enact-core 0.0.2

//! Composite Callable - Callables that invoke other callables
//!
//! This module provides the infrastructure for:
//! - Callable-within-callable invocation
//! - Dynamic callable discovery
//! - Resource allocation strategies
//!
//! @see packages/enact-schemas/src/execution.schemas.ts

use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::time::Instant;

use super::{Callable, CallableRegistry, DynCallable};
use crate::kernel::ids::{CallableType, ExecutionId, SpawnMode};
use crate::kernel::TokenUsage;

/// CostTier - Estimated cost tier for resource planning
/// @see packages/enact-schemas/src/execution.schemas.ts - callableDescriptorSchema.costTier
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
#[serde(rename_all = "snake_case")]
pub enum CostTier {
    Free,
    Low,
    #[default]
    Medium,
    High,
    Premium,
}

/// CallableDescriptor - Describes a callable for discovery
/// @see packages/enact-schemas/src/execution.schemas.ts - callableDescriptorSchema
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct CallableDescriptor {
    /// Callable name (unique identifier)
    pub name: String,

    /// Human-readable description
    #[serde(skip_serializing_if = "Option::is_none")]
    pub description: Option<String>,

    /// Callable type
    pub callable_type: CallableType,

    /// Input schema (JSON Schema)
    #[serde(skip_serializing_if = "Option::is_none")]
    pub input_schema: Option<serde_json::Value>,

    /// Output schema (JSON Schema)
    #[serde(skip_serializing_if = "Option::is_none")]
    pub output_schema: Option<serde_json::Value>,

    /// Tags for categorization
    #[serde(default)]
    pub tags: Vec<String>,

    /// Whether this callable can spawn children
    #[serde(default)]
    pub can_spawn_children: bool,

    /// Estimated cost tier
    #[serde(default)]
    pub cost_tier: CostTier,

    /// Average latency in milliseconds
    #[serde(skip_serializing_if = "Option::is_none")]
    pub avg_latency_ms: Option<u64>,
}

impl CallableDescriptor {
    /// Create a new descriptor from a callable
    pub fn from_callable(callable: &dyn Callable, callable_type: CallableType) -> Self {
        Self {
            name: callable.name().to_string(),
            description: callable.description().map(String::from),
            callable_type,
            input_schema: None,
            output_schema: None,
            tags: Vec::new(),
            can_spawn_children: false,
            cost_tier: CostTier::Medium,
            avg_latency_ms: None,
        }
    }

    /// Add tags
    pub fn with_tags(mut self, tags: Vec<String>) -> Self {
        self.tags = tags;
        self
    }

    /// Set cost tier
    pub fn with_cost_tier(mut self, tier: CostTier) -> Self {
        self.cost_tier = tier;
        self
    }

    /// Set can spawn children
    pub fn with_spawn_capability(mut self, can_spawn: bool) -> Self {
        self.can_spawn_children = can_spawn;
        self
    }
}

/// CallableInvocation - Request to invoke a callable from another callable
/// @see packages/enact-schemas/src/execution.schemas.ts - callableInvocationSchema
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct CallableInvocation {
    /// Target callable name
    pub callable_name: String,

    /// Input to pass
    pub input: String,

    /// Context to pass
    #[serde(skip_serializing_if = "Option::is_none")]
    pub context: Option<HashMap<String, String>>,

    /// Spawn mode for child execution
    #[serde(default)]
    pub spawn_mode: SpawnMode,

    /// Priority (higher = more important)
    #[serde(default = "default_priority")]
    pub priority: u8,

    /// Timeout in milliseconds
    #[serde(skip_serializing_if = "Option::is_none")]
    pub timeout_ms: Option<u64>,
}

fn default_priority() -> u8 {
    50
}

/// CallableInvocationResult - Result of a callable invocation
/// @see packages/enact-schemas/src/execution.schemas.ts - callableInvocationResultSchema
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct CallableInvocationResult {
    /// Whether the invocation succeeded
    pub success: bool,

    /// Output (if successful)
    #[serde(skip_serializing_if = "Option::is_none")]
    pub output: Option<String>,

    /// Error message (if failed)
    #[serde(skip_serializing_if = "Option::is_none")]
    pub error: Option<String>,

    /// Child execution ID (for SpawnMode::Child)
    #[serde(skip_serializing_if = "Option::is_none")]
    pub child_execution_id: Option<ExecutionId>,

