Mongo query find top sellers from array

Mongo query find top sellers from array

I'm pretty new to Mongo, I'm having trouble figure out how to write this
query. I have an order collection that looks like this.
{
"_id" : ObjectId("51fade5b8c825bb19d9ef228"),
"o_id" : 1,
...
"order_line" : [
{
"ol_id" : 1,
"ol_o_id" : 1,
"ol_i_id" : 531,
"ol_qty" : 280
},
{
"ol_id" : 2,
"ol_o_id" : 1,
"ol_i_id" : 90,
"ol_qty" : 295
},
{
"ol_id" : 3,
"ol_o_id" : 1,
"ol_i_id" : 963,
"ol_qty" : 184
}
]}
I need to find the top selling related items for each item.
The query needs to find the top 5 items/ol_i_id's that are sold WITH the
ol_i_id that is currently being queried. In order to do so the query would
need to find all orders with the "ol_i_id" in question, say "ol_i_id" :
531, then sum the "ol_qty" of each item sold with "ol_i_id" : 531 over the
entire collection. Then report back with with the top 5 "ol_i_id" that are
sold with "ol_i_id":531.
I tried to make that as understandable as possible.