//! Standalone HTTP server for the rtx-csm pipeline.
//!
//! Loads CSM-1B + (optionally) AudioSeal + (optionally) WavLM-SV at startup
//! and exposes:
//!
//!   GET  /health                                 → "ok"
//!   POST /v1/tts                                 → audio/wav (24 kHz mono)
//!   POST /v1/detect      [multipart audio]       → JSON { mean_presence, message }
//!   POST /v1/speaker_embed [multipart audio]     → JSON { embedding: [512 floats] }
//!   POST /v1/speaker_compare [multipart a + b]   → JSON { cosine }
//!
//! Inference is sync + GPU-heavy → spawn_blocking for every request. The
//! Generator + speaker scorer are wrapped in `std::sync::Mutex` so only
//! one inference runs per process; AudioSeal embed/detect are stateless
//! and run concurrently. Run multiple processes behind a load balancer
//! for higher throughput.
//!
//! Usage (full pipeline):
//! ```bash
//! cargo run -p rtx-csm --release --features metal --example tts_server -- \
//!   --bind 127.0.0.1:8080 \
//!   --audioseal-generator /tmp/audioseal_generator.safetensors \
//!   --audioseal-detector  /tmp/audioseal_detector.safetensors \
//!   --audioseal-message   0xCAFE \
//!   --wavlm-sv /tmp/wavlm_sv.safetensors
//!
//! curl -X POST http://127.0.0.1:8080/v1/tts \
//!   -H 'content-type: application/json' \
//!   -d '{"text":"Hello.","speaker":0}' --output /tmp/out.wav
//! curl -X POST http://127.0.0.1:8080/v1/detect \
//!   -F audio=@/tmp/out.wav -F source_rate=24000
//! curl -X POST http://127.0.0.1:8080/v1/speaker_embed \
//!   -F audio=@/tmp/out.wav -F source_rate=24000
//! curl -X POST http://127.0.0.1:8080/v1/speaker_compare \
//!   -F a=@/tmp/a.wav -F b=@/tmp/b.wav -F source_rate=24000
//! ```

use anyhow::Result;
use axum::{
    Json, Router,
    body::{Body, Bytes},
    extract::{Multipart, State},
    http::{StatusCode, header},
    response::IntoResponse,
    routing::{get, post},
};
use candle_core::DType;
use clap::Parser;
use futures_util::stream::Stream;
use rtx_csm::{
    GenerateOptions, Generator, PostProcess, audio_io, audioseal::AudioSealWatermarker,
    speaker_sim::WavLmSimilarity, watermark::ResampledWatermarker,
};
use serde::{Deserialize, Serialize};
use std::io::Cursor;
use std::net::SocketAddr;
use std::path::PathBuf;
use std::sync::{Arc, Mutex};

const AUDIOSEAL_RATE: u32 = 16_000;

#[derive(Debug, Parser)]
struct Cli {
    /// Bind address (e.g. 127.0.0.1:8080 or 0.0.0.0:8080).
    #[arg(long, default_value = "127.0.0.1:8080")]
    bind: SocketAddr,

    /// Optional path to a quantized GGUF (output of `examples/quantize`).
    #[arg(long)]
    quantized_gguf: Option<PathBuf>,

    /// Force CPU even if metal/cuda features are enabled.
    #[arg(long)]
    cpu: bool,

    /// AudioSeal generator safetensors. When BOTH this and
    /// --audioseal-detector are set, the inline watermarker is installed
    /// on the Generator (every TTS response is watermarked) and
    /// /v1/detect is enabled.
    #[arg(long)]
    audioseal_generator: Option<PathBuf>,
    #[arg(long)]
    audioseal_detector: Option<PathBuf>,
    /// 16-bit watermark message (decimal or 0xHEX).
    #[arg(long, default_value = "0")]
    audioseal_message: String,

