thermogram 0.5.2

//! Consolidation - Dirty → Clean state transitions
//!
//! Consolidation applies accumulated deltas to create a clean snapshot,
//! pruning weak memories and applying plasticity rules.
//!
//! ## Ternary Consolidation
//!
//! For ternary weights, consolidation uses discrete state transitions:
//! - **Pruning**: Only Zero weights are prunable (inactive)
//! - **Merging**: Uses majority voting across observations
//! - **Strength**: Ternary weights use state transitions instead of decay

use crate::delta::{Delta, DeltaType};
use crate::plasticity::PlasticityRule;
use crate::ternary::TernaryWeight;
use crate::error::Result;
use chrono::{DateTime, Utc, Duration};
use serde::{Deserialize, Serialize};
use std::collections::HashMap;

/// Policy for when to consolidate
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ConsolidationPolicy {
    /// Triggers that initiate consolidation
    pub triggers: Vec<ConsolidationTrigger>,

    /// Whether to prune weak memories during consolidation
    pub enable_pruning: bool,

    /// Whether to merge similar memories
    pub enable_merging: bool,
}

/// Triggers for consolidation
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub enum ConsolidationTrigger {
    /// Consolidate after N deltas
    DeltaCount(usize),

    /// Consolidate after time period
    TimePeriod { hours: u64 },

    /// Consolidate when dirty state exceeds size
    DirtySize { bytes: usize },

    /// Manual trigger
    Manual,
}

impl ConsolidationPolicy {
    /// Default policy - consolidate every 1000 deltas or 24 hours
    pub fn default() -> Self {
        Self {
            triggers: vec![
                ConsolidationTrigger::DeltaCount(1000),
                ConsolidationTrigger::TimePeriod { hours: 24 },
            ],
            enable_pruning: true,
            enable_merging: true,
        }
    }

    /// Aggressive consolidation - frequent, with pruning
    pub fn aggressive() -> Self {
        Self {
            triggers: vec![
                ConsolidationTrigger::DeltaCount(100),
                ConsolidationTrigger::TimePeriod { hours: 1 },
            ],
            enable_pruning: true,
            enable_merging: true,
        }
    }

    /// Conservative consolidation - infrequent, no pruning
    pub fn conservative() -> Self {
        Self {
            triggers: vec![
                ConsolidationTrigger::DeltaCount(10000),
                ConsolidationTrigger::TimePeriod { hours: 168 }, // 1 week
            ],
            enable_pruning: false,
            enable_merging: false,
        }
    }

    /// Check if any trigger is met
    pub fn should_consolidate(
        &self,
        delta_count: usize,
        last_consolidation: &DateTime<Utc>,
        dirty_size: usize,
    ) -> bool {
        for trigger in &self.triggers {
            match trigger {
                ConsolidationTrigger::DeltaCount(n) => {
                    if delta_count >= *n {
                        return true;
                    }
                }
                ConsolidationTrigger::TimePeriod { hours } => {
                    let elapsed = Utc::now().signed_duration_since(*last_consolidation);
                    let threshold = Duration::hours(*hours as i64);
                    if elapsed >= threshold {
                        return true;
                    }
                }
                ConsolidationTrigger::DirtySize { bytes } => {
                    if dirty_size >= *bytes {
                        return true;
                    }
                }
                ConsolidationTrigger::Manual => {
                    // Manual triggers don't auto-fire
                }
            }
        }
        false
    }
}

/// Consolidated state entry
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ConsolidatedEntry {
    /// Key
    pub key: String,

    /// Consolidated value
    pub value: Vec<u8>,

    /// Current strength (after plasticity applied) - continuous value
    pub strength: f32,

    /// Ternary strength for quantized weights (+1, 0, -1)
    /// When present, this takes precedence over f32 strength for pruning
    #[serde(default)]
    pub ternary_strength: Option<TernaryWeight>,

    /// Last updated timestamp
    pub updated_at: DateTime<Utc>,

    /// Number of updates contributing to this entry
    pub update_count: usize,
}

impl ConsolidatedEntry {
    /// Check if this entry uses ternary strength
    pub fn is_ternary(&self) -> bool {
        self.ternary_strength.is_some()
    }

