#!/usr/bin/env node
/**
 * Build the owner flag sheet the orbital Cockpit marks a satellite's owner
 * country with (`src/ui/ownerFlag.js`): every flag in OWNER_COUNTRY_CODES
 * (`src/layers/satellites/classes.js`), drawn from the flag-icons 4:3 SVGs
 * at twice the readout's 20 × 15 px, in one PNG the app loads at startup.
 *
 *   src/data/local_data/owner_flags/owner_flags.png   the sheet
 *   src/ui/ownerFlagSheet.js                           its layout (generated)
 *
 * Flag i (in the sorted code list) sits at column i % COLUMNS, row
 * floor(i / COLUMNS), each cell followed by a GUTTER of transparent pixels. A rerun with the same flag-icons and sharp versions
 * reproduces both files.
 *
 * Usage: node scripts/build-owner-flags.mjs
 */

import { readFile, writeFile } from 'node:fs/promises';
import { createRequire } from 'node:module';
import path from 'node:path';
import { fileURLToPath } from 'node:url';
import * as prettier from 'prettier';
import sharp from 'sharp';
import { OWNER_COUNTRY_CODES } from '../src/layers/satellites/classes.js';

const ROOT = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');
const require = createRequire(import.meta.url);
const FLAGS_DIR = path.join(
  path.dirname(require.resolve('flag-icons/package.json')),
  'flags/4x3',
);
const FLAG_ICONS_VERSION = require('flag-icons/package.json').version;

/** One flag's cell, CSS pixels × 2. */
export const CELL = Object.freeze({ width: 40, height: 30 });
/**
 * Transparent sheet pixels after each flag, so a browser smoothing a scaled
 * flag (a 125% display) never reaches into its neighbour.
 */
export const GUTTER = 2;
export const COLUMNS = 16;

const SHEET = path.join(
  ROOT,
  'src/data/local_data/owner_flags/owner_flags.png',
);
const LAYOUT = path.join(ROOT, 'src/ui/ownerFlagSheet.js');

async function flagCell(code) {
  const svg = await readFile(path.join(FLAGS_DIR, `${code.toLowerCase()}.svg`));
  return sharp(svg, { density: 300 })
    .resize(CELL.width, CELL.height, { fit: 'fill' })
    .png()
    .toBuffer();
}

const codes = [...OWNER_COUNTRY_CODES];
const rows = Math.ceil(codes.length / COLUMNS);
const pitchX = CELL.width + GUTTER;
const pitchY = CELL.height + GUTTER;
const cells = await Promise.all(codes.map(flagCell));
const sheet = await sharp({
  create: {
    width: COLUMNS * pitchX,
    height: rows * pitchY,
    channels: 4,
    background: { r: 0, g: 0, b: 0, alpha: 0 },
  },
})
  .composite(
    cells.map((input, i) => ({
      input,
      left: (i % COLUMNS) * pitchX,
      top: Math.floor(i / COLUMNS) * pitchY,
    })),
  )
  .png({ compressionLevel: 9, palette: true, quality: 100, effort: 10 })
  .toBuffer();
await writeFile(SHEET, sheet);

const layout = `// Generated by scripts/build-owner-flags.mjs from flag-icons ${FLAG_ICONS_VERSION}; do not edit.
/** The owner flag sheet's layout: flag i at column i % columns, row i / columns. */
export const OWNER_FLAG_SHEET = Object.freeze({
  cellWidthPx: ${CELL.width},
  cellHeightPx: ${CELL.height},
  gutterPx: ${GUTTER},
  columns: ${COLUMNS},
  rows: ${rows},
  codes: Object.freeze(${JSON.stringify(codes)}),
});
`;
await writeFile(
  LAYOUT,
  await prettier.format(layout, {
    ...(await prettier.resolveConfig(LAYOUT)),
    filepath: LAYOUT,
  }),
);
console.log(
  `Wrote ${codes.length} flags (${COLUMNS} × ${rows}), ${(sheet.length / 1024).toFixed(1)} KB.`,
);