    /// Duration in milliseconds
    pub duration_ms: u64,

    /// Token usage
    #[serde(skip_serializing_if = "Option::is_none")]
    pub token_usage: Option<TokenUsage>,
}

impl CallableInvocationResult {
    /// Create a success result
    pub fn success(output: String, duration_ms: u64) -> Self {
        Self {
            success: true,
            output: Some(output),
            error: None,
            child_execution_id: None,
            duration_ms,
            token_usage: None,
        }
    }

    /// Create a failure result
    pub fn failure(error: impl Into<String>, duration_ms: u64) -> Self {
        Self {
            success: false,
            output: None,
            error: Some(error.into()),
            child_execution_id: None,
            duration_ms,
            token_usage: None,
        }
    }

    /// Create a child spawn result
    pub fn child_spawned(execution_id: ExecutionId, duration_ms: u64) -> Self {
        Self {
            success: true,
            output: None,
            error: None,
            child_execution_id: Some(execution_id),
            duration_ms,
            token_usage: None,
        }
    }
}

/// ResourceAllocationStrategy - How to allocate resources among child callables
/// @see packages/enact-schemas/src/execution.schemas.ts - resourceAllocationStrategySchema
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
#[serde(rename_all = "snake_case")]
pub enum ResourceAllocationStrategy {
    /// Divide resources equally among children
    EqualSplit,
    /// Shared pool with first-come-first-served
    #[default]
    SharedPool,
    /// Higher priority gets more resources
    Priority,
    /// Allocate based on estimated cost
    Proportional,
}

/// ResourceBudget - Budget for a callable execution
/// @see packages/enact-schemas/src/execution.schemas.ts - resourceBudgetSchema
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct ResourceBudget {
    /// Maximum tokens
    #[serde(skip_serializing_if = "Option::is_none")]
    pub max_tokens: Option<u64>,

    /// Maximum time in milliseconds
    #[serde(skip_serializing_if = "Option::is_none")]
    pub max_time_ms: Option<u64>,

    /// Maximum cost in cents
    #[serde(skip_serializing_if = "Option::is_none")]
    pub max_cost_cents: Option<f64>,

    /// Maximum child spawns
    #[serde(skip_serializing_if = "Option::is_none")]
    pub max_children: Option<u32>,

    /// Maximum discovery depth
    #[serde(default = "default_max_depth")]
    pub max_discovery_depth: u32,
}

fn default_max_depth() -> u32 {
    3
}

impl Default for ResourceBudget {
    fn default() -> Self {
        Self {
            max_tokens: None,
            max_time_ms: None,
            max_cost_cents: None,
            max_children: None,
            max_discovery_depth: default_max_depth(),
        }
    }
}

/// ResourceAllocation - Allocated resources for an execution
/// @see packages/enact-schemas/src/execution.schemas.ts - resourceAllocationSchema
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct ResourceAllocation {
    /// Allocation strategy used
    pub strategy: ResourceAllocationStrategy,

    /// Budget for this allocation
    pub budget: ResourceBudget,

    /// Currently used tokens
    #[serde(default)]
    pub used_tokens: u64,

    /// Currently used time in milliseconds
    #[serde(default)]
    pub used_time_ms: u64,

    /// Currently used cost in cents
    #[serde(default)]
    pub used_cost_cents: f64,

    /// Number of children spawned
    #[serde(default)]
    pub children_spawned: u32,

    /// Current discovery depth
    #[serde(default)]
    pub current_depth: u32,
}

impl ResourceAllocation {
    /// Create a new allocation with a budget
    pub fn new(strategy: ResourceAllocationStrategy, budget: ResourceBudget) -> Self {
        Self {
            strategy,
            budget,
            used_tokens: 0,
            used_time_ms: 0,
            used_cost_cents: 0.0,
            children_spawned: 0,
            current_depth: 0,
        }
    }

    /// Check if we can spawn another child
    pub fn can_spawn_child(&self) -> bool {
        match self.budget.max_children {
            Some(max) => self.children_spawned < max,
            None => true,
        }
    }

    /// Check if we can go deeper in discovery
    pub fn can_discover_deeper(&self) -> bool {
        self.current_depth < self.budget.max_discovery_depth
    }

    /// Check if we have token budget remaining
    pub fn has_token_budget(&self, tokens: u64) -> bool {
        match self.budget.max_tokens {
            Some(max) => self.used_tokens + tokens <= max,
            None => true,
        }
    }

    /// Check if we have time budget remaining
    pub fn has_time_budget(&self, time_ms: u64) -> bool {
        match self.budget.max_time_ms {
            Some(max) => self.used_time_ms + time_ms <= max,
            None => true,
        }
    }

