Implemented a basic extraction loop

1 files changed, 76 insertions, 0 deletions

diff --git a/lib/api.js b/lib/api.js
new file mode 100644
index 0000000..b1cdcb8
--- /dev/null
+++ b/lib/api.js
@@ -0,0 +1,76 @@
+import { getToken } from '../database/config.js';
+import { PriorityQueue } from './priority_queue.js';
+
+let busy = false; // lets us know if we are already sending api requests or not.
+let headers = undefined; // a file scope variable so that we only evaluate these once.
+let queue = new PriorityQueue(); // a priority queue to hold api calls we want to send, allows for throttling.
+
+// chain takes an array of actions as argument. For each one it sets the `next` property.
+// example action: {
+//    action: function to call,
+//    next: optional nested action object, would get overriden by this function, except for the last action,
+//    ... other attributes as required by the action function (for example ship or waypoing symbol...)
+// }
+export function chain(actions) {
+	for(let i=actions.length-1;i>0;--i) {
+		actions[i-1].next = actions[i];
+	}
+	actions[0].action(actions[0]);
+}
+
+// send takes a data object as argument
+// example data: {
+//    endpoint: the url endpoint to call,
+//    method: HTTP method for `fetch` call, defaults to 'GET',
+//    next: optional nested action object, as specified above with the chain function,
+//    payload: optional json object that will be send along with the request,
+// }
+export function send(data) {
+	if (!busy) {
+		send_this(data);
+	} else {
+		queue.enqueue(data, data.priority ? data.priority : 10);
+	}
+}
+
+function send_next() {
+	if (queue.isEmpty()) {
+		busy = false;
+	} else {
+		send_this(queue.dequeue().element);
+	}
+}
+
+function send_this(data) {
+	if (headers === undefined) {
+		const token = getToken();
+		if (token === null) {
+			throw 'Could not get token from the database. Did you init or register yet?';
+		}
+		headers = {
+			'Content-Type': 'application/json',
+			'Authorization': `Bearer ${token}`
+		};
+	}
+	let options = {
+		headers: headers,
+	};
+	if (data.method !== undefined) {
+		options['method'] = data.method;
+	}
+	if (data.payload !== undefined) {
+		options['body'] = JSON.stringify(data.payload);
+	}
+	busy = true;
+	fetch(`https://api.spacetraders.io/v2${data.endpoint}`, options)
+		.then(response => response.json())
+		.then(response => {
+			if (data.next !== undefined) { // if we have a next action, call it now
+				data.next.action(data.next, response);
+			} else { // otherwise use this debug action
+				console.log(JSON.stringify(response, null, 2));
+			}
+		})
+		.catch(err => console.error(err));
+	setTimeout(send_next, 500);
+}