feat: run on more operating systems

package.json

@@ -9,6 +9,7 @@
 		"url": "https://github.com/pizzafox/how/issues"
 	},
 	"devDependencies": {
+		"@types/decompress": "4.2.3",
 		"@types/node": "14.14.21",
 		"prettier": "2.2.1",
 		"prettier-config-xo": "1.0.3",
@@ -17,8 +18,7 @@
 		"typescript": "4.1.3"
 	},
 	"files": [
-		"tsc_output",
-		"lib"
+		"tsc_output"
 	],
 	"bin": "./tsc_output/index.js",
 	"license": "Apache-2.0",
@@ -38,13 +38,24 @@
 		"style": "prettier --check ."
 	},
 	"os": [
-		"linux"
+		"darwin",
+		"freebsd",
+		"linux",
+		"openbsd",
+		"win32"
+	],
+	"cpu": [
+		"arm64",
+		"x32",
+		"x64"
 	],
 	"engines": {
 		"node": ">=14.0.0"
 	},
 	"version": "0.0.0-development",
 	"dependencies": {
-		"execa": "5.0.0"
+		"decompress": "4.2.1",
+		"execa": "5.0.0",
+		"got": "11.8.1"
 	}
 }

src/fetch-glow.ts

@@ -0,0 +1,137 @@
+import decompress from 'decompress';
+import fs from 'fs';
+import fsp from 'fs/promises';
+import got from 'got';
+import os from 'os';
+import stream from 'stream';
+import {promisify} from 'util';
+import {desiredGlowVersion, flushOptions, options} from './options.js';
+import {glowPath} from './paths.js';
+import path from 'path';
+
+const pipeline = promisify(stream.pipeline);
+
+namespace Glow {
+	export type Os = 'Darwin' | 'freebsd' | 'linux' | 'openbsd' | 'Windows';
+	export type Arch = 'arm64' | 'armv6' | 'armv7' | 'i386' | 'x86_64';
+}
+
+/** Unix-ish OSs. */
+type Unixes = 'freebsd' | 'linux' | 'openbsd';
+
+/** A type representing the name of a Glow binary asset from GitHub. */
+export type GlowBinaryArchive = `glow_${typeof desiredGlowVersion}_${
+	| `${'Darwin_x86_64' | `${Unixes}_${Glow.Arch}`}.tar.gz`
+	| `Windows_${'i386' | 'x86_64'}.zip`}`;
+
+/** Stricter typings for the `os` module. */
+export namespace Os {
+	/** The operating system CPU architecture for which the Node.js binary was compiled. */
+	export type Arch = 'arm' | 'arm64' | 'ia32' | 'mips' | 'mipsel' | 'ppc' | 'ppc64' | 's390' | 's390x' | 'x32' | 'x64';
+
+	/** String identifying the operating system platform. */
+	export type Platform = 'aix' | 'darwin' | 'freebsd' | 'linux' | 'openbsd' | 'sunos' | 'win32' | 'android';
+}
+
+export interface OsKind {
+	arch: Glow.Arch;
+	os: Glow.Os;
+}
+
+/**
+ * Determine which binary for Glow should be installed for the given operating system.
+ * @example
+ * ```ts
+ * resolveVersion({ os: 'Darwin', arch: 'x86_64' }); // 'glow_1.3.0_Darwin_x86_64.tar.gz'
+ * ```
+ */
+export function resolveVersion(host: OsKind): GlowBinaryArchive {
+	switch (host.os) {
+		case 'Darwin': {
+			if (host.arch === 'x86_64') {
+				return `glow_${desiredGlowVersion}_Darwin_x86_64.tar.gz` as const;
+			}
+			break;
+		}
+		case 'Windows': {
+			if (host.arch === 'i386' || host.arch === 'x86_64') {
+				return `glow_${desiredGlowVersion}_Windows_${host.arch}.zip` as const;
+			}
+			break;
+		}
+		case 'freebsd':
+		case 'linux':
+		case 'openbsd': {
+			switch (host.arch) {
+				case 'arm64':
+				case 'i386':
+				case 'x86_64': {
+					return `glow_${desiredGlowVersion}_${host.os}_${host.arch}.tar.gz` as const;
+				}
+			}
+			break;
+		}
+	}
+
+	throw new RangeError('Unexpected combination of architecture and os');
+}
+
+/** Mapping of Node.js `os.arch` to architectures targeted by Glow builds. */
+enum OsArchToGlowArch {
+	'arm64' = 'arm64',
+	'x32' = 'i386',
+	'x64' = 'x86_64'
+}
+
+/** Mapping of Node.js `os.platform` to OSs targeteted by Glow builds. */
+enum OsPlatformToGlowOs {
+	'darwin' = 'Darwin',
+	'freebsd' = 'freebsd',
+	'linux' = 'linux',
+	'openbsd' = 'openbsd',
+	'win32' = 'Windows'
+}
+
+/**
+ * Get the Glow compatible architecture and OS for this machine.
+ */
+export function getOsKind(): OsKind {
+	const arch = os.arch() as Os.Arch;
+
+	if (!(arch in OsArchToGlowArch)) {
+		throw new Error('Unsupported CPU architecture');
+	}
+
+	const platform = os.platform() as Os.Platform;
+
+	if (!(platform in OsPlatformToGlowOs)) {
+		throw new Error('Unsupported OS platform');
+	}
+
+	return {
+		arch: OsArchToGlowArch[arch as keyof typeof OsArchToGlowArch],
+		os: OsPlatformToGlowOs[platform as keyof typeof OsPlatformToGlowOs]
+	};
+}
+
+/**
+ * Update Glow to the preferred version.
+ * @param archiveName - The name of the Glow binary archive to download
+ */
+export async function updateGlow(archiveName: GlowBinaryArchive): Promise<void> {
+	const url = `https://github.com/charmbracelet/glow/releases/download/v${desiredGlowVersion}/${archiveName}`;
+
+	const archivePath = `${glowPath}-archive`;
+	await pipeline(got.stream(url), fs.createWriteStream(archivePath));
+
+	await decompress(archivePath, path.join(glowPath, '..'), {
+		// Ignore the documentation files in releases
+		filter: file => file.path.startsWith('glow')
+	});
+
+	await fsp.unlink(archivePath);
+
+	options.glowVersion = desiredGlowVersion;
+
+	await flushOptions(options);
+}

