// Node-RED's admin-API client — nodered's own code, living in the module (novox/hq ADR 0044). Only
// this module's tools import it; nodered has nothing to poll, so there is no events entrypoint.
//
// Node-RED exposes a runtime admin API under its base URL: GET/POST /flows for the whole flow
// configuration, GET /nodes for installed node modules. A default install has no auth; when
// adminAuth is on, a bearer token (minted at /auth/token) is required.

import { readFileSync } from "node:fs";

export interface NodeRedFlow {
  /** The tab (flow) node id. */
  id: string;
  label: string;
  disabled: boolean;
}

export interface NodeRedNodeModule {
  name: string;
  version: string;
  types: string[];
}

/** The settings-merged config the mesh delivers (novox/hq ADR 0051): { url, apiKey, token, password, user, ... }. */
function meshConfig(file?: string): Record<string, string> {
  if (!file) return {};
  try { return JSON.parse(readFileSync(file, "utf8")) as Record<string, string>; }
  catch { return {}; }
}

export class NodeRedClient {
  readonly baseUrl: string;

  constructor(
    url: string,
    private readonly token?: string,
  ) {
    this.baseUrl = url.replace(/\/$/, "");
  }

  /**
   * Build from the module's resolved environment. MESH_NODERED_URL locates the admin API and is the
   * "this node runs Node-RED" signal — throws when unset, and the module then contributes nothing
   * rather than failing on every node. MESH_NODERED_TOKEN is the bearer token when adminAuth is on;
   * a default install needs none.
   */
  static fromEnv(env: NodeJS.ProcessEnv = process.env): NodeRedClient {
    const cfg = meshConfig(env.MESH_NODERED_CONFIG_FILE);
    const url = cfg.url ?? env.MESH_NODERED_URL;
    if (!url) throw new Error("no Node-RED URL — set MESH_NODERED_URL");
    return new NodeRedClient(url, cfg.token ?? env.MESH_NODERED_TOKEN);
  }

  private headers(extra: Record<string, string> = {}): Record<string, string> {
    return { Accept: "application/json", ...(this.token ? { Authorization: `Bearer ${this.token}` } : {}), ...extra };
  }

  private async req(path: string, init: RequestInit = {}): Promise<any> {
    const res = await fetch(`${this.baseUrl}${path}`, init);
    if (!res.ok) throw new Error(`Node-RED ${path}: ${res.status} ${await res.text()}`);
    return res.json();
  }

  /** The full flow configuration — the flat array of every node across every tab. */
  async getConfig(): Promise<any[]> {
    const body = await this.req("/flows", { headers: this.headers() });
    // /flows answers a bare array by default, or { rev, flows } to a v2-aware client.
    return Array.isArray(body) ? body : (body.flows ?? []);
  }

  /** The tabs (flows), each a node of type "tab" in the configuration. */
  async listFlows(): Promise<{ flows: NodeRedFlow[]; nodeCount: number }> {
    const config = await this.getConfig();
    const flows = config
      .filter((n) => n.type === "tab")
      .map((n) => ({ id: n.id, label: n.label ?? "(unnamed)", disabled: !!n.disabled }));
    return { flows, nodeCount: config.length };
  }

  async listNodes(): Promise<NodeRedNodeModule[]> {
    const modules = (await this.req("/nodes", { headers: this.headers() })) as any[];
    return modules.map((m) => ({ name: m.name, version: m.version, types: m.types ?? [] }));
  }

  /**
   * Replace the whole flow configuration and deploy. Returns the new revision. `type` maps to
   * Node-RED's deployment types — "full" (default), "nodes", or "flows".
   */
  async deployFlows(config: any[], type = "full"): Promise<{ rev?: string; nodeCount: number }> {
    const body = await this.req("/flows", {
      method: "POST",
      headers: this.headers({ "Content-Type": "application/json", "Node-RED-Deployment-Type": type }),
      body: JSON.stringify(config),
    });
    return { rev: body?.rev, nodeCount: config.length };
  }
}