package com.alttd.webinterface.web_interact;

import com.alttd.webinterface.config.Config;
import jakarta.servlet.http.HttpServletResponse;
import lombok.extern.slf4j.Slf4j;

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.util.Optional;
import java.util.concurrent.CompletableFuture;

/**
 * Service for downloading files from the configured download endpoint.
 */
@Slf4j
public class FileDownloadService {

    /**
     * Asynchronously downloads a file from the configured download endpoint.
     *
     * @param fileName The name of the file to download
     * @return A CompletableFuture containing an Optional with the file content if successful,
     *         or an empty Optional otherwise
     */
    public static CompletableFuture<Optional<byte[]>> downloadFileAsync(String fileName) {
        String downloadUrl = Config.DOWNLOAD_ENDPOINT;
        if (!downloadUrl.endsWith("/")) {
            downloadUrl += "/";
        }
        downloadUrl += fileName;

        log.debug("Downloading file from {}", downloadUrl);

        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder()
                .uri(URI.create(downloadUrl))
                .header("Authorization", "SECRET " + Config.SECRET)
                .GET()
                .build();

        return client.sendAsync(request, HttpResponse.BodyHandlers.ofByteArray())
                .thenApply(response -> {
                    if (response.statusCode() == HttpServletResponse.SC_OK) {
                        log.debug("Successfully downloaded file: {}", fileName);
                        return Optional.of(response.body());
                    } else {
                        log.error("Failed to download file: {}. Status code: {}", fileName, response.statusCode());
                        return Optional.<byte[]>empty();
                    }
                })
                .exceptionally(e -> {
                    log.error("Exception occurred while downloading file: {}", fileName, e);
                    return Optional.empty();
                });
    }
}