# The app of research 119 (docs/design/018 stage 3): a graph whose
# distances a view computes in its body, beside the scoreboard's write
# (benchmarks/http/load's score) that the owner applies.
record Edge {
  link = 0
  to = 0
}
record Seen {
  node = 0
  depth = 0
}
record Step {
  node = 0
}
state edges: list of Edge by link
state nodes = 0
state points = 0
input size = message {
  nodes: u32
}
input load = message {
  rows: list of Edge
}
input score = message {
  points: u32
  name: bytes
}
input route = message {
  start: u32
  goal: u32
}
on size {
  nodes = size.nodes
}
on load {
  for r in load.rows {
    edges.add(Edge { ..r })
  }
}
on score {
  points = points + score.points
}
# The same search as an event, on the owner (to compare).
on route {
  let seen: list of Seen by node
  let queue: list of Step
  queue.append(Step { node: route.start })
  seen.add(Seen { node: route.start })
  for i in 0 .. nodes {
    if i >= queue.count { break }
    let q = queue.first + i
    for e in edges[q.node * 1048576 .. q.node * 1048576 + 1048576] {
      if !seen.has(e.to) {
        seen.add(Seen { node: e.to, depth: seen[q.node].depth + 1 })
        queue.append(Step { node: e.to })
      }
    }
  }
  hops = if seen.has(route.goal) { seen[route.goal].depth } else { -1 }
}
state hops = -1
view total = points
view distance(start: u32, goal: u32) {
  let seen: list of Seen by node
  let queue: list of Step
  queue.append(Step { node: start })
  seen.add(Seen { node: start })
  for i in 0 .. nodes {
    if i >= queue.count { break }
    let q = queue.first + i
    for e in edges[q.node * 1048576 .. q.node * 1048576 + 1048576] {
      if !seen.has(e.to) {
        seen.add(Seen { node: e.to, depth: seen[q.node].depth + 1 })
        queue.append(Step { node: e.to })
      }
    }
  }
  return if seen.has(goal) { seen[goal].depth } else { -1 }
}