"use strict";

const chalk = require("chalk");
const pipe = require("@promistream/pipe");
const filter = require("@promistream/filter");
const map = require("@promistream/map");

const logStatus = require("./log-status");

module.exports = function ({ backend }) {
	function runTask(task, item) {
		let queue = [];
		let api = backend.forItem({ task: task, id: item.id, mutationQueue: queue });

		return Promise.try(() => {
			logStatus(task, chalk.bold.cyan, "started", item.id);

			// NOTE: We only pass in the item data itself, *not* any associated metadata like tags. If the scraping task wants access to that sort of information, it should do a `getItem` call from within its task logic where needed.
			// FIXME: Is that actually still true post-refactor?
			task.run({
				data: item.data,
				... api.exposed
			});
		}).then(() => {
			return backend.topLevel.runInTransaction((tx) => {
				
				// FIXME: use queue
			});
		}).then(async () => {
			await api.internal.markTaskCompleted();
			logStatus(task, chalk.bold.green, "completed", item.id);
			return { status: "completed", item: item };
		}).catch(async (error) => {
			await api.internal.markTaskFailed(null, { error });
			logStatus(task, chalk.bold.red, "failed", `${item.id}: ${error.stack}`);
			return { status: "failed", item: item, error: error };
		});
	}

	return function createTaskKernelStream(task) {
		return pipe([
			backend.topLevel.getTaskStream(null, { task: task }),
			filter((item) => backend.forItem({ task: task, id: item.id }).internal.lock()),
			map((item) => {
				return Promise.try(() => {
					return runTask(task, item);
				}).tap(() => {
					return backend.forItem({ task: task, id: item.id }).internal.unlock();
				});
			})
		]);
	};
};