    /// WavLM-SV safetensors (output of `wavlm_sv_convert`). When set,
    /// /v1/speaker_embed and /v1/speaker_compare are enabled.
    #[arg(long)]
    wavlm_sv: Option<PathBuf>,

    /// LoRA voice adapter (safetensors, output of `lora_train` or
    /// `lora_train_emotional`). Loaded into the backbone (FP or quantized
    /// — combines with --quantized-gguf per Phase 12.6) before serving so
    /// every TTS request uses the trained voice.
    #[arg(long)]
    lora: Option<PathBuf>,

    /// LoRA rank override. When omitted, auto-detected from the adapter's
    /// embedded metadata (Phase 12.5); falls back to 8 for older adapters.
    #[arg(long)]
    lora_rank: Option<usize>,

    /// LoRA alpha override. Auto-detected from metadata when omitted.
    #[arg(long)]
    lora_alpha: Option<f32>,

    /// Force extended LoRA coverage (q+k+v+output_proj + MLP). Auto-
    /// detected from metadata when omitted; setting it on a classic q+v
    /// adapter just allocates extra unused B=0 slots.
    #[arg(long, default_value_t = false)]
    extended_lora: bool,
}

fn parse_message(s: &str) -> Result<u16> {
    let s = s.trim();
    if let Some(rest) = s.strip_prefix("0x").or_else(|| s.strip_prefix("0X")) {
        Ok(u16::from_str_radix(rest, 16)?)
    } else {
        Ok(s.parse::<u16>()?)
    }
}

struct AppState {
    generator: Mutex<Generator>,
    /// Held by the generator's set_watermarker; we keep a separate
    /// detector instance for /v1/detect (mmap'd weights are shared).
    audioseal_detector: Option<AudioSealWatermarker>,
    wavlm: Option<Mutex<WavLmSimilarity>>,
}

#[derive(Debug, Deserialize)]
struct TtsRequest {
    text: String,
    #[serde(default)]
    speaker: u32,
    #[serde(default = "default_max_audio_ms")]
    max_audio_ms: u32,
    #[serde(default = "default_temperature")]
    temperature: f64,
    #[serde(default = "default_top_k")]
    top_k: usize,
    #[serde(default = "default_top_p")]
    top_p: f64,
    #[serde(default = "default_seed")]
    seed: u64,
    /// Optional per-request 16-bit watermark message override. If set
    /// AND the server has AudioSeal loaded, the watermark on this
    /// response carries this message instead of the server-startup
    /// default. Useful for tagging each generation with a unique ID
    /// (e.g. clawsample's job_id mod 0x10000) for audit trails.
    /// Accepts decimal or 0xHEX as a string for safety with JSON.
    #[serde(default)]
    watermark_message: Option<String>,
}

fn default_max_audio_ms() -> u32 {
    10_000
}
fn default_temperature() -> f64 {
    0.9
}
fn default_top_k() -> usize {
    50
}
fn default_top_p() -> f64 {
    0.9
}
fn default_seed() -> u64 {
    42
}

#[derive(Debug, Serialize)]
struct DetectResponse {
    mean_presence: f32,
    message: u16,
    message_hex: String,
}

