use std::io;
use std::path::{Path, PathBuf};
use std::sync::{Arc, Mutex};
use std::time::Duration;

use futures::io::BufReader;
use futures::{AsyncBufReadExt, StreamExt};
use hashbrown::HashMap;
use libloading::{Library, Symbol};
use orchid_base::{log, on_drop, vt_to_future};
use unsync_pipe::pipe;

use crate::api;
use crate::ctx::Ctx;
use crate::extension::ExtPort;
use crate::task_set::TaskSet;

static DYNAMIC_LIBRARIES: Mutex<Option<HashMap<PathBuf, Arc<Library>>>> = Mutex::new(None);
fn load_dylib(path: &Path) -> Result<Arc<Library>, libloading::Error> {
	let mut g = DYNAMIC_LIBRARIES.lock().unwrap();
	let map = g.get_or_insert_default();
	if let Some(lib) = map.get(path) {
		Ok(lib.clone())
	} else {
		let lib = Arc::new(unsafe { Library::new(path) }?);
		map.insert(path.to_owned(), lib.clone());
		Ok(lib)
	}
}

pub async fn ext_dylib(path: &Path, ctx: Ctx) -> Result<ExtPort, libloading::Error> {
	let (write_input, input) = pipe(1024);
	let (output, read_output) = pipe(1024);
	let (write_log, read_log) = pipe(1024);
	let log_path = path.to_string_lossy().to_string();
	let _ = ctx.spawn(Duration::ZERO, async move {
		let mut lines = BufReader::new(read_log).lines();
		while let Some(line) = lines.next().await {
			match line {
				Ok(line) => writeln!(log("stderr"), "dylib {log_path} err> {line}").await,
				Err(e) => match e.kind() {
					io::ErrorKind::BrokenPipe | io::ErrorKind::UnexpectedEof => break,
					_ => panic!("Error while reading stderr {e}"),
				},
			}
		}
	});
	let tasks = TaskSet::default();
	let library = load_dylib(path)?;
	let entrypoint: Symbol<unsafe extern "C" fn(api::binary::ExtensionContext)> =
		unsafe { library.get("orchid_extension_main") }?;

	let data = Box::into_raw(Box::new(SpawnerState { ctx, tasks: tasks.clone() })) as *const ();
	let spawner = api::binary::SpawnerBin { data, drop, spawn };
	let cx = api::binary::ExtensionContext { input, output, log: write_log, spawner };
	unsafe { (entrypoint)(cx) };
	Ok(ExtPort {
		input: Box::pin(write_input),
		output: Box::pin(read_output),
		drop_trigger: Box::new(on_drop(move || tasks.abort_all())),
	})
}

struct SpawnerState {
	ctx: Ctx,
	tasks: TaskSet,
}
extern "C" fn drop(data: *const ()) {
	let state = unsafe { Box::from_raw(data as *mut SpawnerState) };
	state.tasks.abort_all();
}
extern "C" fn spawn(data: *const (), delay: u64, vt: api::binary::FutureBin) {
	let future = vt_to_future(vt);
	// SAFETY: this is technically a Box but it can be used directly as a &mut
	let state = unsafe { (data as *mut SpawnerState).as_mut() }.unwrap();
	state.tasks.with(|store| {
		store.add_with(|id| {
			state.ctx.spawn(Duration::from_millis(delay), async move {
				future.await;
				// SAFETY: We know this is live because the drop handle that frees it also
				// aborts the future
				let state = unsafe { (data as *mut SpawnerState).as_mut() }.unwrap();
				state.tasks.with(|store| store.remove(id));
			})
		});
	});
}