inotify::init().unwrap();

    let mut buffer = [0; 1024];
    assert_eq!(
        inotify.read_events(&mut buffer).unwrap_err().kind(),
        ErrorKind::WouldBlock
    );
}

#[test]
fn it_should_convert_the_name_into_an_os_str() {
    let mut testdir = TestDir::new();
    let (path, mut file) = testdir.new_file();

    let mut inotify = Inotify::init().unwrap();
    inotify
        .watches()
        .add(path.parent().unwrap(), WatchMask::MODIFY)
        .unwrap();

    write_to(&mut file);

    let mut buffer = [0; 1024];
    let mut events = inotify.read_events_blocking(&mut buffer).unwrap();

    if let Some(event) = events.next() {
        assert_eq!(path.file_name(), event.name);
    } else {
        panic!("Expected inotify event");
    }
}

#[test]
fn it_should_set_name_to_none_if_it_is_empty() {
    let mut testdir = TestDir::new();
    let (path, mut file) = testdir.new_file();

    let mut inotify = Inotify::init().unwrap();
    inotify.watches().add(&path, WatchMask::MODIFY).unwrap();

    write_to(&mut file);

    let mut buffer = [0; 1024];
    let mut events = inotify.read_events_blocking(&mut buffer).unwrap();

    if let Some(event) = events.next() {
        assert_eq!(event.name, None);
    } else {
        panic!("Expected inotify event");
    }
}

#[test]
fn it_should_not_accept_watchdescriptors_from_other_instances() {
    let mut testdir = TestDir::new();
    let (path, _) = testdir.new_file();

    let inotify = Inotify::init().unwrap();
    let _ = inotify.watches().add(&path, WatchMask::ACCESS).unwrap();

    let second_inotify = Inotify::init().unwrap();
    let wd2 = second_inotify
        .watches()
        .add(&path, WatchMask::ACCESS)
        .unwrap();

    assert_eq!(
        inotify.watches().remove(wd2).unwrap_err().kind(),
        ErrorKind::InvalidInput
    );
}

#[test]
fn watch_descriptors_from_different_inotify_instances_should_not_be_equal() {
    let mut testdir = TestDir::new();
    let (path, _) = testdir.new_file();

    let inotify_1 = Inotify::init().unwrap();
    let inotify_2 = Inotify::init().unwrap();

    let wd_1 = inotify_1.watches().add(&path, WatchMask::ACCESS).unwrap();
    let wd_2 = inotify_2.watches().add(&path, WatchMask::ACCESS).unwrap();

    // As far as inotify is concerned, watch descriptors are just integers that
    // are scoped per inotify instance. This means that multiple instances will
    // produce the same watch descriptor number, a case we want inotify-rs to
    // detect.
    assert!(wd_1 != wd_2);
}

#[test]
fn watch_descriptor_equality_should_not_be_confused_by_reused_fds() {
    let mut testdir = TestDir::new();
    let (path, _) = testdir.new_file();

    // When a new inotify instance is created directly after closing another
    // one, it is possible that the file descriptor is reused immediately, and
    // we end up with a new instance that has the same file descriptor as the
    // old one.
    // This is quite likely, but it doesn't happen every time. Therefore we may
    // need a few tries until we find two instances where that is the case.
    let (wd_1, inotify_2) = loop {
        let inotify_1 = Inotify::init().unwrap();

        let wd_1 = inotify_1.watches().add(&path, WatchMask::ACCESS).unwrap();
        let fd_1 = inotify_1.as_raw_fd();

        inotify_1.close().unwrap();
        let inotify_2 = Inotify::init().unwrap();

        if fd_1 == inotify_2.as_raw_fd() {
            break (wd_1, inotify_2);
        }
    };

    let wd_2 = inotify_2.watches().add(&path, WatchMask::ACCESS).unwrap();

    // The way we engineered this situation, both `WatchDescriptor` instances
    // have the same fields. They still come from different inotify instances
    // though, so they shouldn't be equal.
    assert!(wd_1 != wd_2);

    inotify_2.close().unwrap();

    // A little extra gotcha: If both inotify instances are closed, and the `Eq`
    // implementation naively compares the weak pointers, both will be `None`,
    // making them equal. Let's make sure this isn't the case.
    assert!(wd_1 != wd_2);
}

#[test]
fn it_should_implement_raw_fd_traits_correctly() {
    let fd = Inotify::init()
        .expect("Failed to initialize inotify instance")
        .into_raw_fd();

    // If `IntoRawFd` has been implemented naively, `Inotify`'s `Drop`
    // implementation will have closed the inotify instance at this point. Let's
    // make sure this didn't happen.
    let mut inotify = unsafe { <Inotify as FromRawFd>::from_raw_fd(fd) };

    let mut buffer = [0; 1024];
    if let Err(error) = inotify.read_events(&mut buffer) {
        if error.kind() != ErrorKind::WouldBlock {
            panic!("Failed to add watch: {}", error);
        }
    }
}

