//! Bounded offline evaluation: PCM16/24/32 and IEEE float32 RIFF/WAVE input.
use patina_core::{Engine, Monitor, Settings};
use std::{
    env, fs,
    io::{Read, Write},
    path::Path,
    time::Instant,
};
fn main() {
    if let Err(e) = run() {
        eprintln!("{e}");
        std::process::exit(1);
    }
}
fn run() -> Result<(), Box<dyn std::error::Error>> {
    let args: Vec<_> = env::args().skip(1).collect();
    if args.is_empty() || args[0] == "--help" {
        println!("patina-render <input.wav> <output.wav> [settings.json] [--delta]\npatina-render --demo <output.wav>\npatina-render --benchmark\nOutput is float32 WAV, latency-trimmed with original length. Existing files are refused.");
        return Ok(());
    }
    if args[0] == "--benchmark" {
        let mut e = Engine::new(48000., 2)?;
        e.set_settings(Settings::preset(1))?;
        let frames = 48000 * 5;
        let start = Instant::now();
        for i in 0..frames {
            let x = (i as f32 * 0.173).sin() * 0.3;
            std::hint::black_box(e.process_sample([x, -x], Monitor::default()));
        }
        println!("Stereo 48 kHz / FFT 2048 / hop 256 / 5 seconds: {:.3}s ({:.1}% of one core, run --release for meaningful results)",start.elapsed().as_secs_f64(),start.elapsed().as_secs_f64()/5.*100.);
        return Ok(());
    }
    let (rate, channels, input, output) = if args[0] == "--demo" && args.len() == 2 {
        let samples = (0..48000 * 3)
            .map(|i| {
                let t = i as f32 / 48000.;
                let envelope = if t % 0.5 < 0.3 { 1. } else { 0.2 };
                [((t * 440. * std::f32::consts::TAU).sin() * 0.14
                    + (t * 3000. * std::f32::consts::TAU).sin() * 0.28)
                    * envelope; 2]
            })
            .collect();
        (48000., 2, samples, args[1].clone())
    } else if args.len() >= 2 {
        let (r, c, x) = read_wave(Path::new(&args[0]))?;
        (r, c, x, args[1].clone())
    } else {
        return Err("Use --help for usage".into());
    };
    let settings = if args.get(2).is_some_and(|s| !s.starts_with("--")) {
        let bytes = read_limit(Path::new(&args[2]), 64 * 1024)?;
        serde_json::from_slice::<Settings>(&bytes)?
    } else {
        Settings::default()
    };
    settings.validate()?;
    let mut engine = Engine::new(rate, channels)?;
    engine.set_settings(settings)?;
    let latency = engine.latency_samples() as usize;
    let start = Instant::now();
    let mut rendered = Vec::with_capacity(input.len());
    let monitor = Monitor {
        delta: args.iter().any(|a| a == "--delta"),
    };
    for i in 0..input.len() + latency {
        let sample = input.get(i).copied().unwrap_or([0.; 2]);
        let out = engine.process_sample(sample, monitor);
        if i >= latency {
            rendered.push(out);
        }
    }
    write_wave(Path::new(&output), rate as u32, channels, &rendered)?;
    println!(
        "Rendered {} frames, {} channel(s), {} Hz in {:.3}s; compensated {} samples → {}",
        rendered.len(),
        channels,
        rate,
        start.elapsed().as_secs_f64(),
        latency,
        output
    );
    Ok(())
}
fn read_limit(path: &Path, limit: usize) -> Result<Vec<u8>, Box<dyn std::error::Error>> {
    let mut bytes = Vec::new();
    fs::File::open(path)?
