leviath-runtime 0.1.0

//! The [`ProviderRegistry`]: a name → [`Provider`] lookup shared by the ECS
//! pipeline (as the `Providers` resource) and the CLI/daemon spawn path.

use crate::script_provider::ScriptProviderLayer;
use leviath_providers::Provider;
use std::collections::HashMap;
use std::sync::Arc;

/// Registry of inference providers, keyed by provider name (e.g. `"anthropic"`).
///
/// The pipeline resolves each agent's stage `ModelConfig` to a concrete
/// provider through this registry. Native providers are registered eagerly;
/// script providers are resolved lazily - and hot-reloaded - via
/// an optional [`ScriptProviderLayer`].
#[derive(Clone, Default)]
pub struct ProviderRegistry {
    providers: HashMap<String, Arc<dyn Provider>>,
    /// Lazy, hot-reloading resolver for `.rhai` script providers. Shared across
    /// registry clones (one compile cache daemon-wide).
    script_layer: Option<Arc<ScriptProviderLayer>>,
}

impl ProviderRegistry {
    /// Create a new empty provider registry.
    pub fn new() -> Self {
        Self::default()
    }

    /// Attach a script-provider layer for lazy/hot-reloading `.rhai` providers.
    pub fn with_script_layer(mut self, layer: Arc<ScriptProviderLayer>) -> Self {
        self.script_layer = Some(layer);
        self
    }

    /// Register a provider by name.
    pub fn register(&mut self, name: String, provider: Arc<dyn Provider>) {
        self.providers.insert(name, provider);
    }

    /// Get a provider by name, returning an owned handle.
    ///
    /// A native provider wins; otherwise the script layer is consulted, which
    /// lazily compiles (or hot-reloads) the matching `.rhai` script.
    pub fn get(&self, name: &str) -> Option<Arc<dyn Provider>> {
        if let Some(p) = self.providers.get(name) {
            return Some(p.clone());
        }
        self.script_layer.as_ref()?.get_or_load(name)
    }

    /// Check if a provider is available: registered natively, or resolvable
    /// (loadable) as a script provider right now. Used at stage-model selection;
    /// network-free because script `initialize` runs offline.
    pub fn has(&self, name: &str) -> bool {
        self.providers.contains_key(name)
            || self
                .script_layer
                .as_ref()
                .is_some_and(|l| l.get_or_load(name).is_some())
    }

    /// Get all *natively-registered* provider names. Script providers are
    /// resolved on demand and so are not enumerated here.
    pub fn provider_names(&self) -> Vec<&str> {
        self.providers.keys().map(|k| k.as_str()).collect()
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use leviath_providers::{
        InferenceRequest, InferenceResponse, ModelCapabilities, ProviderError,
    };

    struct StubProvider;

    #[async_trait::async_trait]
    impl Provider for StubProvider {
        async fn infer(
            &self,
            _request: InferenceRequest,
        ) -> Result<InferenceResponse, ProviderError> {
            Err(ProviderError::ApiError("stub".to_string()))
        }
        async fn count_tokens(&self, text: &str, _model: &str) -> usize {
            text.len()
        }
        fn max_context_tokens(&self, _model: &str) -> usize {
            8192
        }
        fn name(&self) -> &str {
            "stub"
        }
        fn capabilities(&self, _model: &str) -> ModelCapabilities {
            ModelCapabilities::default()
        }
    }

    fn mock() -> Arc<dyn Provider> {
        Arc::new(StubProvider)
    }

    #[test]
    fn register_get_has_and_names() {
        let mut reg = ProviderRegistry::new();
        assert!(!reg.has("anthropic"));
        assert!(reg.get("anthropic").is_none());
        reg.register("anthropic".to_string(), mock());
        assert!(reg.has("anthropic"));
        assert!(reg.get("anthropic").is_some());
        assert_eq!(reg.provider_names(), vec!["anthropic"]);
    }

    #[test]
    fn default_is_empty() {
        let reg = ProviderRegistry::default();
        assert!(reg.provider_names().is_empty());
    }

    #[test]
    fn script_layer_resolves_and_native_wins() {
        use crate::script_provider::ScriptProviderLayer;
        use std::collections::HashMap;

        let dir = tempfile::tempdir().unwrap();
        std::fs::write(
            dir.path().join("groq.rhai"),
            "fn initialize(config) { #{} }\nfn inference(state, request) { #{ content: \"ok\" } }",
        )
        .unwrap();
        let layer = ScriptProviderLayer::new(
            dir.path().to_path_buf(),
            HashMap::new(),
            HashMap::new(),
            None,
            Vec::new(),
        );
        let mut reg = ProviderRegistry::new().with_script_layer(Arc::new(layer));
        reg.register("anthropic".to_string(), mock());

        // Native provider still wins and is found by name.
        assert!(reg.has("anthropic"));
        assert!(reg.get("anthropic").is_some());

        // A script provider is resolved lazily through the layer by both has/get.
        assert!(reg.has("groq"));
        let p = reg.get("groq").expect("script provider resolves");
        assert_eq!(p.name(), "groq");

        // An unknown name resolves to nothing (layer returns None).
        assert!(!reg.has("nope"));
        assert!(reg.get("nope").is_none());
    }

    #[tokio::test]
    async fn stub_provider_methods_are_exercised() {
        let p = StubProvider;
        assert_eq!(p.name(), "stub");
        assert_eq!(p.count_tokens("abcd", "m").await, 4);
        assert_eq!(p.max_context_tokens("m"), 8192);
        let _ = p.capabilities("m");
        let request = InferenceRequest {
            system: Vec::new(),
            messages: Vec::new(),
            model: "m".to_string(),
            max_tokens: 10,
            temperature: 0.0,
            tools: Vec::new(),
            extra: serde_json::Value::Null,
            request_timeout_secs: None,
        };
        assert!(p.infer(request).await.is_err());
    }
}