RequestBuilder.java

package io.github.ModularEnigma;

import java.time.Duration;
import java.util.HashMap;
import java.util.Map;

public class RequestBuilder {
    private String url;
    private Request.Method requestMethod;
    private String requestBody;
    private Duration timeout;
    private final Map<String, String> headers;

    public RequestBuilder() {
        headers = new HashMap<>();
    }

    /**
     * Add a header to the request. Note: Accept and Content-Type are already set to use JSON.
     *
     * @param header Header to set
     * @param value Value of the header
     * @return {@link RequestBuilder}
     * @throws IllegalArgumentException If the header or value is null
     */
    public RequestBuilder addHeader(String header, String value) {
        if (header == null) {
            throw new IllegalArgumentException("Header cannot be null.");
        } else if (value == null) {
            throw new IllegalArgumentException("Header value cannot be null.");
        }
        headers.put(header, value);
        return this;
    }

    /**
     * Set the url of the Request. Validity of the url is checked in {@link RequestBuilder#build()}.
     *
     * @param url The url of the website we will be sending a request to
     * @return {@link RequestBuilder}
     * @throws IllegalArgumentException If the url is null
     */
    public RequestBuilder setURL(String url) throws IllegalArgumentException {
        if (url == null) {
            throw new IllegalArgumentException("url cannot be null.");
        }
        this.url = url;
        return this;
    }

    /**
     * Sets the request method for the request
     *
     * @param requestMethod The Method of the request.
     * @return {@link RequestBuilder}
     */
    public RequestBuilder setMethod(Request.Method requestMethod) throws IllegalArgumentException {
        if (requestMethod == null) {
            throw new IllegalArgumentException("requestMethod cannot be null.");
        }
        this.requestMethod = requestMethod;
        return this;
    }

    /**
     * Set the contents of the request. Only useful for requests that support content
     * such as POST requests.
     *
     * @param body The body of the request
     * @return {@link RequestBuilder}
     * @throws IllegalArgumentException If body is null
     */
    public RequestBuilder setRequestBody(String body) throws IllegalArgumentException {
        if (body == null) {
            throw new IllegalArgumentException("body cannot be null.");
        }
        this.requestBody = body;
        return this;
    }

    /**
     * Sets a timeout for the request. If the server does not respond within this duration,
     * the request will throw a {@link java.net.http.HttpTimeoutException}.
     *
     * @param timeout The maximum time to wait for a response
     * @return {@link RequestBuilder}
     * @throws IllegalArgumentException If timeout is null or non-positive
     */
    public RequestBuilder setTimeout(Duration timeout) {
        if (timeout == null) {
            throw new IllegalArgumentException("timeout cannot be null.");
        } else if (timeout.isNegative() || timeout.isZero()) {
            throw new IllegalArgumentException("timeout must be positive.");
        }
        this.timeout = timeout;
        return this;
    }

    /**
     * Builds the {@link Request} object if the {@link RequestBuilder} has been given enough
     * information to do so.
     *
     * @return A {@link Request} instance containing all data added to the {@link RequestBuilder}
     * @throws IllegalStateException If the url has not been set. If the requestMethod has not been
     *                               set.
     */
    public Request build() throws IllegalStateException {
        if (url == null) {
            throw new IllegalStateException("url is required.");
        } else if (requestMethod == null) {
            throw new IllegalStateException("requestMethod is required.");
        }
        return new Request(url, requestMethod, requestBody, headers, timeout);
    }
}