package com.minicircuits.formatter;

import com.minicircuits.QueryResult;
import com.minicircuits.Utils;
import java.io.*;
import java.nio.charset.StandardCharsets;
import java.sql.SQLException;
import java.sql.Types;
import java.util.Properties;
import javax.servlet.http.HttpServletResponse;

public class JsonFormatter implements ResponseFormatter {

    public JsonFormatter(Properties configProps) {
        // configProps not needed by this formatter
    }

    @Override
    public void format(HttpServletResponse response, QueryResult result) throws IOException, SQLException {
        response.setContentType("application/json");
        response.setCharacterEncoding("UTF-8");
        response.setBufferSize(8192);

        try (BufferedOutputStream bos = new BufferedOutputStream(response.getOutputStream(), 8192);
             OutputStreamWriter osw = new OutputStreamWriter(bos, StandardCharsets.UTF_8)) {

            int colCount = result.metadata.getColumnCount();
            osw.write("[");
            boolean firstRow = true;
            int rowCount = 0;

            while (result.resultSet.next()) {
                if (!firstRow) {
                    osw.write(",");
                }
                firstRow = false;

                osw.write("{");
                for (int i = 1; i <= colCount; i++) {
                    if (i > 1) osw.write(",");
                    String columnName = result.metadata.getColumnName(i);
                    String value = result.resultSet.getString(i);

                    int columnType = result.metadata.getColumnType(i);
                    String columnTypeName = result.metadata.getColumnTypeName(i);

                    osw.write("\"");
                    osw.write(Utils.escapeJson(columnName));
                    osw.write("\":");
                    if (value == null) {
                        osw.write("null");
                    } else if (Utils.isNumericType(columnType, columnTypeName)) {
                        try {
                            String trimmed = value.trim();
                            if (columnType == Types.FLOAT
                                    || columnType == Types.DOUBLE
                                    || columnType == Types.REAL
                                    || result.metadata.getScale(i) > 0) {
                                osw.write(String.valueOf(Double.parseDouble(trimmed)));
                            } else {
                                osw.write(String.valueOf(Long.parseLong(trimmed)));
                            }
                        } catch (NumberFormatException e) {
                            osw.write("\"");
                            osw.write(Utils.escapeJson(Utils.rightTrim(value)));
                            osw.write("\"");
                        }
                    } else if (columnType == Types.BOOLEAN) {
                        osw.write(String.valueOf(result.resultSet.getBoolean(i)));
                    } else {
                        osw.write("\"");
                        osw.write(Utils.escapeJson(Utils.rightTrim(value)));
                        osw.write("\"");
                    }
                }
                osw.write("}");
                rowCount++;

                if (rowCount % 1000 == 0) {
                    osw.flush();
                }
            }

            osw.write("]");
            osw.flush();
        }
    }
}