// nih-plug: plugins, but rewritten in Rust
// Copyright (C) 2022 Robbert van der Helm
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

#[macro_use]
extern crate nih_plug;

use nih_plug::{
    formatters, util, Buffer, BufferConfig, BusConfig, Plugin, ProcessContext, ProcessStatus,
    Vst3Plugin,
};
use nih_plug::{BoolParam, FloatParam, Param, Params, Range, Smoother, SmoothingStyle};
use std::f32::consts;
use std::pin::Pin;

/// A test tone generator.
///
/// TODO: Add MIDI support, this seems like a nice minimal example for that.
struct Sine {
    params: Pin<Box<SineParams>>,
    sample_rate: f32,

    /// The current phase of the sine wave, always kept between in `[0, 1]`.
    phase: f32,
    /// The active frequency, if triggered by MIDI.
    active_note_freq: Option<f32>,
}

#[derive(Params)]
struct SineParams {
    #[id = "gain"]
    pub gain: FloatParam,

    #[id = "freq"]
    pub frequency: FloatParam,

    #[id = "usemid"]
    pub use_midi: BoolParam,
}

impl Default for Sine {
    fn default() -> Self {
        Self {
            params: Box::pin(SineParams::default()),
            sample_rate: 1.0,

            phase: 0.0,
            active_note_freq: None,
        }
    }
}

impl Default for SineParams {
    fn default() -> Self {
        Self {
            gain: FloatParam {
                value: -10.0,
                smoothed: Smoother::new(SmoothingStyle::Linear(3.0)),
                range: Range::Linear {
                    min: -30.0,
                    max: 0.0,
                },
                name: "Gain",
                unit: " dB",
                value_to_string: formatters::f32_rounded(2),
                ..Default::default()
            },
            frequency: FloatParam {
                value: 420.0,
                smoothed: Smoother::new(SmoothingStyle::Linear(10.0)),
                range: Range::Skewed {
                    min: 1.0,
                    max: 20_000.0,
                    factor: Range::skew_factor(-2.0),
                },
                name: "Frequency",
                unit: " Hz",
                value_to_string: formatters::f32_rounded(0),
                ..Default::default()
            },
            use_midi: BoolParam {
                value: false,
                name: "Use MIDI",
                ..Default::default()
            },
        }
    }
}

impl Sine {
    fn calculate_sine(&mut self, frequency: f32) -> f32 {
        let phase_delta = frequency / self.sample_rate;
        let sine = (self.phase * consts::TAU).sin();

        self.phase += phase_delta;
        if self.phase >= 1.0 {
            self.phase -= 1.0;
        }

        sine
    }
}

impl Plugin for Sine {
    const NAME: &'static str = "Sine Test Tone";
    const VENDOR: &'static str = "Moist Plugins GmbH";
    const URL: &'static str = "https://youtu.be/dQw4w9WgXcQ";
    const EMAIL: &'static str = "info@example.com";

    const VERSION: &'static str = "0.0.1";

    const DEFAULT_NUM_INPUTS: u32 = 0;
    const DEFAULT_NUM_OUTPUTS: u32 = 2;

    const ACCEPTS_MIDI: bool = true;

    fn params(&self) -> Pin<&dyn Params> {
        self.params.as_ref()
    }

    fn accepts_bus_config(&self, config: &BusConfig) -> bool {
        // This can output to any number of channels, but it doesn't take any audio inputs
        config.num_input_channels == 0 && config.num_input_channels > 0
    }

    fn initialize(
        &mut self,
        _bus_config: &BusConfig,
        buffer_config: &BufferConfig,
        _context: &dyn ProcessContext,
    ) -> bool {
        self.sample_rate = buffer_config.sample_rate;

        true
    }

    fn process(&mut self, buffer: &mut Buffer, context: &dyn ProcessContext) -> ProcessStatus {
        let mut next_event = context.next_midi_event();
        for (sample_id, samples) in buffer.iter_mut().enumerate() {
            // Smoothing is optionally built into the parameters themselves
            let gain = self.params.gain.smoothed.next();

            // This plugin can be either triggered by MIDI or controleld by a parameter
            let sine = if self.params.use_midi.value {
                // Act on the next MIDI event
                'midi_events: loop {
                    match next_event {
                        Some(event) if event.timing() == sample_id as u32 => match event {
                            nih_plug::NoteEvent::NoteOn { note, .. } => {
                                // Reset the phase if this is a new note
                                if self.active_note_freq.is_none() {
                                    self.phase = 0.0;
                                }

                                self.active_note_freq = Some(util::midi_note_to_freq(note));
                            }
                            nih_plug::NoteEvent::NoteOff { note, .. } => {
                                if self.active_note_freq == Some(util::midi_note_to_freq(note)) {
                                    self.active_note_freq = None;
                                }
                            }
                        },
                        _ => break 'midi_events,
                    }

                    next_event = context.next_midi_event();
                }

                match self.active_note_freq {
                    Some(frequency) => self.calculate_sine(frequency),
                    None => 0.0,
                }
            } else {
                let frequency = self.params.frequency.smoothed.next();
                self.calculate_sine(frequency)
            };

            for sample in samples {
                *sample = sine * util::db_to_gain(gain);
            }
        }

        ProcessStatus::Normal
    }
}

impl Vst3Plugin for Sine {
    const VST3_CLASS_ID: [u8; 16] = *b"SineMoistestPlug";
    const VST3_CATEGORIES: &'static str = "Instrument|Synth|Tools";
}

nih_export_vst3!(Sine);