spectrs 0.2.1

Fast spectrogram creation library
Documentation 
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use anyhow::Result;
use std::fs;
use std::path::Path;
use std::path::PathBuf;
use uuid::Uuid;

/// Creates a fresh test directory for running tests
pub fn setup_test_dir() -> Result<PathBuf> {
    // Create a unique directory name by concatenating strings
    let dir_name = format!("test-data-{}", Uuid::new_v4());
    let test_dir = PathBuf::from(dir_name);

    if test_dir.exists() {
        fs::remove_dir_all(&test_dir)?;
    }
    fs::create_dir(&test_dir)?;
    Ok(test_dir)
}

/// Cleans up the test directory after tests are complete
pub fn cleanup_test_dir(test_dir: &Path) -> Result<()> {
    if test_dir.exists() {
        fs::remove_dir_all(test_dir)?;
    }
    Ok(())
}

/// Create sample wav file with a simple sine wave
pub fn create_test_wav(
    path: &Path,
    duration_sec: f32,
    sample_rate: u32,
    channels: usize,
    bits_per_sample: u16,
) -> Result<()> {
    use hound::{WavSpec, WavWriter};

    let spec = WavSpec {
        channels: channels as u16,
        sample_rate,
        bits_per_sample,
        sample_format: hound::SampleFormat::Int,
    };

    let mut writer = WavWriter::create(path, spec)?;
    let num_samples = (duration_sec * sample_rate as f32) as u32;

    for t in 0..num_samples {
        let sample = (t as f32 * 440.0 * 2.0 * std::f32::consts::PI / sample_rate as f32).sin();

        // Write sample for each channel
        for _ in 0..channels {
            match bits_per_sample {
                8 => writer.write_sample((sample * i8::MAX as f32) as i8)?,
                16 => writer.write_sample((sample * i16::MAX as f32) as i16)?,
                32 => writer.write_sample((sample * i32::MAX as f32) as i32)?,
                _ => {
                    return Err(anyhow::anyhow!(
                        "Unsupported bits per sample: {}",
                        bits_per_sample
                    ));
                }
            }
        }
    }
    Ok(())
}

/// Create a more complex test wav file with multiple frequencies for better spectrogram testing
#[allow(dead_code)]
pub fn create_complex_test_wav(
    path: &Path,
    duration_sec: f32,
    sample_rate: u32,
    channels: usize,
    bits_per_sample: u16,
) -> Result<()> {
    use hound::{WavSpec, WavWriter};

    let spec = WavSpec {
        channels: channels as u16,
        sample_rate,
        bits_per_sample,
        sample_format: hound::SampleFormat::Int,
    };

    let mut writer = WavWriter::create(path, spec)?;
    let num_samples = (duration_sec * sample_rate as f32) as u32;

    // Multiple frequency components for richer spectrogram
    let frequencies = [220.0, 440.0, 880.0, 1320.0]; // A3, A4, A5, E6

    for t in 0..num_samples {
        let mut sample = 0.0;
        for (i, &freq) in frequencies.iter().enumerate() {
            let amplitude = 0.25 / (i + 1) as f32; // Decreasing amplitude
            sample += amplitude
                * (t as f32 * freq * 2.0 * std::f32::consts::PI / sample_rate as f32).sin();
        }

        // Write sample for each channel
        for _ in 0..channels {
            match bits_per_sample {
                8 => writer.write_sample((sample * i8::MAX as f32) as i8)?,
                16 => writer.write_sample((sample * i16::MAX as f32) as i16)?,
                32 => writer.write_sample((sample * i32::MAX as f32) as i32)?,
                _ => {
                    return Err(anyhow::anyhow!(
                        "Unsupported bits per sample: {}",
                        bits_per_sample
                    ));
                }
            }
        }
    }
    Ok(())
}