    /// Get effective strength as f32
    pub fn effective_strength(&self) -> f32 {
        if let Some(t) = self.ternary_strength {
            t.to_f32()
        } else {
            self.strength
        }
    }

    /// Check if this entry should be pruned
    /// For ternary: only Zero weights are prunable
    /// For continuous: uses threshold comparison
    pub fn should_prune(&self, threshold: f32) -> bool {
        if let Some(t) = self.ternary_strength {
            t == TernaryWeight::Zero
        } else {
            self.strength < threshold
        }
    }
}

/// Result of consolidation
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ConsolidationResult {
    /// Number of deltas consolidated
    pub deltas_processed: usize,

    /// Number of entries in clean state
    pub entries_after: usize,

    /// Number of entries pruned
    pub entries_pruned: usize,

    /// Number of entries merged
    pub entries_merged: usize,

    /// Size reduction (bytes)
    pub size_reduction: usize,

    /// When consolidation happened
    pub timestamp: DateTime<Utc>,
}

/// Consolidate deltas into clean state
///
/// Handles both continuous (f32) and ternary weights. When a delta has
/// ternary_strength set, uses discrete state transitions instead of
/// continuous plasticity updates.
pub fn consolidate(
    dirty_deltas: &[Delta],
    clean_state: &HashMap<String, ConsolidatedEntry>,
    plasticity_rule: &PlasticityRule,
    policy: &ConsolidationPolicy,
) -> Result<(HashMap<String, ConsolidatedEntry>, ConsolidationResult)> {
    let mut new_state = clean_state.clone();
    let mut stats = ConsolidationResult {
        deltas_processed: dirty_deltas.len(),
        entries_after: 0,
        entries_pruned: 0,
        entries_merged: 0,
        size_reduction: 0,
        timestamp: Utc::now(),
    };

    // Apply each delta
    for delta in dirty_deltas {
        match delta.delta_type {
            DeltaType::Create | DeltaType::Update => {
                if let Some(existing) = new_state.get_mut(&delta.key) {
                    // Update existing entry
                    if delta.is_ternary() {
                        // Ternary update: use discrete state transitions
                        let current_ternary = existing
                            .ternary_strength
                            .unwrap_or(TernaryWeight::from_f32(existing.strength, 0.3));
                        let observed_ternary = delta.metadata.ternary_strength.unwrap();

                        // Use observation count as confidence proxy
                        let confidence = delta
                            .metadata
                            .observation_count
                            .map(|c| (c as f32 / 10.0).min(1.0))
                            .unwrap_or(0.5);

                        let new_ternary = plasticity_rule.apply_ternary_update(
                            current_ternary,
                            observed_ternary,
                            confidence,
                        );

                        existing.ternary_strength = Some(new_ternary);
                        existing.strength = new_ternary.to_f32();
                    } else {
                        // Continuous update: use traditional plasticity
                        let time_delta = delta
                            .metadata
                            .timestamp
                            .signed_duration_since(existing.updated_at)
                            .num_seconds() as f64;

                        let new_strength = plasticity_rule.apply_update(
                            existing.strength,
                            delta.metadata.strength,
                            time_delta,
                        );

                        existing.strength = new_strength;
                    }

                    existing.value = delta.value.clone();
                    existing.updated_at = delta.metadata.timestamp;
                    existing.update_count += 1;
                } else {
                    // Create new entry
                    new_state.insert(
                        delta.key.clone(),
                        ConsolidatedEntry {
                            key: delta.key.clone(),
                            value: delta.value.clone(),
                            strength: delta.metadata.strength,
                            ternary_strength: delta.metadata.ternary_strength,
                            updated_at: delta.metadata.timestamp,
                            update_count: 1,
                        },
                    );
                }
            }

            DeltaType::Delete => {
                new_state.remove(&delta.key);
            }

            DeltaType::Merge => {
                // Merge operation - combine with existing
                if let Some(existing) = new_state.get_mut(&delta.key) {
                    if delta.is_ternary() {
                        // Ternary merge: use majority voting
                        let current_ternary = existing
                            .ternary_strength
                            .unwrap_or(TernaryWeight::from_f32(existing.strength, 0.3));
                        let observed_ternary = delta.metadata.ternary_strength.unwrap();

