use std::any::Any;
use std::sync::Arc;

use realfft::{num_complex::Complex, ComplexToReal, RealFftPlanner, RealToComplex};

use crate::buffer::AudioBuffer;
use crate::context::{AudioContextRegistration, BaseAudioContext};
use crate::render::{AudioParamValues, AudioProcessor, AudioRenderQuantum, RenderScope};
use crate::RENDER_QUANTUM_SIZE;

use super::{AudioNode, ChannelConfig, ChannelConfigOptions, ChannelInterpretation};

/// Scale buffer by an equal-power normalization
// see - <https://webaudio.github.io/web-audio-api/#dom-convolvernode-normalize>
fn normalize_buffer(buffer: &AudioBuffer) -> f32 {
    let gain_calibration = 0.00125;
    let gain_calibration_sample_rate = 44100.;
    let min_power = 0.000125;

    // Normalize by RMS power.
    let number_of_channels = buffer.number_of_channels();
    let length = buffer.length();
    let sample_rate = buffer.sample_rate();

    let mut power: f32 = buffer
        .channels()
        .iter()
        .map(|c| c.as_slice().iter().map(|&s| s * s).sum::<f32>())
        .sum();

    power = (power / (number_of_channels * length) as f32).sqrt();

    // Protect against accidental overload.
    if !power.is_finite() || power.is_nan() || power < min_power {
        power = min_power;
    }

    let mut scale = 1. / power;

    // Calibrate to make perceived volume same as unprocessed.
    scale *= gain_calibration;

    // Scale depends on sample-rate.
    scale *= gain_calibration_sample_rate / sample_rate;

    // True-stereo compensation.
    if number_of_channels == 4 {
        scale *= 0.5;
    }

    scale
}

/// `ConvolverNode` options
//dictionary ConvolverOptions : AudioNodeOptions {
//  AudioBuffer? buffer;
//  boolean disableNormalization = false;
//};
#[derive(Clone, Debug, Default)]
pub struct ConvolverOptions {
    /// The desired buffer for the ConvolverNode
    pub buffer: Option<AudioBuffer>,
    /// The opposite of the desired initial value for the normalize attribute
    pub disable_normalization: bool,
    /// AudioNode options
    pub channel_config: ChannelConfigOptions,
}

/// Processing node which applies a linear convolution effect given an impulse response.
///
/// - MDN documentation: <https://developer.mozilla.org/en-US/docs/Web/API/ConvolverNode>
/// - specification: <https://webaudio.github.io/web-audio-api/#ConvolverNode>
/// - see also: [`BaseAudioContext::create_convolver`]
///
/// The current implementation only handles mono-to-mono convolutions. The provided impulse
/// response buffer and the input signal will be downmixed appropriately.
///
/// # Usage
///
/// ```no_run
/// use std::fs::File;
///
/// use web_audio_api::context::{AudioContext, BaseAudioContext};
/// use web_audio_api::node::{AudioNode, AudioScheduledSourceNode, ConvolverNode, ConvolverOptions};
///
/// let context = AudioContext::default();
/// let file = File::open("samples/vocals-dry.wav").unwrap();
/// let audio_buffer = context.decode_audio_data_sync(file).unwrap();
///
/// let impulse_file = File::open("samples/small-room-response.wav").unwrap();
/// let impulse_buffer = context.decode_audio_data_sync(impulse_file).unwrap();
///
/// let mut src = context.create_buffer_source();
/// src.set_buffer(audio_buffer);
///
/// let mut convolve = ConvolverNode::new(&context, ConvolverOptions::default());
/// convolve.set_buffer(impulse_buffer);
///
/// src.connect(&convolve);
/// convolve.connect(&context.destination());
/// src.start();
/// std::thread::sleep(std::time::Duration::from_millis(4_000));
/// ```
///
/// # Examples
///
/// - `cargo run --release --example convolution`
///
pub struct ConvolverNode {
    /// Represents the node instance and its associated audio context
    registration: AudioContextRegistration,
    /// Info about audio node channel configuration
    channel_config: ChannelConfig,
    /// Perform equal power normalization on response buffer
    normalize: bool,
    /// The response buffer, nullable
    buffer: Option<AudioBuffer>,
}

