//! Canonical P1 voice frame helpers.
//!
//! The network contract remains 48 kHz mono, 20 ms Opus frames. P1
//! processing works internally on 10 ms f32 frames so VAD and future
//! processors can share a stable frame size without changing the
//! transport layer.

/// P1 sample rate in Hz.
pub const SAMPLE_RATE_HZ: u32 = 48_000;
/// Network frame duration in milliseconds.
pub const NETWORK_FRAME_MS: u32 = 20;
/// Processing frame duration in milliseconds.
pub const PROCESSING_FRAME_MS: u32 = 10;
/// Samples in one 10 ms mono frame at 48 kHz.
pub const FRAME_10MS_SAMPLES: usize = 480;
/// Samples in one 20 ms mono frame at 48 kHz.
pub const FRAME_20MS_SAMPLES: usize = 960;

/// Convert i16 PCM to normalized f32 PCM.
pub fn i16_to_f32(sample: i16) -> f32 {
    sample as f32 / i16::MAX as f32
}

/// Convert normalized f32 PCM to saturated i16 PCM.
pub fn f32_to_i16(sample: f32) -> i16 {
    (sample.clamp(-1.0, 1.0) * i16::MAX as f32) as i16
}

/// RMS dBFS for a normalized f32 slice. Silence returns `-120.0`.
pub fn dbfs(samples: &[f32]) -> f32 {
    if samples.is_empty() {
        return -120.0;
    }
    let sum = samples.iter().map(|s| s * s).sum::<f32>();
    let rms = (sum / samples.len() as f32).sqrt();
    if rms <= 0.000_001 {
        -120.0
    } else {
        20.0 * rms.log10()
    }
}