/**
 * @module mcp-server/tools/topology
 * MCP Tool: AS-level topology — graph analysis, submarine cables, facilities.
 *
 * Provides AS topology visualization data, submarine cable mapping, and
 * facility/colocation analysis using CAIDA, PeeringDB, and bgproutes.io data.
 */

import { z } from "zod";
import type { ASN } from "../../types/common.js";

// ── Tool Schemas ─────────────────────────────────────────

/** Input schema for AS graph query */
export const asGraphSchema = z.object({
  asn: z
    .union([z.string(), z.number()])
    .describe("Center ASN for the graph (e.g., 13335)"),
  depth: z
    .number()
    .optional()
    .default(2)
    .describe("Graph depth (hops from center ASN, default: 2)"),
  includeCustomers: z
    .boolean()
    .optional()
    .default(true)
    .describe("Include customer ASes in the graph"),
  includeProviders: z
    .boolean()
    .optional()
    .default(true)
    .describe("Include provider ASes in the graph"),
  includePeers: z
    .boolean()
    .optional()
    .default(true)
    .describe("Include peering ASes in the graph"),
});

/** Input schema for submarine cable lookup */
export const submarineCableSchema = z.object({
  region: z
    .string()
    .optional()
    .describe("Geographic region to filter (e.g., 'transatlantic', 'transpacific', 'europe')"),
  landingPoint: z
    .string()
    .optional()
    .describe("Landing point city or country to search for"),
  asn: z
    .union([z.string(), z.number()])
    .optional()
    .describe("ASN to find connected submarine cables for"),
});

/** Input schema for facility analysis */
export const facilityAnalysisSchema = z.object({
  asn: z
    .union([z.string(), z.number()])
    .describe("ASN to analyze facility presence for"),
  targetAsn: z
    .union([z.string(), z.number()])
    .optional()
    .describe("Optional target ASN to find common facilities"),
});

// ── Result Types ─────────────────────────────────────────

/** Node in the AS topology graph */
export interface ASGraphNode {
  readonly asn: ASN;
  readonly name: string;
  readonly rank: number | null;
  readonly type: "transit" | "content" | "enterprise" | "access" | "ixp";
  readonly country: string;
  readonly customerConeSize: number;
}

/** Edge in the AS topology graph */
export interface ASGraphEdge {
  readonly from: ASN;
  readonly to: ASN;
  readonly relationship: "provider-customer" | "peer-to-peer" | "sibling";
  readonly pathCount: number;
  readonly active: boolean;
}

/** AS topology graph */
export interface ASGraph {
  readonly centerAsn: ASN;
  readonly centerName: string;
  readonly nodes: ReadonlyArray<ASGraphNode>;
  readonly edges: ReadonlyArray<ASGraphEdge>;
  readonly depth: number;
  readonly totalNodes: number;
  readonly totalEdges: number;
}

/** Submarine cable information */
export interface SubmarineCable {
  readonly name: string;
  readonly readyForService: string;
  readonly lengthKm: number;
  readonly capacityTbps: number;
  readonly owners: ReadonlyArray<string>;
  readonly landingPoints: ReadonlyArray<{
    readonly city: string;
    readonly country: string;
    readonly latitude: number;
    readonly longitude: number;
  }>;
}

/** Facility presence analysis */
export interface FacilityAnalysis {
  readonly asn: ASN;
  readonly name: string;
  readonly facilities: ReadonlyArray<{
    readonly id: number;
    readonly name: string;
    readonly city: string;
    readonly country: string;
    readonly networks: number;
    readonly ixesPresent: ReadonlyArray<string>;
  }>;
  readonly commonFacilities?: ReadonlyArray<{
    readonly facility: string;
    readonly city: string;
    readonly bothPresent: boolean;
  }>;
  readonly recommendations: ReadonlyArray<string>;
}

// ── Tool Handlers ────────────────────────────────────────

/**
 * Generate an AS-level topology graph centered on an ASN.
 *
 * Builds a graph of provider, customer, and peer relationships up to
 * the specified depth using CAIDA AS-Relationships and bgproutes.io topology.
 *
 * @param input - Validated graph parameters
 * @returns AS topology graph with nodes and edges
 *
 * @example
 * ```
 * > Show me the AS graph around Cloudflare (AS13335) with 2 hops depth
 *
 * Returns: Graph with Cloudflare at center, transit providers (e.g., AS714 Apple),
 * peers, and customers, annotated with relationship types.
 * ```
 */
export async function handleASGraph(
  input: z.infer<typeof asGraphSchema>
): Promise<ASGraph> {
  // TODO: Fetch relationships from CAIDA client
  // TODO: Fetch topology from bgproutes.io client
  // TODO: Build graph with BFS up to specified depth
  // TODO: Annotate nodes with AS Rank and type
  // TODO: Deduplicate edges from multiple sources

  return {
    centerAsn: 0, // TODO: parseASN(input.asn)
    centerName: "",
    nodes: [],
    edges: [],
    depth: input.depth ?? 2,
    totalNodes: 0,
    totalEdges: 0,
  };
}

/**
 * Look up submarine cable information.
 *
 * Returns data about submarine cables, their landing points, capacity,
 * and ownership. Can be filtered by region, landing point, or ASN.
 *
 * @param input - Validated cable query parameters
 * @returns Array of matching submarine cables
 *
 * @example
 * ```
 * > What submarine cables connect Europe to North America?
 *
 * Returns: List of transatlantic cables with capacity, owners, and landing points.
 * ```
 */
export async function handleSubmarineCables(
  input: z.infer<typeof submarineCableSchema>
): Promise<ReadonlyArray<SubmarineCable>> {
  // TODO: Query submarine cable dataset (e.g., TeleGeography)
  // TODO: Filter by region, landing point, or ASN facilities
  // TODO: Cross-reference with facility data from PeeringDB

  const _input = input;
  return []; // TODO: Implement
}

/**
 * Analyze facility presence and colocation opportunities for an ASN.
 *
 * Lists all facilities where the ASN has presence, and optionally finds
 * common facilities with a target ASN for potential peering.
 *
 * @param input - Validated analysis parameters
 * @returns Facility presence analysis with recommendations
 *
 * @example
 * ```
 * > Where can AS32934 (Meta) and AS13335 (Cloudflare) interconnect?
 *
 * Returns: Facilities where both are present, IXPs at those facilities,
 * and recommendations for establishing interconnection.
 * ```
 */
export async function handleFacilityAnalysis(
  input: z.infer<typeof facilityAnalysisSchema>
): Promise<FacilityAnalysis> {
  // TODO: Query PeeringDB for facility presence (netfac)
  // TODO: If targetAsn provided, find overlap
  // TODO: List IXPs present at each facility
  // TODO: Generate interconnection recommendations

  return {
    asn: 0, // TODO: parseASN(input.asn)
    name: "",
    facilities: [],
    commonFacilities: input.targetAsn ? [] : undefined,
    recommendations: [],
  };
}
