// The InfluxDB API client — influxdb's own code, living in the module (novox/hq ADR 0039). Only
// this module's tools import it. Talks to the InfluxDB 2.x HTTP API (/api/v2) with a token.

import { readFileSync } from "node:fs";

export interface InfluxHealth {
  name?: string;
  status?: string;
  message?: string;
  version?: string;
}

export interface InfluxBucket {
  id: string;
  name: string;
  orgID?: string;
  retentionSeconds?: number;
}

/** 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 InfluxDBClient {
  readonly baseUrl: string;

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

  /**
   * Build from the module's resolved environment. The token is the InfluxDB API token (the admin
   * token the server was initialised with, or a scoped one) — required, since every /api/v2 call
   * is token-authenticated. The org scopes bucket listing and queries.
   */
  static fromEnv(env: NodeJS.ProcessEnv = process.env): InfluxDBClient {
    const cfg = meshConfig(env.MESH_INFLUXDB_CONFIG_FILE);
    const url = cfg.url ?? env.MESH_INFLUXDB_URL ?? `http://127.0.0.1:${env.INFLUXDB_PORT ?? "8086"}`;
    const token = cfg.token ?? env.MESH_INFLUXDB_TOKEN;
    if (!token) throw new Error("no InfluxDB token — set MESH_INFLUXDB_TOKEN");
    const org = cfg.org ?? env.MESH_INFLUXDB_ORG ?? "mesh";
    return new InfluxDBClient(url, token, org);
  }

  private async request(path: string, init?: RequestInit): Promise<Response> {
    const res = await fetch(`${this.baseUrl}${path}`, {
      ...init,
      headers: {
        Authorization: `Token ${this.token}`,
        ...(init?.headers ?? {}),
      },
    });
    if (!res.ok) throw new Error(`InfluxDB API ${path}: ${res.status} ${await res.text()}`);
    return res;
  }

  /** Server health — the one endpoint that needs no token, but we send it anyway. */
  async health(): Promise<InfluxHealth> {
    return (await (await this.request("/health")).json()) as InfluxHealth;
  }

  async listBuckets(): Promise<InfluxBucket[]> {
    const body = (await (await this.request("/api/v2/buckets")).json()) as { buckets?: unknown[] };
    return (body.buckets ?? []).map((b) => {
      const bucket = b as Record<string, unknown>;
      const rules = (bucket.retentionRules as { everySeconds?: number }[] | undefined) ?? [];
      return {
        id: String(bucket.id),
        name: String(bucket.name),
        orgID: bucket.orgID ? String(bucket.orgID) : undefined,
        retentionSeconds: rules[0]?.everySeconds,
      };
    });
  }

  /**
   * Run a read-only Flux query and return the raw CSV InfluxDB answers with, plus a light parse
   * into rows. Read-only: Flux has no write verb, and the token's own permissions bound the rest —
   * this client never calls the write endpoint.
   */
  async query(flux: string): Promise<{ csv: string; rows: Record<string, string>[] }> {
    const res = await this.request(`/api/v2/query?org=${encodeURIComponent(this.org)}`, {
      method: "POST",
      headers: {
        "Content-Type": "application/vnd.flux",
        Accept: "application/csv",
      },
      body: flux,
    });
    const csv = await res.text();
    return { csv, rows: parseAnnotatedCsv(csv) };
  }
}

/** Parse InfluxDB's annotated CSV into rows keyed by column header. Annotation lines (starting
 *  with #) and blanks are skipped; the first non-annotation line is the header. */
function parseAnnotatedCsv(csv: string): Record<string, string>[] {
  const lines = csv.split("\n").filter((l) => l.trim() && !l.startsWith("#"));
  if (lines.length < 2) return [];
  const header = lines[0].split(",");
  return lines.slice(1).map((line) => {
    const cells = line.split(",");
    const row: Record<string, string> = {};
    header.forEach((h, i) => {
      if (h) row[h] = cells[i] ?? "";
    });
    return row;
  });
}