#[derive(Debug, Serialize)]
struct EmbedResponse {
    embedding: Vec<f32>,
}

#[derive(Debug, Serialize)]
struct CompareResponse {
    cosine: f32,
}

async fn health() -> &'static str {
    "ok"
}

async fn tts(
    State(state): State<Arc<AppState>>,
    Json(req): Json<TtsRequest>,
) -> Result<impl IntoResponse, (StatusCode, String)> {
    if req.text.trim().is_empty() {
        return Err((StatusCode::BAD_REQUEST, "text is required".to_string()));
    }
    let opts = GenerateOptions {
        max_audio_ms: req.max_audio_ms,
        temperature: req.temperature,
        top_k: req.top_k,
        top_p: req.top_p,
        seed: req.seed,
        ..GenerateOptions::default()
    };
    let state2 = state.clone();
    let text = req.text.clone();
    let speaker = req.speaker;
    // Per-request message override; None falls back to startup default.
    let req_msg = match req.watermark_message.as_deref() {
        Some(s) => Some(
            parse_message(s)
                .map_err(|e| (StatusCode::BAD_REQUEST, format!("watermark_message: {e}")))?,
        ),
        None => None,
    };
    let result: Result<Vec<f32>, String> = tokio::task::spawn_blocking(move || {
        let mut g = state2.generator.lock().expect("generator mutex poisoned");
        let mut pcm = g
            .generate(&text, speaker, &[], opts)
            .map_err(|e| format!("inference: {e}"))?;
        PostProcess::default()
            .apply(&mut pcm, g.config.sample_rate)
            .map_err(|e| format!("post: {e}"))?;
        if let Some(wm) = g.watermarker.as_ref() {
            pcm = match req_msg {
                Some(m) => wm.embed_with_message(&pcm, m),
                None => wm.embed(&pcm),
            }
            .map_err(|e| format!("watermark: {e}"))?;
        }
        Ok(pcm)
    })
    .await
    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("join: {e}")))?;
    let pcm = result.map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e))?;

    let mut buf: Vec<u8> = Vec::new();
    {
        let cursor = Cursor::new(&mut buf);
        let spec = hound::WavSpec {
            channels: 1,
            sample_rate: 24_000,
            bits_per_sample: 16,
            sample_format: hound::SampleFormat::Int,
        };
        let mut w = hound::WavWriter::new(cursor, spec).map_err(|e| {
            (
                StatusCode::INTERNAL_SERVER_ERROR,
                format!("wav writer: {e}"),
            )
        })?;
        for &s in pcm.iter() {
            let v = (s.clamp(-1.0, 1.0) * i16::MAX as f32) as i16;
            w.write_sample(v)
                .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("wav write: {e}")))?;
        }
        w.finalize().map_err(|e| {
            (
                StatusCode::INTERNAL_SERVER_ERROR,
                format!("wav finalize: {e}"),
            )
        })?;
    }

    let _ = audio_io::TARGET_SAMPLE_RATE;
    Ok((
        StatusCode::OK,
        [(header::CONTENT_TYPE, "audio/wav")],
        Bytes::from(buf),
    ))
}

/// Streaming TTS: chunks of raw 16-bit little-endian PCM (24 kHz mono)
/// are emitted as soon as Mimi produces them. Content-Type is
/// `audio/L16; rate=24000; channels=1` per RFC 2586. First chunk arrives
/// in roughly `chunk_frames × 80ms + per-frame compute × chunk_frames`
/// — typically ~600 ms with `chunk_frames=4` on Metal.
///
/// Clients: `curl --output - http://.../v1/tts_stream | aplay -f S16_LE -r 24000`
/// or pipe directly into a player. Note: this endpoint does NOT apply
/// post-processing or the inline watermarker; streaming watermarking
/// requires a chunked AudioSeal port (deferred). Use /v1/tts for the
/// post-processed + watermarked path.
async fn tts_stream(
    State(state): State<Arc<AppState>>,
    Json(req): Json<TtsRequest>,
) -> Result<impl IntoResponse, (StatusCode, String)> {
    if req.text.trim().is_empty() {
        return Err((StatusCode::BAD_REQUEST, "text is required".to_string()));
    }
    let opts = GenerateOptions {
        max_audio_ms: req.max_audio_ms,
        temperature: req.temperature,
        top_k: req.top_k,
        top_p: req.top_p,
        seed: req.seed,
        ..GenerateOptions::default()
    };
    // mpsc channel: blocking inference task pushes chunks, async response
    // consumer yields them as the body stream.
    let (tx, rx) = tokio::sync::mpsc::channel::<Result<Bytes, std::io::Error>>(8);
    let state2 = state.clone();
    let text = req.text.clone();
    let speaker = req.speaker;
    tokio::task::spawn_blocking(move || {
        let mut g = state2.generator.lock().expect("generator mutex poisoned");
        // chunk_frames=4 → ~320ms of audio per emitted chunk; first chunk
        // arrives after ~4 frames × per-frame-compute. Tunable.
        let chunk_frames = 4usize;
        let res = g.generate_streaming(
            &text,
            speaker,
            &[],
            opts,
            chunk_frames,
            |samples: &[f32]| {
                // Encode chunk as 16-bit LE PCM.
                let mut buf = Vec::with_capacity(samples.len() * 2);
                for &s in samples {
                    let v = (s.clamp(-1.0, 1.0) * i16::MAX as f32) as i16;
                    buf.extend_from_slice(&v.to_le_bytes());
                }
                // blocking_send is correct here — we're inside spawn_blocking.
                let _ = tx.blocking_send(Ok(Bytes::from(buf)));
                Ok(())
            },
        );
        if let Err(e) = res {
            let _ = tx.blocking_send(Err(std::io::Error::new(
                std::io::ErrorKind::Other,
                format!("stream: {e}"),
            )));
        }
        // dropping tx closes the channel
    });
    let stream = ReceiverStream { rx };
    let body = Body::from_stream(stream);
    Ok((
        StatusCode::OK,
        [(header::CONTENT_TYPE, "audio/L16; rate=24000; channels=1")],
        body,
    ))
}

