-- M003: Routing Cost Kernel Module
-- Source: nuvmap_routing_v2 (3-Mathematical-Models)
-- Kernel Function: MemoryRouter
--
-- Routing cost metric C(route) = Σ (distance × traffic_density × energy_factor)
-- Truth Seal: [ SSS-ENE-ROUTING-2026-05-03 ]

module M003_RoutingCost where

import BaseTypes
import NUVMAPKernelIntegration (NUVMAPCoordinate, computeNUVMAPPath, nuvmapDistance)
import Semantics.Q0_16 (Q0_16)

structure RouteNode where
  coord     : NUVMAPCoordinate
  traffic   : Q0_16          -- Current load [0,1]
  energy    : Q0_16          -- Energy per packet [0,1]
  bandwidth : Q0_16          -- Available bandwidth [0,1]
  
def routeCost (route : Array RouteNode) : Q0_16 :=
  route.windows(2).foldl (\acc (a,b) =>
    let dist := nuvmapDistance a.coord b.coord
    let loadFactor := Q0_16.div a.traffic a.bandwidth
    let energyFactor := a.energy
    acc + (dist × loadFactor × energyFactor)
  ) Q0_16.zero

-- Kernel interface: select route with minimum cost
def syscallSelectRoute (src : NUVMAPCoordinate) (dst : NUVMAPCoordinate) : IO Route := do
  let candidates ← findAllRoutes src dst MAX_ROUTE_HOPS
  let scored := candidates.map (\r => { route := r, cost := routeCost r })
  let best := scored.minBy (\s => s.cost)
  
  return {
    path := best.route
    expectedCost := best.cost
    alternatives := scored.filter (\s => s.cost < best.cost × 1.5)
  }

end M003_RoutingCost