//! Unsafe and atomic patterns extractor for Rust.
//!
//! Tracks `unsafe` blocks and `Ordering::*` patterns for correctness conventions.
//! Enables learning loop to establish patterns like:
//! - "All wallet operations use Ordering::SeqCst"
//! - "Unsafe code requires documented safety invariants"

use regex::Regex;
use stemedb_core::types::ObjectValue;

use super::Extractor;
use crate::types::{ExtractedClaim, Language};

/// Extractor for unsafe blocks and atomic ordering patterns.
///
/// Detects safety-critical patterns in Rust code to enable
/// correctness conventions.
pub struct UnsafeAtomicExtractor {
    /// Matches: Ordering::SeqCst, Ordering::Relaxed, etc.
    ordering_pattern: Regex,
    /// Matches: unsafe { ... } or unsafe fn
    unsafe_keyword: Regex,
}

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

impl UnsafeAtomicExtractor {
    /// Create a new unsafe/atomic extractor.
    ///
    /// # Panics
    /// Panics if any regex pattern is invalid (programmer error).
    #[allow(clippy::expect_used)]
    pub fn new() -> Self {
        Self {
            // Ordering::SeqCst, Ordering::Relaxed, etc.
            ordering_pattern: Regex::new(r"Ordering::(SeqCst|Acquire|Release|AcqRel|Relaxed)")
                .expect("valid regex"),

            // unsafe keyword (blocks or functions)
            unsafe_keyword: Regex::new(r"\b(unsafe)\s*(\{|fn)").expect("valid regex"),
        }
    }

    /// Determine confidence based on context.
    fn confidence_for_file(&self, file: &str) -> f32 {
        if file.contains("test") || file.contains("example") || file.contains("bench") {
            0.5
        } else {
            1.0
        }
    }
}

impl Extractor for UnsafeAtomicExtractor {
    fn name(&self) -> &str {
        "unsafe_atomic"
    }

    fn languages(&self) -> &[Language] {
        &[Language::Rust]
    }

    fn extract(
        &self,
        path_segments: &[String],
        content: &str,
        _language: Language,
        file: &str,
    ) -> Vec<ExtractedClaim> {
        let mut claims = Vec::new();
        let confidence = self.confidence_for_file(file);

        // Track unique patterns to avoid excessive claims
        let mut seen_orderings = std::collections::HashSet::new();
        let mut unsafe_count = 0;

        for (line_idx, line) in content.lines().enumerate() {
            let line_num = line_idx + 1;

            // Check for atomic ordering patterns
            if let Some(cap) = self.ordering_pattern.captures(line) {
                let ordering = cap.get(1).map_or("", |m| m.as_str());

                if !seen_orderings.contains(ordering) {
                    seen_orderings.insert(ordering.to_string());

                    let mut concept_path = path_segments.to_vec();
                    concept_path.push("atomics".to_string());
                    concept_path.push("ordering".to_string());

                    claims.push(ExtractedClaim {
                        concept_path: format!("code://{}", concept_path.join("/")),
                        predicate: "pattern".to_string(),
                        value: ObjectValue::Text(ordering.to_string()),
                        file: file.to_string(),
                        line: line_num,
                        matched_text: line.trim().to_string(),
                        confidence,
                        description: format!("Atomic operation uses Ordering::{}", ordering),
                    });
                }
            }

            // Check for unsafe blocks/functions
            if self.unsafe_keyword.is_match(line) {
                unsafe_count += 1;
            }
        }

        // Add a summary claim for unsafe usage if found
        if unsafe_count > 0 {
            let mut concept_path = path_segments.to_vec();
            concept_path.push("unsafe".to_string());
            concept_path.push("count".to_string());

            claims.push(ExtractedClaim {
                concept_path: format!("code://{}", concept_path.join("/")),
                predicate: "occurrences".to_string(),
                value: ObjectValue::Number(unsafe_count as f64),
                file: file.to_string(),
                line: 1,
                matched_text: format!("{} unsafe blocks/functions", unsafe_count),
                confidence: confidence * 0.9, // Slightly lower as this is a summary
                description: format!(
                    "File contains {} unsafe block(s) or function(s)",
                    unsafe_count
                ),
            });
        }

        claims
    }
}

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

    #[test]
    fn test_atomic_ordering() {
        let extractor = UnsafeAtomicExtractor::new();
        let content = r#"
let balance = self.balance.load(Ordering::SeqCst);
self.balance.store(new_balance, Ordering::SeqCst);
        "#;

        let claims = extractor.extract(
            &["rust".to_string(), "maxwell".to_string(), "wallet".to_string()],
            content,
            Language::Rust,
            "src/wallet.rs",
        );

