use std::{
    fmt::Debug,
    iter::repeat_n,
    num::NonZero,
    ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Sub, SubAssign},
};

use triomphe::ThinArc;

use crate::{audio_processing::Frame, project::note_event::Note};

// implemented for f32 and Frame
pub(crate) trait ProcessingFrame:
    Add<Self, Output = Self>
    + AddAssign<Self>
    + Sub<Self, Output = Self>
    + SubAssign<Self>
    + Mul<f32, Output = Self>
    + MulAssign<f32>
    + Div<f32, Output = Self>
    + DivAssign<f32>
    + Copy
{
    fn mul_add(self, mul: f32, add: Self) -> Self;
}

impl ProcessingFrame for f32 {
    fn mul_add(self, mul: f32, add: Self) -> Self {
        f32::mul_add(self, mul, add)
    }
}

pub(crate) trait ProcessingFunction<const N: usize, Fr: ProcessingFrame> {
    fn process(position: f32, data: &[Fr; N]) -> Fr;
}

#[derive(Clone)]
pub struct Sample {
    // also stores the mono state on the heap to make the packing in arrays more efficient
    data: ThinArc<bool, f32>,
}

impl Sample {
    pub const MAX_LENGTH: usize = 16_000_000;
    pub const MAX_RATE: usize = 192_000;
    /// this many frames need to be put on the start and the end to ensure that the interpolation algorithms work correctly.
    pub const PAD_SIZE_EACH: usize = 4;

    pub fn is_mono(&self) -> bool {
        self.data.header.header
    }

    /// len in Frames
    pub fn len_with_pad(&self) -> usize {
        if self.is_mono() {
            self.data.header.length
        } else {
            self.data.header.length
        }
    }

    /// This function also offsets the loaded sample data correctly, depending on the size of required processing data
    pub(crate) fn compute<
        const N: usize,
        // all implementations are generic over the ProcessingFrame type. here both possible ProcessingFrame types
        // are required, so that it can be decided at runtime which one to call. both are generated by the compiler
        // from the generic implementation
        Proc: ProcessingFunction<N, f32> + ProcessingFunction<N, Frame>,
    >(
        &self,
        position: (usize, f32),
    ) -> Frame {
        const { assert!(N / 2 <= Self::PAD_SIZE_EACH) };
        let half = const { (N - 1) / 2 };
        let start_idx = position.0 - half;
        let end_idx = start_idx + N;
        if self.is_mono() {
            let data: &[f32; N] = self.data.slice[start_idx..end_idx].try_into().unwrap();
            Frame::from(Proc::process(position.1, data))
        } else {
            let data: &[Frame; N] =
                Frame::from_interleaved(&self.data.slice[start_idx * 2..end_idx * 2])
                    .try_into()
                    .unwrap();
            Proc::process(position.1, data)
        }
    }

    pub fn index(&self, idx: usize) -> Frame {
        if self.is_mono() {
            Frame::from(self.data.slice[idx])
        } else {
            Frame::from([self.data.slice[idx * 2], self.data.slice[idx * 2 + 1]])
        }
    }

    pub(crate) fn strongcount(&self) -> usize {
        ThinArc::strong_count(&self.data)
    }

    pub fn new_stereo_interpolated<I: IntoIterator<Item = f32>>(data: I) -> Self {
        Self::new_stereo_interpolated_padded(
            repeat_n(0f32, 2 * Self::PAD_SIZE_EACH)
                .chain(data)
                .chain(repeat_n(0f32, 2 * Self::PAD_SIZE_EACH)),
        )
    }

    /// Should only be called if the Iterator already includes enough padding
    pub fn new_stereo_interpolated_padded<I: IntoIterator<Item = f32>>(data: I) -> Self {
        let data = Vec::from_iter(data);
        Self {
            data: ThinArc::from_header_and_slice(false, &data),
        }
    }

    // replace these with some kind of specialization as soon as it becomes available
    pub fn new_stereo_interpolated_padded_exact<I: Iterator<Item = f32> + ExactSizeIterator>(
        data: I,
    ) -> Self {
        Self {
            data: ThinArc::from_header_and_iter(false, data),
        }
    }

    pub fn new_mono<I: IntoIterator<Item = f32>>(data: I) -> Self {
        Self::new_mono_padded(
            repeat_n(0f32, Self::PAD_SIZE_EACH)
                .chain(data)
                .chain(repeat_n(0f32, Self::PAD_SIZE_EACH)),
        )
    }

    pub fn new_mono_padded<I: IntoIterator<Item = f32>>(data: I) -> Self {
        let data = Vec::from_iter(data);
        Self {
            data: ThinArc::from_header_and_slice(true, &data),
        }
    }

    // replace these with some kind of specialization as soon as it becomes available
    pub fn new_mono_padded_exact<I: Iterator<Item = f32> + ExactSizeIterator>(data: I) -> Self {
        Self {
            data: ThinArc::from_header_and_iter(true, data),
        }
    }
}

impl Debug for Sample {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("Sample")
            .field("mono", &self.is_mono())
            .field("data_len", &self.len_with_pad())
            .finish_non_exhaustive()
    }
}

#[derive(Debug, Default, Clone, Copy)]
pub enum VibratoWave {
    #[default]
    Sine = 0,
    RampDown = 1,
    Square = 2,
    Random = 3,
}

#[derive(Clone, Copy, Debug)]
pub struct SampleMetaData {
    pub default_volume: u8,
    pub global_volume: u8,
    pub default_pan: Option<u8>,
    pub vibrato_speed: u8,
    pub vibrato_depth: u8,
    pub vibrato_rate: u8,
    pub vibrato_waveform: VibratoWave,
    pub sample_rate: NonZero<u32>,
    pub base_note: Note,
}