    /// Record token usage
    pub fn record_tokens(&mut self, tokens: u64) {
        self.used_tokens += tokens;
    }

    /// Record time usage
    pub fn record_time(&mut self, time_ms: u64) {
        self.used_time_ms += time_ms;
    }

    /// Record child spawn
    pub fn record_child_spawn(&mut self) {
        self.children_spawned += 1;
    }

    /// Increment depth
    pub fn increment_depth(&mut self) {
        self.current_depth += 1;
    }

    /// Create a child allocation (for nested invocations)
    pub fn child_allocation(&self) -> Self {
        let mut child = self.clone();
        child.increment_depth();

        // Adjust budget based on strategy
        match self.strategy {
            ResourceAllocationStrategy::EqualSplit => {
                // Split remaining budget
                if let Some(max) = child.budget.max_tokens {
                    let remaining = max.saturating_sub(self.used_tokens);
                    child.budget.max_tokens = Some(remaining / 2);
                }
                if let Some(max) = child.budget.max_time_ms {
                    let remaining = max.saturating_sub(self.used_time_ms);
                    child.budget.max_time_ms = Some(remaining / 2);
                }
            }
            ResourceAllocationStrategy::SharedPool => {
                // Share the same budget (just track separately)
            }
            ResourceAllocationStrategy::Priority => {
                // High priority children get more (80%)
                if let Some(max) = child.budget.max_tokens {
                    let remaining = max.saturating_sub(self.used_tokens);
                    child.budget.max_tokens = Some((remaining * 80) / 100);
                }
            }
            ResourceAllocationStrategy::Proportional => {
                // Based on cost tier - would need callable info
                // For now, same as equal split
                if let Some(max) = child.budget.max_tokens {
                    let remaining = max.saturating_sub(self.used_tokens);
                    child.budget.max_tokens = Some(remaining / 2);
                }
            }
        }

        child
    }
}

/// DiscoveryQuery - Query for discovering callables
/// @see packages/enact-schemas/src/execution.schemas.ts - discoveryQuerySchema
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct DiscoveryQuery {
    /// Filter by callable type
    #[serde(skip_serializing_if = "Option::is_none")]
    pub callable_type: Option<CallableType>,

    /// Filter by tags (any match)
    #[serde(skip_serializing_if = "Option::is_none")]
    pub tags: Option<Vec<String>>,

    /// Filter by name pattern (glob-like)
    #[serde(skip_serializing_if = "Option::is_none")]
    pub name_pattern: Option<String>,

    /// Filter by maximum cost tier
    #[serde(skip_serializing_if = "Option::is_none")]
    pub max_cost_tier: Option<CostTier>,

    /// Maximum results
    #[serde(default = "default_limit")]
    pub limit: usize,
}

fn default_limit() -> usize {
    10
}

impl Default for DiscoveryQuery {
    fn default() -> Self {
        Self {
            callable_type: None,
            tags: None,
            name_pattern: None,
            max_cost_tier: None,
            limit: default_limit(),
        }
    }
}

/// DiscoveryResult - Result of a callable discovery query
/// @see packages/enact-schemas/src/execution.schemas.ts - discoveryResultSchema
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct DiscoveryResult {
    /// Matching callables
    pub callables: Vec<CallableDescriptor>,

    /// Total count (before limit)
    pub total_count: usize,

    /// Query that was executed
    pub query: DiscoveryQuery,
}

/// CallableInvoker - Invokes callables from a registry
///
/// This is the core mechanism for callable-within-callable invocation.
pub struct CallableInvoker {
    registry: CallableRegistry,
    descriptors: HashMap<String, CallableDescriptor>,
}

impl CallableInvoker {
    /// Create a new invoker with a registry
    pub fn new(registry: CallableRegistry) -> Self {
        Self {
            registry,
            descriptors: HashMap::new(),
        }
    }

    /// Register a descriptor for a callable
    pub fn register_descriptor(&mut self, descriptor: CallableDescriptor) {
        self.descriptors.insert(descriptor.name.clone(), descriptor);
    }

    /// Get a callable from the registry
    pub fn get(&self, name: &str) -> Option<DynCallable> {
        self.registry.get(name)
    }