/// Adapter: tokio mpsc Receiver<T> → futures Stream<Item = T>.
struct ReceiverStream {
    rx: tokio::sync::mpsc::Receiver<Result<Bytes, std::io::Error>>,
}

impl Stream for ReceiverStream {
    type Item = Result<Bytes, std::io::Error>;
    fn poll_next(
        mut self: std::pin::Pin<&mut Self>,
        cx: &mut std::task::Context<'_>,
    ) -> std::task::Poll<Option<Self::Item>> {
        self.rx.poll_recv(cx)
    }
}

/// Read a multipart `audio` field as raw WAV bytes, decode at the given
/// `source_rate` (default 24 kHz, CSM-1B native), then resample to 16 kHz
/// for AudioSeal/WavLM-SV consumption.
async fn read_audio_at(
    multipart: &mut Multipart,
    field_name: &str,
    source_rate: u32,
    target_rate: u32,
) -> Result<Vec<f32>, (StatusCode, String)> {
    while let Some(field) = multipart
        .next_field()
        .await
        .map_err(|e| (StatusCode::BAD_REQUEST, format!("multipart: {e}")))?
    {
        let name = field.name().unwrap_or_default().to_string();
        if name != field_name {
            continue;
        }
        let bytes = field
            .bytes()
            .await
            .map_err(|e| (StatusCode::BAD_REQUEST, format!("read field: {e}")))?;
        let tmp = std::env::temp_dir().join(format!(
            "tts_server_in_{}_{:x}.wav",
            field_name,
            std::process::id() as u64 ^ rand::random::<u64>()
        ));
        std::fs::write(&tmp, &bytes).map_err(|e| {
            (
                StatusCode::INTERNAL_SERVER_ERROR,
                format!("temp write: {e}"),
            )
        })?;
        let raw = audio_io::load_mono_at_rate(&tmp, source_rate)
            .map_err(|e| (StatusCode::BAD_REQUEST, format!("decode: {e}")))?;
        let _ = std::fs::remove_file(&tmp);
        let resampled = audio_io::resample(&raw, source_rate, target_rate)
            .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("resample: {e}")))?;
        return Ok(resampled);
    }
    Err((
        StatusCode::BAD_REQUEST,
        format!("missing field: {field_name}"),
    ))
}

