create-schematic-gen-site/source/app.d

import handy_httpd;
import handy_httpd.handlers.path_delegating_handler;
import handy_httpd.handlers.file_resolving_handler;
import slf4d;
import slf4d.default_provider;
import std.path;
import std.file;
import std.json;

const EXTRACTS_DIR = "extracts";
const EXTRACT_FILENAME = "__EXTRACT__.json";
const EXTRACT_COMMAND = ["java", "-jar", "materials-extractor-v1.0.0.jar"];

void main() {
	auto provider = new shared DefaultProvider(true, Levels.INFO);
	configureLoggingProvider(provider);
	info("Starting create-schematic-gen-site API.");

	ServerConfig config = ServerConfig.defaultValues();
	config.workerPoolSize = 3;
	config.connectionQueueSize = 10;
	config.port = 8100;

	PathDelegatingHandler handler = new PathDelegatingHandler();
	handler.addMapping("POST", "/extracts", &handleExtract);
	handler.addMapping("GET", "/extracts/{extractId}", &getExtract);

	FileResolvingHandler fileHandler = new FileResolvingHandler("site", DirectoryResolutionStrategies.serveIndexFiles);
	handler.addMapping("/**", fileHandler);
	new HttpServer(handler, config).start();
}

void handleExtract(ref HttpRequestContext ctx) {
	import std.json;
	import std.uuid;
	import std.process;
	import std.stdio;

	immutable UUID extractId = randomUUID();
	MultipartFormData data = ctx.request.readBodyAsMultipartFormData();
	if (!validateExtractRequest(data, ctx.response)) return;
	const extractDir = buildPath(EXTRACTS_DIR, extractId.toString());
	if (!exists(extractDir)) {
		mkdirRecurse(extractDir);
	}
	string[] filenames;
	uint[] counts;
	foreach (MultipartElement element; data.elements) {
		if (element.name == "schematics") {
			const filePath = buildPath(extractDir, element.filename.get());
			std.file.write(filePath, element.content);
			filenames ~= filePath;
		} else if (element.name == "counts") {
			import std.conv;
			immutable uint count = element.content.to!uint;
			counts ~= count;
		}
	}
	
	infoF!"Running extract process on files: %s"(filenames);
	auto extractionResult = execute(EXTRACT_COMMAND ~ filenames);
	immutable int exitCode = extractionResult.status;
	infoF!"Exit code: %d"(exitCode);
	rmdirRecurse(extractDir);
	if (exitCode != 0) {
		ctx.response.setStatus(HttpStatus.INTERNAL_SERVER_ERROR);
		ctx.response.writeBodyString(extractionResult.output);
	} else {
		const extractJsonPath = extractDir ~ ".json";
		// It was successful, so add __COUNT__ to each object in the extract data.
		JSONValue extractData = parseJSON(extractionResult.output);
		for (uint i = 0; i < extractData.array.length; i++) {
			extractData.array[i].object["__COUNT__"] = JSONValue(counts[i]);
		}
		std.file.write(extractJsonPath, extractData.toPrettyString());

		JSONValue result = JSONValue.emptyObject;
		result.object["extractId"] = JSONValue(extractId.toString());
		ctx.response.writeBodyString(result.toJSON(), "application/json");
	}
}

private bool validateExtractRequest(ref MultipartFormData data, ref HttpResponse response) {
	if (data.elements.length < 2) {
		response.setStatus(HttpStatus.BAD_REQUEST);
		response.writeBodyString("Requires at least 2 form data elements (schematic file and count).");
		return false;
	}
	uint nextElementIdx = 0;
	while (nextElementIdx < data.elements.length) {
		MultipartElement element = data.elements[nextElementIdx++];
		if (element.name == "schematics") {
			if (element.filename.isNull || element.filename.get().length < 5 || element.content.length < 10) {
				response.setStatus(HttpStatus.BAD_REQUEST);
				response.writeBodyString("Invalid or missing schematic file.");
				return false;
			}
			const string filename = element.filename.get();
			if (nextElementIdx == data.elements.length) {
				response.setStatus(HttpStatus.BAD_REQUEST);
				response.writeBodyString("Missing count element for schematic: " ~ filename);
				return false;
			}
			MultipartElement countElement = data.elements[nextElementIdx++];
			import std.conv;
			try {
				immutable uint count = countElement.content.to!uint;
				if (count < 1 || count > 1000) throw new Exception("out of range: count should be between 1 and 1000, inclusive.");
			} catch (Exception e) {
				response.setStatus(HttpStatus.BAD_REQUEST);
				response.writeBodyString("Invalid count element: " ~ e.msg);
				return false;
			}
		} else if (element.name == "processing-terminal") {
			// TODO: Check processing-terminal format.
		} else {
			response.setStatus(HttpStatus.BAD_REQUEST);
			response.writeBodyString("Unknown element: " ~ element.name);
			return false;
		}
	}

	return true;
}

void getExtract(ref HttpRequestContext ctx) {
	string extractId = ctx.request.getPathParamAs!string("extractId");
	const extractFile = buildPath(EXTRACTS_DIR, extractId ~ ".json");
	fileResponse(ctx.response, extractFile, "application/json");
}