oxirs-chat 0.2.4

//! Quantum-Inspired RAG Enhancement Module
//!
//! Implements quantum superposition principles for enhanced retrieval,
//! quantum interference optimization, and entanglement-based result ranking.

use super::types::RagDocument;
use fastrand;
use serde::{Deserialize, Serialize};
use std::f64::consts::PI;
use std::time::Duration;

/// Quantum-inspired state for retrieval optimization
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct QuantumRetrievalState {
    pub amplitude: f64,
    pub phase: f64,
    pub entanglement_factor: f64,
    pub coherence_time: Duration,
}

impl QuantumRetrievalState {
    /// Create a new quantum retrieval state based on query complexity
    pub fn new(query_complexity: f64) -> Self {
        Self {
            amplitude: (query_complexity * PI / 4.0).sin(),
            phase: query_complexity * PI / 2.0,
            entanglement_factor: 1.0 / (1.0 + (-query_complexity).exp()),
            coherence_time: Duration::from_secs((query_complexity * 10.0) as u64),
        }
    }

    /// Quantum superposition for multiple retrieval paths
    pub fn superposition_search(&self, candidates: &[RagDocument]) -> Vec<QuantumSearchResult> {
        candidates
            .iter()
            .map(|doc| {
                let probability = self.amplitude.powi(2)
                    * (self.phase + doc.content.len() as f64 * 0.001).cos().abs();

                QuantumSearchResult {
                    document: doc.clone(),
                    quantum_probability: probability,
                    entanglement_score: self.entanglement_factor * probability,
                    coherence_remaining: self.coherence_time,
                }
            })
            .collect()
    }

    /// Quantum interference for result optimization
    pub fn interference_optimization(&self, results: &mut [QuantumSearchResult]) {
        for result in results.iter_mut() {
            let interference = (self.phase - result.quantum_probability * PI).sin();
            result.quantum_probability *= (1.0 + interference * 0.1).max(0.1);
        }

        // Sort by quantum probability
        results.sort_by(|a, b| {
            b.quantum_probability
                .partial_cmp(&a.quantum_probability)
                .unwrap_or(std::cmp::Ordering::Equal)
        });
    }

    /// Apply quantum tunneling effect for unexpected relevant results
    pub fn quantum_tunneling(&self, results: &mut [QuantumSearchResult], barrier_height: f64) {
        for result in results.iter_mut() {
            // Calculate tunneling probability based on barrier height
            let tunneling_prob = (-2.0 * barrier_height.sqrt()).exp();

            // If tunneling occurs, boost probability of low-scoring but potentially relevant results
            if result.quantum_probability < 0.3 && fastrand::f64() < tunneling_prob {
                result.quantum_probability *= 1.5;
                result.entanglement_score *= 1.2;
            }
        }
    }

    /// Quantum decoherence simulation for result stability
    pub fn apply_decoherence(&mut self, elapsed_time: Duration) {
        let decoherence_factor =
            (-elapsed_time.as_secs_f64() / self.coherence_time.as_secs_f64()).exp();
        self.amplitude *= decoherence_factor;
        self.entanglement_factor *= decoherence_factor;
    }

    /// Quantum error correction for result consistency
    pub fn error_correction(&self, results: &mut [QuantumSearchResult]) {
        let mean_probability =
            results.iter().map(|r| r.quantum_probability).sum::<f64>() / results.len() as f64;

        // Apply error correction based on deviation from mean
        for result in results.iter_mut() {
            let deviation = (result.quantum_probability - mean_probability).abs();
            if deviation > 0.5 {
                // Correct extreme deviations
                result.quantum_probability = mean_probability + (deviation - 0.5) * 0.1;
            }
        }
    }
}

/// Quantum search result with probability amplitudes
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct QuantumSearchResult {
    pub document: RagDocument,
    pub quantum_probability: f64,
    pub entanglement_score: f64,
    pub coherence_remaining: Duration,
}

impl QuantumSearchResult {
    /// Convert to classical search result
    pub fn to_classical(&self) -> super::types::SearchResult {
        super::types::SearchResult {
            document: self.document.clone(),
            score: self.quantum_probability,
            relevance_factors: vec![
                format!("quantum_probability: {:.4}", self.quantum_probability),
                format!("entanglement_score: {:.4}", self.entanglement_score),
                format!("coherence_remaining: {:?}", self.coherence_remaining),
            ],
        }
    }

    /// Check if result is still quantum coherent
    pub fn is_coherent(&self) -> bool {
        self.coherence_remaining > Duration::from_secs(1) && self.quantum_probability > 0.01
    }

    /// Measure quantum state (collapses superposition)
    pub fn measure(&mut self) -> f64 {
        // Measurement collapses the quantum state
        let measured_value = self.quantum_probability;
        self.quantum_probability = if measured_value > 0.5 { 1.0 } else { 0.0 };
        self.coherence_remaining = Duration::from_secs(0);
        measured_value
    }
}

