Yahoo Finance Crawler as a Python script

fetchStockData.py

#!/usr/bin/env python

##############################################################################
# fetchStockData.py - a friendly Yahoo Finance crawler.                      #
#                                                                            #
# Requirements                                                               #
#                                                                            #
# - Python 3                                                                 #
# - Selenium package for Python                                              #
# - The web driver for Chrome                                                #
#                                                                            #
# 2018, Michael Chen; Apache 2.0                                             #                    
##############################################################################


import os
import sys
import time

from random import randint

from selenium import webdriver


# Parameters
targetAsset = None
timeSpan = "5Y"
downloadPath = os.path.dirname(os.path.abspath(__file__))

if len(sys.argv) < 2:
    sys.stderr.write("No valid target asset\n")
    sys.exit(1)

targetAsset = sys.argv[1]

# Change default downloading path.
options = webdriver.ChromeOptions()
prefs = {'download.default_directory' : downloadPath}
options.add_experimental_option('prefs', prefs)

# Create a new instance of the Chrome driver
driver = webdriver.Chrome(chrome_options=options)

# Go to the Yahoo Finance page
driver.get("https://finance.yahoo.com/")

# Wait the page to fresh.
time.sleep(10)

# Find the input box.
inputElement = driver.find_element_by_css_selector("#fin-srch-assist input")

# Type in the search.
inputElement.send_keys(targetAsset)

# Submit the form.
inputElement.submit()

# Wait the page to fresh.
time.sleep(10)

# Select the subpage of Historical Data.
items = driver.find_elements_by_css_selector("a span")
for item in items:
    if item.text == "Historical Data":
        item.click()
        break

time.sleep(randint(1, 3))  # Simulate idling

# Help Yahoo to earn some money.
ad = driver.find_element_by_css_selector("#sb_rel_defaultdestLDRB")
ad.click()

time.sleep(randint(1, 3))  # Simulate idling

# Select the dialog.
arrows = driver.find_elements_by_css_selector(".historical div div span svg")
arrows[0].click()

time.sleep(randint(1, 3))  # Simulate idling

# Select some time span.
durations = driver.find_elements_by_css_selector("[data-test=\"date-picker-menu\"] div span")
for duration in durations:
    if duration.text == timeSpan:
        duration.click()
        break

time.sleep(randint(1, 3))  # Simulate idling

# Finish the selection by clicking Done button.
buttons = driver.find_elements_by_css_selector("[data-test=\"date-picker-menu\"] div button")
for button in buttons:
    if button.text == "Done":
        button.click()
        break

time.sleep(randint(1, 3))  # Simulate idling

# Apply the change.
buttons = driver.find_elements_by_css_selector("button span")
for button in buttons:
    if button.text == "Apply":
        button.click()
        break

time.sleep(randint(1, 3))  # Simulate idling

# Remove old file.
csvpath = os.path.join(downloadPath, "%s.csv" % targetAsset)
if os.path.exists(csvpath):
    os.remove(csvpath)

# Download the data.
links = driver.find_elements_by_css_selector("a span")
for link in links:
    if link.text == "Download Data":
        link.click()
        break

time.sleep(5)

# Close the browser.
driver.quit()