feat(compiler): create declaration files for plugin builds

Robo plugins may sometimes need to export things to be used from the package directly. Declaration files for plugins built with Typescript are kinda expected, so let's output them!

.changeset/lemon-items-grin.md

@@ -0,0 +1,5 @@
+---
+'@roboplay/robo.js': minor
+---
+
+feat(compiler): create declaration files for plugin builds

packages/robo/src/cli/commands/build/plugin.ts

@@ -40,7 +40,7 @@ async function pluginAction() {
 
 	// Use SWC to compile into .robo/build
 	const { compile } = await import('../../utils/compiler.js')
-	const compileTime = await compile()
+	const compileTime = await compile({ plugin: true })
 	logger.debug(`Compiled in ${compileTime}ms`)
 
 	// Generate manifest.json

packages/robo/src/cli/utils/compiler.ts

@@ -109,6 +109,7 @@ interface RoboCompileOptions {
 	files?: string[]
 	parallel?: number
 	paths?: Record<string, string[]>
+	plugin?: boolean
 }
 
 export async function compile(options?: RoboCompileOptions) {
@@ -174,6 +175,14 @@ export async function compile(options?: RoboCompileOptions) {
 	logger.debug(`Copying additional non-TypeScript files from ${srcDir} to ${distDir}...`)
 	await copyDir(srcDir, distDir, ['.ts', '.tsx'])
 
+	// Generate declaration files for plugins
+	if (options?.plugin) {
+		const declarationTime = Date.now()
+		logger.debug(`Generating declaration files for plugins...`)
+		compileDeclarationFiles()
+		logger.debug(`Generated declaration files in ${Date.now() - declarationTime}ms`)
+	}
+
 	logger.debug(`Compiled successfully!`)
 	return Date.now() - startTime
 }
@@ -198,3 +207,37 @@ async function copyDir(src: string, dest: string, excludeExtensions: string[] =
 		}
 	}
 }
+
+function compileDeclarationFiles() {
+	// Define the compiler options specifically for declaration files
+	const options: CompilerOptions = {
+		rootDir: 'src',
+		outDir: '.robo/build',
+		declaration: true,
+		emitDeclarationOnly: true,
+		skipLibCheck: true,
+		noEmit: false
+	}
+
+	// Emit the declaration files
+	const fileNames = ts.sys.readDirectory('src', ['.ts', '.tsx'])
+	const program = ts.createProgram(fileNames, options)
+	const emitResult = program.emit()
+
+	// Collect and display the diagnostics, if any
+	const allDiagnostics = ts.getPreEmitDiagnostics(program).concat(emitResult.diagnostics)
+	allDiagnostics.forEach((diagnostic) => {
+		if (diagnostic.file) {
+			const { line, character } = ts.getLineAndCharacterOfPosition(diagnostic.file, diagnostic.start!)
+			const message = ts.flattenDiagnosticMessageText(diagnostic.messageText, '\n')
+			logger.error(`${diagnostic.file.fileName} (${line + 1},${character + 1}): ${message}`)
+		} else {
+			logger.error(ts.flattenDiagnosticMessageText(diagnostic.messageText, '\n'))
+		}
+	})
+
+	// Exit the process if there were any errors
+	if (emitResult.emitSkipped) {
+		process.exit(1)
+	}
+}