/**
 * Yonexus Server - Fabric Notification Service
 *
 * Sends pairing notifications to a human admin via a Fabric channel.
 *
 * Flow:
 * 1. Exchange the Center API key for a user session
 *    (POST {centerApiBase}/auth/agent/login → user + guild tokens)
 * 2. Resolve the target guild's endpoint + access token by guildNodeId
 * 3. POST the formatted pairing message to the configured channel
 *    ({guildEndpoint}/api/channels/{channelId}/messages)
 *
 * Self-contained (global fetch) and dependency-free, mirroring the
 * Discord notifier; it does not import the Fabric.OpenclawPlugin.
 */

import type { PairingRequest } from "../services/pairing.js";
import type { PairingNotificationService } from "./types.js";
import { formatPairingMessage } from "./discord.js";
import { redactPairingCode, safeErrorMessage } from "../core/logging.js";

export interface FabricNotificationConfig {
  /** Fabric Center API base, e.g. http://localhost:7001/api */
  centerApiBase: string;
  /** Fabric Center API key (fak_…) for the notifier identity */
  apiKey: string;
  /** Target guild node id the admin channel lives on */
  guildNodeId: string;
  /** Channel id (a Fabric channel the admin watches) */
  channelId: string;
}

interface FabricSession {
  user: { id: string };
  guilds: Array<{ nodeId: string; endpoint: string }>;
  guildAccessTokens: Array<{ guildNodeId: string; token: string }>;
}

export interface FabricApiResponse {
  ok: boolean;
  status: number;
  json(): Promise<unknown>;
}

export type FabricFetch = (
  input: string,
  init?: { method?: string; headers?: Record<string, string>; body?: string }
) => Promise<FabricApiResponse>;

/**
 * Create a Fabric notification service backed by the Fabric Center +
 * Guild REST API.
 */
export function createFabricNotificationService(
  config: FabricNotificationConfig,
  options: { fetcher?: FabricFetch } = {}
): PairingNotificationService {
  const fetcher = options.fetcher ?? getDefaultFetch();

  return {
    async sendPairingNotification(request: PairingRequest): Promise<boolean> {
      if (
        !config.centerApiBase.trim() ||
        !config.apiKey.trim() ||
        !config.guildNodeId.trim() ||
        !config.channelId.trim()
      ) {
        console.error("[Yonexus.Server] Fabric notification misconfigured", {
          hasCenterApiBase: Boolean(config.centerApiBase.trim()),
          hasApiKey: Boolean(config.apiKey.trim()),
          hasGuildNodeId: Boolean(config.guildNodeId.trim()),
          hasChannelId: Boolean(config.channelId.trim())
        });
        return false;
      }

      try {
        const base = config.centerApiBase.replace(/\/+$/, "");
        const loginRes = await fetcher(`${base}/auth/agent/login`, {
          method: "POST",
          headers: { "Content-Type": "application/json" },
          body: JSON.stringify({ apiKey: config.apiKey })
        });
        if (!loginRes.ok) {
          throw new Error(`agent/login failed with status ${loginRes.status}`);
        }
        const session = (await loginRes.json()) as FabricSession;

        const endpoint = session.guilds
          .find((g) => g.nodeId === config.guildNodeId)
          ?.endpoint?.replace(/\/+$/, "");
        const token = session.guildAccessTokens.find(
          (t) => t.guildNodeId === config.guildNodeId
        )?.token;
        if (!endpoint || !token) {
          throw new Error(
            `notifier identity is not a member of guild ${config.guildNodeId}`
          );
        }

        const msgRes = await fetcher(
          `${endpoint}/api/channels/${config.channelId}/messages`,
          {
            method: "POST",
            headers: {
              Authorization: `Bearer ${token}`,
              "Content-Type": "application/json"
            },
            body: JSON.stringify({
              content: formatPairingMessage(request),
              authorUserId: session.user.id
            })
          }
        );
        if (!msgRes.ok) {
          throw new Error(`message post failed with status ${msgRes.status}`);
        }
        await msgRes.json();

        console.log("[Yonexus.Server] Pairing notification sent via Fabric", {
          identifier: request.identifier,
          pairingCode: redactPairingCode(request.pairingCode),
          expiresAt: request.expiresAt,
          ttlSeconds: request.ttlSeconds,
          guildNodeId: config.guildNodeId,
          channelId: config.channelId
        });
        return true;
      } catch (error) {
        console.error(
          "[Yonexus.Server] Failed to send Fabric pairing notification",
          {
            identifier: request.identifier,
            pairingCode: redactPairingCode(request.pairingCode),
            guildNodeId: config.guildNodeId,
            channelId: config.channelId,
            error: safeErrorMessage(error)
          }
        );
        return false;
      }
    }
  };
}

function getDefaultFetch(): FabricFetch {
  if (typeof fetch !== "function") {
    throw new Error("Global fetch is not available in this runtime");
  }
  return (input, init) =>
    fetch(input, {
      method: init?.method,
      headers: init?.headers,
      body: init?.body
    }) as Promise<FabricApiResponse>;
}