// The Baserow API client — baserow's own code, living in the module (novox/hq ADR 0039). Both this
// module's tools and anything else baserow-specific import it; nothing outside baserow does.
//
// Baserow authenticates a person with email + password, exchanged for a JWT at /api/user/token-auth/.
// The standard image creates no admin from env, so the account is one a person made in Baserow: its
// password is the module's `admin` secret, accepted from the operator, and its email and the public
// host Baserow answers to reach the runtime config file the mesh mounts (the email from the
// assignment's settings). Until both are there fromEnv throws and the module exposes no tools — the
// same dormant-until-configured shape gitea uses for its token.

import { readFileSync } from "node:fs";
import { request as httpRequest } from "node:http";
import { request as httpsRequest } from "node:https";

export interface BaserowApplication {
  id: number;
  name: string;
  type: string;
}

export interface BaserowRow {
  id: number;
  [key: string]: unknown;
}

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 BaserowClient {
  readonly baseUrl: string;
  private token: string | null = null;

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

  /**
   * Build from the module's resolved environment. URL, credentials and an optional Host override
   * come from the runtime config file first (MESH_BASEROW_CONFIG_FILE), then the mesh's own env
   * names, then the bare BASEROW_* names. Credentials are required — without them there is no
   * authenticated call to make, so this throws rather than hand back a client that fails on first use.
   */
  static fromEnv(env: NodeJS.ProcessEnv = process.env): BaserowClient {
    const cfg = meshConfig(env.MESH_BASEROW_CONFIG_FILE);
    const url = cfg.url ?? env.MESH_BASEROW_URL ?? env.BASEROW_URL ?? "http://127.0.0.1:80";
    const email = cfg.email ?? env.MESH_BASEROW_EMAIL ?? env.BASEROW_EMAIL;
    const password = cfg.password ?? env.MESH_BASEROW_PASSWORD ?? env.BASEROW_PASSWORD;
    // Baserow's bundled Caddy routes by the Host header against BASEROW_PUBLIC_URL; a co-located
    // caller reaching it over the container network may need to present that host.
    const hostHeader = cfg.host ?? env.MESH_BASEROW_HOST;
    if (!email || !password) {
      throw new Error("no Baserow credentials — set MESH_BASEROW_EMAIL and MESH_BASEROW_PASSWORD");
    }
    return new BaserowClient(url, email, password, hostHeader);
  }

  private headers(extra: Record<string, string> = {}): Record<string, string> {
    const h: Record<string, string> = { "Content-Type": "application/json", ...extra };
    if (this.hostHeader) h.Host = this.hostHeader;
    return h;
  }

  /**
   * One HTTP exchange. Not `fetch`: Node's fetch drops a caller's Host header and sends the URL's
   * own, and Baserow answers only the host of its BASEROW_PUBLIC_URL — any other Host is looked up
   * as a published builder site and gets 404, `/api/_health/` included. A co-located caller reaching
   * it by container name must present the public host, so the request is made with node:http, which
   * sends the Host it is given.
   */
  private send(path: string, method: string, headers: Record<string, string>, body?: string): Promise<{ status: number; text: string }> {
    const url = new URL(`${this.baseUrl}${path}`);
    const request = url.protocol === "https:" ? httpsRequest : httpRequest;
    // A length, never chunked: Baserow's server reads a chunked body as empty.
    const sent = body === undefined ? headers : { ...headers, "Content-Length": String(Buffer.byteLength(body)) };
    return new Promise((resolve, reject) => {
      const req = request(url, { method, headers: sent }, (res) => {
        let text = "";
        res.setEncoding("utf8");
        res.on("data", (chunk: string) => (text += chunk));
        res.on("end", () => resolve({ status: res.statusCode ?? 0, text }));
        res.on("error", reject);
      });
      req.on("error", reject);
      if (body !== undefined) req.write(body);
      req.end();
    });
  }

  /** Exchange email + password for a JWT, caching it until Baserow refuses it. Handles both the
   *  older `{ token }` and the newer `{ access_token }` response shapes. */
  async authenticate(): Promise<string> {
    if (this.token) return this.token;
    const res = await this.send(
      "/api/user/token-auth/",
      "POST",
      this.headers(),
      JSON.stringify({ email: this.email, password: this.password }),
    );
    if (res.status < 200 || res.status >= 300) throw new Error(`baserow auth failed: ${res.status} ${res.text}`);
    const data = JSON.parse(res.text) as { token?: string; access_token?: string };
    const token = data.access_token ?? data.token;
    if (!token) throw new Error("baserow auth returned no token");
    this.token = token;
    return token;
  }

  /** An authenticated GET. A refused token is dropped and the call made once more with a fresh one:
   *  Baserow's access tokens expire after minutes, and the runtime lives for weeks. */
  private async authed<T>(path: string): Promise<T> {
    for (let attempt = 0; ; attempt++) {
      const token = await this.authenticate();
      const res = await this.send(path, "GET", this.headers({ Authorization: `JWT ${token}` }));
      if (res.status === 401 && attempt === 0) {
        this.token = null;
        continue;
      }
      if (res.status < 200 || res.status >= 300) throw new Error(`baserow ${path}: ${res.status} ${res.text}`);
      return (res.text ? JSON.parse(res.text) : null) as T;
    }
  }

  /** The applications (databases) the account can see, across all its workspaces. */
  async listApplications(): Promise<BaserowApplication[]> {
    return (await this.authed<BaserowApplication[]>(`/api/applications/`)) ?? [];
  }

  /** Rows of a table, by numeric table id, with human field names. */
  async listRows(tableId: number, size = 100): Promise<BaserowRow[]> {
    const data = await this.authed<{ results: BaserowRow[] }>(
      `/api/database/rows/table/${tableId}/?size=${size}&user_field_names=true`,
    );
    return data?.results ?? [];
  }
}