import "@fluencelabs/aqua-lib/builtin.aqua"

-- per-node timeout to decide if it's down
const TIMEOUT = 2000

-- simple timestamp getter for kademlia neigborhood which is max size 20
func collect_timestamps_from_neighborhood() -> []u64, []PeerId:
  timestamps: *u64
  statuses: *string
  dead_peers: *PeerId
  -- on this peer
  on HOST_PEER_ID:
    -- convert peer id to b58
    k <- Op.string_to_b58(HOST_PEER_ID)
    -- get all neighbors
    nodes <- Kademlia.neighborhood(k, nil, nil)
    -- for each neighbor
    for n <- nodes par:
      status: *string
      -- on selected neighbor peer
      on n:
        -- get the timestamp from that node
        timestamps <- Peer.timestamp_ms()
        status <<- "ok"
      -- run timeout task in parallel, so if node `n` is down, we'll get `timed out` status
      -- this pattern is documented: https://doc.fluence.dev/aqua-book/language/flow/parallel#timeout-and-race-patterns 
      par status <- Peer.timeout(TIMEOUT, "timed out")
      statuses <<- status!
      if status! != "ok":
        dead_peers <<- n
    
    -- wait for all nodes to respond or timeout
    length <- Op.array_length(nodes)
    if length != 0:
      join statuses[length - 1]
  <- timestamps, dead_peers