Check prices and report on the cheapest price found

find_prices.py

"""
Check and store the prices of an item.

Create a find_prices.json file and run daily to see if prices changed.

..code-block:: json

    {
        "Coffee Maker": {
            "Vendor": {
                "url": "https://vendor.url",
            },
            "Amazon": {
                "url": "https://www.amazon.com/...",
            }
    }

On windows use taskschd.msc as a cron job.
"""
import sys
try:
    import local
except (ImportError, Exception):
    print("Could not import local env!", file=sys.stderr)

import json
import requests
from bs4 import BeautifulSoup
from selenium import webdriver
from selenium.webdriver.chrome.options import Options
from script_utils import send_mail


FILENAME = "find_prices.json"


def find_price(url):
    r = requests.get(url)
    if r.status_code != 200:
        chrome_options = Options()
        chrome_options.add_argument("--headless")
        chrome_options.add_experimental_option("excludeSwitches", ["enable-logging"])
        browser = webdriver.Chrome(options=chrome_options)
        browser.get(url)
        page = browser.page_source
        browser.close()
    else:
        page = r.text

    # Stock
    in_stock = "out of stock" not in page.lower()

    if "amazon" in url:
        soup = BeautifulSoup(page, "html.parser")
        try:
            a_price = soup.find("span", class_="a-offscreen").text
        except (AttributeError, Exception):
            a_price = (
                soup.find("span", class_="a-price-whole").text
                + soup.find("span", class_="a-price-fraction").text
            )
        price = float(a_price.replace("$", "").replace(",", ""))
    else:
        page_lower = page.lower()
        price = None
        try:
            button_idx = page_lower.find("add to cart")
            price_idx = page_lower[:button_idx].rfind("$")
            s_price = page[price_idx:button_idx].split(" ", 1)[0].split("<", 1)[0]
            price = float(s_price.replace("$", "").replace(",", ""))
        except (TypeError, ValueError):
            for i in range(100):
                try:
                    price_idx = page_lower.rfind("$")
                    page_lower = page_lower[price_idx + 1 :]
                    s_price = page_lower.split(" ", 1)[0].split("<", 1)[0]
                    price = float(s_price.replace("$", "").replace(",", ""))
                    break
                except (TypeError, ValueError):
                    pass

    return price, in_stock


def main():
    with open(FILENAME, "r") as f:
        prices = json.loads(f.read())

    cheaper = {}
    for product, stores in prices.items():
        print(f"{product}: ")
        for store, store_prices in stores.items():
            price, stock = find_price(store_prices["url"])
            if price is None:
                continue

            try:
                old_price = store_prices["cheapest_price"]
            except KeyError:
                # Initialize cheapest price
                old_price = store_prices["cheapest_price"] = price

            cheap = old_price > price
            print(
                f"\t{store}\tprice: ${price:.02f}\tstock: {stock}\tcheaper: {cheap}\tdiff: ${old_price - price:.02f}",
                flush=True,
            )

            store_prices[f"last_price"] = price
            if cheap:
                if not cheaper.get(product) or cheaper[product][1] > price:
                    cheaper[product] = (store, price, store_prices["url"])
                store_prices[f"cheapest_price"] = price

    with open(FILENAME, "w") as f:
        json.dump(prices, f, indent=4)

    if cheaper:
        body = []
        for product, (store, price, url) in cheaper.items():
            body.append(f"{product} found a cheaper price at {store} for ${price:.02f}\n\t{url}\n")

        send_mail(
            "Cheaper price found!",
            "\n".join(body),
            "[email protected]",
            ["[email protected]"],
        )
        print("\nCheaper price found!\n\n" + '\n'.join(body))
    else:
        print("\tNo cheaper prices found!", file=sys.stderr)


if __name__ == "__main__":
    with local.env():
        main()