#[test]
fn it_should_watch_correctly_with_a_watches_clone() {
    let mut testdir = TestDir::new();
    let (path, mut file) = testdir.new_file();

    let mut inotify = Inotify::init().unwrap();
    let mut watches1 = inotify.watches();
    let mut watches2 = watches1.clone();
    let watch1 = watches1.add(&path, WatchMask::MODIFY).unwrap();
    let watch2 = watches2.add(&path, WatchMask::MODIFY).unwrap();

    // same path and same Inotify should return same descriptor
    assert_eq!(watch1, watch2);

    write_to(&mut file);

    let mut buffer = [0; 1024];
    let events = inotify.read_events_blocking(&mut buffer).unwrap();

    let mut num_events = 0;
    for event in events {
        assert_eq!(watch2, event.wd);
        num_events += 1;
    }
    assert!(num_events > 0);
}

#[test]
fn watch_descriptor_equality_should_work_for_multiple_fds_of_same_instance() {
    let mut testdir = TestDir::new();
    let (path, _) = testdir.new_file();
    let inotify = Inotify::init().unwrap();
    // Clone the fd of the inotify instance to create a second reference to the same instance
    let second_inotify_reference = Inotify::from(
        inotify
            .as_fd()
            .try_clone_to_owned()
            .expect("failed to clone fd of inotify"),
    );
    // Since both descriptors point to the same inotify instance, attempting to add a watch twice
    // should return the same watch descriptor
    let first_watch = inotify.watches().add(&path, WatchMask::MODIFY).unwrap();
    let second_watch = second_inotify_reference
        .watches()
        .add(&path, WatchMask::MODIFY)
        .unwrap();
    assert_eq!(
        first_watch, second_watch,
        "first and second watch descriptors should be equal"
    );
}

#[cfg(feature = "stream")]
#[tokio::test]
/// Testing if two files with the same name but different directories
/// (e.g. "file_a" and "another_dir/file_a") are distinguished when _randomly_
/// triggering a DELETE_SELF for the two files.
async fn it_should_distinguish_event_for_files_with_same_name() {
    let mut testdir = TestDir::new();
    let testdir_path = testdir.dir.path().to_owned();
    let file_order = Arc::new(Mutex::new(vec!["file_a", "another_dir/file_a"]));
    file_order.lock().unwrap().shuffle(&mut thread_rng());
    let file_order_clone = file_order.clone();

    let inotify = Inotify::init().expect("Failed to initialize inotify instance");

    // creating file_a inside `TestDir.dir`
    let (path_1, _) = testdir.new_file_with_name("file_a");
    // creating a directory inside `TestDir.dir`
    testdir.new_directory_with_name("another_dir");
    // creating a file inside `TestDir.dir/another_dir`
    let (path_2, _) = testdir.new_file_in_directory_with_name("another_dir", "file_a");

    // watching both files for `DELETE_SELF`
    let wd_1 = inotify
        .watches()
        .add(&path_1, WatchMask::DELETE_SELF)
        .unwrap();
    let wd_2 = inotify
        .watches()
        .add(&path_2, WatchMask::DELETE_SELF)
        .unwrap();

    let expected_ids = hashmap! {
        wd_1.get_watch_descriptor_id() => "file_a",
        wd_2.get_watch_descriptor_id() => "another_dir/file_a"
    };
    let mut buffer = [0; 1024];

    let file_removal_handler = tokio::spawn(async move {
        for file in file_order.lock().unwrap().iter() {
            testdir.delete_file(file);
        }
    });

    let event_handle = tokio::spawn(async move {
        let mut events = inotify.into_event_stream(&mut buffer).unwrap();
        while let Some(Ok(event)) = events.next().await {
            if event.mask == EventMask::DELETE_SELF {
                let id = event.wd.get_watch_descriptor_id();
                let file = expected_ids.get(&id).unwrap();
                let full_path = testdir_path.join(*file);
                println!("file {:?} was deleted", full_path);
                file_order_clone.lock().unwrap().retain(|&x| x != *file);

                if file_order_clone.lock().unwrap().is_empty() {
                    break;
                }
            }
        }
    });

    let () = event_handle.await.unwrap();
    let () = file_removal_handler.await.unwrap();
}

#[cfg(feature = "stream")]
#[tokio::test]
async fn it_should_yield_all_events_with_small_buffer() {
    let testdir = TestDir::new();
    let dir_path = testdir.dir.path().to_owned();

    let inotify = Inotify::init().expect("Failed to initialize inotify instance");

    inotify
        .watches()
        .add(&dir_path, WatchMask::CREATE)
        .expect("Failed to add watch");

    let num_files = 3usize;
    for i in 0..num_files {
        let file_path = dir_path.join(format!("{}", i));
        File::create(&file_path).expect("Failed to create file");
    }

    let event_struct_size = mem::size_of::<inotify_sys::inotify_event>();
    let name_len_padded = 4; // "0\0" padded to 4-byte alignment
    let single_event_size = event_struct_size + name_len_padded;

