cohost/serverside/prngnouns.ts

// TODO: randomly pick color
import { contentType } from "https://deno.land/std@0.202.0/media_types/mod.ts";
import {
  Image,
  TextLayout,
} from "https://deno.land/x/imagescript@1.2.15/ImageScript.js";

const font = await fetch("https://static.pyrope.net/courier-std-bold.otf")
  .then((r) => r.arrayBuffer())
  .then((b) => new Uint8Array(b));

function make_image(
  { text, color = 0, outline_color = 0xff_ff_ff_ff }: {
    text: string;
    color?: number;
    outline_color?: number;
  },
): Image {
  let image = Image.renderText(
    font,
    64,
    text,
    0,
    new TextLayout({ verticalAlign: "center", horizontalAlign: "middle" }),
  );

  const outline = Image.renderText(
    font,
    64,
    text,
    outline_color,
    new TextLayout({ verticalAlign: "center", horizontalAlign: "middle" }),
  );

  for (const hshift of [-2, 0, 2]) {
    for (const vshift of [-2, 0, 2]) {
      image = image.composite(outline, hshift, vshift);
    }
  }
  const text_img = Image.renderText(
    font,
    64,
    text,
    color,
    new TextLayout({ verticalAlign: "center", horizontalAlign: "middle" }),
  );

  const final = image.composite(text_img);
  return final.crop(0, 0, final.width, final.height - 22);
}

// the whole cache thing def sketches me out, but people probably won't be *that* malicious
const MAX_PRN_LENGTH = 128;
// shouldn't really be a problem
const MAX_PRN_CHOICES = 256;

// let's stick to hex even though BigInt() can handle prefixes (prefices?)
const hex_string_to_color = (s: string): number | undefined => {
  const parsed = parseInt(s, 16);
  if (Number.isNaN(parsed)) return;
  // JANK! SORRY
  return Number((BigInt(parsed) << 8n) | 0xffn);
};

const image_response = (data: Uint8Array): Response =>
  new Response(data, {
    headers: { "Content-Type": contentType("png") },
  });

Deno.serve({ port: 61265 }, async (req) => {
  const url = new URL(req.url);
  const params = url.searchParams;
  const prns = params.getAll("p");

  if (prns.some((p) => p.length > MAX_PRN_LENGTH)) {
    return new Response(`MAX_PRN_LENGTH = ${MAX_PRN_LENGTH}`, { status: 413 });
  }

  if (prns.length > MAX_PRN_CHOICES) {
    return new Response(`MAX_PRN_CHOICES = ${MAX_PRN_CHOICES}`, {
      status: 413,
    });
  }

  const prn = prns[Math.floor(Math.random() * prns.length)] ??
    "NONE, APPARENTLY";

  const fg_str = params.get("fg");
  const outline_str = params.get("outline");

  const sentence_id = params.get("sentence_id");
  const sentence_index = params.get("sentence_index");

  console.log(
    `${sentence_id}#${sentence_index}: chose ${prn} from ${prns}. ${fg_str} on ${outline_str}`,
  );

  const fg = hex_string_to_color(fg_str ?? "0");
  const outline = hex_string_to_color(outline_str ?? "ffffff");

  const resp = image_response(
    await make_image({ text: prn, color: fg, outline_color: outline }).encode(),
  );
  return resp;
});