package com.megatim.fdxcommons.tools.database.queries;

import com.megatim.fdxcommons.tools.database.queries.metadata.QueryCriterion;
import com.megatim.fdxcommons.tools.database.contrat.DefaultPreparedStatementProcessor;
import com.megatim.fdxcommons.tools.database.contrat.QueryMetaData;
import com.megatim.fdxcommons.tools.database.queries.metadata.WhereQueryParameters;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.IntStream;

/**
 *
 * @author Gabuntu
 */
public class CountQuery implements QueryMetaData<List<String[]>> {

    private final String tableName;
    private final Connection connection;
    private final QueryCriterion queryCriterion;
    private final List<String> groupingColumns;

    public CountQuery(String tableName, Connection connection, QueryCriterion queryCriterion, List<String> groupingColumns) {
        this.tableName = tableName;
        this.connection = connection;
        this.queryCriterion = queryCriterion;
        this.groupingColumns = groupingColumns;
    }

    @Override
    public List<String[]> execute() throws Exception {

        System.out.println("<------------------------------------------------------------------------------------------------------------------------------->");
        System.out.println(countQuery());
        System.out.println("<------------------------------------------------------------------------------------------------------------------------------->");

        try ( PreparedStatement statement = connection.prepareStatement(countQuery())) {

            new DefaultPreparedStatementProcessor().process(statement, new WhereQueryParameters(queryCriterion).parameters());

            try ( ResultSet resultSet = statement.executeQuery()) {

                List<String[]> results = new ArrayList<>();

                while (resultSet.next()) {

                    String[] result = new String[groupingColumns.size() + 1];
                    result[0] = resultSet.getString(countColumnName());
                    for (int i = 0; i < groupingColumns.size(); i++) {

                        String r = resultSet.getString(groupingColumns.get(i));
                        result[i + 1] = r != null ? r : "";
                    }

                    results.add(result);
                }

                return results;
            }
        }
    }

    private String countQuery() {
        StringBuilder query = new StringBuilder("SELECT COUNT(*) AS " + countColumnName() + groupingColumnsSelection() + " FROM ").append(tableName);
        query.append(new WhereQueryString(queryCriterion).query());

        query.append(new GroupByQuery(groupingColumns).query());
        return query.toString();
    }

    private String countColumnName() {
        return tableName + "_count";
    }

    private String groupingColumnsSelection() {
        StringBuilder query = new StringBuilder();

        int size = groupingColumns.size();
        if (size > 0) {
            query.append(", ");
        }
        IntStream.range(0, size).forEach(index -> {
            String column = groupingColumns.get(index);
            query.append(column);
            if ((index + 1) < size) {
                query.append(",");
            }
        });

        return query.toString();
    }

}