use std::{collections::HashSet, fs};

use flexi_logger::Logger;
use ra_vfs::{Vfs, VfsChange};
use tempfile::tempdir;

fn process_tasks(vfs: &mut Vfs, num_tasks: u32) {
    for _ in 0..num_tasks {
        let task = vfs.task_receiver().recv().unwrap();
        log::debug!("{:?}", task);
        vfs.handle_task(task);
    }
}

macro_rules! assert_match {
    ($x:expr, $pat:pat) => {
        assert_match!($x, $pat, assert!(true))
    };
    ($x:expr, $pat:pat, $assert:expr) => {
        match $x {
            $pat => $assert,
            x => assert!(false, "Expected {}, got {:?}", stringify!($pat), x),
        };
    };
}

#[test]
fn test_vfs_works() -> std::io::Result<()> {
    Logger::with_str("vfs=debug,ra_vfs=debug").start().unwrap();

    let files = [
        ("a/foo.rs", "hello"),
        ("a/bar.rs", "world"),
        ("a/b/baz.rs", "nested hello"),
    ];

    let dir = tempdir().unwrap();
    for (path, text) in files.iter() {
        let file_path = dir.path().join(path);
        fs::create_dir_all(file_path.parent().unwrap()).unwrap();
        fs::write(file_path, text)?
    }

    let a_root = dir.path().join("a");
    let b_root = dir.path().join("a/b");

    let (mut vfs, _) = Vfs::new(vec![a_root, b_root]);
    process_tasks(&mut vfs, 2);
    {
        let files = vfs
            .commit_changes()
            .into_iter()
            .flat_map(|change| {
                let files = match change {
                    VfsChange::AddRoot { files, .. } => files,
                    _ => panic!("unexpected change"),
                };
                files.into_iter().map(|(_id, path, text)| {
                    let text: String = (&*text).clone();
                    (format!("{}", path.display()), text)
                })
            })
            .collect::<HashSet<_>>();

        let expected_files = [
            ("foo.rs", "hello"),
            ("bar.rs", "world"),
            ("baz.rs", "nested hello"),
        ]
        .iter()
        .map(|(path, text)| (path.to_string(), text.to_string()))
        .collect::<HashSet<_>>();

        assert_eq!(files, expected_files);
    }

    fs::write(&dir.path().join("a/b/baz.rs"), "quux").unwrap();
    // 2 tasks per change, HandleChange and then LoadChange
    process_tasks(&mut vfs, 2);
    assert_match!(
        vfs.commit_changes().as_slice(),
        [VfsChange::ChangeFile { text, .. }],
        assert_eq!(text.as_str(), "quux")
    );

    vfs.change_file_overlay(&dir.path().join("a/b/baz.rs"), "m".to_string());
    assert_match!(
        vfs.commit_changes().as_slice(),
        [VfsChange::ChangeFile { text, .. }],
        assert_eq!(text.as_str(), "m")
    );

    // removing overlay restores data on disk
    vfs.remove_file_overlay(&dir.path().join("a/b/baz.rs"));
    assert_match!(
        vfs.commit_changes().as_slice(),
        [VfsChange::ChangeFile { text, .. }],
        assert_eq!(text.as_str(), "quux")
    );

    vfs.add_file_overlay(&dir.path().join("a/b/spam.rs"), "spam".to_string());
    assert_match!(
        vfs.commit_changes().as_slice(),
        [VfsChange::AddFile { text, path, .. }],
        {
            assert_eq!(text.as_str(), "spam");
            assert_eq!(path, "spam.rs");
        }
    );

    vfs.remove_file_overlay(&dir.path().join("a/b/spam.rs"));
    assert_match!(
        vfs.commit_changes().as_slice(),
        [VfsChange::RemoveFile { path, .. }],
        assert_eq!(path, "spam.rs")
    );

    fs::create_dir_all(dir.path().join("a/sub1/sub2")).unwrap();
    fs::write(dir.path().join("a/sub1/sub2/new.rs"), "new hello").unwrap();
    process_tasks(&mut vfs, 3);
    assert_match!(
        vfs.commit_changes().as_slice(),
        [VfsChange::AddFile { text, path, .. }],
        {
            assert_eq!(text.as_str(), "new hello");
            assert_eq!(path, "sub1/sub2/new.rs");
        }
    );

    fs::rename(
        &dir.path().join("a/sub1/sub2/new.rs"),
        &dir.path().join("a/sub1/sub2/new1.rs"),
    )
    .unwrap();
    process_tasks(&mut vfs, 4);
    assert_match!(
        vfs.commit_changes().as_slice(),
        [VfsChange::RemoveFile {
            path: removed_path, ..
        }, VfsChange::AddFile {
            text,
            path: added_path,
            ..
        }],
        {
            assert_eq!(removed_path, "sub1/sub2/new.rs");
            assert_eq!(added_path, "sub1/sub2/new1.rs");
            assert_eq!(text.as_str(), "new hello");
        }
    );

    fs::remove_file(&dir.path().join("a/sub1/sub2/new1.rs")).unwrap();
    process_tasks(&mut vfs, 2);
    assert_match!(
        vfs.commit_changes().as_slice(),
        [VfsChange::RemoveFile { path, .. }],
        assert_eq!(path, "sub1/sub2/new1.rs")
    );

    fs::create_dir_all(dir.path().join("a/target")).unwrap();
    // should be ignored
    fs::write(&dir.path().join("a/target/new.rs"), "ignore me").unwrap();
    process_tasks(&mut vfs, 1); // 1 task because no LoadChange will happen, just HandleChange for dir creation

    assert_match!(
        vfs.task_receiver().try_recv(),
        Err(crossbeam_channel::TryRecvError::Empty)
    );

    vfs.shutdown().unwrap();
    Ok(())
}