added mailroom 3 solution

Author: PythonCHB

source/solutions/Lesson05/mailroom3.py

@@ -0,0 +1,253 @@
+#!/usr/bin/env python
+"""
+mailroom assignment
+
+This version uses a dict for the main db, and a dict to"switch" on the user's
+input choices.
+
+it also write the thank you letters to files.
+
+"""
+
+import sys
+import math
+from operator import itemgetter
+
+# handy utility to make pretty printing easier
+from textwrap import dedent
+
+
+# In memory representation of the donor database
+# using a tuple for each donor
+# -- kind of like a record in a database table
+# using a dict with a lower case version of the donor's name as the key
+# This makes it easier to have a 'normalized' key.
+#  you could get a bit fancier by having each "record" be a dict, with
+#   "name" and "donations" as keys.
+
+def get_donor_db():
+    return {'william gates iii': ("William Gates III", [653772.32, 12.17]),
+            'jeff bezos': ("Jeff Bezos", [877.33]),
+            'paul allen': ("Paul Allen", [663.23, 43.87, 1.32]),
+            'mark zuckerberg': ("Mark Zuckerberg", [1663.23, 4300.87, 10432.0]),
+            }
+
+
+def list_donors():
+    """
+    Create a list of the donors as a string, so they can be printed
+
+    Not calling print from here makes it more flexible and easier to
+    test
+    """
+    listing = ["Donor list:"]
+    for donor in donor_db.values():
+        listing.append(donor[0])
+    return "\n".join(listing)
+
+
+def print_donor_list():
+    """
+    Doesn't do much, but keeps the printing separate
+    """
+    print(list_donors())
+    print()
+
+
+def find_donor(name):
+    """
+    Find a donor in the donor db
+
+    :param: the name of the donor
+    :returns: The donor data structure -- None if not in the donor_db
+    """
+    key = name.strip().lower()
+    return donor_db.get(key)
+
+
+def add_donor(name):
+    """
+    Add a new donor to the donor db
+
+    :param: the name of the donor
+    :returns: the new Donor data structure
+    """
+    name = name.strip()
+    donor = (name, [])
+    donor_db[name.lower()] = donor
+    return donor
+
+
+def gen_letter(donor):
+    """
+    Generate a thank you letter for the donor
+
+    :param: donor tuple
+    :returns: string with letter
+
+    note: This doesn't actually write to a file -- that's a separate
+          function. This makes it more flexible and easier to test.
+    """
+    return dedent('''Dear {0:s},
+
+          Thank you for your very kind donation of ${1:.2f}.
+          It will be put to very good use.
+
+                         Sincerely,
+                            -The Team
+          '''.format(donor[0], donor[1][-1]))
+
+
+def take_donation():
+    """
+    Ask user for donation amount, and then add it  to the DB
+    """
+    # Now prompt the user for a donation amount to apply. Since this is
+    # also an exit point to the main menu, we want to make sure this is
+    # done before mutating the db.
+    print("in take_donation")
+    name = input("Enter a donor name (new or existing): \n >")
+    while True:
+        amount_str = input("Enter a donation amount (or <enter> to exit)> ").strip()
+        if not amount_str:
+            # if they provide no input, go back to previous menu
+            return
+        # Make sure amount is a valid amount before leaving the input loop
+        try:
+            amount = float(amount_str)
+            # extra check here -- unlikely that someone will type "NaN", but
+            # it IS possible, and it is a valid floating point number:
+            # http://en.wikipedia.org/wiki/NaN
+            if math.isnan(amount) or math.isinf(amount) or round(amount, 2) == 0.00:
+                raise ValueError
+        except ValueError:
+            print("error: donation amount is invalid\n")
+            continue
+        else:
+            break
+
+    donor = find_donor(name)
+    # If the donor is not found, it's a new donor
+    if donor is None:
+        # add the new donor to the database
+        donor = add_donor(name)
+
+    # Record the donation
+    donor[1].append(amount)
+    # print the thank you letter
+    print(gen_letter(donor))
+
+
+def sort_key(item):
+    # used to sort on name in donor_db
+    return item[1]
+
+
+def generate_donor_report():
+    """
+    Generate the report of the donors and amounts donated.
+
+    :returns: the donor report as a string.
+    """
+    # First, reduce the raw data into a summary list view
+    report_rows = []
+    for (name, gifts) in donor_db.values():
+        total_gifts = sum(gifts)
+        num_gifts = len(gifts)
+        avg_gift = total_gifts / num_gifts
+        report_rows.append((name, total_gifts, num_gifts, avg_gift))
+
+    # sort the report data
+    report_rows.sort(key=itemgetter(1), reverse=True)
+    report = []
+    report.append("{:25s} | {:11s} | {:9s} | {:12s}".format("Donor Name",
+                                                            "Total Given",
+                                                            "Num Gifts",
+                                                            "Average Gift"))
+    report.append("-" * 66)
+    for row in report_rows:
+        report.append("{:25s}   ${:10.2f}   {:9d}   ${:11.2f}".format(*row))
+    return "\n".join(report)
+
+
+def save_letters_to_disk():
+    """
+    make a letter for each donor, and save it to disk.
+    """
+    for donor in donor_db.values():
+        letter = gen_letter(donor)
+        # I don't like spaces in filenames...
+        filename = donor[0].replace(" ", "_") + ".txt"
+        print("writing letter to:", donor[0])
+        open(filename, 'w').write(letter)
+
+
+def print_donor_report():
+    print(generate_donor_report())
+
+
+def return_to_menu():
+    ''' Return True to trigger exit out of sub-loop'''
+    return True
+
+
+def send_thank_you():
+    """
+    Execute the logic to record a donation and generate a thank you message.
+    """
+    # Read a valid donor to send a thank you from, handling special commands to
+    # let the user navigate as defined.
+    prompt = ("To send a thank you, select one:\n\n"
+              "(1) Update donor and send thank-you\n"
+              "(2) List all existing DONORS\n"
+              "(3) Return to main menu\n > ")
+    selection_dict = {"1": take_donation,
+                      "2": print_donor_list,
+                      "3": return_to_menu,
+                      }
+    run_menu(prompt, selection_dict)
+
+def main_menu():
+    """
+    Run the main menu for mailroom
+    """
+    prompt = dedent('''
+                    Choose an action:
+
+                    (1) - Send a Thank You
+                    (2) - Create a Report
+                    (3) - Send letters to everyone
+                    (4) - Quit
+
+                    > ''')
+
+    selection_dict = {"1": send_thank_you,
+                      "2": print_donor_report,
+                      "3": save_letters_to_disk,
+                      "4": quit}
+
+    run_menu(prompt, selection_dict)
+
+
+def run_menu(prompt, selection_dict):
+    """
+    run an interactive menu
+
+    :param prompt: What you want to ask the user
+
+    :param selection_dict: Dict of possible user impots mapped to
+                           the actions to take.
+    """
+    while True:
+        selection = input(prompt).strip().lower()
+        try:
+            if selection_dict[selection]():
+                # break out of the loop if action returns True
+                break
+        except KeyError:
+            print("error: menu selection is invalid!")
+
+
+if __name__ == "__main__":
+    donor_db = get_donor_db()
+    main_menu()