impl AudioNode for ConvolverNode {
    fn registration(&self) -> &AudioContextRegistration {
        &self.registration
    }

    fn channel_config(&self) -> &ChannelConfig {
        &self.channel_config
    }

    fn number_of_inputs(&self) -> usize {
        1
    }

    fn number_of_outputs(&self) -> usize {
        1
    }
}

impl ConvolverNode {
    /// returns a `ConvolverNode` instance
    ///
    /// # Arguments
    ///
    /// * `context` - audio context in which the audio node will live.
    /// * `options` - convolver options
    ///
    /// # Panics
    ///
    /// Panics when an AudioBuffer is provided via the `ConvolverOptions` with a sample rate
    /// different from the audio context sample rate.
    pub fn new<C: BaseAudioContext>(context: &C, options: ConvolverOptions) -> Self {
        let ConvolverOptions {
            buffer,
            disable_normalization,
            channel_config,
        } = options;

        let mut node = context.base().register(move |registration| {
            let renderer = ConvolverRenderer { inner: None };

            let node = Self {
                registration,
                channel_config: channel_config.into(),
                normalize: !disable_normalization,
                buffer: None,
            };

            (node, Box::new(renderer))
        });

        // renderer has been sent to render thread, we can send it messages
        if let Some(buffer) = buffer {
            node.set_buffer(buffer);
        }

        node
    }

    /// Get the current impulse response buffer
    pub fn buffer(&self) -> Option<&AudioBuffer> {
        self.buffer.as_ref()
    }

    /// Set or update the impulse response buffer
    ///
    /// # Panics
    ///
    /// Panics when the sample rate of the provided AudioBuffer differs from the audio context
    /// sample rate.
    pub fn set_buffer(&mut self, buffer: AudioBuffer) {
        // If the buffer number of channels is not 1, 2, 4, or if the sample-rate of the buffer is
        // not the same as the sample-rate of its associated BaseAudioContext, a NotSupportedError
        // MUST be thrown.

        let sample_rate = buffer.sample_rate();
        assert_eq!(
            sample_rate,
            self.context().sample_rate(),
            "NotSupportedError - sample rate of the convolution buffer must match the audio context"
        );

        let number_of_channels = buffer.number_of_channels();
        assert!(
            [1, 2, 4].contains(&number_of_channels),
            "NotSupportedError - the convolution buffer must consist of 1, 2 or 4 channels"
        );

        // normalize before padding because the length of the buffer affects the scale
        let scale = if self.normalize {
            normalize_buffer(&buffer)
        } else {
            1.
        };

        // Pad the response buffer with zeroes so its size is a power of 2, with 2 * 128 as min size
        let length = buffer.length();
        let padded_length = length.next_power_of_two().max(2 * RENDER_QUANTUM_SIZE);
        let samples: Vec<_> = (0..number_of_channels)
            .map(|_| {
                let mut samples = vec![0.; padded_length];
                samples[..length]
                    .iter_mut()
                    .zip(buffer.get_channel_data(0))
                    .for_each(|(o, i)| *o = *i * scale);
                samples
            })
            .collect();

        let padded_buffer = AudioBuffer::from(samples, sample_rate);
        let convolve = ConvolverRendererInner::new(padded_buffer);

        self.registration.post_message(Some(convolve));
        self.buffer = Some(buffer);
    }

    /// Denotes if the response buffer will be scaled with an equal-power normalization
    pub fn normalize(&self) -> bool {
        self.normalize
    }

    /// Update the `normalize` setting. This will only have an effect when `set_buffer` is called.
    pub fn set_normalize(&mut self, value: bool) {
        self.normalize = value;
    }
}

fn roll_zero<T: Default + Copy>(signal: &mut [T], n: usize) {
    // roll array by n elements
    // zero out the last n elements
    let len = signal.len();
    signal.copy_within(n.., 0);
    signal[len - n..].fill(T::default());
}

struct Fft {
    fft_forward: Arc<dyn RealToComplex<f32>>,
    fft_inverse: Arc<dyn ComplexToReal<f32>>,
    fft_input: Vec<f32>,
    fft_scratch: Vec<Complex<f32>>,
    fft_output: Vec<Complex<f32>>,
}

impl Fft {
    fn new(length: usize) -> Self {
        let mut fft_planner = RealFftPlanner::<f32>::new();

        let fft_forward = fft_planner.plan_fft_forward(length);
        let fft_inverse = fft_planner.plan_fft_inverse(length);

        let fft_input = fft_forward.make_input_vec();
        let fft_scratch = fft_forward.make_scratch_vec();
        let fft_output = fft_forward.make_output_vec();

