Hi there,
To all my Devloper friends. I am facing a challenge at this moment. I have this Apex class fetching data from an custom Object and displaying it through a Visual force page. My problem is this class has been written by previous developer and i have no clue what is the logic behind this class to sort, match and display data on Visual force page.
It would be a great help if anyone can let me know how this class is matching data. What is the logic behind it and if i need to change this logic how can i do that.
Here is the Apex Class.

public class RegulationOCheckCtrl {
    
    public class Wrapper {
        public Boolean success { get; set; }
        public Object message { get; set; }
        public Object response { get; set; }
    }

    public class Match {
        public String accountName { get; set; }
        public Double similarity { get; set; }
    }

    public static List<String> tokenize(String str){

        List<String> allPairs = new List<String>();

        String[] tokens = str.split(' ');

        for (Integer t = 0; t < tokens.size(); t++)
        {
            if (!String.isEmpty(tokens[t]))
            {
                String[] pairs = generateBigrams(tokens[t]);

                for (Integer p = 0; p < pairs.size(); p++)
                {
                    allPairs.add(pairs[p]);
                }
            }
        }

        return allPairs;        

    }

    public static List<String> generateBigrams(String str){

        Integer numPairs = str.length() - 1;

        String[] bigrams = new String[numPairs];

        System.debug(numPairs);

        for(Integer i = 0; i < numPairs; i++){
            bigrams[i] = str.substring(i, i + 2);
        }

        return bigrams;

    }
    
    public static String cleanString (String str){
        
        String searchString = str;
        String specialChars = '!|@|#|$|%|^|&|*|(|)|_|-|+|=|{|}|[|]|:|;|"|\'|<|>|,|.|?|/|\\|~|`';
        
        for(Integer i = 0; i<specialChars.split('|').size(); i++){
            searchString = searchString.replace(specialChars.split('|')[i], '');
        }
        
        return searchString;
        
    }

    @RemoteAction
    public static Wrapper compare (Id accountId){

        Wrapper w = new Wrapper();

        try{

            Account context = [SELECT Id, Name FROM Account WHERE Id = :accountId LIMIT 1];

            List<String> source = tokenize(cleanString(context.Name.toUpperCase()));
        
            List <Match> matches = new List<Match>();

            for(RegOInsiders__c r: [SELECT Id, Name FROM RegOInsiders__c WHERE RecordType.DeveloperName = 'Current']){

                List <String> target = tokenize(cleanString(r.Name.toUpperCase()));

                Integer intersection = 0;
                Integer union = source.size() + target.size();

                for(Integer o = 0; o < source.size(); o++){
                    for(Integer i = 0; i < target.size(); i++){
                        if(source[o] == target[i]){
                            intersection++;
                            target.remove(i);
                            break;
                        }
                    }
                }

                Match m = new Match();
                m.accountName = r.Name;     
                m.similarity = (2.0 * intersection) / union;
                if(m.similarity !=0)
                {
                    matches.add(m);
                }
                
                         
            }

            String[] messages = new String[]{'All Reg-O insiders compared and retrieved!'};

            w.success = true;
            w.message = messages;
            w.response = matches;

        }catch(Exception ex){

            String[] messages = new String[]{ex.getMessage()};

            w.success = false;
            w.message = messages;

        }
    
        return w;

    }

    @RemoteAction
    public static Wrapper record (Id accountId, String data){

        Wrapper w = new Wrapper();

        try{
        
            Datetime d = Datetime.now();     
            String now = d.format('yyyy-MM-dd_HH-mm-ss');

            Boolean match = false;
            Account context = [SELECT Id, Name FROM Account WHERE Id = :accountId LIMIT 1];

            List<Match> matches = (List<Match>)JSON.deserialize(data, List<Match>.class);

            for(Match m: matches){
                if(m.similarity > .80){
                    match = true;
                }
            }
        
            Regulation_O_Check_History__c insertRegulationOCheckHistory = new Regulation_O_Check_History__c();
            insertRegulationOCheckHistory.Associated_Account__c = context.Id;
            insertRegulationOCheckHistory.Match__c = match;
        
            INSERT insertRegulationOCheckHistory; 
            Regulation_O_Check_History__c regulationOCheckHistory = [SELECT Id, Name FROM Regulation_O_Check_History__c WHERE Id = :insertRegulationOCheckHistory.Id];

            String csv = 'Comparing Against:,' + context.Name + '\n';
            csv += '\n';
            csv += 'Insider,% Similarity\n';
            for(Match m: matches){
                csv += m.accountName.escapeCSV() + ',' + m.similarity + '\n';
            }

            Blob blobCSV = Blob.valueOf(csv);
    
            Attachment attachment = new Attachment();
            attachment.ParentId = regulationOCheckHistory.Id;
            attachment.Name = context.Name + '_' + regulationOCheckHistory.Name + '_' + now + '.csv';
            attachment.ContentType = 'application/csv';
            attachment.Body = blobCSV;

            INSERT attachment; 

            String[] messages = new String[]{
                'Created Reg-O Check History Record',
                '/' + regulationOCheckHistory.Id
            };

            w.success = true;
            w.message = messages;

        }catch(Exception ex){
      
            String[] messages = new String[]{ex.getMessage()};

            w.success = true;
            w.message = ex.getMessage();

        }

        return w;
          
    }

    public RegulationOCheckCtrl(ApexPages.StandardController ctrl){}

}
Your helpp is really appreciated