service-host.js

const { dirname } = require('path');
const ts = require('typescript');
const { findTsconfig } = require('./find-tsconfig');

const { getCompilerOptions } = require('./get-compiler-options');

/**
 * Create the most basic TS language service host for the given file to make import sorting work.
 *
 * @param {string} path path to file
 * @param {string} content file's content
 *
 * @returns {ts.LanguageServiceHost}
 */
function getTypeScriptLanguageServiceHost(path, content) {
	const tsconfig = findTsconfig(path);
	const compilerOptions = getCompilerOptions(tsconfig);
	const snapshot = ts.ScriptSnapshot.fromString(content);

	return {
		directoryExists: ts.sys.directoryExists,
		fileExists: ts.sys.fileExists,
		getDefaultLibFileName: ts.getDefaultLibFileName,
		getDirectories: ts.sys.getDirectories,
		readDirectory: ts.sys.readDirectory,
		readFile: ts.sys.readFile,
		getCurrentDirectory: () => (tsconfig ? dirname(tsconfig) : ts.sys.getCurrentDirectory()),
		getCompilationSettings: () => compilerOptions,
		getNewLine: () => ts.sys.newLine,
		getScriptFileNames: () => [path],
		getScriptVersion: () => '0',
		getScriptSnapshot: (filePath) => {
			if (filePath === path) {
				return snapshot;
			}
		},
		getScriptKind: (fileName) => {
			const ext = fileName.substring(fileName.lastIndexOf('.') + 1);
			switch (ext) {
				case 'ts':
					return ts.ScriptKind.TS;
				case 'tsx':
					return ts.ScriptKind.TSX;
				case 'js':
					return ts.ScriptKind.JS;
				case 'jsx':
					return ts.ScriptKind.JSX;
				case 'json':
					return ts.ScriptKind.JSON;
				default:
					return ts.ScriptKind.Unknown;
			}
		},
	};
}

module.exports = { getTypeScriptLanguageServiceHost };