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

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Heap = require "heap"
module.exports = ProjectIterator =
class ProjectIterator
constructor: (packs, @before, @getPackByIdFn) ->
byEndTs = (a,b) -> (b.meta.end_ts - a.meta.end_ts) || (a.fromIndex - b.fromIndex)
@packs = packs.slice().sort byEndTs
@queue = new Heap(byEndTs)
next: (callback) ->
# what's up next
#console.log ">>> top item", iterator.packs[0]
iterator = this
before = @before
queue = iterator.queue
opsToReturn = []
nextPack = iterator.packs[0]
lowWaterMark = nextPack?.meta.end_ts || 0
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? and nextPack?.meta.start_ts > before
# discard pack that is outside range
iterator.packs.shift()
nextPack = iterator.packs[0]
lowWaterMark = nextPack?.meta.end_ts || 0
if (queue.empty() or nextItem?.meta.end_ts <= lowWaterMark) and nextPack?
# retrieve the next pack and populate the queue
return @getPackByIdFn nextPack.project_id, nextPack.doc_id, nextPack._id, (err, pack) ->
return callback(err) if err?
iterator.packs.shift() # have now retrieved this pack, remove it
#console.log "got pack", pack
for op in pack.pack when (not before? or op.meta.end_ts < before)
#console.log "adding op", op
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? and (nextItem?.meta.end_ts > lowWaterMark)
opsToReturn.push nextItem
queue.pop()
nextItem = queue.peek()
#console.log "queue empty?", queue.empty()
#console.log "nextPack", nextPack?
if queue.empty() and not nextPack? # got everything
iterator._done = true
callback(null, opsToReturn)
done: () ->
return @_done