/**
 * Generates a sprite sheet and emoji JSON file for use by the plugin.
 * Takes one argument, the root directory of your emoji files.
 * This makes a few assumptions:
 * - All emojis are PNG files.
 * - All emojis are the same size.
 * - All emojis are static.
 * - No filenames have spaces.
 */

import { exec as nodeExec } from "node:child_process";
import { argv } from "node:process";
import { promisify } from "node:util";
import * as fs from "node:fs";
import { join as joinPath } from "node:path";

const writeFile = promisify(fs.writeFile);
const readDir = promisify(fs.readdir);
const exec = promisify(nodeExec);

let directory = ".";
let outname = "spritesheet";
let scale = 0;
if (argv.length < 2) {
  throw "Not enough arguments, need a folder to process";
}

if (argv[0].indexOf("node") !== -1 && argv[1].indexOf("generate.js") !== -1) {
  if (argv.length < 3) throw "Not enough arguments, need a folder to process";
  directory = argv[2];
  if (argv.length > 3) outname = argv[3];
  if (argv.length > 4) scale = parseInt(argv[4]);
} else {
  directory = argv[1];
  if (argv.length > 2) outname = argv[2];
  if (argv.length > 3) scale = parseInt(argv[3]);
}

async function getFiles() {
  return (await readDir(directory))
    .filter((f) => f.endsWith(".png"))
    .sort((a, b) => a.localeCompare(b));
}

console.log(`Directory: ${directory}
Output files: ${outname}.png, ${outname}.json
Scale: ${scale}`);

const files = await getFiles();
const { size } = await createSpriteSheet(files);
await createJSON(files, size);

/**
 * @param {string[]} files
 */
async function createSpriteSheet(files) {
  const size = Math.ceil(Math.sqrt(files.length));

  // i don't wanna pull in any more dependencies, so lol
  if (!scale) {
    const { stdout: rawImageSize } = await exec(
      [
        "magick",
        "identify",
        "-ping",
        "-format",
        "'%w'",
        joinPath(directory, files[0]),
      ].join(" ")
    );
    scale = parseInt(rawImageSize);
  }

  const { stdout, stderr } = await exec(
    [
      "magick",
      "montage",
      "-tile",
      `${size}x${size}`,
      "-geometry",
      "+0+0",
      "-scale",
      `${scale}`,
      "-background",
      "transparent",
      ...files.map((f) => joinPath(directory, f)),
      `${outname}.png`,
    ].join(" ")
  );
  if (stderr) {
    console.error("Error from ImageMagick:", stderr);
    return;
  }
  if (stdout) console.log(stdout);

  const { stdout2, stderr2 } = await exec(
    [
      "magick",
      "montage",
      "-tile",
      `${size}x${size}`,
      "-geometry",
      "+0+0",
      "-scale",
      `${scale * 2}`,
      "-background",
      "transparent",
      ...files.map((f) => joinPath(directory, f)),
      `${outname}_2x.png`,
    ].join(" ")
  );
  if (stderr2) {
    console.error("Error from ImageMagick:", stderr2);
    return;
  }
  if (stdout2) console.log(stdout2);

  return { size };
}

/**
 * @param {string[]} files The image filenames.
 * @param {number} size The size of the sprite sheet in number of sprites horizontally and vertically.
 */
async function createJSON(files, size) {
  let json = {
    source: `${outname}.png`,
    hidpiSource: `${outname}_2x.png`,
    size: scale,
    emojis: {},
  };

  files.forEach((filename, index) => {
    const shortcode = filename.split(".", 2)[0];
    const xPos = Math.floor(index % size);
    const yPos = Math.floor(index / size);
    json.emojis[shortcode] = [xPos * scale, yPos * scale];
  });

  await writeFile(`${outname}.json`, JSON.stringify(json, undefined, "  "));
}