        Self {
            fft_forward,
            fft_inverse,
            fft_input,
            fft_scratch,
            fft_output,
        }
    }

    fn real(&mut self) -> &mut [f32] {
        &mut self.fft_input[..]
    }

    fn complex(&mut self) -> &mut [Complex<f32>] {
        &mut self.fft_output[..]
    }

    fn process(&mut self) -> &[Complex<f32>] {
        self.fft_forward
            .process_with_scratch(
                &mut self.fft_input,
                &mut self.fft_output,
                &mut self.fft_scratch,
            )
            .unwrap();
        &self.fft_output[..]
    }

    fn inverse(&mut self) -> &[f32] {
        self.fft_inverse
            .process_with_scratch(
                &mut self.fft_output,
                &mut self.fft_input,
                &mut self.fft_scratch,
            )
            .unwrap();
        &self.fft_input[..]
    }
}

struct ConvolverRendererInner {
    num_ir_blocks: usize,
    h: Vec<Complex<f32>>,
    fdl: Vec<Complex<f32>>,
    out: Vec<f32>,
    fft2: Fft,
}

impl ConvolverRendererInner {
    fn new(response: AudioBuffer) -> Self {
        // mono processing only for now
        let response = response.channel_data(0).as_slice();

        let mut fft2 = Fft::new(2 * RENDER_QUANTUM_SIZE);
        let p = response.len();

        let num_ir_blocks = p / RENDER_QUANTUM_SIZE;

        let mut h = vec![Complex::default(); num_ir_blocks * 2 * RENDER_QUANTUM_SIZE];
        for (resp_fft, resp) in h
            .chunks_mut(2 * RENDER_QUANTUM_SIZE)
            .zip(response.chunks(RENDER_QUANTUM_SIZE))
        {
            // fill resp_fft with FFT of resp.zero_pad(RENDER_QUANTUM_SIZE)
            fft2.real()[..RENDER_QUANTUM_SIZE].copy_from_slice(resp);
            fft2.real()[RENDER_QUANTUM_SIZE..].fill(0.);
            resp_fft[..fft2.complex().len()].copy_from_slice(fft2.process());
        }

        let fdl = vec![Complex::default(); 2 * RENDER_QUANTUM_SIZE * num_ir_blocks];
        let out = vec![0.; 2 * RENDER_QUANTUM_SIZE - 1];

        Self {
            num_ir_blocks,
            h,
            fdl,
            out,
            fft2,
        }
    }

    fn process(&mut self, input: &[f32], output: &mut [f32]) {
        self.fft2.real()[..RENDER_QUANTUM_SIZE].copy_from_slice(input);
        self.fft2.real()[RENDER_QUANTUM_SIZE..].fill(0.);
        let spectrum = self.fft2.process();

        self.fdl
            .chunks_mut(2 * RENDER_QUANTUM_SIZE)
            .zip(self.h.chunks(2 * RENDER_QUANTUM_SIZE))
            .for_each(|(fdl_c, h_c)| {
                fdl_c
                    .iter_mut()
                    .zip(h_c)
                    .zip(spectrum)
                    .for_each(|((f, h), s)| *f += h * s)
            });

        let c_len = self.fft2.complex().len();
        self.fft2.complex().copy_from_slice(&self.fdl[..c_len]);
        let inverse = self.fft2.inverse();
        self.out.iter_mut().zip(inverse).for_each(|(o, i)| {
            *o += i / (2 * RENDER_QUANTUM_SIZE) as f32;
        });

        output.copy_from_slice(&self.out[..RENDER_QUANTUM_SIZE]);

