//! Timeout configuration extractor.
//!
//! Detects timeout values that are misconfigured (zero/infinite,
//! too low, or too high) which can cause availability issues.

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

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

/// Configuration for timeout extraction thresholds.
#[derive(Debug, Clone)]
pub struct TimeoutThresholds {
    /// Minimum reasonable timeout in milliseconds.
    pub min_reasonable_ms: u64,
    /// Maximum reasonable timeout in milliseconds.
    pub max_reasonable_ms: u64,
}

impl Default for TimeoutThresholds {
    fn default() -> Self {
        Self { min_reasonable_ms: 1000, max_reasonable_ms: 300_000 }
    }
}

/// Extractor for timeout configuration values.
pub struct TimeoutConfigExtractor {
    /// Zero/infinite timeout patterns
    zero_timeout: Regex,
    /// Numeric timeout patterns (captures the value)
    numeric_timeout: Regex,
    /// Duration patterns (Rust/Go style, reserved for future use)
    #[allow(dead_code)]
    duration_timeout: Regex,
    /// Configuration thresholds
    thresholds: TimeoutThresholds,
}

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

impl TimeoutConfigExtractor {
    /// Create a new timeout extractor with the given thresholds.
    ///
    /// # Panics
    /// Panics if any regex pattern is invalid (programmer error).
    #[allow(clippy::expect_used)]
    pub fn new(thresholds: TimeoutThresholds) -> Self {
        Self {
            zero_timeout: Regex::new(
                r"(?i)timeout\s*[:=]\s*(0|None|null|nil|infinity|Inf|never|\-1)",
            )
            .expect("valid regex"),
            numeric_timeout: Regex::new(r"(?i)timeout\s*[:=]\s*(\d+)").expect("valid regex"),
            duration_timeout: Regex::new(
                r"(?i)(?:Duration::from_(?:secs|millis|nanos)|time\.(?:Second|Millisecond)|timeout)\s*[:=\(]\s*(\d+)",
            )
            .expect("valid regex"),
            thresholds,
        }
    }

    #[allow(clippy::too_many_arguments)]
    fn extract_claim(
        &self,
        path_segments: &[String],
        file: &str,
        line: usize,
        matched_text: &str,
        context: &str,
        value: f64,
        description: &str,
    ) -> Observation {
        let mut concept_path = path_segments.to_vec();
        concept_path.push(context.to_string());
        concept_path.push("timeout".to_string());

        Observation {
            concept_path: format!("code://{}", concept_path.join("/")),
            predicate: "config_value".to_string(),
            value: ObjectValue::Number(value),
            file: file.to_string(),
            line,
            matched_text: matched_text.to_string(),
            confidence: 1.0,
            description: description.to_string(),
        }
    }

    fn detect_context(&self, line: &str) -> &str {
        let lower = line.to_lowercase();
        if lower.contains("http") || lower.contains("client") || lower.contains("request") {
            "http"
        } else if lower.contains("db") || lower.contains("database") || lower.contains("sql") {
            "database"
        } else if lower.contains("redis") || lower.contains("cache") || lower.contains("memcache") {
            "cache"
        } else if lower.contains("grpc") || lower.contains("rpc") {
            "rpc"
        } else {
            "general"
        }
    }

    fn estimate_milliseconds(&self, value: u64, line: &str) -> u64 {
        // Strip comments before analyzing
        let code_part = line.split("//").next().unwrap_or(line);
        let code_part = code_part.split('#').next().unwrap_or(code_part);
        let lower = code_part.to_lowercase();

        // Explicit unit markers in code (not comments)
        if lower.contains("from_secs") || lower.contains("_secs") {
            return value * 1000;
        }
        if lower.contains("from_millis") || lower.contains("millisecond") || lower.contains("_ms") {
            return value;
        }
        if lower.contains("from_nanos") || lower.contains("nanosecond") {
            return value / 1_000_000;
        }

        // Heuristics based on magnitude
        if value > 1_000_000 {
            // Likely nanoseconds
            value / 1_000_000
        } else if value > 1000 && value < 1_000_000 {
            // Likely milliseconds
            value
        } else if value < 100 {
            // Likely seconds
            value * 1000
        } else {
            // Default: assume milliseconds
            value
        }
    }
}

impl Extractor for TimeoutConfigExtractor {
    fn name(&self) -> &str {
        "timeout_config"
    }

    fn languages(&self) -> &[Language] {
        &[
            Language::Rust,
            Language::Go,
            Language::Python,
            Language::TypeScript,
            Language::JavaScript,
            Language::Yaml,
            Language::Toml,
            Language::Json,
        ]
    }