/// Quantum entanglement manager for correlated results
#[derive(Debug, Clone)]
pub struct QuantumEntanglementManager {
    entangled_pairs: Vec<(usize, usize)>,
    entanglement_strength: f64,
}

impl QuantumEntanglementManager {
    pub fn new() -> Self {
        Self {
            entangled_pairs: Vec::new(),
            entanglement_strength: 0.8,
        }
    }

    /// Create entanglement between two results
    pub fn entangle_results(&mut self, index1: usize, index2: usize) {
        self.entangled_pairs.push((index1, index2));
    }

    /// Apply entanglement effects to search results
    pub fn apply_entanglement(&self, results: &mut [QuantumSearchResult]) {
        for &(idx1, idx2) in &self.entangled_pairs {
            if idx1 < results.len() && idx2 < results.len() {
                let avg_probability =
                    (results[idx1].quantum_probability + results[idx2].quantum_probability) / 2.0;

                // Entangled results have correlated probabilities
                let strength = self.entanglement_strength;
                results[idx1].quantum_probability = results[idx1].quantum_probability
                    * (1.0 - strength)
                    + avg_probability * strength;
                results[idx2].quantum_probability = results[idx2].quantum_probability
                    * (1.0 - strength)
                    + avg_probability * strength;

                // Update entanglement scores
                results[idx1].entanglement_score = strength;
                results[idx2].entanglement_score = strength;
            }
        }
    }

    /// Break entanglement (decoherence)
    pub fn break_entanglement(&mut self, index: usize) {
        self.entangled_pairs
            .retain(|&(idx1, idx2)| idx1 != index && idx2 != index);
    }
}

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

/// Quantum-inspired ranking algorithm
pub struct QuantumRanker {
    quantum_state: QuantumRetrievalState,
    entanglement_manager: QuantumEntanglementManager,
}

impl QuantumRanker {
    pub fn new(query_complexity: f64) -> Self {
        Self {
            quantum_state: QuantumRetrievalState::new(query_complexity),
            entanglement_manager: QuantumEntanglementManager::new(),
        }
    }

    /// Perform quantum-enhanced ranking
    pub fn rank_documents(&mut self, documents: &[RagDocument]) -> Vec<QuantumSearchResult> {
        // Create quantum superposition of all possible rankings
        let mut quantum_results = self.quantum_state.superposition_search(documents);

        // Apply quantum interference for optimization
        self.quantum_state
            .interference_optimization(&mut quantum_results);

        // Create entanglements between semantically related documents
        self.create_semantic_entanglements(&quantum_results);

        // Apply entanglement effects
        self.entanglement_manager
            .apply_entanglement(&mut quantum_results);

        // Apply quantum tunneling for serendipitous discoveries
        self.quantum_state
            .quantum_tunneling(&mut quantum_results, 0.5);

        // Error correction
        self.quantum_state.error_correction(&mut quantum_results);

        quantum_results
    }

    /// Create entanglements between semantically related documents
    fn create_semantic_entanglements(&mut self, results: &[QuantumSearchResult]) {
        for i in 0..results.len() {
            for j in (i + 1)..results.len() {
                // Simple semantic similarity check (would use actual embedding similarity in production)
                let doc1 = &results[i].document;
                let doc2 = &results[j].document;

                if self.are_semantically_similar(doc1, doc2) {
                    self.entanglement_manager.entangle_results(i, j);
                }
            }
        }
    }

    /// Check if two documents are semantically similar (simplified implementation)
    fn are_semantically_similar(&self, doc1: &RagDocument, doc2: &RagDocument) -> bool {
        // Simplified similarity check - in production would use embeddings
        let common_words: Vec<&str> = doc1
            .content
            .split_whitespace()
            .filter(|word| doc2.content.contains(word))
            .collect();

        common_words.len() > 3 // Threshold for semantic similarity
    }
}

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

    #[test]
    fn test_quantum_state_creation() {
        let state = QuantumRetrievalState::new(1.0);
        assert!(state.amplitude >= 0.0 && state.amplitude <= 1.0);
        assert!(state.entanglement_factor >= 0.0 && state.entanglement_factor <= 1.0);
    }

    #[test]
    fn test_quantum_superposition() {
        let state = QuantumRetrievalState::new(0.5);
        let docs = vec![RagDocument {
            id: "doc1".to_string(),
            content: "test content".to_string(),
            metadata: std::collections::HashMap::new(),
            embedding: None,
            timestamp: chrono::Utc::now(),
            source: "test".to_string(),
        }];

        let results = state.superposition_search(&docs);
        assert_eq!(results.len(), 1);
        assert!(results[0].quantum_probability >= 0.0);
    }

    #[test]
    fn test_entanglement_manager() {
        let mut manager = QuantumEntanglementManager::new();
        manager.entangle_results(0, 1);
        assert_eq!(manager.entangled_pairs.len(), 1);

        manager.break_entanglement(0);
        assert_eq!(manager.entangled_pairs.len(), 0);
    }
}