oxiz-sat 0.2.0

//! Parallel Proof Checking.
#![allow(missing_docs, dead_code)] // Under development
//!
//! Validates SAT proofs in parallel for faster verification.

#[allow(unused_imports)]
use crate::prelude::*;
use rayon::iter::{IndexedParallelIterator, IntoParallelRefIterator, ParallelIterator};

/// Configuration for parallel proof checking.
#[derive(Debug, Clone)]
pub struct ProofCheckConfig {
    /// Number of parallel workers
    pub num_workers: usize,
    /// Chunk size for parallel processing
    pub chunk_size: usize,
    /// Enable detailed error reporting
    pub detailed_errors: bool,
}

impl Default for ProofCheckConfig {
    fn default() -> Self {
        Self {
            num_workers: std::thread::available_parallelism()
                .map(|n| n.get())
                .unwrap_or(4),
            chunk_size: 100,
            detailed_errors: true,
        }
    }
}

/// Result of proof checking.
#[derive(Debug, Clone)]
pub enum ProofCheckResult {
    /// Proof is valid
    Valid,
    /// Proof is invalid with error details
    Invalid { step_id: usize, reason: String },
    /// Checking incomplete (timeout or resource limit)
    Incomplete,
}

/// Parallel proof checker.
pub struct ParallelProofChecker {
    config: ProofCheckConfig,
}

impl ParallelProofChecker {
    /// Create a new parallel proof checker.
    pub fn new(config: ProofCheckConfig) -> Self {
        Self { config }
    }

    /// Create with default configuration.
    pub fn default_config() -> Self {
        Self::new(ProofCheckConfig::default())
    }

    /// Check a proof in parallel.
    pub fn check_proof(&self, _proof_steps: &[ProofStep]) -> ProofCheckResult {
        // Simplified proof checking logic
        // Real implementation would validate each step in parallel

        // Divide proof into chunks
        let chunks: Vec<_> = _proof_steps.chunks(self.config.chunk_size).collect();

        // Validate chunks in parallel
        let results: Vec<_> = chunks
            .par_iter()
            .enumerate()
            .map(|(chunk_idx, chunk)| self.check_chunk(chunk, chunk_idx * self.config.chunk_size))
            .collect();

        // Aggregate results
        for result in results {
            if let ProofCheckResult::Invalid { .. } = result {
                return result;
            }
        }

        ProofCheckResult::Valid
    }

    /// Check a chunk of proof steps.
    fn check_chunk(&self, _steps: &[ProofStep], _base_idx: usize) -> ProofCheckResult {
        // Simplified: would validate each step
        // Check that each step follows from previous steps
        ProofCheckResult::Valid
    }

    /// Verify a single proof step.
    fn verify_step(&self, _step: &ProofStep, _context: &ProofContext) -> bool {
        // Simplified: would check step validity
        true
    }
}

/// A proof step (simplified).
#[derive(Debug, Clone)]
pub struct ProofStep {
    pub id: usize,
    pub rule: ProofRule,
    pub premises: Vec<usize>,
}

/// Proof rules (simplified).
#[derive(Debug, Clone, Copy)]
pub enum ProofRule {
    Input,
    Resolution,
    Deletion,
}

/// Proof checking context.
#[derive(Debug, Clone)]
struct ProofContext {
    derived_clauses: FxHashMap<usize, Vec<i32>>,
}

impl ProofContext {
    fn new() -> Self {
        Self {
            derived_clauses: FxHashMap::default(),
        }
    }
}

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

    #[test]
    fn test_proof_checker_creation() {
        let checker = ParallelProofChecker::default_config();
        assert_eq!(checker.config.chunk_size, 100);
    }

    #[test]
    fn test_empty_proof() {
        let checker = ParallelProofChecker::default_config();
        let result = checker.check_proof(&[]);
        assert!(matches!(result, ProofCheckResult::Valid));
    }

    #[test]
    fn test_proof_check_result() {
        let valid = ProofCheckResult::Valid;
        assert!(matches!(valid, ProofCheckResult::Valid));

        let invalid = ProofCheckResult::Invalid {
            step_id: 42,
            reason: "test".to_string(),
        };
        assert!(matches!(invalid, ProofCheckResult::Invalid { .. }));
    }
}