export function loadMessageBundle()

in src/node/main.ts [380:451]
67 lines of code
22 McCabe index (conditional complexity)

export function loadMessageBundle(file?: string): LocalizeFunc {
	if (!file) {
		// No file. We are in dev mode. Return the default
		// localize function.
		return localize;
	}
	// Remove extension since we load json files.
	let ext = path.extname(file);
	if (ext) {
		file = file.substr(0, file.length - ext.length);
	}

	if (options.messageFormat === MessageFormat.both || options.messageFormat === MessageFormat.bundle) {
		let headerFile = tryFindMetaDataHeaderFile(file);
		if (headerFile) {
			let bundlePath = path.dirname(headerFile);
			let bundle: LanguageBundle = resolvedBundles[bundlePath];
			if (bundle === undefined) {
				try {
					let header: MetadataHeader = JSON.parse(fs.readFileSync(headerFile, 'utf8'));
					try {
						let nlsBundle = loadNlsBundle(header, bundlePath);
						bundle = cacheBundle(bundlePath, nlsBundle ? { header, nlsBundle } : null);
					} catch (err) {
						console.error('Failed to load nls bundle', err);
						bundle = cacheBundle(bundlePath, null);
					}
				} catch (err) {
					console.error('Failed to read header file', err);
					bundle = cacheBundle(bundlePath, null);
				}
			}
			if (bundle) {
				let module = file.substr(bundlePath.length + 1).replace(/\\/g, '/');
				let messages = bundle.nlsBundle[module];
				if (messages === undefined) {
					console.error(`Messages for file ${file} not found. See console for details.`);
					return function (): string {
						return 'Messages not found.';
					};
				}
				return createScopedLocalizeFunction(messages);
			}
		}
	}
	if (options.messageFormat === MessageFormat.both || options.messageFormat === MessageFormat.file) {
		// Try to load a single file bundle
		try {
			let json: SingleFileJsonFormat = readJsonFileSync(resolveLanguage(file));
			if (Array.isArray(json)) {
				return createScopedLocalizeFunction(json);
			} else {
				if (isDefined(json.messages) && isDefined(json.keys)) {
					return createScopedLocalizeFunction(json.messages);
				} else {
					console.error(`String bundle '${file}' uses an unsupported format.`);
					return function () {
						return 'File bundle has unsupported format. See console for details';
					};
				}
			}
		} catch (err) {
			if (err.code !== 'ENOENT') {
				console.error('Failed to load single file bundle', err);
			}
		}
	}
	console.error(`Failed to load message bundle for file ${file}`);
	return function (): string {
		return 'Failed to load message bundle. See console for details.';
	};
}