overleaf/services/track-changes/app/coffee/ProjectIterator.js

/*
 * decaffeinate suggestions:
 * DS101: Remove unnecessary use of Array.from
 * DS102: Remove unnecessary code created because of implicit returns
 * DS207: Consider shorter variations of null checks
 * Full docs: https://github.com/decaffeinate/decaffeinate/blob/master/docs/suggestions.md
 */
let ProjectIterator;
const Heap = require("heap");

module.exports = (ProjectIterator =

	(ProjectIterator = class ProjectIterator {
		constructor(packs, before, getPackByIdFn) {
			this.before = before;
			this.getPackByIdFn = getPackByIdFn;
			const byEndTs = (a,b) => (b.meta.end_ts - a.meta.end_ts) || (a.fromIndex - b.fromIndex);
			this.packs = packs.slice().sort(byEndTs);
			this.queue = new Heap(byEndTs);
		}

		next(callback) {
			//  what's up next
			//console.log ">>> top item", iterator.packs[0]
			const iterator = this;
			const { before } = this;
			const { queue } = iterator;
			const opsToReturn = [];
			let nextPack = iterator.packs[0];
			let lowWaterMark = (nextPack != null ? nextPack.meta.end_ts : undefined) || 0;
			let nextItem = queue.peek();

			//console.log "queue empty?", queue.empty()
			//console.log "nextItem", nextItem
			//console.log "nextItem.meta.end_ts", nextItem?.meta.end_ts
			//console.log "lowWaterMark", lowWaterMark

			while ((before != null) && ((nextPack != null ? nextPack.meta.start_ts : undefined) > before)) {
				// discard pack that is outside range
				iterator.packs.shift();
				nextPack = iterator.packs[0];
				lowWaterMark = (nextPack != null ? nextPack.meta.end_ts : undefined) || 0;
			}

			if ((queue.empty() || ((nextItem != null ? nextItem.meta.end_ts : undefined) <= lowWaterMark)) && (nextPack != null)) {
				// retrieve the next pack and populate the queue
				return this.getPackByIdFn(nextPack.project_id, nextPack.doc_id, nextPack._id, function(err, pack) {
					if (err != null) { return callback(err); }
					iterator.packs.shift(); // have now retrieved this pack, remove it
					//console.log "got pack", pack
					for (let op of Array.from(pack.pack)) {
						//console.log "adding op", op
						if ((before == null) || (op.meta.end_ts < before)) {
							op.doc_id = nextPack.doc_id;
							op.project_id = nextPack.project_id;
							queue.push(op);
						}
					}
					// now try again
					return iterator.next(callback);
				});
			}

			//console.log "nextItem", nextItem, "lowWaterMark", lowWaterMark
			while ((nextItem != null) && ((nextItem != null ? nextItem.meta.end_ts : undefined) > lowWaterMark)) {
				opsToReturn.push(nextItem);
				queue.pop();
				nextItem = queue.peek();
			}

			//console.log "queue empty?", queue.empty()
			//console.log "nextPack", nextPack?

			if (queue.empty() && (nextPack == null)) { // got everything
				iterator._done = true;
			}

			return callback(null, opsToReturn);
		}

		done() {
			return this._done;
		}
	}));