package research.loghunter.service;

import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service;
import research.loghunter.entity.Pattern;

import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;

@Service
@RequiredArgsConstructor
@Slf4j
public class LogParserService {

    /**
     * 로그 내용에서 패턴 매칭
     */
    public List<MatchResult> parseAndMatch(String content, List<Pattern> patterns, String filePath) {
        List<MatchResult> results = new ArrayList<>();
        String[] lines = content.split("\n");

        for (Pattern pattern : patterns) {
            if (!pattern.getActive()) continue;
            
            try {
                java.util.regex.Pattern compiledPattern = java.util.regex.Pattern.compile(pattern.getRegex());
                
                for (int i = 0; i < lines.length; i++) {
                    Matcher matcher = compiledPattern.matcher(lines[i]);
                    
                    if (matcher.find()) {
                        // 컨텍스트 추출
                        String context = extractContext(lines, i, pattern.getContextLines());
                        String summary = createSummary(lines[i]);
                        
                        results.add(new MatchResult(
                                pattern,
                                filePath,
                                i + 1,  // 1-based line number
                                summary,
                                context,
                                pattern.getSeverity()
                        ));
                    }
                }
            } catch (Exception e) {
                log.warn("Failed to match pattern {}: {}", pattern.getName(), e.getMessage());
            }
        }

        return results;
    }

    /**
     * 컨텍스트 추출 (에러 전후 라인)
     */
    private String extractContext(String[] lines, int matchIndex, int contextLines) {
        int start = Math.max(0, matchIndex - contextLines);
        int end = Math.min(lines.length - 1, matchIndex + contextLines);

        StringBuilder context = new StringBuilder();
        for (int i = start; i <= end; i++) {
            if (i == matchIndex) {
                context.append(">>> ");  // 에러 라인 표시
            }
            context.append(String.format("[%d] %s\n", i + 1, lines[i]));
        }
        return context.toString();
    }

    /**
     * 요약 생성 (첫 줄, 최대 200자)
     */
    private String createSummary(String line) {
        if (line == null) return "";
        String trimmed = line.trim();
        if (trimmed.length() <= 200) return trimmed;
        return trimmed.substring(0, 200) + "...";
    }

    // DTO
    public record MatchResult(
            Pattern pattern,
            String filePath,
            int lineNumber,
            String summary,
            String context,
            String severity
    ) {}
}