export type OspfNeighborState = "Full" | "2-Way" | "ExStart" | "Down" | "Attempt" | "Init" | "Exchange" | "Loading" | "Unknown"
export type BfdState = "Up" | "Down" | "Init" | "AdminDown" | "Unknown"
const neighborStates: Record<string, OspfNeighborState> = { full: "Full", "2-way": "2-Way", exstart: "ExStart", down: "Down", attempt: "Attempt", init: "Init", exchange: "Exchange", loading: "Loading" }
const bfdStates: Record<string, BfdState> = { up: "Up", down: "Down", init: "Init", admindown: "AdminDown" }
export function normalizeOspfState(value: string): OspfNeighborState { return neighborStates[value.trim().toLowerCase()] ?? "Unknown" }
export function normalizeBfdState(value: string): BfdState { return bfdStates[value.trim().toLowerCase()] ?? "Unknown" }
export function ospfNodeState(states: OspfNeighborState[]): "Full" | "2-Way" | "Pending" | "Down" | "Unknown" | "none" {
  if (!states.length) return "none"
  if (states.includes("Full")) return "Full"
  if (states.includes("Unknown")) return "Unknown"
  if (states.includes("2-Way")) return "2-Way"
  if (states.some(state => state !== "Down")) return "Pending"
  return "Down"
}

/** Correlate only a single observed direct BFD session on an explicitly configured interface. */
export function ospfBfdConflicts<T extends { localRouter: string; localIface: string; neighborAddress?: string; state: OspfNeighborState; dataUnknown?: boolean }>(
  neighbors: T[],
  interfaces: Array<{ serverId: string; interfaceName: string; useBfd?: boolean | null; active?: boolean | null; dataUnknown?: boolean }>,
  sessions: Array<{ serverId: string; iface: string; remoteAddr: string; state: BfdState; multihop?: boolean | null; dataUnknown?: boolean }>,
): T[] {
  const ip = (value: string, iface: string): string | null => {
    const [address, zone, ...extra] = value.trim().split("%")
    if (!address || extra.length || (zone !== undefined && zone !== iface)) return null
    if (address.includes(":")) {
      if (!/^[0-9a-f:.]+$/i.test(address)) return null
      try { return new URL(`http://[${address}]/`).hostname } catch { return null }
    }
    const parts = address.split(".")
    return parts.length === 4 && parts.every(p => /^(0|[1-9]\d{0,2})$/.test(p) && Number(p) <= 255) ? address : null
  }
  return neighbors.filter(n => {
    if (n.dataUnknown || n.state !== "Full" || !n.neighborAddress || !n.localIface) return false
    if (!interfaces.some(i => !i.dataUnknown && i.active === true && i.useBfd === true && i.serverId === n.localRouter && i.interfaceName === n.localIface)) return false
    const peer = ip(n.neighborAddress, n.localIface)
    if (!peer) return false
    const matching = sessions.filter(s => s.multihop === false && s.serverId === n.localRouter && s.iface === n.localIface && ip(s.remoteAddr, s.iface) === peer)
    return matching.length === 1 && !matching[0]!.dataUnknown && (matching[0]!.state === "Down" || matching[0]!.state === "AdminDown")
  })
}