src/model/session.rs

//! ONNX Runtime session management (stubbed for initial conversion)

use crate::{Error, Result};
use ndarray::{Array, IxDyn};
use std::collections::HashMap;
use std::path::{Path, PathBuf};
use std::sync::{Arc, RwLock};

/// ONNX Runtime session wrapper (placeholder)
pub struct OnnxSession {
    input_names: Vec<String>,
    output_names: Vec<String>,
}

impl OnnxSession {
    /// Load ONNX model from file (placeholder)
    pub fn load<P: AsRef<Path>>(path: P) -> Result<Self> {
        let path = path.as_ref();
        if !path.exists() {
            return Err(Error::FileNotFound(path.display().to_string()));
        }

        // Placeholder - actual ONNX loading would go here
        log::info!("Loading ONNX model from: {}", path.display());

        Ok(Self {
            input_names: vec!["input".to_string()],
            output_names: vec!["output".to_string()],
        })
    }

    /// Run inference (placeholder)
    pub fn run(
        &self,
        _inputs: HashMap<String, Array<f32, IxDyn>>,
    ) -> Result<HashMap<String, Array<f32, IxDyn>>> {
        // Placeholder - returns empty output
        let mut result = HashMap::new();
        for name in &self.output_names {
            let dummy = Array::zeros(IxDyn(&[1, 1]));
            result.insert(name.clone(), dummy);
        }
        Ok(result)
    }

    /// Run inference with i64 inputs (placeholder)
    pub fn run_i64(
        &self,
        _inputs: HashMap<String, Array<i64, IxDyn>>,
    ) -> Result<HashMap<String, Array<f32, IxDyn>>> {
        let mut result = HashMap::new();
        for name in &self.output_names {
            let dummy = Array::zeros(IxDyn(&[1, 1]));
            result.insert(name.clone(), dummy);
        }
        Ok(result)
    }

    pub fn input_names(&self) -> &[String] {
        &self.input_names
    }

    pub fn output_names(&self) -> &[String] {
        &self.output_names
    }
}

/// Model cache for managing multiple ONNX sessions
pub struct ModelCache {
    sessions: RwLock<HashMap<String, Arc<OnnxSession>>>,
    model_dir: PathBuf,
}

impl ModelCache {
    pub fn new<P: AsRef<Path>>(model_dir: P) -> Self {
        Self {
            sessions: RwLock::new(HashMap::new()),
            model_dir: model_dir.as_ref().to_path_buf(),
        }
    }

    pub fn get_or_load(&self, name: &str) -> Result<Arc<OnnxSession>> {
        {
            let cache = self.sessions.read().unwrap();
            if let Some(session) = cache.get(name) {
                return Ok(Arc::clone(session));
            }
        }

        let model_path = self.model_dir.join(format!("{}.onnx", name));
        let session = OnnxSession::load(&model_path)?;
        let session = Arc::new(session);

        {
            let mut cache = self.sessions.write().unwrap();
            cache.insert(name.to_string(), Arc::clone(&session));
        }

        Ok(session)
    }

    pub fn preload(&self, model_names: &[&str]) -> Result<()> {
        for name in model_names {
            self.get_or_load(name)?;
        }
        Ok(())
    }

    pub fn clear(&self) {
        let mut cache = self.sessions.write().unwrap();
        cache.clear();
    }

    pub fn is_cached(&self, name: &str) -> bool {
        let cache = self.sessions.read().unwrap();
        cache.contains_key(name)
    }

    pub fn cached_models(&self) -> Vec<String> {
        let cache = self.sessions.read().unwrap();
        cache.keys().cloned().collect()
    }
}

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

    #[test]
    fn test_model_cache_creation() {
        let cache = ModelCache::new("/tmp/models");
        assert!(cache.cached_models().is_empty());
    }
}