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

const PROJ_DIR = join(process.env["HOME"] ?? "/tmp", ".pi", "projections");

function ensureDir() {
  if (!existsSync(PROJ_DIR)) mkdirSync(PROJ_DIR, { recursive: true });
}

export function saveProjection(name: string, data: unknown): void {
  ensureDir();
  const proj = JSON.stringify({ name, version: 1, createdAt: new Date().toISOString(), data });
  appendFileSync(join(PROJ_DIR, `${name}.jsonl`), proj + "\n");
}

export function loadProjections(name: string): string[] {
  const path = join(PROJ_DIR, `${name}.jsonl`);
  if (!existsSync(path)) return [];
  try {
    return readFileSync(path, "utf8").split("\n").filter(Boolean);
  } catch {
    return [];
  }
}