import os
import re
import sys
import yaml

def modify_files(config_path):
    """
    Modifiziert Dateien basierend auf einer YAML-Konfigurationsdatei.
    
    :param config_path: Pfad zur Konfigurationsdatei
    """
    # load config
    with open(config_path, 'r', encoding='utf-8') as config_file:
        config = yaml.safe_load(config_file)
    
    files_modified = 0
    
    # iterate trough every config
    for entry in config['modifications']:
        search_pattern = entry.get('file_pattern')
        insert_rules = entry.get('insert_rules', [])
        replace_rules = entry.get('replace_rules', [])
        
        # recursiv search starting at start dir
        for root, dirs, files in os.walk(config.get('start_directory', '.')):
            for filename in files:
                # check filenamepattern
                if re.search(search_pattern, filename):
                    full_path = os.path.join(root, filename)
                    
                    try:
                        with open(full_path, 'r', encoding='utf-8') as file:
                            content = file.read()
                        
                        modified = False
                        modified_content = content
                        
                        # iterate trough insert rules
                        for rule in insert_rules:
                            insert_text = rule.get('insert_text')
                            
                            # insert after specific text
                            if 'after_text' in rule:
                                search_text = rule.get('after_text')
                                if insert_text not in modified_content:
                                    modified_content = modified_content.replace(
                                        search_text, 
                                        f'{search_text}\n{insert_text}'
                                    )
                                    modified = True
                            
                            # insert before spicific text
                            elif 'before_text' in rule:
                                search_text = rule.get('before_text')
                                if insert_text not in modified_content:
                                    modified_content = modified_content.replace(
                                        search_text, 
                                        f'{insert_text}\n{search_text}'
                                    )
                                    modified = True
                        
                        # iterate replace rules
                        for rule in replace_rules:
                            old_text = rule.get('old_text')
                            new_text = rule.get('new_text')
                            
                            # check, if the text to be replaced, exists
                            if old_text in modified_content:
                                modified_content = modified_content.replace(old_text, new_text)
                                modified = True
                        
                        # save changed files
                        if modified:
                            with open(full_path, 'w', encoding='utf-8') as file:
                                file.write(modified_content)
                            
                            files_modified += 1
                            print(f'Modified: {full_path}')
                    
                    except Exception as e:
                        print(f'Error modifying file {full_path}: {e}')
    
    print(f'\nAnzahl modifizierter Dateien: {files_modified}')

def main():
    # path of config file as argument
    if len(sys.argv) < 2:
        print("Error: Provide a path to the config.yaml file")
        sys.exit(1)
    
    config_path = sys.argv[1]
    modify_files(config_path)

if __name__ == '__main__':
    main()