oxi-ai 0.26.0

//! Model auto-routing for oxi.
//!
//! Provides intelligent model selection based on conversation structure
//! and behavioral signals. This is an **opt-in** feature — the user must
//! explicitly select `router/auto` or another profile in model selection.

#![allow(missing_docs)]

pub mod classifier;
pub mod fallback;
pub mod profiles;
pub mod scoring;
pub mod signals;
pub mod types;

use crate::context::Context;
use crate::error::ProviderError;
use crate::messages::Message;
use crate::providers::ProviderRegistry;
use crate::providers::StreamOptions;
use crate::types::Model;
use crate::{register_model, register_provider, Api, Provider, ProviderEvent, ThinkingLevel};

/// Global router state snapshot — updated after each routing decision.
static ROUTER_SNAPSHOT: parking_lot::RwLock<Option<RouterSnapshot>> =
    parking_lot::RwLock::new(None);

/// Global pin tier override — set by /router pin command.
static ROUTER_PIN_TIER: parking_lot::RwLock<Option<RouterTier>> = parking_lot::RwLock::new(None);

/// Snapshot of the current router state for UI display.
#[derive(Debug, Clone, Default)]
pub struct RouterSnapshot {
    pub last_tier: Option<RouterTier>,
    pub last_score: f64,
    pub last_model: Option<String>,
    pub last_provider: Option<String>,
    pub accumulated_cost: f64,
    pub turn_count: usize,
    pub profile: Option<String>,
}
use futures::Stream;
use parking_lot::RwLock;
use std::pin::Pin;
use std::sync::Arc;

pub use fallback::FallbackChain;
pub use profiles::{parse_tier_model, ProviderModel, RouterProfiles};
pub use scoring::{compute_score, lerp};
pub use signals::{
    BehavioralSignal, ContextBudgetSignal, MessageContentSignal, StructuralSignal, VisionSignal,
};
pub use types::{
    DecisionMethod, RoutedTierConfig, RouterConfig, RouterPhase, RouterProfile, RouterState,
    RouterTier, RoutingDecision, RoutingScore, ScoringWeights,
};

// ── Helpers ──────────────────────────────────────────────────────────────────

fn message_chars(msg: &Message) -> usize {
    match msg {
        Message::User(u) => u.content.as_str().map(|s| s.len()).unwrap_or(0),
        Message::Assistant(a) => a
            .content
            .iter()
            .map(|b| b.as_text().map(|t| t.len()).unwrap_or(0))
            .sum(),
        Message::ToolResult(t) => t
            .content
            .iter()
            .map(|b| b.as_text().map(|t| t.len()).unwrap_or(0))
            .sum(),
    }
}

fn build_target_model(pm: &ProviderModel, reasoning: bool) -> Model {
    let mut m = Model::new(
        &pm.model_id,
        &pm.model_id,
        Api::AnthropicMessages,
        &pm.provider,
        "",
    );
    m.reasoning = reasoning;
    m
}

// ── Pipeline ─────────────────────────────────────────────────────────────────

/// Routing pipeline state for a session.
#[derive(Debug)]
pub struct RouterPipeline {
    pub weights: ScoringWeights,
    decision_history: Vec<RoutingDecision>,
    accumulated_cost: f64,
    budget_limit: Option<f64>,
    context_upgrade_threshold: Option<usize>,
    last_score: f64,
    pin_tier: Option<RouterTier>,
    phase_bias: f64,
    classifier_model: Option<String>,
}

impl RouterPipeline {
    pub fn new() -> Self {
        Self {
            weights: ScoringWeights::default(),
            decision_history: Vec::new(),
            accumulated_cost: 0.0,
            budget_limit: None,
            context_upgrade_threshold: None,
            last_score: 0.5,
            pin_tier: None,
            phase_bias: 0.5,
            classifier_model: None,
        }
    }

    pub fn from_config(config: &RouterConfig) -> Self {
        Self {
            weights: config.weights.clone(),
            decision_history: Vec::new(),
            accumulated_cost: 0.0,
            budget_limit: config.max_session_budget,
            context_upgrade_threshold: config.context_upgrade_threshold,
            last_score: 0.5,
            pin_tier: config.pin_tier,
            phase_bias: config.phase_bias.unwrap_or(0.5).clamp(0.0, 1.0),
            classifier_model: config.classifier_model.clone(),
        }
    }