                        // For merge, collect both weights and vote
                        let merged = PlasticityRule::ternary_majority_vote(&[
                            current_ternary,
                            observed_ternary,
                        ]);

                        existing.ternary_strength = Some(merged);
                        existing.strength = merged.to_f32();
                    } else {
                        // Continuous merge
                        let time_delta = delta
                            .metadata
                            .timestamp
                            .signed_duration_since(existing.updated_at)
                            .num_seconds() as f64;

                        let new_strength = plasticity_rule.apply_update(
                            existing.strength,
                            delta.metadata.strength,
                            time_delta,
                        );

                        existing.strength = new_strength;
                    }

                    existing.updated_at = delta.metadata.timestamp;
                    existing.update_count += 1;
                    stats.entries_merged += 1;
                }
            }
        }
    }

    // Prune weak entries if enabled
    if policy.enable_pruning {
        let before_count = new_state.len();
        new_state.retain(|_, entry| {
            // Use entry's own should_prune method which handles ternary
            !entry.should_prune(plasticity_rule.prune_threshold)
        });
        stats.entries_pruned = before_count - new_state.len();
    }

    stats.entries_after = new_state.len();

    Ok((new_state, stats))
}

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

    #[test]
    fn test_consolidation_policy_delta_count() {
        let policy = ConsolidationPolicy::default();
        let last_consolidation = Utc::now();

        assert!(!policy.should_consolidate(500, &last_consolidation, 0));
        assert!(policy.should_consolidate(1000, &last_consolidation, 0));
    }

    #[test]
    fn test_consolidation_policy_time() {
        let policy = ConsolidationPolicy::default();
        let last_consolidation = Utc::now() - Duration::hours(25);

        assert!(policy.should_consolidate(0, &last_consolidation, 0));
    }

    #[test]
    fn test_consolidate_create() {
        let deltas = vec![
            Delta::create("key1", b"value1".to_vec(), "source"),
        ];

        let clean_state = HashMap::new();
        let plasticity = PlasticityRule::stdp_like();
        let policy = ConsolidationPolicy::default();

        let (new_state, stats) = consolidate(&deltas, &clean_state, &plasticity, &policy).unwrap();

        assert_eq!(new_state.len(), 1);
        assert_eq!(stats.deltas_processed, 1);
        assert_eq!(stats.entries_after, 1);
    }

    #[test]
    fn test_consolidate_update() {
        let mut clean_state = HashMap::new();
        clean_state.insert(
            "key1".to_string(),
            ConsolidatedEntry {
                key: "key1".to_string(),
                value: b"old_value".to_vec(),
                strength: 0.5,
                ternary_strength: None,
                updated_at: Utc::now(),
                update_count: 1,
            },
        );

        let deltas = vec![
            Delta::update("key1", b"new_value".to_vec(), "source", 0.8, None),
        ];

        let plasticity = PlasticityRule::stdp_like();
        let policy = ConsolidationPolicy::default();

        let (new_state, _) = consolidate(&deltas, &clean_state, &plasticity, &policy).unwrap();

        let entry = new_state.get("key1").unwrap();
        assert_eq!(entry.value, b"new_value");
        assert!(entry.strength > 0.5); // Should have strengthened
    }

    #[test]
    fn test_consolidate_with_pruning() {
        let mut clean_state = HashMap::new();
        clean_state.insert(
            "weak_key".to_string(),
            ConsolidatedEntry {
                key: "weak_key".to_string(),
                value: b"value".to_vec(),
                strength: 0.05, // Below prune threshold
                ternary_strength: None,
                updated_at: Utc::now(),
                update_count: 1,
            },
        );

        let deltas = vec![];
        let plasticity = PlasticityRule::stdp_like();
        let policy = ConsolidationPolicy::default();

        let (new_state, stats) = consolidate(&deltas, &clean_state, &plasticity, &policy).unwrap();

        assert_eq!(new_state.len(), 0);
        assert_eq!(stats.entries_pruned, 1);
    }
}