#!/usr/bin/env node
// Display widths for node:readline's terminal mode (scr_readline_tty.c),
// derived from the pinned Node release: getStringWidth (internal/util/inspect,
// backed by ICU) of each code point on its own, and the Emoji_Presentation
// and Emoji_Modifier code points, which getStringWidth skips after a ZWJ.
// kGetDisplayPos measures one code point at a time and the completion
// listing measures whole completions.
//
//   node scripts/gen-readline-width-table.mjs          regenerate the table
//   node scripts/gen-readline-width-table.mjs --check  verify only
import { spawnSync } from "node:child_process";
import { readFileSync } from "node:fs";
import { writeFile } from "node:fs/promises";
import { createRequire } from "node:module";
import { fileURLToPath } from "node:url";
import { join } from "node:path";

if (!process.execArgv.includes("--expose-internals")) {
  const self = fileURLToPath(import.meta.url);
  const run = spawnSync(process.execPath, ["--expose-internals", self, ...process.argv.slice(2)], {
    stdio: "inherit",
  });
  process.exit(run.status ?? 1);
}

const root = fileURLToPath(new URL("..", import.meta.url));
const out = join(root, "packages/runtime/src/scr_readline_width_data.h");
const checkOnly = process.argv.includes("--check");
const pinned = readFileSync(join(root, ".node-version"), "utf8").trim();
if (process.version !== `v${pinned}`) {
  throw new Error(`run with Node v${pinned} (this is ${process.version})`);
}
const { getStringWidth } = createRequire(import.meta.url)("internal/util/inspect");

// [start, end, width] for the code points whose width is not 1
const widths = [];
for (let cp = 0; cp <= 0x10ffff; cp++) {
  const w = getStringWidth(String.fromCodePoint(cp), false);
  const last = widths.at(-1);
  if (w === 1) continue;
  if (last && last[2] === w && last[1] === cp - 1) last[1] = cp;
  else widths.push([cp, cp, w]);
}
const emoji = [];
const isEmoji = /^(?:\p{Emoji_Presentation}|\p{Emoji_Modifier})$/u;
for (let cp = 0; cp <= 0x10ffff; cp++) {
  if (cp >= 0xd800 && cp <= 0xdfff) continue;
  if (!isEmoji.test(String.fromCodePoint(cp))) continue;
  const last = emoji.at(-1);
  if (last && last[1] === cp - 1) last[1] = cp;
  else emoji.push([cp, cp]);
}

const hex = (n) => `0x${n.toString(16)}`;
const lines = [
  `/* Generated by scripts/gen-readline-width-table.mjs from Node ${process.version}`,
  ` * (ICU ${process.versions.icu}, Unicode ${process.versions.unicode}). Do not edit. */`,
  "#ifndef SCR_READLINE_WIDTH_DATA_H",
  "#define SCR_READLINE_WIDTH_DATA_H",
  "/* getStringWidth(String.fromCodePoint(cp), false) where it is not 1 */",
  "typedef struct { uint32_t start, end; uint8_t width; } ScrRlWidthRange;",
  "static const ScrRlWidthRange scr_rl_width_ranges[] = {",
  ...widths.map(([a, b, w]) => `  { ${hex(a)}, ${hex(b)}, ${w} },`),
  "};",
  "/* Emoji_Presentation and Emoji_Modifier */",
  "typedef struct { uint32_t start, end; } ScrRlEmojiRange;",
  "static const ScrRlEmojiRange scr_rl_emoji_ranges[] = {",
  ...emoji.map(([a, b]) => `  { ${hex(a)}, ${hex(b)} },`),
  "};",
  "#endif",
];
const text = lines.join("\n") + "\n";
if (checkOnly) {
  if (readFileSync(out, "utf8") !== text) {
    console.error(`${out} is stale: run node scripts/gen-readline-width-table.mjs`);
    process.exit(1);
  }
  console.log(`${out} is current`);
} else {
  await writeFile(out, text);
  console.log(`wrote ${out}`);
}