/*************************************************************************/
/*  audio.worklet.js                                                     */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
/*                      https://godotengine.org                          */
/*************************************************************************/
/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md).   */
/*                                                                       */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the       */
/* "Software"), to deal in the Software without restriction, including   */
/* without limitation the rights to use, copy, modify, merge, publish,   */
/* distribute, sublicense, and/or sell copies of the Software, and to    */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions:                                             */
/*                                                                       */
/* The above copyright notice and this permission notice shall be        */
/* included in all copies or substantial portions of the Software.       */
/*                                                                       */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
/*************************************************************************/

class RingBuffer {
	constructor(p_buffer, p_state) {
		this.buffer = p_buffer;
		this.avail = p_state;
		this.rpos = 0;
		this.wpos = 0;
	}

	data_left() {
		return Atomics.load(this.avail, 0);
	}

	space_left() {
		return this.buffer.length - this.data_left();
	}

	read(output) {
		const size = this.buffer.length;
		let from = 0;
		let to_write = output.length;
		if (this.rpos + to_write > size) {
			const high = size - this.rpos;
			output.set(this.buffer.subarray(this.rpos, size));
			from = high;
			to_write -= high;
			this.rpos = 0;
		}
		output.set(this.buffer.subarray(this.rpos, this.rpos + to_write), from);
		this.rpos += to_write;
		Atomics.add(this.avail, 0, -output.length);
		Atomics.notify(this.avail, 0);
	}

	write(p_buffer) {
		const to_write = p_buffer.length;
		const mw = this.buffer.length - this.wpos;
		if (mw >= to_write) {
			this.buffer.set(p_buffer, this.wpos);
			this.wpos += to_write;
			if (mw === to_write) {
				this.wpos = 0;
			}
		} else {
			const high = p_buffer.subarray(0, mw);
			const low = p_buffer.subarray(mw);
			this.buffer.set(high, this.wpos);
			this.buffer.set(low);
			this.wpos = low.length;
		}
		Atomics.add(this.avail, 0, to_write);
		Atomics.notify(this.avail, 0);
	}
}

class GodotProcessor extends AudioWorkletProcessor {
	constructor() {
		super();
		this.running = true;
		this.lock = null;
		this.notifier = null;
		this.output = null;
		this.output_buffer = new Float32Array();
		this.input = null;
		this.input_buffer = new Float32Array();
		this.port.onmessage = (event) => {
			const cmd = event.data['cmd'];
			const data = event.data['data'];
			this.parse_message(cmd, data);
		};
	}

	process_notify() {
		Atomics.add(this.notifier, 0, 1);
		Atomics.notify(this.notifier, 0);
	}

	parse_message(p_cmd, p_data) {
		if (p_cmd === 'start' && p_data) {
			const state = p_data[0];
			let idx = 0;
			this.lock = state.subarray(idx, ++idx);
			this.notifier = state.subarray(idx, ++idx);
			const avail_in = state.subarray(idx, ++idx);
			const avail_out = state.subarray(idx, ++idx);
			this.input = new RingBuffer(p_data[1], avail_in);
			this.output = new RingBuffer(p_data[2], avail_out);
		} else if (p_cmd === 'stop') {
			this.running = false;
			this.output = null;
			this.input = null;
		}
	}

	static array_has_data(arr) {
		return arr.length && arr[0].length && arr[0][0].length;
	}

	process(inputs, outputs, parameters) {
		if (!this.running) {
			return false; // Stop processing.
		}
		if (this.output === null) {
			return true; // Not ready yet, keep processing.
		}
		const process_input = GodotProcessor.array_has_data(inputs);
		if (process_input) {
			const input = inputs[0];
			const chunk = input[0].length * input.length;
			if (this.input_buffer.length !== chunk) {
				this.input_buffer = new Float32Array(chunk);
			}
			if (this.input.space_left() >= chunk) {
				GodotProcessor.write_input(this.input_buffer, input);
				this.input.write(this.input_buffer);
			} else {
				this.port.postMessage('Input buffer is full! Skipping input frame.');
			}
		}
		const process_output = GodotProcessor.array_has_data(outputs);
		if (process_output) {
			const output = outputs[0];
			const chunk = output[0].length * output.length;
			if (this.output_buffer.length !== chunk) {
				this.output_buffer = new Float32Array(chunk);
			}
			if (this.output.data_left() >= chunk) {
				this.output.read(this.output_buffer);
				GodotProcessor.write_output(output, this.output_buffer);
			} else {
				this.port.postMessage('Output buffer has not enough frames! Skipping output frame.');
			}
		}
		this.process_notify();
		return true;
	}

	static write_output(dest, source) {
		const channels = dest.length;
		for (let ch = 0; ch < channels; ch++) {
			for (let sample = 0; sample < dest[ch].length; sample++) {
				dest[ch][sample] = source[sample * channels + ch];
			}
		}
	}

	static write_input(dest, source) {
		const channels = source.length;
		for (let ch = 0; ch < channels; ch++) {
			for (let sample = 0; sample < source[ch].length; sample++) {
				dest[sample * channels + ch] = source[ch][sample];
			}
		}
	}
}

registerProcessor('godot-processor', GodotProcessor);