use crate::*;

audio!(|self: Sampler, _client, scope|{
    self.process_midi_in(scope);
    self.process_audio_out(scope);
    self.process_audio_in(scope);
    Control::Continue
});

impl Sampler {

    pub fn process_audio_in (&mut self, scope: &ProcessScope) {
        self.reset_input_meters();
        if self.recording.is_some() {
            self.record_into(scope);
        } else {
            self.update_input_meters(scope);
        }
    }

    /// Make sure that input meter count corresponds to input channel count
    fn reset_input_meters (&mut self) {
        let channels = self.audio_ins.len();
        if self.input_meters.len() != channels {
            self.input_meters = vec![f32::MIN;channels];
        }
    }

    /// Record from inputs to sample
    fn record_into (&mut self, scope: &ProcessScope) {
        let mut sample = self.recording
            .as_mut().expect("no recording sample").1
            .write().unwrap();
        if sample.channels.len() != self.audio_ins.len() {
            panic!("channel count mismatch");
        }
        let samples_with_meters = self.audio_ins.iter()
            .zip(self.input_meters.iter_mut())
            .zip(sample.channels.iter_mut());
        let mut length = 0;
        for ((input, meter), channel) in samples_with_meters {
            let slice = input.port().as_slice(scope);
            length = length.max(slice.len());
            *meter = to_rms(slice);
            channel.extend_from_slice(slice);
        }
        sample.end += length;
    }

    /// Update input meters
    fn update_input_meters (&mut self, scope: &ProcessScope) {
        for (input, meter) in self.audio_ins.iter().zip(self.input_meters.iter_mut()) {
            let slice = input.port().as_slice(scope);
            *meter = to_rms(slice);
        }
    }

    /// Make sure that output meter count corresponds to input channel count
    fn reset_output_meters (&mut self) {
        let channels = self.audio_outs.len();
        if self.output_meters.len() != channels {
            self.output_meters = vec![f32::MIN;channels];
        }
    }

    /// Mix all currently playing samples into the output.
    pub fn process_audio_out (&mut self, scope: &ProcessScope) {
        self.clear_output_buffer();
        self.populate_output_buffer(scope.n_frames() as usize);
        self.write_output_buffer(scope);
    }

    /// Zero the output buffer.
    fn clear_output_buffer (&mut self) {
        for buffer in self.buffer.iter_mut() {
            buffer.fill(0.0);
        }
    }

    /// Write playing voices to output buffer
    fn populate_output_buffer (&mut self, frames: usize) {
        let Sampler { ref mut buffer, voices, output_gain, mixing_mode, .. } = self;
        let channel_count = buffer.len();
        match mixing_mode {
            MixingMode::Summing => voices.write().unwrap().retain_mut(|voice|{
                mix_summing(buffer.as_mut_slice(), *output_gain, frames, ||voice.next())
            }),
            MixingMode::Average => voices.write().unwrap().retain_mut(|voice|{
                mix_average(buffer.as_mut_slice(), *output_gain, frames, ||voice.next())
            }),
        }
    }

    /// Write output buffer to output ports.
    fn write_output_buffer (&mut self, scope: &ProcessScope) {
        let Sampler { ref mut audio_outs, buffer, .. } = self;
        for (i, port) in audio_outs.iter_mut().enumerate() {
            let buffer = &buffer[i];
            for (i, value) in port.port_mut().as_mut_slice(scope).iter_mut().enumerate() {
                *value = *buffer.get(i).unwrap_or(&0.0);
            }
        }
    }

}

impl Iterator for Voice {
    type Item = [f32;2];
    fn next (&mut self) -> Option<Self::Item> {
        if self.after > 0 {
            self.after -= 1;
            return Some([0.0, 0.0])
        }
        let sample = self.sample.read().unwrap();
        if self.position < sample.end {
            let position = self.position;
            self.position += 1;
            return sample.channels[0].get(position).map(|_amplitude|[
                sample.channels[0][position] * self.velocity * sample.gain,
                sample.channels[0][position] * self.velocity * sample.gain,
            ])
        }
        None
    }
}