/**
 * @module mcp-server/tools/bgp
 * MCP Tool: BGP analysis and anomaly detection.
 *
 * Analyzes BGP routing data from RIPE Stat, Route Views, and bgp.he.net
 * to detect route leaks, hijacks, MOAS conflicts, and other anomalies.
 */

import { z } from "zod";
import type { BGPAnomaly, BGPRoute } from "../../types/common.js";
import type { BGPPathAnalysis } from "../../types/bgp.js";
import { parseASN } from "../../types/common.js";

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

/** Input schema for BGP analysis */
export const bgpAnalysisSchema = z.object({
  resource: z
    .string()
    .describe("ASN (e.g., 'AS13335') or prefix (e.g., '1.1.1.0/24') to analyze"),
  include_paths: z
    .boolean()
    .optional()
    .default(true)
    .describe("Include AS path analysis"),
  include_anomalies: z
    .boolean()
    .optional()
    .default(true)
    .describe("Run anomaly detection"),
  time_range: z
    .string()
    .optional()
    .describe("Time range for analysis (e.g., '24h', '7d', '30d')"),
});

/** Input schema for anomaly detection */
export const bgpAnomalySchema = z.object({
  prefixes: z
    .array(z.string())
    .describe("Prefixes to monitor for anomalies"),
  severity_threshold: z
    .enum(["critical", "high", "medium", "low", "info"])
    .optional()
    .default("medium")
    .describe("Minimum severity level to report"),
  lookback: z
    .string()
    .optional()
    .default("24h")
    .describe("How far back to check (e.g., '1h', '24h', '7d')"),
});

/** Input schema for route leak detection */
export const routeLeakSchema = z.object({
  asn: z
    .union([z.string(), z.number()])
    .describe("ASN to check for route leaks involving their prefixes"),
  lookback: z
    .string()
    .optional()
    .default("7d")
    .describe("How far back to check"),
});

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

/**
 * Perform comprehensive BGP analysis for a resource.
 *
 * Combines data from RIPE Stat, Route Views, and bgp.he.net to provide
 * a complete picture of the routing state for an ASN or prefix.
 *
 * @example
 * ```
 * > Are there any BGP anomalies for 185.1.0.0/24 right now?
 *
 * Returns: Path analysis, visibility report, detected anomalies,
 *          and AI-generated assessment.
 * ```
 */
export async function handleBGPAnalysis(
  input: z.infer<typeof bgpAnalysisSchema>
): Promise<{
  resource: string;
  pathAnalysis?: BGPPathAnalysis;
  anomalies: ReadonlyArray<BGPAnomaly>;
  routes: ReadonlyArray<BGPRoute>;
  aiAnalysis: string;
}> {
  // TODO: Implementation steps:
  // 1. Determine if resource is ASN or prefix
  // 2. Query RIPE Stat for BGP state and updates
  // 3. Query Route Views for path diversity
  // 4. Query bgp.he.net for peer/upstream info
  // 5. Run anomaly detection if requested
  // 6. Use AI to generate comprehensive analysis

  return {
    resource: input.resource,
    pathAnalysis: undefined, // TODO: From Route Views client
    anomalies: [], // TODO: From anomaly detection
    routes: [], // TODO: From RIPE Stat BGP state
    aiAnalysis: "", // TODO: AI-generated analysis
  };
}

/**
 * Detect BGP anomalies for a set of prefixes.
 *
 * Checks for:
 * - Route leaks (unexpected transit)
 * - BGP hijacks (unauthorized origin)
 * - MOAS conflicts (multiple origins)
 * - RPKI-invalid routes
 * - Path anomalies (unusual AS paths)
 *
 * @example
 * ```
 * > Show me all route leaks involving my prefixes in the last 7 days
 * ```
 */
export async function handleAnomalyDetection(
  input: z.infer<typeof bgpAnomalySchema>
): Promise<ReadonlyArray<BGPAnomaly>> {
  // TODO: Implementation steps:
  // 1. For each prefix, get BGP updates from RIPE Stat
  // 2. Check for MOAS (multiple origin AS) events
  // 3. Validate each route against RPKI
  // 4. Analyze AS paths for leak patterns:
  //    - Unexpected AS in path (potential leak)
  //    - New origin AS (potential hijack)
  //    - Abnormally long path (potential leak)
  //    - More-specific prefix announcement (potential hijack)
  // 5. Filter by severity threshold
  // 6. Use AI to assess severity and recommend actions

  const severityOrder: Record<string, number> = {
    critical: 4,
    high: 3,
    medium: 2,
    low: 1,
    info: 0,
  };

  const threshold = severityOrder[input.severity_threshold] ?? 2;

  // TODO: Collect anomalies from analysis
  const anomalies: BGPAnomaly[] = [];

  // Filter by severity threshold
  return anomalies.filter(
    (a) => (severityOrder[a.severity] ?? 0) >= threshold
  );
}

/**
 * Detect route leaks involving an ASN's prefixes.
 *
 * Analyzes BGP updates to find instances where an ASN's prefixes
 * were announced by unexpected paths, indicating potential route leaks.
 */
export async function handleRouteLeakDetection(
  input: z.infer<typeof routeLeakSchema>
): Promise<{
  asn: number;
  leaks: ReadonlyArray<BGPAnomaly>;
  summary: string;
}> {
  const asn = parseASN(input.asn);

  // TODO: Implementation steps:
  // 1. Get all announced prefixes for the ASN
  // 2. For each prefix, check BGP updates in the lookback period
  // 3. Identify routes with unexpected AS paths
  // 4. Cross-reference with known upstreams from bgp.he.net
  // 5. Generate summary with AI

  return {
    asn,
    leaks: [],
    summary: "", // TODO: AI-generated summary
  };
}

/**
 * Parse a time range string into milliseconds.
 *
 * @param range - Time range string (e.g., "1h", "24h", "7d", "30d")
 * @returns Duration in milliseconds
 */
export function parseTimeRange(range: string): number {
  const match = range.match(/^(\d+)(h|d|m|w)$/);
  if (!match) {
    throw new Error(`Invalid time range: ${range}. Use format like '24h', '7d', '30d'`);
  }

  const value = parseInt(match[1], 10);
  const unit = match[2];

  const multipliers: Record<string, number> = {
    m: 60 * 1000,
    h: 60 * 60 * 1000,
    d: 24 * 60 * 60 * 1000,
    w: 7 * 24 * 60 * 60 * 1000,
  };

  return value * (multipliers[unit] ?? 0);
}