    /// Invoke a callable by name
    pub async fn invoke(&self, invocation: CallableInvocation) -> CallableInvocationResult {
        let start = Instant::now();

        let callable = match self.registry.get(&invocation.callable_name) {
            Some(c) => c,
            None => {
                return CallableInvocationResult::failure(
                    format!("Callable '{}' not found", invocation.callable_name),
                    start.elapsed().as_millis() as u64,
                );
            }
        };

        match invocation.spawn_mode {
            SpawnMode::Inline => {
                // Inline execution - run directly
                match callable.run(&invocation.input).await {
                    Ok(output) => CallableInvocationResult::success(
                        output,
                        start.elapsed().as_millis() as u64,
                    ),
                    Err(e) => CallableInvocationResult::failure(
                        e.to_string(),
                        start.elapsed().as_millis() as u64,
                    ),
                }
            }
            SpawnMode::Child { background, .. } => {
                if background {
                    // Background execution - spawn and return immediately
                    let execution_id = ExecutionId::new();
                    // In a real implementation, this would spawn a background task
                    CallableInvocationResult::child_spawned(
                        execution_id,
                        start.elapsed().as_millis() as u64,
                    )
                } else {
                    // Child execution - run and wait
                    match callable.run(&invocation.input).await {
                        Ok(output) => CallableInvocationResult::success(
                            output,
                            start.elapsed().as_millis() as u64,
                        ),
                        Err(e) => CallableInvocationResult::failure(
                            e.to_string(),
                            start.elapsed().as_millis() as u64,
                        ),
                    }
                }
            }
        }
    }

    /// Discover callables matching a query
    pub fn discover(&self, query: DiscoveryQuery) -> DiscoveryResult {
        let mut matches: Vec<CallableDescriptor> = self
            .descriptors
            .values()
            .filter(|desc| {
                // Filter by type
                if let Some(ref t) = query.callable_type {
                    if &desc.callable_type != t {
                        return false;
                    }
                }

                // Filter by tags
                if let Some(ref tags) = query.tags {
                    if !tags.iter().any(|t| desc.tags.contains(t)) {
                        return false;
                    }
                }

                // Filter by name pattern (simple glob)
                if let Some(ref pattern) = query.name_pattern {
                    if !matches_glob(&desc.name, pattern) {
                        return false;
                    }
                }

                // Filter by cost tier
                if let Some(ref max_tier) = query.max_cost_tier {
                    if !is_cost_tier_within(&desc.cost_tier, max_tier) {
                        return false;
                    }
                }

                true
            })
            .cloned()
            .collect();

        let total_count = matches.len();
        matches.truncate(query.limit);

        DiscoveryResult {
            callables: matches,
            total_count,
            query,
        }
    }

    /// List all registered callable names
    pub fn list(&self) -> Vec<String> {
        self.registry.list()
    }
}

/// Simple glob matching (supports * and ?)
fn matches_glob(name: &str, pattern: &str) -> bool {
    // Simple glob matching without regex
    let mut name_chars = name.chars().peekable();
    let mut pattern_chars = pattern.chars().peekable();

    while let Some(p) = pattern_chars.next() {
        match p {
            '*' => {
                // * matches zero or more characters
                if pattern_chars.peek().is_none() {
                    return true; // Trailing * matches everything
                }
                // Try matching zero characters first, then more
                let remaining_pattern: String = pattern_chars.collect();
                let mut remaining_name = String::new();
                loop {
                    if matches_glob(&remaining_name, &remaining_pattern) {
                        return true;
                    }
                    match name_chars.next() {
                        Some(c) => remaining_name.push(c),
                        None => return matches_glob("", &remaining_pattern),
                    }
                }
            }
            '?' => {
                // ? matches exactly one character
                if name_chars.next().is_none() {
                    return false;
                }
            }
            c => {
                // Literal character must match
                match name_chars.next() {
                    Some(nc) if nc == c => continue,
                    _ => return false,
                }
            }
        }
    }

    // Pattern exhausted - name should be too
    name_chars.next().is_none()
}

/// Check if cost tier is within limit
fn is_cost_tier_within(tier: &CostTier, max_tier: &CostTier) -> bool {
    let tier_value = match tier {
        CostTier::Free => 0,
        CostTier::Low => 1,
        CostTier::Medium => 2,
        CostTier::High => 3,
        CostTier::Premium => 4,
    };
    let max_value = match max_tier {
        CostTier::Free => 0,
        CostTier::Low => 1,
        CostTier::Medium => 2,
        CostTier::High => 3,
        CostTier::Premium => 4,
    };
    tier_value <= max_value
}