async fn detect(
    State(state): State<Arc<AppState>>,
    mut multipart: Multipart,
) -> Result<Json<DetectResponse>, (StatusCode, String)> {
    let det = state.audioseal_detector.as_ref().ok_or((
        StatusCode::SERVICE_UNAVAILABLE,
        "AudioSeal not loaded — pass --audioseal-generator + --audioseal-detector at startup"
            .to_string(),
    ))?;
    // Multipart fields are consumed once; read source_rate first if present,
    // then pull audio. Most clients send audio first; fall back to default 24k.
    let source_rate = 24_000u32;
    let samples = read_audio_at(&mut multipart, "audio", source_rate, AUDIOSEAL_RATE).await?;
    let result = det
        .detect(&samples)
        .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("detect: {e}")))?;
    let message = result.message.unwrap_or(0);
    Ok(Json(DetectResponse {
        mean_presence: result.mean_presence,
        message,
        message_hex: format!("0x{:04X}", message),
    }))
}

async fn speaker_embed(
    State(state): State<Arc<AppState>>,
    mut multipart: Multipart,
) -> Result<Json<EmbedResponse>, (StatusCode, String)> {
    let scorer_mu = state.wavlm.as_ref().ok_or((
        StatusCode::SERVICE_UNAVAILABLE,
        "WavLM-SV not loaded — pass --wavlm-sv at startup".to_string(),
    ))?;
    let source_rate = 24_000u32;
    let samples = read_audio_at(&mut multipart, "audio", source_rate, AUDIOSEAL_RATE).await?;
    let scorer = scorer_mu.lock().expect("wavlm mutex poisoned");
    let embedding = scorer
        .embed(&samples)
        .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("embed: {e}")))?;
    Ok(Json(EmbedResponse { embedding }))
}

async fn speaker_compare(
    State(state): State<Arc<AppState>>,
    mut multipart: Multipart,
) -> Result<Json<CompareResponse>, (StatusCode, String)> {
    let scorer_mu = state.wavlm.as_ref().ok_or((
        StatusCode::SERVICE_UNAVAILABLE,
        "WavLM-SV not loaded — pass --wavlm-sv at startup".to_string(),
    ))?;
    let source_rate = 24_000u32;
    // Read both `a` and `b` audio fields. We can't seek over the multipart
    // stream, so collect any audio fields we see in order.
    let mut a: Option<Vec<f32>> = None;
    let mut b: Option<Vec<f32>> = None;
    while let Some(field) = multipart
        .next_field()
        .await
        .map_err(|e| (StatusCode::BAD_REQUEST, format!("multipart: {e}")))?
    {
        let name = field.name().unwrap_or_default().to_string();
        match name.as_str() {
            "a" | "b" => {
                let bytes = field
                    .bytes()
                    .await
                    .map_err(|e| (StatusCode::BAD_REQUEST, format!("read field: {e}")))?;
                let tmp = std::env::temp_dir().join(format!(
                    "tts_server_cmp_{name}_{:x}.wav",
                    std::process::id() as u64 ^ rand::random::<u64>()
                ));
                std::fs::write(&tmp, &bytes).map_err(|e| {
                    (
                        StatusCode::INTERNAL_SERVER_ERROR,
                        format!("temp write: {e}"),
                    )
                })?;
                let raw = audio_io::load_mono_at_rate(&tmp, source_rate)
                    .map_err(|e| (StatusCode::BAD_REQUEST, format!("decode {name}: {e}")))?;
                let _ = std::fs::remove_file(&tmp);
                let resampled = audio_io::resample(&raw, source_rate, AUDIOSEAL_RATE)
                    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("resample: {e}")))?;
                if name == "a" {
                    a = Some(resampled);
                } else {
                    b = Some(resampled);
                }
            }
            _ => {}
        }
    }
    let a = a.ok_or((StatusCode::BAD_REQUEST, "missing 'a' audio".to_string()))?;
    let b = b.ok_or((StatusCode::BAD_REQUEST, "missing 'b' audio".to_string()))?;
    let scorer = scorer_mu.lock().expect("wavlm mutex poisoned");
    use rtx_csm::speaker_sim::SpeakerSimilarity;
    let cosine = scorer
        .score(&a, &b)
        .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("score: {e}")))?;
    Ok(Json(CompareResponse { cosine }))
}

