# regex_checker.py
import re
import traceback
from typing import List, Dict, Any

def perform_regex_checks(plain_text_from_original_pdf: str) -> Dict[str, Any]:
    """
    Performs custom regex checks on plain text from the original PDF.
    Filters issues to only include those between "abstract" and "references/bibliography"
    found within this specific text.
    Assumes plain_text_from_original_pdf is already space-normalized.
    """
    text_for_regex_analysis = plain_text_from_original_pdf

    if not text_for_regex_analysis or not text_for_regex_analysis.strip():
        print("RegexChecker: Input plain text is empty.")
        return {"total_issues": 0, "issues_list": [], "text_used_for_analysis": ""}

    text_for_regex_analysis_lower = text_for_regex_analysis.lower()
    
    abstract_match = re.search(r'\babstract\b', text_for_regex_analysis_lower)
    content_start_index = abstract_match.start() if abstract_match else 0
    if abstract_match:
        print(f"RegexChecker: Found 'abstract' at index {content_start_index} in its text.")
    else:
        print(f"RegexChecker: Did not find 'abstract', Regex analysis from index 0 of its text.")

    references_match = re.search(r'\breferences\b', text_for_regex_analysis_lower)
    bibliography_match = re.search(r'\bbibliography\b', text_for_regex_analysis_lower)
    content_end_index = len(text_for_regex_analysis)

    if references_match and bibliography_match:
        content_end_index = min(references_match.start(), bibliography_match.start())
        print(f"RegexChecker: Found 'references' at {references_match.start()} and 'bibliography' at {bibliography_match.start()}. Using {content_end_index} as end boundary.")
    elif references_match:
        content_end_index = references_match.start()
        print(f"RegexChecker: Found 'references' at {content_end_index}. Using it as end boundary.")
    elif bibliography_match:
        content_end_index = bibliography_match.start()
        print(f"RegexChecker: Found 'bibliography' at {content_end_index}. Using it as end boundary.")
    else:
        print(f"RegexChecker: Did not find 'references' or 'bibliography'. Regex analysis up to end of its text (index {content_end_index}).")


    if content_start_index >= content_end_index:
        print(f"RegexChecker: Warning: Content start index ({content_start_index}) is not before end index ({content_end_index}) in its text. No Regex issues will be reported from this range.")

    processed_regex_issues: List[Dict[str, Any]] = []
    try:
        # Regex: Missing space before bracketed citation, e.g., "word[1]"
        regex_pattern = r'\b(\w+)\[(\d+)\]' 
        regex_matches = list(re.finditer(regex_pattern, text_for_regex_analysis))
        
        regex_issues_in_range = 0
        for reg_idx, match in enumerate(regex_matches):
            if not (content_start_index <= match.start() < content_end_index):
                continue
            regex_issues_in_range += 1
            
            word = match.group(1)
            number = match.group(2)
            context_str = text_for_regex_analysis[match.start():match.end()]
            processed_regex_issues.append({
                '_internal_id': f"regex_{reg_idx}",
                'ruleId': "SPACE_BEFORE_BRACKET",
                'message': f"Missing space before '[' in '{context_str}'. Should be '{word} [{number}]'.",
                'context_text': context_str,
                'offset_in_text': match.start(),
                'error_length': match.end() - match.start(),
                'replacements_suggestion': [f"{word} [{number}]"],
                'category_name': "Formatting",
                'source_check_type': 'CustomRegex',
                'is_mapped_to_pdf': False,
                'pdf_coordinates_list': [],
                'mapped_page_number': -1
            })
        print(f"RegexChecker: Regex check found {len(regex_matches)} raw matches, {regex_issues_in_range} issues within defined content range of its text.")
        
        return {
            "total_issues": len(processed_regex_issues),
            "issues_list": processed_regex_issues,
            "text_used_for_analysis": text_for_regex_analysis
        }
    except Exception as e:
        print(f"Error in perform_regex_checks: {e}\n{traceback.format_exc()}")
        return {"error": str(e), "total_issues": 0, "issues_list": [], "text_used_for_analysis": text_for_regex_analysis}