#[cfg(test)]
mod tests {
    use super::*;
    use async_trait::async_trait;
    use std::sync::Arc;

    struct TestCallable {
        name: String,
        output: String,
    }

    #[async_trait]
    impl Callable for TestCallable {
        fn name(&self) -> &str {
            &self.name
        }

        async fn run(&self, _input: &str) -> anyhow::Result<String> {
            Ok(self.output.clone())
        }
    }

    #[test]
    fn test_callable_descriptor() {
        let callable = TestCallable {
            name: "test".to_string(),
            output: "output".to_string(),
        };

        let desc = CallableDescriptor::from_callable(&callable, CallableType::Agent)
            .with_tags(vec!["research".to_string(), "analysis".to_string()])
            .with_cost_tier(CostTier::High)
            .with_spawn_capability(true);

        assert_eq!(desc.name, "test");
        assert_eq!(desc.callable_type, CallableType::Agent);
        assert_eq!(desc.tags.len(), 2);
        assert_eq!(desc.cost_tier, CostTier::High);
        assert!(desc.can_spawn_children);
    }

    #[test]
    fn test_resource_allocation() {
        let budget = ResourceBudget {
            max_tokens: Some(1000),
            max_time_ms: Some(5000),
            max_children: Some(3),
            ..Default::default()
        };

        let mut allocation =
            ResourceAllocation::new(ResourceAllocationStrategy::EqualSplit, budget);

        assert!(allocation.can_spawn_child());
        assert!(allocation.has_token_budget(500));

        allocation.record_tokens(400);
        allocation.record_child_spawn();

        assert!(allocation.has_token_budget(500));
        assert!(!allocation.has_token_budget(700));
        assert!(allocation.can_spawn_child());

        allocation.record_child_spawn();
        allocation.record_child_spawn();
        assert!(!allocation.can_spawn_child());
    }

    #[test]
    fn test_child_allocation() {
        let budget = ResourceBudget {
            max_tokens: Some(1000),
            ..Default::default()
        };

        let allocation = ResourceAllocation::new(ResourceAllocationStrategy::EqualSplit, budget);
        let child = allocation.child_allocation();

        assert_eq!(child.current_depth, 1);
        assert_eq!(child.budget.max_tokens, Some(500)); // Half of parent
    }

    #[tokio::test]
    async fn test_callable_invoker() {
        let registry = CallableRegistry::new();
        let callable = Arc::new(TestCallable {
            name: "test".to_string(),
            output: "test output".to_string(),
        });
        registry.register("test".to_string(), callable);

        let invoker = CallableInvoker::new(registry);

        let invocation = CallableInvocation {
            callable_name: "test".to_string(),
            input: "input".to_string(),
            context: None,
            spawn_mode: SpawnMode::Inline,
            priority: 50,
            timeout_ms: None,
        };

        let result = invoker.invoke(invocation).await;
        assert!(result.success);
        assert_eq!(result.output, Some("test output".to_string()));
    }

    #[test]
    fn test_discovery() {
        let registry = CallableRegistry::new();
        let mut invoker = CallableInvoker::new(registry);

        invoker.register_descriptor(
            CallableDescriptor::from_callable(
                &TestCallable {
                    name: "research-agent".to_string(),
                    output: "".to_string(),
                },
                CallableType::Agent,
            )
            .with_tags(vec!["research".to_string()])
            .with_cost_tier(CostTier::Medium),
        );

        invoker.register_descriptor(
            CallableDescriptor::from_callable(
                &TestCallable {
                    name: "analysis-agent".to_string(),
                    output: "".to_string(),
                },
                CallableType::Agent,
            )
            .with_tags(vec!["analysis".to_string()])
            .with_cost_tier(CostTier::High),
        );

        // Query by tag
        let result = invoker.discover(DiscoveryQuery {
            tags: Some(vec!["research".to_string()]),
            ..Default::default()
        });
        assert_eq!(result.callables.len(), 1);
        assert_eq!(result.callables[0].name, "research-agent");

        // Query by cost tier
        let result = invoker.discover(DiscoveryQuery {
            max_cost_tier: Some(CostTier::Medium),
            ..Default::default()
        });
        assert_eq!(result.callables.len(), 1);

        // Query all
        let result = invoker.discover(DiscoveryQuery::default());
        assert_eq!(result.total_count, 2);
    }

    #[test]
    fn test_cost_tier_comparison() {
        assert!(is_cost_tier_within(&CostTier::Free, &CostTier::High));
        assert!(is_cost_tier_within(&CostTier::Medium, &CostTier::Medium));
        assert!(!is_cost_tier_within(&CostTier::High, &CostTier::Low));
    }
}