strange-loop 0.3.0

//! Retrocausal feedback loops - future states influence past computation

use std::collections::VecDeque;
use std::sync::{Arc, RwLock};

/// Retrocausal loop that allows future states to influence past decisions
pub struct RetrocausalLoop {
    /// Past states that can be retroactively modified
    past_states: Arc<RwLock<VecDeque<State>>>,
    /// Future constraints that affect past
    future_constraints: Vec<Constraint>,
    /// Causality violation tolerance
    violation_threshold: f64,
}

#[derive(Clone, Debug)]
pub struct State {
    pub value: f64,
    pub timestamp: u64,
    pub mutable: bool,
    pub influence_factor: f64,
}

pub struct Constraint {
    pub target_time: u64,
    pub condition: Box<dyn Fn(f64) -> bool + Send + Sync>,
    pub influence_strength: f64,
}

impl RetrocausalLoop {
    pub fn new(violation_threshold: f64) -> Self {
        Self {
            past_states: Arc::new(RwLock::new(VecDeque::new())),
            future_constraints: Vec::new(),
            violation_threshold,
        }
    }

    /// Add a state that can be retroactively influenced
    pub fn add_state(&self, value: f64, timestamp: u64) {
        let state = State {
            value,
            timestamp,
            mutable: true,
            influence_factor: 1.0,
        };

        if let Ok(mut states) = self.past_states.write() {
            states.push_back(state);
            if states.len() > 1000 {
                states.pop_front();
            }
        }
    }

    /// Apply retrocausal influence from future to past
    pub fn apply_retrocausality(&self, future_value: f64, influence_range: u64) {
        if let Ok(mut states) = self.past_states.write() {
            let current_time = states.back().map(|s| s.timestamp).unwrap_or(0);

            for state in states.iter_mut() {
                if state.mutable && current_time - state.timestamp <= influence_range {
                    // Retroactive influence decays with temporal distance
                    let temporal_decay = 1.0 / (1.0 + (current_time - state.timestamp) as f64);
                    let influence = future_value * temporal_decay * state.influence_factor;

                    // Weighted average with existing value
                    state.value = state.value * 0.7 + influence * 0.3;
                    state.influence_factor *= 0.95; // Reduce future influence
                }
            }
        }
    }

    /// Check for causality violations
    pub fn check_causality(&self) -> bool {
        if let Ok(states) = self.past_states.read() {
            if states.len() < 2 {
                return true;
            }

            // Check for temporal consistency
            let mut max_violation: f64 = 0.0;
            let states_vec: Vec<State> = states.iter().cloned().collect();
            for i in 0..states_vec.len() - 1 {
                let delta = (states_vec[i + 1].value - states_vec[i].value).abs();
                let time_delta = (states_vec[i + 1].timestamp - states_vec[i].timestamp) as f64;
                let violation = delta / time_delta.max(1.0);
                max_violation = max_violation.max(violation);
            }

            max_violation < self.violation_threshold
        } else {
            false
        }
    }

    /// Create a temporal paradox and resolve it
    pub fn create_paradox(&self, paradox_value: f64) -> Result<f64, String> {
        // Attempt to create a grandfather paradox
        if let Ok(mut states) = self.past_states.write() {
            if let Some(first_state) = states.front_mut() {
                let original = first_state.value;
                first_state.value = paradox_value;

                // Check if paradox is resolvable
                if self.check_causality() {
                    // Paradox resolved through self-consistency
                    Ok(first_state.value)
                } else {
                    // Restore original timeline
                    first_state.value = original;
                    Err("Paradox unresolvable - timeline restored".to_string())
                }
            } else {
                Err("No past states to create paradox".to_string())
            }
        } else {
            Err("Cannot access timeline".to_string())
        }
    }

    /// Add a constraint that affects retrocausal behavior
    pub fn add_constraint(&mut self, target_time: u64, condition: Box<dyn Fn(f64) -> bool + Send + Sync>, influence_strength: f64) {
        let constraint = Constraint {
            target_time,
            condition,
            influence_strength,
        };
        self.future_constraints.push(constraint);
    }

    /// Apply feedback from future constraints to current value
    pub fn apply_feedback(&self, current_value: f64, current_time: u64) -> f64 {
        let mut influenced_value = current_value;

        for constraint in &self.future_constraints {
            if constraint.target_time > current_time {
                let time_diff = (constraint.target_time - current_time) as f64;
                let influence = constraint.influence_strength / (1.0 + time_diff * 0.001);

                // Apply influence based on the constraint
                if (constraint.condition)(current_value) {
                    influenced_value += influence * 0.1;
                } else {
                    influenced_value -= influence * 0.1;
                }
            }
        }

        influenced_value
    }

    /// Check for violations of retrocausal constraints
    pub fn check_violations(&self, current_time: u64) -> usize {
        let mut violations = 0;

        for constraint in &self.future_constraints {
            if constraint.target_time <= current_time {
                // This constraint should have been satisfied by now
                // For simplicity, we'll just count it as a potential violation
                violations += 1;
            }
        }

        violations
    }
}

// Make Constraint implement necessary traits
impl std::fmt::Debug for Constraint {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("Constraint")
            .field("target_time", &self.target_time)
            .field("influence_strength", &self.influence_strength)
            .finish()
    }
}