        roll_zero(&mut self.fdl[..], 2 * RENDER_QUANTUM_SIZE);
        roll_zero(&mut self.out[..], RENDER_QUANTUM_SIZE);
    }

    fn tail(&mut self, output: &mut AudioRenderQuantum) -> bool {
        if self.num_ir_blocks == 0 {
            output.make_silent();
            return false;
        }

        self.num_ir_blocks -= 1;

        let c_len = self.fft2.complex().len();
        self.fft2.complex().copy_from_slice(&self.fdl[..c_len]);
        let inverse = self.fft2.inverse();
        self.out.iter_mut().zip(inverse).for_each(|(o, i)| {
            *o += i / (2 * RENDER_QUANTUM_SIZE) as f32;
        });

        output
            .channel_data_mut(0)
            .copy_from_slice(&self.out[..RENDER_QUANTUM_SIZE]);

        roll_zero(&mut self.fdl[..], 2 * RENDER_QUANTUM_SIZE);
        roll_zero(&mut self.out[..], RENDER_QUANTUM_SIZE);

        self.num_ir_blocks > 0
    }
}

struct ConvolverRenderer {
    inner: Option<ConvolverRendererInner>,
}

impl AudioProcessor for ConvolverRenderer {
    fn process(
        &mut self,
        inputs: &[AudioRenderQuantum],
        outputs: &mut [AudioRenderQuantum],
        _params: AudioParamValues<'_>,
        _scope: &RenderScope,
    ) -> bool {
        // single input/output node
        let input = &inputs[0];
        let output = &mut outputs[0];
        output.force_mono();

        let convolver = match &mut self.inner {
            None => {
                // no convolution buffer set, passthrough
                *output = input.clone();
                return !input.is_silent();
            }
            Some(convolver) => convolver,
        };

        // handle tail time
        if input.is_silent() {
            return convolver.tail(output);
        }

        let mut mono = input.clone();
        mono.mix(1, ChannelInterpretation::Speakers);
        let input = &mono.channel_data(0)[..];
        let output = &mut output.channel_data_mut(0)[..];

        convolver.process(input, output);

        true
    }

    fn onmessage(&mut self, msg: &mut dyn Any) {
        if let Some(convolver) = msg.downcast_mut::<Option<ConvolverRendererInner>>() {
            // Avoid deallocation in the render thread by swapping the convolver.
            std::mem::swap(&mut self.inner, convolver);
            return;
        }

        log::warn!("ConvolverRenderer: Dropping incoming message {msg:?}");
    }
}

#[cfg(test)]
mod tests {
    use float_eq::assert_float_eq;

    use crate::context::{BaseAudioContext, OfflineAudioContext};
    use crate::node::{AudioBufferSourceNode, AudioBufferSourceOptions, AudioScheduledSourceNode};

    use super::*;

    #[test]
    fn test_roll_zero() {
        let mut input = vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
        roll_zero(&mut input, 3);
        assert_eq!(&input, &[4, 5, 6, 7, 8, 9, 10, 0, 0, 0]);
    }

    #[test]
    #[should_panic]
    fn test_buffer_sample_rate_matches() {
        let context = OfflineAudioContext::new(1, 128, 44100.);

        let ir = vec![1.];
        let ir = AudioBuffer::from(vec![ir; 1], 48000.); // sample_rate differs
        let options = ConvolverOptions {
            buffer: Some(ir),
            ..ConvolverOptions::default()
        };

        let _ = ConvolverNode::new(&context, options);
    }

    #[test]
    #[should_panic]
    fn test_buffer_must_have_1_2_4_channels() {
        let context = OfflineAudioContext::new(1, 128, 48000.);

        let ir = vec![1.];
        let ir = AudioBuffer::from(vec![ir; 3], 48000.); // three channels
        let options = ConvolverOptions {
            buffer: Some(ir),
            ..ConvolverOptions::default()
        };

        let _ = ConvolverNode::new(&context, options);
    }

    #[test]
    fn test_constructor_options_buffer() {
        let sample_rate = 44100.;
        let mut context = OfflineAudioContext::new(1, 10, sample_rate);

        let ir = vec![1.];
        let calibration = 0.00125;
        let channel_data = vec![0., 1., 0., -1., 0.];
        let expected = [0., calibration, 0., -calibration, 0., 0., 0., 0., 0., 0.];

