package vn.sis.appointment;

import com.sun.net.httpserver.HttpExchange;

import java.io.IOException;
import java.net.URLDecoder;
import java.nio.charset.StandardCharsets;
import java.util.LinkedHashMap;
import java.util.Map;

final class FormData {
    private static final int MAX_REQUEST_BYTES = 256 * 1024;

    private FormData() {
    }

    static Map<String, String> read(HttpExchange exchange) throws IOException {
        byte[] data = exchange.getRequestBody().readNBytes(MAX_REQUEST_BYTES + 1);
        if (data.length > MAX_REQUEST_BYTES) {
            throw new IllegalArgumentException("Du lieu gui len vuot qua gioi han 256 KB.");
        }

        String body = new String(data, StandardCharsets.UTF_8);
        Map<String, String> result = new LinkedHashMap<>();
        if (body.isBlank()) {
            return result;
        }

        for (String pair : body.split("&")) {
            int separator = pair.indexOf('=');
            String rawKey = separator >= 0 ? pair.substring(0, separator) : pair;
            String rawValue = separator >= 0 ? pair.substring(separator + 1) : "";
            result.put(decode(rawKey), decode(rawValue));
        }
        return result;
    }

    private static String decode(String value) {
        return URLDecoder.decode(value, StandardCharsets.UTF_8);
    }
}