    /// Route a context to (score, tier, phase, method).
    ///
    /// Decision cascade:
    ///   1. Override? (pin / rule / scenario / context) → return immediately
    ///   2. Signal fusion scoring (5 signals) → heuristic score → tier
    ///   3. The caller (stream) handles LLM classification for ambiguous scores.
    pub fn route(&mut self, context: &Context) -> (f64, RouterTier, RouterPhase, DecisionMethod) {
        // ── Layer 0: Override check ────────────────────────────────────────
        if let Some((tier, method)) = self.check_override(context) {
            let phase = BehavioralSignal::extract(&context.messages, &self.decision_history).phase;
            return (self.last_score, tier, phase, method);
        }

        // ── Layer 1: Signal fusion scoring ─────────────────────────────────
        let structural = StructuralSignal::extract(&context.messages);
        let behavioral = BehavioralSignal::extract(&context.messages, &self.decision_history);
        let budget = ContextBudgetSignal::extract(
            structural.estimated_tokens,
            self.accumulated_cost,
            self.budget_limit,
            self.context_upgrade_threshold,
        );
        let message = MessageContentSignal::extract(&context.messages);

        let raw_score = compute_score(
            &structural,
            &behavioral,
            &budget,
            None,
            Some(&message),
            &self.weights,
        );

        // Apply phase bias — blend toward previous score
        let blended = if self.decision_history.is_empty() {
            raw_score
        } else {
            let prev = self.last_score;
            lerp(raw_score, prev, self.phase_bias * 0.3) // dampened bias
        };

        self.last_score = blended;

        let score = RoutingScore(blended);
        let mut tier = score.to_tier(0.65, 0.35);
        let mut method = DecisionMethod::Heuristic;

        // Context upgrade
        if budget.should_upgrade_context() && tier != RouterTier::High {
            tier = RouterTier::High;
            method = DecisionMethod::ContextUpgrade;
        }
        // Budget downgrade
        if budget.is_over_budget() && tier == RouterTier::High {
            tier = RouterTier::Medium;
            method = DecisionMethod::BudgetDowngrade;
        }

        (blended, tier, behavioral.phase, method)
    }

    /// Layer 0: Check for definitive overrides.
    fn check_override(&self, _context: &Context) -> Option<(RouterTier, DecisionMethod)> {
        // Global pin (set by /router pin)
        if let Some(tier) = *ROUTER_PIN_TIER.read() {
            return Some((tier, DecisionMethod::PinOverride));
        }
        // Config pin
        if let Some(tier) = self.pin_tier {
            return Some((tier, DecisionMethod::PinOverride));
        }
        None
    }

    pub fn record_decision(&mut self, decision: RoutingDecision) {
        self.decision_history.push(decision);
        if self.decision_history.len() > 20 {
            self.decision_history.remove(0);
        }
    }

    pub fn record_turn_cost(&mut self, cost: f64) {
        self.accumulated_cost += cost;
    }

    pub fn accumulated_cost(&self) -> f64 {
        self.accumulated_cost
    }
    pub fn last_score(&self) -> f64 {
        self.last_score
    }
    pub fn history(&self) -> &[RoutingDecision] {
        &self.decision_history
    }

    /// Get the classifier model identifier, if configured.
    pub fn classifier_model(&self) -> Option<String> {
        self.classifier_model.clone()
    }
}

impl Default for RouterPipeline {
    fn default() -> Self {
        Self::new()
    }
}

// ── Provider ───────────────────────────────────────────────────────────────────