        // identity ir
        let ir = AudioBuffer::from(vec![ir; 1], sample_rate);
        let options = ConvolverOptions {
            buffer: Some(ir),
            ..ConvolverOptions::default()
        };
        let conv = ConvolverNode::new(&context, options);
        conv.connect(&context.destination());

        let buffer = AudioBuffer::from(vec![channel_data; 1], sample_rate);
        let mut src = context.create_buffer_source();
        src.connect(&conv);
        src.set_buffer(buffer);
        src.start();

        let output = context.start_rendering_sync();

        assert_float_eq!(output.get_channel_data(0), &expected[..], abs_all <= 1E-6);
    }

    fn test_convolve(signal: &[f32], impulse_resp: Option<Vec<f32>>, length: usize) -> AudioBuffer {
        let sample_rate = 44100.;
        let mut context = OfflineAudioContext::new(1, length, sample_rate);

        let input = AudioBuffer::from(vec![signal.to_vec()], sample_rate);
        let mut src = AudioBufferSourceNode::new(&context, AudioBufferSourceOptions::default());
        src.set_buffer(input);
        src.start();

        let mut conv = ConvolverNode::new(&context, ConvolverOptions::default());
        if let Some(ir) = impulse_resp {
            conv.set_buffer(AudioBuffer::from(vec![ir.to_vec()], sample_rate));
        }

        src.connect(&conv);
        conv.connect(&context.destination());

        context.start_rendering_sync()
    }

    #[test]
    fn test_passthrough() {
        let output = test_convolve(&[0., 1., 0., -1., 0.], None, 10);
        let expected = [0., 1., 0., -1., 0., 0., 0., 0., 0., 0.];
        assert_float_eq!(output.get_channel_data(0), &expected[..], abs_all <= 1E-6);
    }

    #[test]
    fn test_empty() {
        let ir = vec![];
        let output = test_convolve(&[0., 1., 0., -1., 0.], Some(ir), 10);
        let expected = [0.; 10];
        assert_float_eq!(output.get_channel_data(0), &expected[..], abs_all <= 1E-6);
    }

    #[test]
    fn test_zeroed() {
        let ir = vec![0., 0., 0., 0., 0., 0.];
        let output = test_convolve(&[0., 1., 0., -1., 0.], Some(ir), 10);
        let expected = [0.; 10];
        assert_float_eq!(output.get_channel_data(0), &expected[..], abs_all <= 1E-6);
    }

    #[test]
    fn test_identity() {
        let ir = vec![1.];
        let calibration = 0.00125;
        let output = test_convolve(&[0., 1., 0., -1., 0.], Some(ir), 10);
        let expected = [0., calibration, 0., -calibration, 0., 0., 0., 0., 0., 0.];
        assert_float_eq!(output.get_channel_data(0), &expected[..], abs_all <= 1E-6);
    }

    #[test]
    fn test_two_id() {
        let ir = vec![1., 1.];
        let calibration = 0.00125;
        let output = test_convolve(&[0., 1., 0., -1., 0.], Some(ir), 10);
        let expected = [
            0.,
            calibration,
            calibration,
            -calibration,
            -calibration,
            0.,
            0.,
            0.,
            0.,
            0.,
        ];
        assert_float_eq!(output.get_channel_data(0), &expected[..], abs_all <= 1E-6);
    }

    #[test]
    fn test_should_have_tail_time() {
        // impulse response of length 256
        const IR_LEN: usize = 256;
        let ir = vec![1.; IR_LEN];

        // unity input signal
        let input = &[1.];

        // render into a buffer of size 512
        let output = test_convolve(input, Some(ir), 512);

        // we expect non-zero output in the range 0 to IR_LEN
        let output = output.channel_data(0).as_slice();
        assert!(!output[..IR_LEN].iter().any(|v| *v <= 1E-6));
        assert_float_eq!(&output[IR_LEN..], &[0.; 512 - IR_LEN][..], abs_all <= 1E-6);
    }
}