//! The `audio` crate stores all audio assets that need to be loaded during runtime

use raylib::audio::RaylibAudio;
use std::{
	collections::BinaryHeap,
	sync::atomic::Ordering,
	time::{Duration, Instant},
};

use channel::Device;
use data::Data;

use crate::{
	channel::Channels,
	program::{Program, Track},
};

mod channel;
mod data;
mod parse;
mod program;

/// The `Error` type used within this crate
pub type Error = Box<dyn std::error::Error>;

/// The `Result` type used witin this crate
pub type Result<T> = std::result::Result<T, crate::Error>;

const AUDIO_FPS: u32 = 60;
const TIME_SLICE: Duration = Duration::from_millis(1000 / AUDIO_FPS as u64);

/// The `Audio` container initalizes the audio subsystem
/// for raylib, leaks it (to gurentee audio is statically loaded),
/// then loads all needed audio samples
pub struct Audio {
	device: Device<'static>,
	last: Instant,
	queue: BinaryHeap<Program>,
	pub data: Data,
}
impl Audio {
	pub fn load() -> crate::Result<Self> {
		// Phantom handle to the raylib audio subsystem
		// Raylib doesnt use a handle, but the rust bindings
		// have one to ensure memory safety.
		//
		// We must leak this handle after allocating it,
		// if we dont then all audio will be unloaded :(
		//
		// NOTE: would this cause issues if `Audio::load` was
		// called multiple times?
		let handle = Box::leak(Box::new(RaylibAudio::init_audio_device()?));
		let device = Device::load(handle)?;
		let last = Instant::now();
		let queue = BinaryHeap::new();
		let data = Data::load()?;

		Ok(Self {
			device,
			last,
			queue,
			data,
		})
	}

	pub fn schedule(&mut self, track: Track, priority: u32, looping: bool) {
		let program = Program::new(track, priority, looping);
		self.queue.push(program);
	}

	pub fn clear(&mut self) {
		self.queue.clear();
	}

	pub fn update(&mut self) {
		if self.last.elapsed() >= TIME_SLICE {
			let res_opt = self
				.queue
				.peek_mut()
				.map(|mut program| (program.exec(), program.is_finished()));
			let channels = match res_opt {
				Some((res, finished)) => {
					if finished {
						self.queue.pop();
					}
					res
				}
				// make the output quiet!
				None => Channels::new(),
			};
			self.device.channels.store(channels, Ordering::Relaxed);
			self.last = Instant::now();
		}
	}
}