/// Router provider implementing the [`Provider`] trait.
///
/// Registers as provider `"router"` and accepts profile names as model IDs
/// (e.g. `"auto"`, `"budget"`). Delegation uses global provider resolution
/// (`get_provider_arc`) when `use_global_resolution` is true.
pub struct RouterProvider {
    pipeline: RwLock<RouterPipeline>,
    profiles: RwLock<RouterProfiles>,
    provider_registry: Arc<ProviderRegistry>,
    use_global_resolution: bool,
}

impl RouterProvider {
    /// Create with an instance-based ProviderRegistry.
    pub fn new(config: &RouterConfig, registry: Arc<ProviderRegistry>) -> Self {
        Self {
            pipeline: RwLock::new(RouterPipeline::from_config(config)),
            profiles: RwLock::new(RouterProfiles::from_config(config)),
            provider_registry: registry,
            use_global_resolution: false,
        }
    }

    /// Create with global provider resolution (for CLI use).
    pub fn new_global(config: &RouterConfig) -> Self {
        Self {
            pipeline: RwLock::new(RouterPipeline::from_config(config)),
            profiles: RwLock::new(RouterProfiles::from_config(config)),
            provider_registry: Arc::new(ProviderRegistry::new()),
            use_global_resolution: true,
        }
    }

    /// Hot-reload configuration at runtime.
    pub fn reload_config(&self, config: &RouterConfig) {
        let mut p = self.pipeline.write();
        p.weights = config.weights.clone();
        p.budget_limit = config.max_session_budget;
        p.context_upgrade_threshold = config.context_upgrade_threshold;
        drop(p);
        *self.profiles.write() = RouterProfiles::from_config(config);
    }

    /// Resolve a target provider (instance or global fallback).
    fn resolve_provider(&self, name: &str) -> Option<Arc<dyn Provider>> {
        if self.use_global_resolution {
            crate::get_provider_arc(name)
        } else {
            self.provider_registry.get(name)
        }
    }

    /// Resolve model from registry (instance or global fallback).
    #[allow(dead_code)]
    fn resolve_model(&self, provider: &str, model_id: &str) -> Option<Model> {
        crate::lookup_model(provider, model_id)
    }

    /// Update the global snapshot after a routing decision.
    fn update_snapshot(&self) {
        let p = self.pipeline.read();
        let last = p.history().last();
        let mut snap = ROUTER_SNAPSHOT.write();
        *snap = Some(RouterSnapshot {
            last_tier: last.map(|d| d.tier),
            last_score: p.last_score(),
            last_model: last.map(|d| d.target_label.clone()),
            last_provider: last.map(|d| d.target_provider.clone()),
            accumulated_cost: p.accumulated_cost(),
            turn_count: p.history().len(),
            profile: last.map(|d| d.profile.clone()),
        });
    }

    /// Get the current router state snapshot (global).
    pub fn get_snapshot() -> Option<RouterSnapshot> {
        ROUTER_SNAPSHOT.read().clone()
    }

    /// Route with vision awareness — extracts VisionSignal and adjusts tier/model.
    ///
    /// Returns `(vision_signal, adjusted_tier_config)`.
    pub fn route_with_vision(
        &self,
        context: &Context,
        profile_name: &str,
        tier: RouterTier,
    ) -> (VisionSignal, RoutedTierConfig) {
        // Extract vision signal from recent messages
        let vision = VisionSignal::extract(&context.messages, 10);

        // Get base tier config
        let tier_config = self
            .profiles
            .read()
            .tier_config(profile_name, tier)
            .cloned()
            .unwrap_or_else(|| RoutedTierConfig {
                model: String::new(),
                thinking: None,
                fallbacks: vec![],
            });

        // If vision is required, ensure we have a vision-capable model
        if vision.requires_vision() {
            let adjusted = self.ensure_vision_model(tier_config, tier, profile_name);
            (vision, adjusted)
        } else {
            (vision, tier_config)
        }
    }

