WebInterface/src/main/java/com/alttd/webinterface/http/NotificationServer.java

package com.alttd.webinterface.http;

import com.alttd.webinterface.config.Config;
import com.alttd.webinterface.web_interact.FileDownloadService;
import io.javalin.Javalin;
import io.javalin.http.Context;
import io.javalin.http.HttpStatus;
import lombok.extern.slf4j.Slf4j;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Optional;
import java.util.UUID;
import java.util.concurrent.CompletableFuture;

/**
 * HTTP server that exposes the /notify/<file>.json endpoint.
 */
@Slf4j
public class NotificationServer {
    private final int port;
    private Javalin app;

    /**
     * Creates a new NotificationServer that listens on the specified port.
     *
     * @param port The port to listen on
     */
    public NotificationServer(int port) {
        this.port = port;
    }

    /**
     * Starts the server.
     */
    public void startServer() {
        try {
            app = Javalin.create(config -> {
                config.showJavalinBanner = false;
            }).start(port);

            app.get("/notify/{file}.json", this::handleNotifyRequest);
            app.get("/notify/{uuid}/{file}.json", this::handleNotifyRequestUuid);

            log.info("NotificationServer started on port {}", port);
        } catch (Exception e) {
            log.error("Failed to start NotificationServer", e);
        }
    }

    /**
     * Stops the server.
     */
    public void stopServer() {
        if (app != null) {
            app.stop();
            log.info("NotificationServer stopped");
        }
    }

    /**
     * Handles requests to the /notify/<file>.json endpoint.
     */
    private void handleNotifyRequest(Context ctx) {
        String uri = ctx.path();
        log.info("Received download request: {} {}", ctx.method(), uri);

        String fileName = ctx.pathParam("file") + ".json";
        log.info("Requested file: {}", fileName);

        CompletableFuture<Optional<byte[]>> optionalCompletableFuture = FileDownloadService.downloadFileAsync(fileName);
        downloadFile(ctx, optionalCompletableFuture);
    }

    /**
     * Handles requests to the /notify/<file>.json endpoint.
     */
    private void handleNotifyRequestUuid(Context ctx) {
        String uri = ctx.path();
        log.info("Received UUID request: {} {}", ctx.method(), uri);

        String stringUUID = ctx.pathParam("uuid");
        log.info("Requested uuid: {}", stringUUID);

        UUID uuid;
        try {
            uuid = UUID.fromString(stringUUID);
        } catch (Exception e) {
            log.error("Invalid UUID: {}", stringUUID, e);
            ctx.status(HttpStatus.BAD_REQUEST);
            ctx.contentType("text/plain");
            ctx.result("Invalid UUID format");
            return;
        }

        String fileName = ctx.pathParam("file") + ".json";
        log.info("Requested uuid file: {}", fileName);

        CompletableFuture<Optional<byte[]>> optionalCompletableFuture = FileDownloadService.downloadFileAsync(uuid, fileName);
        downloadFile(ctx, optionalCompletableFuture);
    }

    private void downloadFile(Context ctx, CompletableFuture<Optional<byte[]>> optionalCompletableFuture) {
        optionalCompletableFuture.thenAccept(fileData -> {
            if (fileData.isPresent()) {
                String fileName = ctx.pathParam("file") + ".json";
                String uuid = null;
                try {
                    uuid = ctx.pathParam("uuid");
                } catch (Exception ignored) {
                    log.debug("UUID not present");
                }

                boolean saved = saveFileToDisk(fileData.get(), fileName, uuid);

                if (saved) {
                    ctx.status(HttpStatus.OK);
                    ctx.contentType("text/plain");
                    ctx.result("File downloaded and saved successfully");
                } else {
                    ctx.status(HttpStatus.INTERNAL_SERVER_ERROR);
                    ctx.contentType("text/plain");
                    ctx.result("Failed to save file to disk");
                }
            } else {
                ctx.status(HttpStatus.NOT_FOUND);
                ctx.contentType("text/plain");
                ctx.result("File not found or download failed");
            }
        }).exceptionally(e -> {
            log.error("Error downloading file", e);
            ctx.status(HttpStatus.INTERNAL_SERVER_ERROR);
            ctx.contentType("text/plain");
            ctx.result("Failed to handle download");
            return null;
        });
    }

    /**
     * Saves the downloaded file to disk.
     *
     * @param fileData The binary content of the file
     * @param fileName The name of the file
     * @param uuid Optional UUID for organizing files
     * @return true if the file was saved successfully, false otherwise
     */
    private boolean saveFileToDisk(byte[] fileData, String fileName, String uuid) {
        try {
            Path basePath = Paths.get(Config.DOWNLOAD_DIR);

            Path filePath;
            if (uuid != null) {
                filePath = basePath.resolve(uuid).resolve(fileName);
            } else {
                filePath = basePath.resolve(fileName);
            }

            Files.createDirectories(filePath.getParent());
            Files.write(filePath, fileData);

            log.info("File saved to: {}", filePath.toAbsolutePath());
            return true;
        } catch (IOException e) {
            log.error("Error saving file to disk", e);
            return false;
        }
    }
}