package eg.edu.alexu.csd.oop.CheckingQuery;
import com.sun.org.apache.xpath.internal.operations.Bool;

import java.util.regex.Matcher;
import java.util.regex.Pattern;



public class checkingInputs {
    Pattern pattern1;
    Matcher matcher1;

    static String RI1 = "INSERT +INTO +([a-zA-Z_][a-zA-Z0-9_]*) *\\( *(([a-zA-Z_][a-zA-Z0-9_]*)( *, *([a-zA-Z_][a-zA-Z0-9_]*))*) *\\) *"
            + "VALUES *\\( *((('[^']+')|(\\d+)|(\"[^\"]+\"))( *, *(('[^']+')|(\\d+)|(\"[^\"]+\")))*) *\\) *;*";
    static String RI2 = "INSERT +INTO +([a-zA-Z_][a-zA-Z0-9_]*) *"
            + "VALUES *\\( *((('[^']+')|(\\d+)|(\"[^\"]+\"))( *, *(('[^']+')|(\\d+)|(\"[^\"]+\")))*) *\\) *;*";
    static String RCT = "CREATE+\\s+TABLE+\\s+([a-zA-Z_][a-zA-Z0-9_]*) *\\( *([a-zA-Z_][a-zA-Z0-9_]* + *(int|varchar))( *, *([a-zA-Z_][a-zA-Z0-9_]* *+(int|varchar)))* *\\) *;";
    static String RDD = "DROP\\s*+DATABASE\\s*+([A-Za-z_][A-Za-z0-9_]*) *;";
    static String RDT = "DROP\\s*+DATABASE\\s*+([A-Za-z_][A-Za-z0-9_]*) *;";
    static String RC = "CREATE\\s*+DATABASE\\s*+([A-Za-z_][A-Za-z0-9_]*) *;";
    static String RD1 = "DELETE +FROM +([a-zA-Z_][a-zA-Z0-9_]*) +WHERE +(.+) *;";
    static String RD2 = "DELETE +FROM +([a-zA-Z_][a-zA-Z0-9_]*) *;";
    static String RS1 = "SELECT\\s*+(\\*) +FROM\\s*+([A-Za-z_][A-Za-z0-9_]*) +WHERE +([^;]+)*+;";
    static String RS2 = "SELECT\\s*+(\\*) +FROM\\s*+([A-Za-z_][A-Za-z0-9_]*)*+;";
    static String RS3 = "SELECT\\s*+(([A-Za-z_][A-Za-z0-9_]*)( *, *[A-Za-z_][A-Za-z0-9_]*)*) +FROM\\s*+([A-Za-z_][A-Za-z0-9_]*)*+;";
    static String RS4 = "SELECT\\s*+(([A-Za-z_][A-Za-z0-9_]*)( *, *[A-Za-z_][A-Za-z0-9_]*)*) +FROM\\s*+([A-Za-z_][A-Za-z0-9_]*) +WHERE +([^;]+)*+;";
    static String RU1 = "UPDATE+\\s+([a-zA-Z_][a-zA-Z0-9_]*)+\\s+SET+\\s+([a-zA-Z_][a-zA-Z0-9_]*) *= *(('[^']+')|(\\d+)|(\"[^\"]+\"))"
            + "( *, *([A-Za-z_][A-Za-z0-9_]*) *= *((\".+\")|('.+')|(\\d+)))* +WHERE +([^;]+) *;";
    static String RU2 = "UPDATE+\\s+([a-zA-Z_][a-zA-Z0-9_]*)+\\s+SET+\\s+([a-zA-Z_][a-zA-Z0-9_]*) *= *(('[^']+')|(\\d+)|(\"[^\"]+\"))"
            + "( *, *([A-Za-z_][A-Za-z0-9_]*) *= *((\".+\")|('.+')|(\\d+)))* *;";

    static String[] Regex = new String[]{RI1,RI2,RCT,RDD,RDT,RC,RD1,RD2,RS1,RS2,RS3,RS4,RU1,RU2};

    public static boolean sytnaxVlidator(String sqlQueries, String operation) {
        boolean check=false;
        String REGEX = "((CREATE +TABLE)|(CREATE +DATABASE)|(DROP +TABLE)|(DROP +DATABASE)|(UPDATE +FROM)|(SELECT +FROM)|(INSERT +INTO)|(DELETE +FROM)).*";
        Pattern pattern = Pattern.compile(REGEX, Pattern.CASE_INSENSITIVE);
        Matcher m = pattern.matcher(sqlQueries);
        if (m.matches()) {
            String keyWord = m.group(1);
            keyWord = keyWord.toUpperCase();
            keyWord = keyWord.replaceAll(" +", "");
            if (keyWord.equals(operation.toUpperCase())) {
                check=inputParser(sqlQueries);
            }
        } else {
            System.out.println("syntax error");
        }
        return check;
    }

    public static boolean inputParser(String query){
        Pattern pattern1;
        Matcher matcher1;
        for(int i=0;i<Regex.length;i++){
            pattern1 = Pattern.compile(Regex[i], Pattern.CASE_INSENSITIVE);
            matcher1 = pattern1.matcher(query);
            if (matcher1.matches())
                return true;
        }
        return false;
    }
}