    /// Ensure the selected model supports vision.
    ///
    /// Fallback priority:
    /// 1. Current model already supports vision → keep it
    /// 2. Fallback list contains a vision model → swap
    /// 3. Higher tier has a vision model → upgrade
    /// 4. No vision model found → warn and keep original
    fn ensure_vision_model(
        &self,
        tier_config: RoutedTierConfig,
        tier: RouterTier,
        profile_name: &str,
    ) -> RoutedTierConfig {
        // 1. Current model already supports vision?
        if let Some(pm) = parse_tier_model(&tier_config) {
            if let Some(model) = crate::lookup_model(&pm.provider, &pm.model_id) {
                if model.supports_vision() {
                    return tier_config;
                }
            }
        }

        let original_model = tier_config.model.clone();
        let thinking = tier_config.thinking;
        let fallbacks = tier_config.fallbacks.clone();

        // 2. Fallback list contains a vision model?
        for fb in &fallbacks {
            if let Some(pm) = ProviderModel::parse(fb) {
                if let Some(model) = crate::lookup_model(&pm.provider, &pm.model_id) {
                    if model.supports_vision() {
                        tracing::info!(
                            "Vision override: {} → {} (vision-capable fallback)",
                            original_model,
                            fb
                        );
                        return RoutedTierConfig {
                            model: fb.clone(),
                            thinking,
                            fallbacks,
                        };
                    }
                }
            }
        }

        // 3. Higher tier has a vision model?
        let profiles = self.profiles.read();
        if let Some(profile) = profiles.get_with_fallback(profile_name) {
            for higher_tier in [RouterTier::High, RouterTier::Medium] {
                if higher_tier.rank() > tier.rank() {
                    let tc = profile.tier_config(higher_tier);
                    if let Some(pm) = parse_tier_model(tc) {
                        if let Some(model) = crate::lookup_model(&pm.provider, &pm.model_id) {
                            if model.supports_vision() {
                                tracing::info!(
                                    "Vision upgrade: tier {:?} → {:?}, model {} → {}",
                                    tier,
                                    higher_tier,
                                    original_model,
                                    tc.model
                                );
                                return tc.clone();
                            }
                        }
                    }
                }
            }
        }

        // 4. No vision model found — warn and keep original
        tracing::warn!(
            "Vision required but no vision-capable model found for tier {:?}. \
             Model {} may fail with image content.",
            tier,
            original_model
        );
        tier_config
    }
}

#[async_trait::async_trait]
impl Provider for RouterProvider {
    fn name(&self) -> &str {
        "router"
    }

    async fn stream(
        &self,
        model: &Model,
        context: &Context,
        options: Option<StreamOptions>,
    ) -> Result<Pin<Box<dyn Stream<Item = ProviderEvent> + Send>>, ProviderError> {
        let profile_name = &model.id;

        // 1. Route through pipeline.
        let (score, tier, phase, method) = self.pipeline.write().route(context);

        // 2. Resolve tier config.
        let tier_config = match self
            .profiles
            .read()
            .tier_config(profile_name, tier)
            .cloned()
        {
            Some(tc) => tc,
            None => {
                return Err(ProviderError::StreamError(format!(
                    "Router profile '{}' is not configured. \
                     Run /router setup or edit ~/.oxi/settings.toml",
                    profile_name
                )));
            }
        };

        // 3. LLM classifier for ambiguous scores (optional).
        let (score, tier, method) = {
            let classifier_model = self.pipeline.read().classifier_model();
            if (0.25..0.75).contains(&score) && classifier_model.is_some() {
                let input = classifier::ClassifierInput {
                    message: context
                        .messages
                        .iter()
                        .rev()
                        .find_map(|m| match m {
                            Message::User(u) => Some(u.content.as_str().unwrap_or("").to_string()),
                            _ => None,
                        })
                        .unwrap_or_default(),
                    context_tokens: 0, // filled below
                    turn_count: self.pipeline.read().history().len(),
                    available_tools: vec![],
                };
                let llm = classifier::LlmClassifier::new(classifier_model);
                match llm.classify(&input, score).await {
                    Ok(llm_score) => {
                        let llm_tier = RoutingScore(llm_score).to_tier(0.65, 0.35);
                        tracing::info!(
                            "LLM classifier: score {score:.2} → {llm_score:.2}, tier {tier:?} → {llm_tier:?}"
                        );
                        (llm_score, llm_tier, DecisionMethod::LlmClassifier)
                    }
                    Err(e) => {
                        tracing::warn!("LLM classifier failed: {e}, using heuristic score");
                        (score, tier, method)
                    }
                }
            } else {
                (score, tier, method)
            }
        };

