//! Coverage Executor with Work-Stealing (Heijunka)
//!
//! Per spec §5.4: Heijunka-balanced coverage executor
//!
//! Uses work-stealing scheduler for parallel coverage collection.

use super::{CoverageReport, Superblock, SuperblockId};

/// Result of executing a superblock
#[derive(Debug, Clone)]
pub struct SuperblockResult {
    /// Superblock that was executed
    pub id: SuperblockId,
    /// Whether execution succeeded
    pub success: bool,
    /// Error message if failed
    pub error: Option<String>,
}

/// Heijunka-balanced coverage executor with superblock scheduling
#[derive(Debug)]
pub struct CoverageExecutor {
    /// Superblocks to execute
    superblocks: Vec<Superblock>,
    /// Number of workers
    worker_count: usize,
    /// Enable work stealing
    work_stealing: bool,
}

impl CoverageExecutor {
    /// Create a new executor
    #[must_use]
    pub fn new(superblocks: Vec<Superblock>) -> Self {
        Self {
            superblocks,
            worker_count: num_cpus(),
            work_stealing: true,
        }
    }

    /// Set the number of workers
    #[must_use]
    pub fn with_workers(mut self, count: usize) -> Self {
        self.worker_count = count;
        self
    }

    /// Enable or disable work stealing
    #[must_use]
    pub fn with_work_stealing(mut self, enabled: bool) -> Self {
        self.work_stealing = enabled;
        self
    }

    /// Execute coverage collection for all superblocks
    ///
    /// In a full implementation, this would use Simular's WorkStealingMonteCarlo
    /// for parallel execution.
    pub fn execute<F>(&self, test_fn: F) -> CoverageReport
    where
        F: Fn(&Superblock) -> SuperblockResult + Send + Sync,
    {
        // Calculate total blocks
        let total_blocks = self.superblocks.iter().map(|sb| sb.block_count()).sum();

        let mut report = CoverageReport::new(total_blocks);

        // Execute each superblock (sequentially for now)
        // In production, this would use work-stealing parallel execution
        for superblock in &self.superblocks {
            let result = test_fn(superblock);
            if result.success {
                // Record hits for all blocks in the superblock
                for block in superblock.iter() {
                    report.record_hit(*block);
                }
            }
        }

        report
    }

    /// Get the number of superblocks
    #[must_use]
    pub fn superblock_count(&self) -> usize {
        self.superblocks.len()
    }

    /// Get the total number of blocks across all superblocks
    #[must_use]
    pub fn total_block_count(&self) -> usize {
        self.superblocks.iter().map(|sb| sb.block_count()).sum()
    }

    /// Get the worker count
    #[must_use]
    pub fn worker_count(&self) -> usize {
        self.worker_count
    }
}

/// Get the number of CPUs (simplified)
fn num_cpus() -> usize {
    // In a real implementation, this would detect CPU count
    4
}