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

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

            // Zero/infinite timeout detection
            if let Some(matched) = self.zero_timeout.find(line) {
                claims.push(self.extract_claim(
                    path_segments,
                    file,
                    line_num,
                    matched.as_str(),
                    context,
                    0.0,
                    "Timeout is disabled (infinite wait)",
                ));
                continue;
            }

            // Numeric timeout detection
            if let Some(captures) = self.numeric_timeout.captures(line) {
                if let Some(value_match) = captures.get(1) {
                    if let Ok(value) = value_match.as_str().parse::<u64>() {
                        let ms = self.estimate_milliseconds(value, line);

                        if ms > 0 && ms < self.thresholds.min_reasonable_ms {
                            claims.push(self.extract_claim(
                                path_segments,
                                file,
                                line_num,
                                captures.get(0).map(|m| m.as_str()).unwrap_or(""),
                                context,
                                ms as f64,
                                &format!(
                                    "Timeout {}ms is below minimum reasonable {}ms",
                                    ms, self.thresholds.min_reasonable_ms
                                ),
                            ));
                        } else if ms > self.thresholds.max_reasonable_ms {
                            claims.push(self.extract_claim(
                                path_segments,
                                file,
                                line_num,
                                captures.get(0).map(|m| m.as_str()).unwrap_or(""),
                                context,
                                ms as f64,
                                &format!(
                                    "Timeout {}ms exceeds maximum reasonable {}ms",
                                    ms, self.thresholds.max_reasonable_ms
                                ),
                            ));
                        }
                    }
                }
            }
        }

        claims
    }

    fn screening_patterns(&self) -> Vec<&str> {
        vec![
            r"(?i)timeout",
            r"(?i)read_timeout|write_timeout|connect_timeout",
            r"(?i)request_timeout|idle_timeout|keep_alive",
        ]
    }
}

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

    #[test]
    fn test_zero_timeout_detection() {
        let extractor = TimeoutConfigExtractor::default();
        let content = r#"
            client.timeout = 0
        "#;

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

        assert_eq!(claims.len(), 1);
        assert!(claims[0].description.contains("disabled"));
    }

    #[test]
    fn test_nil_timeout_detection() {
        let extractor = TimeoutConfigExtractor::default();
        let content = r#"
            timeout: nil
        "#;

        let claims = extractor.extract(&["go".to_string()], content, Language::Go, "config.go");

        assert_eq!(claims.len(), 1);
    }

    #[test]
    fn test_unreasonably_low_timeout() {
        let extractor = TimeoutConfigExtractor::default();
        let content = r#"
            http_client.timeout = 100  // 100ms
        "#;

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

        assert_eq!(claims.len(), 1);
        assert!(claims[0].description.contains("below minimum"));
    }

    #[test]
    fn test_unreasonably_high_timeout() {
        let extractor = TimeoutConfigExtractor::default();
        let content = r#"
            db_timeout = 600000  // 10 minutes
        "#;

        let claims =
            extractor.extract(&["python".to_string()], content, Language::Python, "config.py");

        assert_eq!(claims.len(), 1);
        assert!(claims[0].description.contains("exceeds maximum"));
    }

    #[test]
    fn test_reasonable_timeout_no_claims() {
        let extractor = TimeoutConfigExtractor::default();
        let content = r#"
            timeout = 30000  // 30 seconds
        "#;

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

        assert!(claims.is_empty(), "Expected no claims for reasonable 30000ms timeout");
    }

    #[test]
    fn test_context_detection() {
        let extractor = TimeoutConfigExtractor::default();

        let content_http = "http_client.timeout = 0";
        let claims =
            extractor.extract(&["rust".to_string()], content_http, Language::Rust, "src/http.rs");
        assert!(claims[0].concept_path.contains("http"));

        let content_db = "database_timeout = 0";
        let claims =
            extractor.extract(&["rust".to_string()], content_db, Language::Rust, "src/db.rs");
        assert!(claims[0].concept_path.contains("database"));
    }
}