Add dir with some small projects

small-projects/maze-puzzle/src/clients/product_detail_client.py

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+"""
+Interview note:
+    This is a client "stub", here for demonstration and documentation
+    purposes only.
+
+    In a real production environment, this client would send requests over
+    the network to a product detail backend service.
+
+The product detail backend service is responsible for retrieving product
+detail records from its datastore (e.g., a mysql database), and
+returning them to callers.
+"""
+class ProductDetailClient:
+
+    def lookup(product_token):
+        """
+        Given a product token, makes a blocking call to the lookup endpoint of
+        the product detail backend service,
+        and returns a corresponding product detail record, if found.
+        If no record is found, returns None.
+
+        Example result:
+
+        {"token": "AAA",
+         "description": "Red Bike",
+         "price_cents": 45000}
+        """
+        pass
+
+    def batch_lookup(product_tokens):
+        """
+        Given a list of product tokens, makes a blocking call to the
+        batch lookup endpoint of the product detail backend service,
+        and returns a map of product token to product detail record, for all
+        that are found.
+        Any records that cannot be found are ommitted from the result.
+
+        Example result:
+
+        {"AAA": {
+            "token": "AAA",
+            "description": "Red Bike",
+            "price_cents": 45000},
+         "BBB": {
+            "token": "BBB",
+            "description": "Blue Bike",
+            "price_cents": 37500}}
+        """
+        pass

small-projects/maze-puzzle/src/clients/product_search_client.py

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+"""
+Interview note:
+    This is a client "stub", here for demonstration and documentation
+    purposes only.
+
+    In a real production environment, this client would send requests over
+    the network to a product search backend service.
+
+The product search backend service is responsible for performing lookups
+against a product search index (e.g., elasticsearch) and returning product
+tokens that are search result "hits".
+"""
+class ProductSearchClient:
+
+    def search_for_all_in_price_range(lower_cents, upper_cents, start_record, num_records):
+        """
+        Given a price range plus pagination information,
+        returns a list of product tokens of products
+        whose price falls in the range.
+
+        The price range is inclusive - that is,
+        a given price "p" matches if:
+
+        upper_cents >= p >= lower_cents
+
+        If no products have prices in the price range,
+        returns an empty list.
+
+        Product tokens are ordered by price, from lowest to highest.
+
+        Out of the total list of possible product tokens,
+        only the "page" of product tokens starting at the list position
+        start_record, and ending at start_record+num_records, are returned.
+
+        If start_record+num_records is greater than the number of actual
+        result records, the resulting list size will be (accordingly)
+        smaller than num_records.
+
+        Example result:
+
+        ["AAA",
+         "BBB"]
+        """
+        pass

small-projects/maze-puzzle/src/service.py

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+import re
+
+TOKEN_REGEX = re.compile("^[0-9A-F-]+$")
+
+class Service:
+    def __init__(self, product_detail_client, product_search_client):
+        self.product_detail_client = product_detail_client
+        self.product_search_client = product_search_client
+
+    def lookup(self, product_token):
+        """
+        Given a valid product token,
+        lookup product detail information from the product detail backend service.
+
+        - Results in Bad Request if the token is invalid
+        - Results in Not Found if the product is unknown to the backend service
+        """
+        if not TOKEN_REGEX.match(product_token):
+            return {"status": 400}
+
+        lookup_result = self.product_detail_client.lookup(product_token)
+        if lookup_result:
+            return {"status": 200, "product": lookup_result}
+        else:
+            return {"status": 404}
+
+    def search_by_price_range(self, lower_cents, upper_cents, start_record, num_records):
+        page_of_product_tokens = \
+            self.product_search_client.search_for_all_in_price_range(
+                lower_cents,
+                upper_cents,
+                start_record,
+                num_records)
+
+        product_detail_results = []
+        for product_token in page_of_product_tokens:
+            product_detail_results.append(self.lookup(product_token)["product"])
+
+        return {"status": 200, "products": product_detail_results}
+
+if __name__ == "__main__":
+    a = Service()
+    print(a.lookup('aaa'))