import csv
import requests

def WriteSymbolsToCSVFile(csvWriter, response):
	count = 0
	for symObj in response[1:]:
		if 'Attr' in symObj and 'Data' in symObj:
			symbol = symObj['Attr']['TickerSymbol']
			description = symObj['Data'].get('IssueDescription', 'No description')
			csvWriter.writerow([symbol, description])
			count += 1
			
	return count
		
def main():
	fp = open('symbols.csv', 'w', newline='')
	csvWriter = csv.writer(fp)

	username = "username"
	password = "password"
	URL = "http://pxweb.dtn.com/PXWebSvc/PXServiceWeb.svc/GetQuoteSnap"
	
	paramters = {
		'UserID' : username,
		'Password' : password,
		'Type' : 'IssueDescription',
		'Symbol' : '*',
		'SymbolLimit' : '4000',
		'Format' : 'JSON'
	}
	
	totalSymbols = 0
	
	responseObj = requests.get(URL, paramters)
	response = responseObj.json()
	metaData = response[0]
	totalSymbols += WriteSymbolsToCSVFile(csvWriter, response)
	print(f'Response received in {responseObj.elapsed.total_seconds()} seconds.  Total symbols = {totalSymbols}')

	while 'PageToken' in metaData:
		paramters['PageToken'] = metaData['PageToken']
		responseObj = requests.get(URL, paramters)
		response = responseObj.json()
		metaData = response[0]
		totalSymbols += WriteSymbolsToCSVFile(csvWriter, response)
		print(f'Response received in {responseObj.elapsed.total_seconds()} seconds.  Total symbols = {totalSymbols}')

if __name__ == '__main__':
	main()