index.js

"use strict";
var through = require("through");
var path = require("path");
var PluginError = require("plugin-error");
var Vinyl = require("vinyl");

module.exports = function(fileName, converter) {
	if (!fileName) {
		throw new PluginError(
			"gulp-jsoncombine",
			"Missing fileName option for gulp-jsoncombine"
		);
	}
	if (!converter) {
		throw new PluginError(
			"gulp-jsoncombine",
			"Missing converter option for gulp-jsoncombine"
		);
	}

	var data = {};
	var meta = {};
	var firstFile = null;

	// We keep track of when we should skip the conversion for error cases
	var skipConversion = false;

	function bufferContents(file) {
		if (!firstFile) {
			firstFile = file;
		}

		if (file.isNull()) {
			return; // ignore
		}
		if (file.isStream()) {
			skipConversion = true;
			return this.emit(
				"error",
				new PluginError("gulp-jsoncombine", "Streaming not supported")
			);
		}
		try {
			var name = file.relative.substr(0, file.relative.length - 5);
			data[name] = JSON.parse(file.contents.toString());
			meta[name] = { cwd: file.cwd, base: file.base, path: file.path };
		} catch (err) {
			skipConversion = true;
			return this.emit(
				"error",
				new PluginError(
					"gulp-jsoncombine",
					"Error parsing JSON: " +
						err +
						", file: " +
						file.path.slice(file.base.length)
				)
			);
		}
	}

	function endStream() {
		if (firstFile && !skipConversion) {
			var joinedPath = path.join(firstFile.base, fileName);

			try {
				var joinedFile = new Vinyl({
					cwd: firstFile.cwd,
					base: firstFile.base,
					path: joinedPath,
					contents: converter(data, meta)
				});
				this.emit("data", joinedFile);
			} catch (e) {
				return this.emit(
					"error",
					new PluginError("gulp-jsoncombine", e, { showStack: true })
				);
			}
		}
		this.emit("end");
	}

	return through(bufferContents, endStream);
};