// export-data.ts: add this to a val on Val Town as an HTTP file, and set an
// environment variable EXPORT_TOKEN on that val (openssl rand -hex 32).
// pull-data.ts on your VM then reads the val's SQLite and blobs through it,
// and pull-env.ts the environment variables you name. It only reads:
// SELECT and PRAGMA table_xinfo, blob list and get, named variables.
// Delete the file and the variable once your data has moved.
import { sqlite as scopedDb } from "https://esm.town/v/std/sqlite/main.ts";
import { sqlite as globalDb } from "https://esm.town/v/std/sqlite/global.ts";
import { blob as scopedBlobs } from "https://esm.town/v/std/blob/main.ts";
import { blob as globalBlobs } from "https://esm.town/v/std/blob";

export default async function (req: Request): Promise<Response> {
  const token = Deno.env.get("EXPORT_TOKEN");
  if (!token || req.headers.get("Authorization") !== `Bearer ${token}`) {
    return new Response("Unauthorized", { status: 401, headers: { "Cache-Control": "no-store" } });
  }
  const url = new URL(req.url);
  const global = url.searchParams.get("scope") === "global";
  const db = global ? globalDb : scopedDb;
  const blobs = global ? globalBlobs : scopedBlobs;
  if (url.pathname === "/sql" && req.method === "POST") {
    const { sql, args } = await req.json();
    if (!/^\s*(select|pragma table_xinfo)\b/i.test(sql)) {
      return new Response("read-only", { status: 400 });
    }
    const r = await db.execute({ sql, args: args ?? [] });
    const rows = r.rows.map((row) => r.columns.map((_, i) => row[i]));
    return Response.json({ columns: r.columns, rows });
  }
  if (url.pathname === "/blobs") {
    return Response.json(await blobs.list(url.searchParams.get("prefix") ?? ""));
  }
  if (url.pathname === "/blob") {
    const res = await blobs.get(url.searchParams.get("key") ?? "");
    return new Response(res.body);
  }
  if (url.pathname === "/env") {
    const names = (url.searchParams.get("names") ?? "").split(",").filter(Boolean);
    const blocked = (n: string) => n === "EXPORT_TOKEN" || /^val_?town/i.test(n);
    const missing = names.filter((n) => blocked(n) || Deno.env.get(n) === undefined);
    if (missing.length) return new Response(`not set: ${missing.join(",")}`, { status: 404 });
    return Response.json(Object.fromEntries(names.map((n) => [n, Deno.env.get(n)])), {
      headers: { "Cache-Control": "no-store" },
    });
  }
  return new Response("export-data: /sql, /blobs, /blob?key=, /env?names=", { status: 404 });
}