#[tokio::main]
async fn main() -> Result<()> {
    tracing_subscriber::fmt().init();
    let cli = Cli::parse();

    let device = if cli.cpu {
        candle_core::Device::Cpu
    } else {
        Generator::default_device()?
    };
    tracing::info!("device: {device:?}");

    let mut generator = if let Some(gguf) = cli.quantized_gguf.as_ref() {
        tracing::info!("loading quantized CSM from {}", gguf.display());
        Generator::load_csm_1b_quantized(gguf, &device, false)?
    } else {
        Generator::load_csm_1b(&device)?
    };
    tracing::info!("CSM-1B loaded");

    // Optional LoRA adapter (Phase 12.4 + 12.5 self-describing metadata).
    if let Some(lora_path) = cli.lora.as_ref() {
        let extended_override = if cli.extended_lora { Some(true) } else { None };
        rtx_csm::training::apply_lora_adapter(
            &mut generator,
            lora_path,
            cli.lora_rank,
            cli.lora_alpha,
            extended_override,
            &device,
        )?;
    }

    // Optional AudioSeal — install inline + keep a detector instance.
    let audioseal_message = parse_message(&cli.audioseal_message)?;
    let audioseal_detector = if let (Some(g), Some(d)) = (
        cli.audioseal_generator.as_ref(),
        cli.audioseal_detector.as_ref(),
    ) {
        let g_vb =
            unsafe { candle_nn::VarBuilder::from_mmaped_safetensors(&[g], DType::F32, &device) }?;
        let d_vb =
            unsafe { candle_nn::VarBuilder::from_mmaped_safetensors(&[d], DType::F32, &device) }?;
        let inner =
            AudioSealWatermarker::from_var_builders(g_vb, d_vb, device.clone(), audioseal_message)?;
        let wm = ResampledWatermarker::new(inner, generator.config.sample_rate, AUDIOSEAL_RATE);
        generator.set_watermarker(Box::new(wm));
        // Build a second detector instance for /v1/detect (mmap'd weights shared).
        let g_vb2 =
            unsafe { candle_nn::VarBuilder::from_mmaped_safetensors(&[g], DType::F32, &device) }?;
        let d_vb2 =
            unsafe { candle_nn::VarBuilder::from_mmaped_safetensors(&[d], DType::F32, &device) }?;
        let det = AudioSealWatermarker::from_var_builders(
            g_vb2,
            d_vb2,
            device.clone(),
            audioseal_message,
        )?;
        tracing::info!(
            "AudioSeal installed (message=0x{:04X}); /v1/tts auto-watermarks, /v1/detect enabled",
            audioseal_message
        );
        Some(det)
    } else {
        None
    };

    let wavlm = if let Some(p) = cli.wavlm_sv.as_ref() {
        let scorer = WavLmSimilarity::load(p, &device)?;
        tracing::info!("WavLM-SV loaded; /v1/speaker_embed and /v1/speaker_compare enabled");
        Some(Mutex::new(scorer))
    } else {
        None
    };

    let _ = audioseal_message; // captured into the watermarker; field not needed on AppState.
    let state = Arc::new(AppState {
        generator: Mutex::new(generator),
        audioseal_detector,
        wavlm,
    });

    let app = Router::new()
        .route("/health", get(health))
        .route("/v1/tts", post(tts))
        .route("/v1/tts_stream", post(tts_stream))
        .route("/v1/detect", post(detect))
        .route("/v1/speaker_embed", post(speaker_embed))
        .route("/v1/speaker_compare", post(speaker_compare))
        .with_state(state);

    let listener = tokio::net::TcpListener::bind(&cli.bind).await?;
    tracing::info!("listening on http://{}", cli.bind);
    axum::serve(listener, app).await?;
    Ok(())
}