        // Should have one claim for SeqCst (deduplicated)
        assert!(claims.iter().any(|c| {
            c.concept_path.contains("atomics/ordering")
                && c.value == ObjectValue::Text("SeqCst".to_string())
        }));
    }

    #[test]
    fn test_multiple_orderings() {
        let extractor = UnsafeAtomicExtractor::new();
        let content = r#"
let a = atomic.load(Ordering::Acquire);
let b = atomic.load(Ordering::Relaxed);
atomic.store(x, Ordering::Release);
        "#;

        let claims =
            extractor.extract(&["rust".to_string()], content, Language::Rust, "src/sync.rs");

        // Should have 3 distinct ordering claims (Acquire, Relaxed, Release)
        let ordering_claims: Vec<_> =
            claims.iter().filter(|c| c.concept_path.contains("ordering")).collect();

        assert_eq!(ordering_claims.len(), 3);
    }

    #[test]
    fn test_unsafe_block() {
        let extractor = UnsafeAtomicExtractor::new();
        let content = r#"
unsafe {
    let ptr = mem::transmute(addr);
}
        "#;

        let claims =
            extractor.extract(&["rust".to_string()], content, Language::Rust, "src/lib.rs");

        // Should have one unsafe count claim
        let unsafe_claim = claims.iter().find(|c| c.concept_path.contains("unsafe/count"));
        assert!(unsafe_claim.is_some());
        assert_eq!(unsafe_claim.unwrap().value, ObjectValue::Number(1.0));
    }

    #[test]
    fn test_unsafe_fn() {
        let extractor = UnsafeAtomicExtractor::new();
        let content = r#"
unsafe fn read_msr(reg: u32) -> u64 {
    // ...
}
        "#;

        let claims =
            extractor.extract(&["rust".to_string()], content, Language::Rust, "src/msr.rs");

        let unsafe_claim = claims.iter().find(|c| c.concept_path.contains("unsafe"));
        assert!(unsafe_claim.is_some());
    }

    #[test]
    fn test_multiple_unsafe_blocks() {
        let extractor = UnsafeAtomicExtractor::new();
        let content = r#"
unsafe fn foo() {}

fn bar() {
    unsafe {
        // block 1
    }

    unsafe {
        // block 2
    }
}
        "#;

        let claims =
            extractor.extract(&["rust".to_string()], content, Language::Rust, "src/lib.rs");

        let unsafe_claim = claims.iter().find(|c| c.concept_path.contains("unsafe/count")).unwrap();
        assert_eq!(unsafe_claim.value, ObjectValue::Number(3.0)); // 1 fn + 2 blocks
    }

    #[test]
    fn test_confidence_in_test_file() {
        let extractor = UnsafeAtomicExtractor::new();
        let content = r#"
unsafe { test_something(); }
        "#;

        let claims =
            extractor.extract(&["rust".to_string()], content, Language::Rust, "src/test.rs");

        assert!(!claims.is_empty());
        // Confidence should be reduced for test files
        assert!(claims.iter().all(|c| c.confidence <= 0.5));
    }

    #[test]
    fn test_real_world_wallet() {
        let extractor = UnsafeAtomicExtractor::new();
        let content = r#"
//! Wallet with atomic balance tracking

use std::sync::atomic::{AtomicU64, Ordering};

pub struct Wallet {
    balance: AtomicU64,
}

impl Wallet {
    pub fn deposit(&self, amount: u64) {
        self.balance.fetch_add(amount, Ordering::SeqCst);
    }

    pub fn withdraw(&self, amount: u64) -> bool {
        let current = self.balance.load(Ordering::SeqCst);
        if current >= amount {
            self.balance.fetch_sub(amount, Ordering::SeqCst);
            true
        } else {
            false
        }
    }

    pub fn balance(&self) -> u64 {
        self.balance.load(Ordering::SeqCst);
    }
}
        "#;

        let claims = extractor.extract(
            &["rust".to_string(), "maxwell".to_string(), "wallet".to_string()],
            content,
            Language::Rust,
            "src/wallet.rs",
        );

        // Should detect SeqCst ordering (all wallet ops use it consistently)
        assert!(claims.iter().any(|c| c.concept_path.contains("ordering")
            && c.value == ObjectValue::Text("SeqCst".to_string())));

        // Should NOT have unsafe claims (no unsafe code)
        assert!(!claims.iter().any(|c| c.concept_path.contains("unsafe")));
    }
}