use std::f32::consts::PI;

use super::error::DspError;

pub struct SinSource {
    sampling_rate: f32,
    frequency: f32,
    phase_acc: f32,
}

impl SinSource {
    pub fn new(frequency: f32, sampling_rate: f32) -> SinSource {
        SinSource {
            sampling_rate: sampling_rate,
            frequency: frequency,
            phase_acc: 0.0,
        }
    }
}

impl Iterator for SinSource {
    type Item = Result<f32, DspError>;

    fn next(&mut self) -> Option<Self::Item> {
        self.phase_acc += (1.0 / self.sampling_rate) * self.frequency * 2.0 * PI;
        if self.phase_acc > 2.0 * PI {
            self.phase_acc -= 2.0 * PI;
        }

        Some(Ok(self.phase_acc.sin()))
    }
}

pub struct CosSource {
    sampling_rate: f32,
    frequency: f32,
    phase_acc: f32,
}

impl CosSource {
    pub fn new(frequency: f32, sampling_rate: f32) -> CosSource {
        CosSource {
            sampling_rate: sampling_rate,
            frequency: frequency,
            phase_acc: 0.0,
        }
    }
}

impl Iterator for CosSource {
    type Item = Result<f32, DspError>;

    fn next(&mut self) -> Option<Self::Item> {
        self.phase_acc += (1.0 / self.sampling_rate) * self.frequency * 2.0 * PI;
        if self.phase_acc > 2.0 * PI {
            self.phase_acc -= 2.0 * PI;
        }

        Some(Ok(self.phase_acc.cos()))
    }
}

pub struct VFOSource<'a> {
    sampling_rate: f32,
    phase_acc: f32,
    frequency_iterator: Box<dyn Iterator<Item = Result<f32, DspError>> + 'a>,
}

impl<'a> VFOSource<'a> {
    pub fn new<I>(frequency_iterator: I, sampling_rate: f32) -> VFOSource<'a>
    where
        I: Iterator<Item = Result<f32, DspError>> + 'a,
    {
        VFOSource {
            sampling_rate: sampling_rate,
            phase_acc: 0.0,
            frequency_iterator: Box::new(frequency_iterator),
        }
    }
}

impl<'a> Iterator for VFOSource<'a> {
    type Item = Result<f32, DspError>;

    fn next(&mut self) -> Option<Self::Item> {
        let current_frequency = match self.frequency_iterator.next() {
            Some(Ok(x)) => x,
            // Propagate any upstream errors
            Some(Err(e)) => return Some(Err(e)),
            None => return None,
        };

        self.phase_acc += (1.0 / self.sampling_rate) * current_frequency * 2.0 * PI;
        if self.phase_acc > 2.0 * PI {
            self.phase_acc -= 2.0 * PI;
        }

        Some(Ok(self.phase_acc.sin()))
    }
}