/**
 * @module mcp-server/tools/latency
 * MCP Tool: Latency measurements — RTT and traceroute via RIPE Atlas.
 *
 * Provides network latency analysis by creating RIPE Atlas measurements
 * and interpreting the results. Supports both ping (RTT) and traceroute
 * with AS-path correlation.
 */

import { z } from "zod";

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

/** Input schema for RTT measurement */
export const rttMeasurementSchema = z.object({
  target: z
    .string()
    .describe("Target IP address or hostname (e.g., '1.1.1.1', 'cloudflare.com')"),
  sourceAsn: z
    .number()
    .optional()
    .describe("Source ASN to select probes from (e.g., 13335)"),
  sourceCountry: z
    .string()
    .optional()
    .describe("Source country code to select probes from (e.g., 'DE', 'US')"),
  probeCount: z
    .number()
    .optional()
    .default(10)
    .describe("Number of RIPE Atlas probes to use (default: 10)"),
  af: z
    .union([z.literal(4), z.literal(6)])
    .optional()
    .default(4)
    .describe("Address family: 4 for IPv4, 6 for IPv6"),
});

/** Input schema for traceroute */
export const tracerouteSchema = z.object({
  target: z
    .string()
    .describe("Target IP address or hostname"),
  sourceAsn: z
    .number()
    .optional()
    .describe("Source ASN to select probes from"),
  sourceCountry: z
    .string()
    .optional()
    .describe("Source country code for probe selection"),
  probeCount: z
    .number()
    .optional()
    .default(5)
    .describe("Number of RIPE Atlas probes (default: 5)"),
  af: z
    .union([z.literal(4), z.literal(6)])
    .optional()
    .default(4)
    .describe("Address family: 4 for IPv4, 6 for IPv6"),
  resolveAsns: z
    .boolean()
    .optional()
    .default(true)
    .describe("Resolve each hop IP to its origin ASN"),
});

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

/** RTT measurement result */
export interface RTTResult {
  readonly target: string;
  readonly probeResults: ReadonlyArray<{
    readonly probeId: number;
    readonly probeAsn: number;
    readonly probeCountry: string;
    readonly avgRttMs: number;
    readonly minRttMs: number;
    readonly maxRttMs: number;
    readonly packetLossPercent: number;
  }>;
  readonly summary: {
    readonly globalAvgRttMs: number;
    readonly globalMinRttMs: number;
    readonly globalMaxRttMs: number;
    readonly probesResponded: number;
    readonly totalProbes: number;
  };
  readonly measurementId: number;
}

/** Traceroute hop with ASN annotation */
export interface AnnotatedHop {
  readonly hopNumber: number;
  readonly ip: string | null;
  readonly hostname: string | null;
  readonly asn: number | null;
  readonly asnName: string | null;
  readonly rttMs: number | null;
  readonly isIxp: boolean;
}

/** Traceroute result */
export interface TracerouteAnalysis {
  readonly target: string;
  readonly probeResults: ReadonlyArray<{
    readonly probeId: number;
    readonly probeAsn: number;
    readonly probeCountry: string;
    readonly hops: ReadonlyArray<AnnotatedHop>;
    readonly totalHops: number;
    readonly asPathFromTrace: ReadonlyArray<number>;
  }>;
  readonly summary: {
    readonly avgHopCount: number;
    readonly commonAsPath: ReadonlyArray<number>;
    readonly uniquePaths: number;
    readonly ixpCrossings: ReadonlyArray<string>;
  };
  readonly measurementId: number;
}

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

/**
 * Measure RTT (round-trip time) to a target using RIPE Atlas probes.
 *
 * Creates a one-off ping measurement from distributed probes and returns
 * latency statistics per probe and a global summary.
 *
 * @param input - Validated measurement parameters
 * @returns RTT results with per-probe and summary statistics
 *
 * @example
 * ```
 * > What's the latency from Germany to Cloudflare's 1.1.1.1?
 *
 * Creates ping from DE probes to 1.1.1.1, returns avg/min/max RTT.
 * ```
 */
export async function handleRTTMeasurement(
  input: z.infer<typeof rttMeasurementSchema>
): Promise<RTTResult> {
  // TODO: Create RIPE Atlas ping measurement via atlas client
  // TODO: Wait for measurement to complete (poll status)
  // TODO: Fetch and aggregate results
  // TODO: Calculate global summary stats

  return {
    target: input.target,
    probeResults: [],
    summary: {
      globalAvgRttMs: 0,
      globalMinRttMs: 0,
      globalMaxRttMs: 0,
      probesResponded: 0,
      totalProbes: input.probeCount ?? 10,
    },
    measurementId: 0, // TODO: Real measurement ID from Atlas
  };
}

/**
 * Run a traceroute to a target using RIPE Atlas probes.
 *
 * Creates a one-off traceroute measurement, resolves each hop to its
 * origin ASN, and identifies IXP crossings.
 *
 * @param input - Validated traceroute parameters
 * @returns Annotated traceroute with AS path analysis
 *
 * @example
 * ```
 * > Trace the path from AS32934 (Meta) to AS13335 (Cloudflare)
 *
 * Creates traceroute from Meta probes to Cloudflare, annotates each hop
 * with ASN, hostname, and IXP identification.
 * ```
 */
export async function handleTraceroute(
  input: z.infer<typeof tracerouteSchema>
): Promise<TracerouteAnalysis> {
  // TODO: Create RIPE Atlas traceroute measurement
  // TODO: Wait for completion, fetch results
  // TODO: Resolve each hop IP to ASN (via RIPE Stat or Team Cymru)
  // TODO: Identify IXP crossings (match hop IPs against PeeringDB IX prefixes)
  // TODO: Extract AS path from traceroute and compare with BGP AS path

  return {
    target: input.target,
    probeResults: [],
    summary: {
      avgHopCount: 0,
      commonAsPath: [],
      uniquePaths: 0,
      ixpCrossings: [],
    },
    measurementId: 0, // TODO: Real measurement ID from Atlas
  };
}
