"use strict"

var fs = require("fs")
var path = require("path")

module.exports = function(input, output, options) {
	function run(e, file) {
		var modules = {}
		var usedVariables = {}

		function resolve(dir, data) {
			var replacements = []
			data = data.replace(/((?:var|let|const|)[\t ]*)([\w_$\.]+)(\s*=\s*)require\(([^\)]+)\)/g, function(match, def, variable, eq, dep) {
				usedVariables[variable] = usedVariables[variable] ? usedVariables[variable]++ : 1

				var filename = new Function("return " + dep).call()
				
				//resolve npm dependencies
				if (filename[0] !== ".") {
					var meta = fs.statSync("./node_modules/" + filename + "/package.json").isFile() ? JSON.parse(fs.readFileSync("./node_modules/" + filename + "/package.json")) : {}
					var dependencyEntry = "./node_modules/" + filename + "/" + (meta.main || filename + ".js")
					try {fs.statSync(dependencyEntry).isFile()} catch (e) {dependencyEntry = "./node_modules/" + filename + "/index.js"}
					return resolve(path.dirname(dependencyEntry), exportCode(dependencyEntry, def + variable + eq))
				}
				
				//resolve local dependencies
				var normalized = path.resolve(dir, filename)
				var pathname = path.dirname(normalized)
				if (modules[normalized] === undefined) {
					modules[normalized] = variable
					var exported = exportCode(dir + "/" + filename + ".js", def + variable + eq)
					return resolve(pathname, exported)
				}
				else {
					if (modules[normalized] !== variable) {
						replacements.push({variable: variable, replacement: modules[normalized]})
					}
					return ""
				}
			})
			if (replacements.length > 0) {
				for (var i = 0; i < replacements.length; i++) {
					data = data.replace(new RegExp("\\b" + replacements[i].variable + "\\b", "g"), replacements[i].replacement)
				}
			}
			return data
				.replace(/(?:var|let|const)[\t ]([\w_$\.]+)(\s*=\s*)\1([\r\n;]+)/g, "$3") // remove assignments to itself
				.replace(/([\r\n]){2,}/g, "$1") // remove multiple consecutive line breaks
				.replace(/\}[\r\n]+\(/g, "}(") // remove space from iife
		}

		function exportCode(file, assignment) {
			return fixCollisions(fs.readFileSync(file, "utf8"))
				.replace(/("|')use strict\1;?\s*/gm, "") // remove extraneous "use strict"
				.replace(/module\.exports\s*=\s*/gm, assignment)
		}

		function fixCollisions(code) {
			for (var variable in usedVariables) {
				var collision = new RegExp("(?!.)\\b" + variable + "\\b(?![\"'`])", "g")
				var exported = new RegExp("module\\.exports\\s*=\\s*" + variable)
				if (collision.test(code) && !exported.test(code)) {
					var fixed = variable + usedVariables[variable]++
					code = code.replace(collision, fixed)
				}
			}
			return code
		}

		function setVersion(code) {
			var metadata = JSON.parse(fs.readFileSync(__dirname + "/../package.json"))
			return code.replace("bleeding-edge", metadata.version)
		}

		function bundle(input, output) {
			console.log("bundling...")
			var code = setVersion(resolve(path.dirname(input), fs.readFileSync(input, "utf8")))
			/*if (new Function(code)) */fs.writeFileSync(output, code, "utf8")
			console.log("done")
		}
		
		if (file !== output && file !== output.replace(/\.js$/, ".min.js")) bundle(input, output)
	}
	run()

	if (options && options.watch) fs.watch(process.cwd(), {recursive: true}, run)
}