extension String {

	var trimmed: String {
		return self.trimmingCharacters(in: .whitespacesAndNewlines)
	}

}

enum Errors: Error {
	case filePathFailed
	case contentDataFailed
	case contentStringFailed
}

func readFile() throws {
	guard let filePath = Bundle.main.path(forResource:"SLP2 - Copy", ofType: "csv")
		else { throw Errors.filePathFailed }
	guard let contentData = FileManager.default.contents(atPath: filePath)
		else { throw Errors.contentDataFailed }
	guard let contentString = String(data: contentData, encoding: .utf8)
		else { throw Errors.contentStringFailed }
	let lines = contentString.components(separatedBy: "\n")
	print("Line Count: \(lines.count)")

	let dateFormatter_0 = DateFormatter()
	dateFormatter_0.calendar = Calendar.current
	dateFormatter_0.locale = Locale.current
	dateFormatter_0.dateFormat = "M/d/yy H:mm"

	let dateFormatter_1 = DateFormatter()
	dateFormatter_1.calendar = Calendar.current
	dateFormatter_1.locale = Locale.current
	dateFormatter_1.dateFormat = "M/d/yy HH:mm:ss"

	let dateFormatter_2 = DateFormatter()
	dateFormatter_2.calendar = Calendar.current
	dateFormatter_2.locale = Locale.current
	dateFormatter_2.dateFormat = "yyyy-MM-dd HH:mm"

	let finalString = lines
		.filter { (line) -> Bool in !line.trimmed.isEmpty }
		.map { (line) -> [String] in return line.components(separatedBy: "\",") }
		.map { (array) -> (start: String, end: String) in return (array[0] + "\"", array[1].trimmed) }
		.compactMap { (item) -> (text: String, date: Date)? in
			let d = dateFormatter_0.date(from: item.end) ?? dateFormatter_1.date(from: item.end)
			guard let date = d else { return nil }
			return (item.start, date)
		}
		.map { (item) -> String in return "\(item.text),\(dateFormatter_2.string(from: item.date))" }
		.joined(separator: "\n")

	let fileUrl = URL(fileURLWithPath: filePath)
	let finalFileUrl = fileUrl
		.deletingLastPathComponent()
		.appendingPathComponent("FinalCSVFile.csv")

	do {
		print("Start Writing File...")
		try ("kwh, Datetime" + "\n" + finalString).write(to: finalFileUrl, atomically: false, encoding: .utf8)
		print("File Created: \(finalFileUrl.absoluteString)")
	} catch {
		print("Write String to File Failed: \(error)")
	}
}

do {
	try readFile()
} catch {
	print("Error: \(error as! Errors)")
}