src/index.ts

@@ -1,29 +1,43 @@
 #!/usr/bin/env node
 import execa from 'execa';
 import fs from 'fs/promises';
-import {homedir} from 'os';
-import path, {dirname} from 'path';
+import path from 'path';
 import {stdout} from 'process';
-import {fileURLToPath} from 'url';
+import {getOsKind, resolveVersion, updateGlow} from './fetch-glow.js';
 import {format} from './format.js';
-
-const __dirname = dirname(fileURLToPath(import.meta.url));
-
-const tldrPath = path.join(homedir(), '.cache', 'how', 'tldr');
+import {desiredGlowVersion, options} from './options.js';
+import {glowPath, tldrPath} from './paths.js';
 
 try {
 	await fs.access(tldrPath);
 } catch (error) {
 	await fs.mkdir(tldrPath, {recursive: true});
 	await execa('git', ['clone', 'https://github.com/tldr-pages/tldr.git', tldrPath]);
+	console.log('downloaded the database of Markdown examples');
+}
+
+if (options.glowVersion !== desiredGlowVersion) {
+	// Currently installed version is not the same as the desired version
+
+	const osKind = getOsKind();
+	const version = resolveVersion(osKind);
+
+	try {
+		await updateGlow(version);
+
+		console.log('downloaded a new binary for Glow (makes Markdown pretty)');
+	} catch (error) {
+		console.error('failed to download a new binary for Glow (makes Markdown pretty)');
+		process.exit(1);
+	}
 }
 
 if (Math.random() > 0.95) {
 	try {
 		await execa('git', ['pull'], {cwd: tldrPath});
-		console.error('you got unlucky and the cache was refreshed');
+		console.log('you got unlucky and the cache for the Markdown database was refreshed');
 	} catch (error) {
-		console.error('failed to refresh cache');
+		console.error('failed to refresh the cache for the Markdown database');
 	}
 }
 
@@ -47,7 +61,7 @@ for (const potentialPath of potentialPaths) {
 	const contents = await fs.readFile(potentialPath, 'utf-8');
 	const formatted = format(contents);
 
-	const tldr = await execa(path.join(__dirname, '..', 'lib', 'glow-1.3.0'), ['-s', 'dark', '-'], {
+	const tldr = await execa(glowPath, ['-s', 'dark', '-'], {
 		input: formatted
 	});
 

src/options.ts

@@ -0,0 +1,38 @@
+import * as fs from 'fs/promises';
+import os from 'os';
+import path from 'path';
+import {cacheDir, optionsPath} from './paths.js';
+
+export interface Options {
+	/** Currently installed version for glow. */
+	glowVersion: string | null;
+	versionNumber: 1;
+}
+
+/**
+ * The desired version of Glow to download locally.
+ * @see https://github.com/charmbracelet/glow/releases
+ */
+export const desiredGlowVersion = '1.3.0';
+
+export const defaultOptions: Options = {
+	glowVersion: null,
+	versionNumber: 1
+};
+
+/**
+ * Flush options object to filesystem.
+ * @param data - Options to flush
+ */
+export async function flushOptions(data: Options): Promise<void> {
+	await fs.writeFile(optionsPath, JSON.stringify(data, undefined, 2) + os.EOL, 'utf-8');
+}
+
+try {
+	await fs.access(optionsPath);
+} catch (error) {
+	await fs.mkdir(cacheDir, {recursive: true});
+	await flushOptions(defaultOptions);
+}
+
+export const options: Options = JSON.parse(await fs.readFile(path.join(optionsPath), 'utf-8'));

src/paths.ts

@@ -0,0 +1,10 @@
+import {homedir} from 'os';
+import path, {dirname} from 'path';
+import {fileURLToPath} from 'url';
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+
+export const cacheDir = path.join(homedir(), '.cache', 'how');
+export const optionsPath = path.join(cacheDir, 'options.json');
+export const tldrPath = path.join(cacheDir, 'tldr');
+export const glowPath = path.join(cacheDir, 'glow');