        // 4. Resolve tier config.
        let pm = parse_tier_model(&tier_config).unwrap_or_else(|| ProviderModel {
            provider: model.provider.clone(),
            model_id: model.id.clone(),
        });

        // 4. Record decision.
        let decision = RoutingDecision {
            profile: profile_name.clone(),
            tier,
            phase,
            target_provider: pm.provider.clone(),
            target_model_id: pm.model_id.clone(),
            target_label: tier_config.model.clone(),
            reasoning: format!(
                "tier={tier:?}, score={score:.2}, method={method:?}, provider={}, model={}",
                pm.provider, pm.model_id
            ),
            thinking: tier_config.thinking.unwrap_or(ThinkingLevel::Off),
            timestamp: chrono::Utc::now().timestamp_millis(),
            score,
            is_fallback: false,
            is_context_triggered: method == DecisionMethod::ContextUpgrade,
            is_budget_forced: method == DecisionMethod::BudgetDowngrade,
            is_vision_triggered: false,
            vision_images: 0,
            decision_method: method,
        };
        self.pipeline.write().record_decision(decision);
        self.update_snapshot();

        // 4. Resolve target provider.
        let target_provider = self
            .resolve_provider(&pm.provider)
            .ok_or_else(|| ProviderError::UnknownProvider(pm.provider.clone()))?;

        // 5. Build target model.
        let target_model = build_target_model(&pm, tier_config.thinking.is_some());

        // 6. Inject thinking.
        let mut opts = options.unwrap_or_default();
        if let Some(thinking) = tier_config.thinking {
            opts.thinking_level = Some(thinking);
        }

        // 7. Truncate context if needed (preserve first message — system prompt).
        let estimated_chars: usize = context.messages.iter().map(message_chars).sum();
        let estimated_tokens = estimated_chars / 4;
        let adjusted_context = if estimated_tokens > target_model.context_window {
            let mut ctx = context.clone();
            let max_chars = target_model.context_window * 3;
            let mut total: usize = ctx.messages.iter().map(message_chars).sum();
            while total > max_chars && ctx.messages.len() > 2 {
                let removed = ctx.messages.remove(1);
                total -= message_chars(&removed);
            }
            ctx
        } else {
            context.clone()
        };

        // 8. Try primary model.
        match target_provider
            .stream(&target_model, &adjusted_context, Some(opts.clone()))
            .await
        {
            Ok(stream) => Ok(stream),
            Err(primary_err) => {
                if tier_config.fallbacks.is_empty() {
                    return Err(primary_err);
                }
                let chain = FallbackChain::new(tier_config.fallbacks.clone());
                chain
                    .try_models_with_resolver(
                        |name| self.resolve_provider(name),
                        &adjusted_context,
                        Some(opts),
                    )
                    .await
            }
        }
    }
}

// ── Registration ───────────────────────────────────────────────────────────────

/// Register the router provider and its profile models.
///
/// This is **opt-in** — the router is only active when the user selects
/// `router/auto` or another profile in model selection.
pub fn register_router(config: &RouterConfig) {
    let provider = RouterProvider::new_global(config);
    register_provider("router", provider);
    tracing::info!("Model router registered (opt-in: select router/auto)");
    for name in config.profiles.keys() {
        let model = Model::new(
            name,
            format!("Router ({name})"),
            Api::AnthropicMessages,
            "router",
            "router://local",
        );
        register_model(model);
        tracing::debug!("Registered router model: router/{}", name);
    }
}

/// Set the global router pin tier. Used by `/router pin <tier>`.
pub fn set_router_pin(tier: Option<RouterTier>) {
    *ROUTER_PIN_TIER.write() = tier;
}

/// Get the current global router pin tier.
pub fn get_router_pin() -> Option<RouterTier> {
    *ROUTER_PIN_TIER.read()
}