lessence 0.3.1

// Unified Timestamp Detection Engine
// Constitutional requirement: Replace both timestamp.rs and essence/processor.rs

use super::{DetectionResult, TimestampMatch, TimestampRegistry, Token};
use std::sync::LazyLock;

/// Central timestamp pattern detection system
/// Replaces both src/patterns/timestamp.rs and src/essence/processor.rs patterns
pub struct UnifiedTimestampDetector;

/// Static registry for efficient pattern access
static TIMESTAMP_REGISTRY: LazyLock<TimestampRegistry> = LazyLock::new(TimestampRegistry::new);

impl UnifiedTimestampDetector {
    /// Primary detection interface - replaces TimestampDetector::detect_and_replace
    ///
    /// Constitutional requirements:
    /// - Support all 30+ timestamp formats without shortcuts
    /// - Thread-safe for parallel processing
    /// - Preserve 100% of unique information
    /// - Replace only longest/most specific match when overlaps occur
    /// - Unix timestamps lowest priority to prevent false positives
    pub fn detect_and_replace(text: &str) -> (String, Vec<Token>) {
        let result = Self::detect_with_metadata(text);

        // Convert to legacy format for compatibility
        let tokens = result
            .matches
            .iter()
            .map(|m| Token::Timestamp(m.original.clone()))
            .collect();

        (result.normalized_text, tokens)
    }

    /// Advanced detection interface for detailed analysis
    ///
    /// Provides full detection metadata for debugging and validation
    pub fn detect_with_metadata(text: &str) -> DetectionResult {
        // Quick pre-filter to avoid expensive regex operations
        if !Self::has_timestamp_indicators(text) {
            return DetectionResult {
                normalized_text: text.to_string(),
                matches: Vec::new(),
            };
        }

        let registry = &*TIMESTAMP_REGISTRY;
        let patterns = registry.get_patterns();

        let mut all_matches = Vec::new();

        // Find all possible matches
        for pattern in patterns {
            for regex_match in pattern.regex.find_iter(text) {
                let timestamp_match = TimestampMatch {
                    original: regex_match.as_str().to_string(),
                    start_pos: regex_match.start(),
                    end_pos: regex_match.end(),
                    priority: pattern.priority.clone(),
                };
                all_matches.push(timestamp_match);
            }
        }

        // Sort by position for overlap resolution
        all_matches.sort_by_key(|m| m.start_pos);

        // Resolve overlaps - select longest/most specific match
        let resolved_matches = Self::resolve_overlaps(all_matches);

        // Apply replacements
        let normalized_text = Self::apply_replacements(text, &resolved_matches);

        DetectionResult {
            normalized_text,
            matches: resolved_matches,
        }
    }

    /// Fast pre-filter for timestamp indicators
    fn has_timestamp_indicators(text: &str) -> bool {
        text.contains(':')
            && (text.contains("20") || // Years 20xx
            text.contains("19") || // Years 19xx
            text.contains('-') ||  // Date separators
            text.contains('T') ||  // ISO 8601 separator
            text.contains('[') ||  // Log brackets
            // Kubernetes/Go log levels
            text.contains("I09") || text.contains("W09") || text.contains("E09") || text.contains("F09") ||
            text.contains("I10") || text.contains("W10") || text.contains("E10") || text.contains("F10") ||
            text.contains("I11") || text.contains("W11") || text.contains("E11") || text.contains("F11") ||
            text.contains("I12") || text.contains("W12") || text.contains("E12") || text.contains("F12") ||
            // Month names
            text.contains("Jan") || text.contains("Feb") || text.contains("Mar") ||
            text.contains("Apr") || text.contains("May") || text.contains("Jun") ||
            text.contains("Jul") || text.contains("Aug") || text.contains("Sep") ||
            text.contains("Oct") || text.contains("Nov") || text.contains("Dec"))
    }

    /// Resolve overlapping matches using longest-match-first rule
    fn resolve_overlaps(mut matches: Vec<TimestampMatch>) -> Vec<TimestampMatch> {
        if matches.is_empty() {
            return matches;
        }

        // Sort by priority first (most specific patterns first)
        matches.sort_by(|a, b| {
            a.priority
                .effective_score()
                .cmp(&b.priority.effective_score())
        });

        let mut resolved = Vec::new();
        let mut used_positions = Vec::new();

        for candidate in matches {
            let candidate_range = candidate.start_pos..candidate.end_pos;

            // Check if this candidate overlaps with any already selected match
            let overlaps = used_positions
                .iter()
                .any(|used_range: &std::ops::Range<usize>| {
                    candidate_range.start < used_range.end && candidate_range.end > used_range.start
                });

            if !overlaps {
                used_positions.push(candidate_range);
                resolved.push(candidate);
            }
        }

        // Sort resolved matches by position for consistent output
        resolved.sort_by_key(|m| m.start_pos);
        resolved
    }

    /// Apply timestamp replacements to text
    fn apply_replacements(text: &str, matches: &[TimestampMatch]) -> String {
        if matches.is_empty() {
            return text.to_string();
        }

        let mut result = text.to_string();

        // Apply replacements in reverse order to maintain positions
        let mut sorted_matches = matches.to_vec();
        sorted_matches.sort_by_key(|m| std::cmp::Reverse(m.start_pos));

        for timestamp_match in sorted_matches {
            let range = timestamp_match.start_pos..timestamp_match.end_pos;
            if range.end <= result.len() {
                result.replace_range(range, "<TIMESTAMP>");
            }
        }

        result
    }
}