// The Jackett API client — jackett's own code, living in the module (novox/hq ADR 0039). Jackett is
// an indexer proxy: it normalises many torrent trackers behind one Torznab surface. This client
// talks its /api/v2.0 REST API, and only jackett's tools import it.

import { existsSync, readFileSync } from "node:fs";
import { join } from "node:path";

export interface JackettIndexer {
  id: string;
  name: string;
  type: string; // "public" | "private" | "semi-public"
  configured: boolean;
  siteLink?: string;
  lastError?: string;
}

export interface JackettResult {
  title: string;
  tracker: string;
  category?: string;
  size: number;
  seeders?: number;
  peers?: number;
  publishDate?: string;
  link?: string;
}

/** The settings-merged config the mesh delivers (novox/hq ADR 0046): { 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 JackettClient {
  readonly baseUrl: string;

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

  /**
   * Build from the module's resolved environment. Jackett's REST API is keyed, so both the URL and
   * the key must be present. The key is read from the settings-merged config or MESH_JACKETT_API_KEY,
   * or, failing those, discovered from Jackett's own ServerConfig.json under MESH_JACKETT_CONFIG_DIR
   * — the file Jackett writes it to, as sonarr/radarr read theirs from config.xml — so a running
   * server needs no key configured by hand and no secret has to be put in an assignment. Without a
   * URL or key there is nothing to talk to, so this throws and the module contributes no tools
   * rather than failing half-configured.
   */
  static fromEnv(env: NodeJS.ProcessEnv = process.env): JackettClient {
    const cfg = meshConfig(env.MESH_JACKETT_CONFIG_FILE);
    const url = cfg.url ?? env.MESH_JACKETT_URL;
    const apiKey = cfg.apiKey ?? env.MESH_JACKETT_API_KEY
      ?? JackettClient.detectApiKey(env.MESH_JACKETT_CONFIG_DIR ?? "/config");
    if (!url) throw new Error("no Jackett URL — set MESH_JACKETT_URL");
    if (!apiKey) throw new Error("no Jackett API key — set MESH_JACKETT_API_KEY or make the config dir readable");
    return new JackettClient(url, apiKey);
  }

  /** Discover the API key from Jackett's ServerConfig.json (the linuxserver image keeps it at
   *  <config>/Jackett/ServerConfig.json), falling back to null. */
  static detectApiKey(configDir: string): string | null {
    for (const file of [join(configDir, "Jackett", "ServerConfig.json"), join(configDir, "ServerConfig.json")]) {
      if (!existsSync(file)) continue;
      try {
        const key = (JSON.parse(readFileSync(file, "utf8")) as { APIKey?: unknown }).APIKey;
        if (typeof key === "string" && key) return key;
      } catch { /* unreadable or mid-write: try the next, then give up */ }
    }
    return null;
  }

  private async get(path: string, params: Record<string, string> = {}): Promise<any> {
    const url = new URL(`${this.baseUrl}${path}`);
    url.searchParams.set("apikey", this.apiKey);
    for (const [k, v] of Object.entries(params)) url.searchParams.set(k, v);
    const res = await fetch(url.toString(), { headers: { Accept: "application/json" } });
    if (!res.ok) throw new Error(`Jackett API ${path}: ${res.status} ${await res.text()}`);
    return res.json();
  }

  /**
   * The configured indexers Jackett proxies. `configured=false` also lists the ones not set up.
   * Read from the Torznab `t=indexers` feed, not /api/v2.0/indexers: that one is the web UI's and
   * wants a login cookie (it answers an API-key request with a redirect), while the Torznab feed is
   * what the key is for. The feed carries no last error, so `lastError` stays unset.
   */
  async getIndexers(configuredOnly = true): Promise<JackettIndexer[]> {
    const url = new URL(`${this.baseUrl}/api/v2.0/indexers/all/results/torznab/api`);
    url.searchParams.set("apikey", this.apiKey);
    url.searchParams.set("t", "indexers");
    url.searchParams.set("configured", configuredOnly ? "true" : "false");
    const res = await fetch(url.toString(), { headers: { Accept: "application/xml" } });
    if (!res.ok) throw new Error(`Jackett API torznab t=indexers: ${res.status} ${await res.text()}`);
    const xml = await res.text();
    // Torznab reports failures (a wrong key among them) as 200 with an <error> body.
    const err = xml.match(/<error code="(\d+)" description="([^"]*)"/);
    if (err) throw new Error(`Jackett API torznab t=indexers: error ${err[1]} ${err[2]}`);
    const text = (block: string, tag: string) =>
      block.match(new RegExp(`<${tag}>([^<]*)</${tag}>`))?.[1];
    const out: JackettIndexer[] = [];
    for (const m of xml.matchAll(/<indexer id="([^"]+)" configured="([^"]+)">([\s\S]*?)<\/indexer>/g)) {
      out.push({
        id: m[1],
        name: text(m[3], "title") ?? m[1],
        type: text(m[3], "type") ?? "unknown",
        configured: m[2] === "true",
        siteLink: text(m[3], "link"),
      });
    }
    return out;
  }

  /**
   * A Torznab search across one indexer, or the "all" aggregate. Jackett returns a normalised JSON
   * result set regardless of the underlying tracker, which is the whole point of the proxy.
   */
  async search(query: string, indexer = "all", limit = 25): Promise<JackettResult[]> {
    const raw = await this.get(`/api/v2.0/indexers/${encodeURIComponent(indexer)}/results`, { Query: query });
    const results = Array.isArray(raw?.Results) ? raw.Results : [];
    return results.slice(0, limit).map((r: any) => ({
      title: r.Title,
      tracker: r.Tracker ?? r.TrackerId ?? "unknown",
      category: Array.isArray(r.CategoryDesc) ? r.CategoryDesc.join(", ") : r.CategoryDesc,
      size: r.Size ?? 0,
      seeders: r.Seeders,
      peers: r.Peers,
      publishDate: r.PublishDate,
      link: r.Link ?? r.Details,
    }));
  }
}