feat: load tsconfig

package.json

@@ -28,7 +28,7 @@
 		"up-hooks": "npx simple-git-hooks",
 		"prepare": "pnpm up-hooks",
 		"build": "tsup",
-		"watch": "nodemon ./src/compiler.ts",
+		"watch": "nodemon ./src/program/index.ts",
 		"check": "tsc -p tsconfig.check.json",
 		"format": "prettier . --write --ignore-path .gitignore",
 		"lint": "eslint . --fix --ext .js,.cjs,.ts --ignore-path .gitignore",

src/program/config.ts

@@ -0,0 +1,89 @@
+import path from 'path';
+import ts from 'typescript';
+import { errorMessage, ErrorCode } from './error';
+import { formatDiagnostics } from './diagnostic';
+import { getCurrentDirectory, fileExists, readFile } from './util';
+
+export interface Options {
+	configName?: string;
+	searchPath?: string;
+	compilerOptions?: ts.CompilerOptions;
+}
+
+export function findConfigFile(options: Options = {}) {
+	const configName = options.configName ?? 'tsconfig.json';
+	const searchPath = options.searchPath ?? getCurrentDirectory();
+	const filePath = ts.findConfigFile(searchPath, fileExists, configName);
+
+	// TODO: allow fallback to default config with a warning?
+	if (!filePath) {
+		return {
+			error: errorMessage(ErrorCode.TSCONFIG_FILE_NOT_FOUND, { searchPath, configName }),
+		};
+	}
+
+	return { filePath };
+}
+
+export function readConfigFile(filePath: string) {
+	try {
+		const jsonText = readFile(filePath);
+
+		if (!jsonText) {
+			return {
+				error: errorMessage(ErrorCode.TSCONFIG_FILE_NOT_READABLE, { filePath }),
+			};
+		}
+
+		return { filePath, jsonText };
+	} catch (_err) {
+		return {
+			error: errorMessage(ErrorCode.TSCONFIG_FILE_NOT_READABLE, { filePath }),
+		};
+	}
+}
+
+export function parseConfigFile(fileName: string, jsonText: string, compilerOptions?: ts.CompilerOptions) {
+	const configObject = ts.parseConfigFileTextToJson(fileName, jsonText);
+
+	if (configObject.error) {
+		return { error: new Error(formatDiagnostics([configObject.error])) };
+	}
+
+	const config = ts.parseJsonConfigFileContent(configObject.config, ts.sys, path.dirname(fileName), compilerOptions);
+
+	if (config.errors.length > 0) {
+		return { error: new Error(formatDiagnostics(config.errors)) };
+	}
+
+	return { fileName, config };
+}
+export function loadConfig(options?: Options) {
+	try {
+		const configFile = findConfigFile(options);
+
+		if (configFile.error) {
+			throw configFile.error;
+		}
+
+		const configFileContent = readConfigFile(configFile.filePath);
+
+		if (configFileContent.error) {
+			throw configFileContent.error;
+		}
+
+		const parsedConfig = parseConfigFile(
+			configFileContent.filePath,
+			configFileContent.jsonText,
+			options?.compilerOptions,
+		);
+
+		if (parsedConfig.error) {
+			throw parsedConfig.error;
+		}
+
+		return { config: parsedConfig };
+	} catch (error) {
+		return { error: error as Error };
+	}
+}

src/program/diagnostic.ts

@@ -0,0 +1,12 @@
+import ts from 'typescript';
+import { getCurrentDirectory, newLine } from './util';
+
+export const diagnosticsHost: ts.FormatDiagnosticsHost = {
+	getNewLine: () => newLine,
+	getCurrentDirectory: () => getCurrentDirectory(),
+	getCanonicalFileName: (fileName: string) => fileName,
+};
+
+export function formatDiagnostics(diagnostics: ts.Diagnostic[]) {
+	return ts.formatDiagnostics(diagnostics, diagnosticsHost);
+}

src/program/error.ts

@@ -0,0 +1,19 @@
+export enum ErrorCode {
+	TSCONFIG_FILE_NOT_FOUND,
+	TSCONFIG_FILE_NOT_READABLE,
+}
+
+export const errorMessages: Record<ErrorCode, string> = {
+	[ErrorCode.TSCONFIG_FILE_NOT_FOUND]: 'TS config file not found. File name: {configName} - Search path: {searchPath}',
+	[ErrorCode.TSCONFIG_FILE_NOT_READABLE]: 'TS config file not readable or empty. File path: {filePath}',
+};
+
+export function errorMessage(code: ErrorCode, data?: Record<string, unknown>) {
+	let message = errorMessages[code];
+
+	Object.entries(data ?? {}).forEach(([index, value]) => {
+		message = message.replace(new RegExp(`{${index}}`, 'g'), String(value));
+	});
+
+	return new Error(message);
+}

src/program/index.ts

@@ -0,0 +1,8 @@
+import { loadConfig } from './config';
+
+const config = loadConfig({
+	configName: 'tsconfig.check.json',
+});
+
+// eslint-disable-next-line no-console
+console.log(config);

src/program/util.ts

@@ -0,0 +1,15 @@
+import ts from 'typescript';
+
+export const newLine = '\n';
+
+export function getCurrentDirectory() {
+	return ts.sys.getCurrentDirectory();
+}
+
+export function fileExists(fileName: string) {
+	return ts.sys.fileExists(fileName);
+}
+
+export function readFile(fileName: string) {
+	return ts.sys.readFile(fileName);
+}