/**
 * @module mcp-server/tools/peering
 * MCP Tool: Peering partner discovery and matching.
 *
 * Uses PeeringDB data combined with AI analysis to find optimal peering
 * partners based on common IXs, facilities, policy compatibility, and
 * traffic patterns.
 */

import { z } from "zod";
import type { PeeringMatch, PeeringRequest } from "../../types/common.js";
import { parseASN } from "../../types/common.js";

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

/** Input schema for peering partner discovery */
export const peeringDiscoverSchema = z.object({
  asn: z
    .union([z.string(), z.number()])
    .describe("Your ASN to find peering partners for"),
  ix: z
    .string()
    .optional()
    .describe("Filter partners by IX name (e.g., 'DE-CIX Frankfurt')"),
  policy: z
    .enum(["open", "selective", "restrictive", "any"])
    .optional()
    .default("any")
    .describe("Filter by peering policy"),
  limit: z
    .number()
    .optional()
    .default(20)
    .describe("Maximum number of results"),
  network_type: z
    .string()
    .optional()
    .describe("Filter by network type (e.g., 'Content', 'NSP', 'Enterprise')"),
});

/** Input schema for peering email generation */
export const peeringEmailSchema = z.object({
  source_asn: z
    .union([z.string(), z.number()])
    .describe("Your ASN"),
  target_asn: z
    .union([z.string(), z.number()])
    .describe("Target ASN to request peering with"),
  ix: z
    .string()
    .describe("IX where you want to establish peering"),
});

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

/**
 * Discover optimal peering partners for an ASN.
 *
 * Algorithm:
 * 1. Get the source network's IX and facility list from PeeringDB
 * 2. Find networks present at the same IXs/facilities
 * 3. Filter by peering policy compatibility
 * 4. Score and rank by match quality
 * 5. Use AI to generate match reasoning
 *
 * @example
 * ```
 * > Find peering partners for AS207613 at DE-CIX with open policy
 *
 * Returns: Ranked list of networks at DE-CIX with open peering policy,
 *          scored by relevance and mutual benefit.
 * ```
 */
export async function handlePeeringDiscover(
  input: z.infer<typeof peeringDiscoverSchema>
): Promise<ReadonlyArray<PeeringMatch>> {
  const asn = parseASN(input.asn);

  // TODO: Implementation steps:
  // 1. Query PeeringDB for the source network's IX connections
  // 2. If IX filter specified, get all participants at that IX
  //    Otherwise, get participants at all source IXs
  // 3. Filter by peering policy if specified
  // 4. Filter by network type if specified
  // 5. Score each potential partner:
  //    - Number of common IXs (more = better)
  //    - Number of common facilities (co-location = bonus)
  //    - Policy compatibility (open = higher score)
  //    - Network type complementarity (content + eyeball = bonus)
  // 6. Use AI to generate human-readable match reasoning
  // 7. Sort by score descending, limit results

  // Placeholder return
  return [];
}

/**
 * Generate a professional peering request email.
 *
 * Uses AI to draft a complete, ready-to-send peering request email
 * based on the source and target network details from PeeringDB.
 *
 * @example
 * ```
 * > Draft a peering request email to AS714 for DE-CIX Frankfurt
 *
 * Returns: Professional email with network details, mutual benefits,
 *          and technical parameters ready for sending.
 * ```
 */
export async function handlePeeringEmail(
  input: z.infer<typeof peeringEmailSchema>
): Promise<PeeringRequest> {
  const sourceASN = parseASN(input.source_asn);
  const targetASN = parseASN(input.target_asn);

  // TODO: Implementation steps:
  // 1. Look up both networks on PeeringDB
  // 2. Find common IXs between them
  // 3. Get contact information for target network
  // 4. Use AI to generate professional peering request email
  //    incorporating real network data

  return {
    targetASN,
    targetName: "", // TODO: From PeeringDB
    ix: input.ix,
    subject: `Peering Request: AS${sourceASN} <-> AS${targetASN} at ${input.ix}`,
    body: "", // TODO: AI-generated email body
  };
}

/**
 * Score a potential peering partnership.
 *
 * @param commonIXCount - Number of common IXs
 * @param commonFacilityCount - Number of common facilities
 * @param policyMatch - Whether peering policies are compatible
 * @param typeComplement - Whether network types are complementary
 * @returns Score from 0 to 100
 */
export function calculatePeeringScore(
  commonIXCount: number,
  commonFacilityCount: number,
  policyMatch: boolean,
  typeComplement: boolean
): number {
  let score = 0;

  // Common IX presence (max 40 points)
  score += Math.min(commonIXCount * 10, 40);

  // Common facility presence (max 20 points)
  score += Math.min(commonFacilityCount * 10, 20);

  // Policy compatibility (20 points)
  if (policyMatch) score += 20;

  // Network type complementarity (20 points)
  if (typeComplement) score += 20;

  return Math.min(score, 100);
}