    // Use a buffer that can fit exactly one event but not two.
    let buffer_size = single_event_size + (single_event_size - 1); // 20 + 19 = 39 bytes
    let mut buffer = vec![0u8; buffer_size];
    let mut stream = inotify.into_event_stream(&mut buffer[..]).unwrap();

    // Await one event to ensure that everything has settled.
    let first_event = stream.next().await.unwrap().unwrap();
    assert!(first_event.mask.contains(EventMask::CREATE));

    // Each call should yield one event since the buffer only fits one.
    let mut events = vec![first_event];
    while let Some(result) = stream.next().now_or_never() {
        match result {
            Some(Ok(event)) => {
                assert!(event.mask.contains(EventMask::CREATE));
                events.push(event);
            }
            Some(Err(e)) => panic!("Error reading event: {}", e),
            None => break, // Stream ended
        }
    }

    assert_eq!(
        events.len(),
        num_files,
        "All events should yield with now_or_never"
    );
}

struct TestDir {
    dir: TempDir,
    counter: u32,
}

impl TestDir {
    fn new() -> TestDir {
        TestDir {
            dir: TempDir::new().unwrap(),
            counter: 0,
        }
    }

    #[cfg(feature = "stream")]
    fn new_file_with_name(&mut self, file_name: &str) -> (PathBuf, File) {
        self.counter += 1;

        let path = self.dir.path().join(file_name);
        let file = File::create(&path)
            .unwrap_or_else(|error| panic!("Failed to create temporary file: {}", error));

        (path, file)
    }

    #[cfg(feature = "stream")]
    fn delete_file(&mut self, relative_path_to_file: &str) {
        let path = &self.dir.path().join(relative_path_to_file);
        std::fs::remove_file(path).unwrap();
    }

    #[cfg(feature = "stream")]
    fn new_file_in_directory_with_name(
        &mut self,
        dir_name: &str,
        file_name: &str,
    ) -> (PathBuf, File) {
        self.counter += 1;

        let path = self.dir.path().join(dir_name).join(file_name);
        let file = File::create(&path)
            .unwrap_or_else(|error| panic!("Failed to create temporary file: {}", error));

        (path, file)
    }

    #[cfg(feature = "stream")]
    fn new_directory_with_name(&mut self, dir_name: &str) -> PathBuf {
        let path = self.dir.path().join(dir_name);
        let () = std::fs::create_dir(&path).unwrap();
        path.to_path_buf()
    }

    fn new_file(&mut self) -> (PathBuf, File) {
        let id = self.counter;
        self.counter += 1;

        let path = self.dir.path().join("file-".to_string() + &id.to_string());
        let file = File::create(&path)
            .unwrap_or_else(|error| panic!("Failed to create temporary file: {}", error));

        (path, file)
    }
}

#[test]
fn it_should_receive_delete_event_when_file_is_deleted() {
    let mut testdir = TestDir::new();
    let (path, _file) = testdir.new_file();

    let mut inotify = Inotify::init().unwrap();
    let _watch = inotify
        .watches()
        .add(path.parent().unwrap(), WatchMask::DELETE)
        .unwrap();

    std::fs::remove_file(&path).unwrap();

    let mut buffer = [0; 1024];
    let mut events = inotify.read_events_blocking(&mut buffer).unwrap();
    match events.next() {
        Some(event) => assert_eq!(event.mask, EventMask::DELETE),
        None => panic!("Expected event, got none."),
    }
}

#[test]
fn it_should_receive_delete_event_watchee_is_deleted() {
    let testdir = TestDir::new();
    let path = testdir.dir.path();

    let mut inotify = Inotify::init().unwrap();
    let _watch = inotify.watches().add(path, WatchMask::DELETE_SELF).unwrap();

    std::fs::remove_dir(path).unwrap();

    let mut buffer = [0; 1024];
    let mut events = inotify.read_events_blocking(&mut buffer).unwrap();
    match events.next() {
        Some(event) => assert!(event.mask.contains(EventMask::DELETE_SELF)),
        None => panic!("Expected event, got none."),
    }
}

#[cfg(feature = "stream")]
#[tokio::test]
async fn it_should_receive_delete_event_when_file_is_deleted_async() {
    use std::time::Duration;
    use tokio::time::timeout;

    let mut testdir = TestDir::new();
    let (path, _file) = testdir.new_file();

    let inotify = Inotify::init().unwrap();
    // Watch the parent directory, not the file itself, to receive DELETE events
    let _watch = inotify
        .watches()
        .add(path.parent().unwrap(), WatchMask::DELETE)
        .unwrap();

    let mut buffer = [0; 1024];
    let mut stream = inotify.into_event_stream(&mut buffer).unwrap();

    std::fs::remove_file(&path).unwrap();

    let event = timeout(Duration::from_secs(2), stream.next())
        .await
        .unwrap() // Timeout
        .unwrap() // End of stream
        .unwrap(); // Stream error
    assert_eq!(event.mask, EventMask::DELETE);
}

fn write_to(file: &mut File) {
    file.write_all(b"This should trigger an inotify event.")
        .unwrap_or_else(|error| panic!("Failed to write to file: {}", error));
}