veza/veza-stream-server/src/codecs/flac.rs

use crate::codecs::{
    AudioDecoder, AudioEncoder, DecodedAudio, DecoderConfig, DecoderInfo, EncoderConfig,
    EncoderInfo, EncoderMetrics,
};
use crate::error::AppError;
use std::time::Instant;

/// Implémentation FLAC Encoder
#[derive(Debug)]
pub struct FlacEncoderImpl {
    config: EncoderConfig,
    metrics: EncoderMetrics,
    compression_level: u8,
    block_size: u16,
    sample_count: u64,
    frame_count: u64,
    start_time: Instant,
}

impl FlacEncoderImpl {
    pub fn new(config: EncoderConfig) -> Result<Self, AppError> {
        let compression_level = match config.quality {
            crate::codecs::CodecQuality::Low => 1,
            crate::codecs::CodecQuality::Medium => 3,
            crate::codecs::CodecQuality::High => 5,
            crate::codecs::CodecQuality::VeryHigh => 8,
            crate::codecs::CodecQuality::Custom(level) => (level * 8.0) as u8,
        };

        Ok(Self {
            config,
            metrics: EncoderMetrics::default(),
            compression_level,
            block_size: 4096,
            sample_count: 0,
            frame_count: 0,
            start_time: Instant::now(),
        })
    }
}

impl AudioEncoder for FlacEncoderImpl {
    fn encode(
        &mut self,
        samples: &[f32],
        _sample_rate: u32,
        _channels: u8,
    ) -> Result<Vec<u8>, AppError> {
        let start_time = Instant::now();

        // Simulation d'encodage FLAC
        let samples_per_channel = samples.len() / self.config.channels as usize;
        let estimated_size = samples_per_channel * 2; // Estimation compression ratio 2:1
        let mut output = Vec::with_capacity(estimated_size);

        // Header FLAC simplifié
        if self.frame_count == 0 {
            output.extend_from_slice(b"fLaC");
            output.extend_from_slice(&[0x00, 0x00, 0x00, 0x22]); // STREAMINFO block
        }

        // Frame data simulation
        for chunk in samples.chunks(self.block_size as usize) {
            let compressed_size = chunk.len() / 2; // Simulation compression lossless
            output.extend(vec![0u8; compressed_size]);
        }

        // Mettre à jour métriques
        self.metrics.frames_encoded += 1;
        self.metrics.bytes_output += output.len() as u64;
        self.metrics.encoding_time_ms += start_time.elapsed().as_millis() as u64;

        self.frame_count += 1;
        self.sample_count += samples_per_channel as u64;

        Ok(output)
    }

    fn finalize(&mut self) -> Result<Vec<u8>, AppError> {
        self.metrics.compression_ratio = if self.sample_count > 0 {
            let input_size = self.sample_count * self.config.channels as u64 * 4;
            input_size as f32 / self.metrics.bytes_output as f32
        } else {
            1.5 // Typical FLAC compression ratio
        };

        self.metrics.quality_score = 1.0; // Lossless = perfect quality
        Ok(Vec::new())
    }

    fn reset(&mut self) -> Result<(), AppError> {
        self.metrics = EncoderMetrics::default();
        self.sample_count = 0;
        self.frame_count = 0;
        self.start_time = Instant::now();
        Ok(())
    }

    fn set_bitrate(&mut self, _bitrate: u32) -> Result<(), AppError> {
        Ok(()) // FLAC est lossless, pas de bitrate fixe
    }

    fn info(&self) -> EncoderInfo {
        EncoderInfo {
            codec_name: "FLAC".to_string(),
            version: "1.3.4-simulation".to_string(),
            bitrate: 0, // Variable
            sample_rate: self.config.sample_rate,
            channels: self.config.channels,
            bit_depth: 16,
            frame_size: self.block_size as usize,
            latency_ms: 40.0,
            quality_mode: format!("Compression Level {}", self.compression_level),
        }
    }

    fn metrics(&self) -> EncoderMetrics {
        self.metrics.clone()
    }
}

/// Implémentation FLAC Decoder
#[derive(Debug)]
pub struct FlacDecoderImpl {
    config: DecoderConfig,
    frame_count: u64,
    sample_count: u64,
}

impl FlacDecoderImpl {
    pub fn new(config: DecoderConfig) -> Result<Self, AppError> {
        Ok(Self {
            config,
            frame_count: 0,
            sample_count: 0,
        })
    }
}

impl AudioDecoder for FlacDecoderImpl {
    fn decode(&mut self, data: &[u8]) -> Result<DecodedAudio, AppError> {
        // Simulation de décodage FLAC
        let samples_per_channel = 4096; // Block size typique
        let total_samples = samples_per_channel * self.config.channels as usize;

        // Simulation : générer des échantillons basés sur les données d'entrée
        let mut samples = Vec::with_capacity(total_samples);
        for i in 0..total_samples {
            let value = if !data.is_empty() {
                (data[i % data.len()] as f32 - 128.0) / 128.0
            } else {
                0.0
            };
            samples.push(value * 0.1); // Amplitude réduite
        }

        self.frame_count += 1;
        self.sample_count += samples_per_channel as u64;

        let duration_ms =
            (samples_per_channel as f32 / self.config.sample_rate as f32 * 1000.0) as u32;

        Ok(DecodedAudio {
            samples,
            sample_rate: self.config.sample_rate,
            channels: self.config.channels,
            duration_ms,
            format: self.config.output_format.clone(),
        })
    }

    fn reset(&mut self) -> Result<(), AppError> {
        self.frame_count = 0;
        self.sample_count = 0;
        Ok(())
    }

    fn info(&self) -> DecoderInfo {
        DecoderInfo {
            codec_name: "FLAC".to_string(),
            version: "1.3.4-simulation".to_string(),
            sample_rate: self.config.sample_rate,
            channels: self.config.channels,
            bit_depth: 16,
            frame_size: 4096,
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_flac_encoder() {
        let config = EncoderConfig::default();
        let mut encoder = FlacEncoderImpl::new(config).unwrap();
        let samples = vec![0.1, -0.1, 0.2, -0.2];

        let result = encoder.encode(&samples, 44100, 2);
        assert!(result.is_ok());
    }
}