        .take(limit as u64 + 1)
        .read_to_end(&mut bytes)?;
    if bytes.len() > limit {
        return Err("Input exceeds size limit".into());
    }
    Ok(bytes)
}
type Wave = (f32, usize, Vec<[f32; 2]>);
fn read_wave(path: &Path) -> Result<Wave, Box<dyn std::error::Error>> {
    let b = read_limit(path, 256 * 1024 * 1024)?;
    if b.len() < 12 || &b[..4] != b"RIFF" || &b[8..12] != b"WAVE" {
        return Err("Expected RIFF/WAVE".into());
    }
    let u16_at = |p| u16::from_le_bytes([b[p], b[p + 1]]);
    let u32_at = |p| u32::from_le_bytes([b[p], b[p + 1], b[p + 2], b[p + 3]]);
    let end = (u32_at(4) as usize)
        .checked_add(8)
        .ok_or("Invalid RIFF length")?;
    if end > b.len() {
        return Err("Truncated RIFF container".into());
    }
    let mut pos = 12;
    let mut format = None;
    let mut data = None;
    while pos + 8 <= end {
        let len = u32_at(pos + 4) as usize;
        let start = pos + 8;
        let stop = start.checked_add(len).ok_or("Invalid chunk length")?;
        if stop > end {
            return Err("Truncated WAV chunk".into());
        }
        match &b[pos..pos + 4] {
            b"fmt " if len >= 16 => {
                format = Some((
                    u16_at(start),
                    u16_at(start + 2) as usize,
                    u32_at(start + 4),
                    u16_at(start + 12) as usize,
                    u16_at(start + 14) as usize,
                ))
            }
            b"data" => data = Some((start, stop)),
            _ => {}
        }
        pos = stop + (len % 2);
    }
    let (tag, channels, rate, align, bits) = format.ok_or("Missing WAV format")?;
    let (start, stop) = data.ok_or("Missing WAV data")?;
    if !(1..=2).contains(&channels) || !matches!((tag, bits), (1, 16) | (1, 24) | (1, 32) | (3, 32))
    {
        return Err("Use mono/stereo PCM16/24/32 or float32 WAV".into());
    }
    let size = bits / 8;
    if align != channels * size || (stop - start) % align != 0 {
        return Err("Invalid WAV block alignment".into());
    }
    let mut samples = Vec::with_capacity((stop - start) / align);
    for p in (start..stop).step_by(align) {
        let mut frame = [0.; 2];
        for (c, value) in frame.iter_mut().enumerate().take(channels) {
            let q = p + c * size;
            *value = match (tag, bits) {
                (3, 32) => f32::from_le_bytes(b[q..q + 4].try_into()?),
                (1, 16) => i16::from_le_bytes(b[q..q + 2].try_into()?) as f32 / 32768.,
                (1, 24) => {
                    ((b[q] as i32 | ((b[q + 1] as i32) << 8) | ((b[q + 2] as i32) << 16)) << 8 >> 8)
                        as f32
                        / 8388608.
                }
                _ => i32::from_le_bytes(b[q..q + 4].try_into()?) as f32 / 2147483648.,
            };
            if !value.is_finite() {
                return Err("Non-finite WAV samples".into());
            }
        }
        samples.push(frame);
    }
    Ok((rate as f32, channels, samples))
}
fn write_wave(
    path: &Path,
    rate: u32,
    channels: usize,
    samples: &[[f32; 2]],
) -> Result<(), Box<dyn std::error::Error>> {
    let bytes = (samples.len() * channels * 4) as u32;
    let mut f = fs::OpenOptions::new()
        .write(true)
        .create_new(true)
        .open(path)?;
    f.write_all(b"RIFF")?;
    f.write_all(&(36 + bytes).to_le_bytes())?;
    f.write_all(b"WAVEfmt ")?;
    f.write_all(&16u32.to_le_bytes())?;
    f.write_all(&3u16.to_le_bytes())?;
    f.write_all(&(channels as u16).to_le_bytes())?;
    f.write_all(&rate.to_le_bytes())?;
    f.write_all(&(rate * channels as u32 * 4).to_le_bytes())?;
    f.write_all(&(channels as u16 * 4).to_le_bytes())?;
    f.write_all(&32u16.to_le_bytes())?;
    f.write_all(b"data")?;
    f.write_all(&bytes.to_le_bytes())?;
    for frame in samples {
        for sample in frame.iter().take(channels) {
            f.write_all(&sample.to_le_bytes())?;
        }
    }
    Ok(())
}