#!/usr/bin/env python

'''
Examples adapted from "Programming for all, part 1: An introduction to writing for computers":

http://arstechnica.com/science/2012/12/programming-for-all-part-1-an-introduction-to-writing-for-computers/

and "Programming for all, part 2: From concept to code":

http://arstechnica.com/science/2012/12/programming-for-all-part-2-from-concept-to-code/

Most examples are fairly close to their original psuedocode; where possible, the code has been
condensed to slightly more standard Python while preserving the original intent. Note that this
means some of these examples aren't exactly "Pythonic," but it will make them easier to match
to the original article. In particular, most of the variable "declarations" have been removed,
since names are untyped in Python and may be arbitrarily assigned at any time in most cases.

In addition, there was a bug in the Fibonacci sequence generation that I fixed (F1 == 1, not 0).
I also skipped translation of the map and fold examples, since those are available via the
straightforward map() and reduce() functions in Python, and you would never manipulate a list in
such a manner anyway.

There may be some remaining bugs (or new ones that I introduced), but I ran through all the
examples and they seem to function as intended.

Happy hacking!
'''

import argparse
import inspect
import sys


def my_first_program():
    # This line is a comment to other humans
    # So is this line
    # Since function bodies can't be completely empty,
    # the following statement performs a no-op
    pass


def my_first_useful_program():
    # store the value retrieved from user input in the variable "x"
    x = float(raw_input('What number would you like to square? '))
    x_squared = x * x   # store the value of x times itself
    print 'Your number squared is', x_squared


def is_it_hot_out():
    # store the temperature retrieved from user input
    temperature = float(raw_input('Temperature: ')) # for all we care, we are reading this from
                                                    # a digital thermometer connected to the
                                                    # computer, or from the Weather Channel!
                                                    # In this Python interpretation of the example,
                                                    # we read it from the command line.
    if temperature > 89:    # here is where we decide what
                            # we are going to do next
                            # only one print statement (branch)
                            # will be executed
        # this will be printed if temperature is above 89
        print 'Wow, it is hot outside!'
    else:
        # this will be printed if temperature is not above 89
        print "It isn't too hot, go outside"


def is_it_nice_out():
    temperature = float(raw_input('Temperature: ')) # from command line
    if temperature > 89:
        print "Wow, it is hot outside!"
    else:
        # if it is not too hot outside, check if it is too cold
        if temperature < 40:
            print "Wow, it is cold outside!"
        else:
            print "It is nice out, you should go outside"


def first_ten_squares():
    # count the variable i from 1 to 10 by 1
    for i in xrange(1, 11):
        # you can use exponents instead of manually squaring numbers
        print "The square of", i, "is", i ** 2


def first_ten_squares_unrolled():
    index = 1
    print "The square of", index, "is", index ** 2
    index = 2
    print "The square of", index, "is", index ** 2
    index = 3
    print "The square of", index, "is", index ** 2
    index = 4
    print "The square of", index, "is", index ** 2
    index = 5
    print "The square of", index, "is", index ** 2
    index = 6
    print "The square of", index, "is", index ** 2
    index = 7
    print "The square of", index, "is", index ** 2
    index = 8
    print "The square of", index, "is", index ** 2
    index = 9
    print "The square of", index, "is", index ** 2
    index = 10
    print "The square of", index, "is", index ** 2


def user_driven_squares():
    choice = "Y"
    while choice == "Y":    # the == sign is the logical comparison
                            # to see if two values are the same, it
                            # should not be confused with the
                            # assignment operator =
        x = float(raw_input("What number would you like to square? "))
        print "Your number squared is", x ** 2
        choice = raw_input("Would you like to enter another number? [Y/N] ")


def weather_station():
    temperature1 = float(raw_input('Temperature 1: ')) # Get three temperatures
    temperature2 = float(raw_input('Temperature 2: ')) # from the user
    temperature3 = float(raw_input('Temperature 3: '))

    # algorithm step 2
    sum = temperature1 + temperature2 + temperature3
    # algorithm step 3
    averageTemp = sum / 3.0
    # steps 4 and half of 5 from the algorithm
    sqDist1 = (temperature1 - averageTemp) ** 2
    sqDist2 = (temperature2 - averageTemp) ** 2
    sqDist3 = (temperature3 - averageTemp) ** 2
    # other half of 5 and step 6 from the algorithm
    stddevTemp = ((sqDist1 + sqDist2 + sqDist3) / 3.0) ** 0.5

    print "Average temperature =", averageTemp, "+/-", stddevTemp


def modular_weather_station():

    def computeAverage(n1, n2, n3):
        # the values passed into this function will be mapped to
        # the values n1, n2, and n3--only in this function
        sum = n1 + n2 + n3
        # at a return statement, the program will return to the
        # point where it left off
        return sum / 3.0

    def standardDeviation(n1, n2, n3, avg):
        sqDist1 = (n1 - avg) ** 2
        sqDist2 = (n2 - avg) ** 2
        sqDist3 = (n3 - avg) ** 2

        return ((sqDist1 + sqDist2 + sqDist3) / 3.0) ** 0.5

    temperature1 = float(raw_input('Temperature 1: '))
    temperature2 = float(raw_input('Temperature 2: '))
    temperature3 = float(raw_input('Temperature 3: '))

    # we will call a function that computes the average for us
    # at this line, control of the program will be transferred
    # to the computeAverage function
    averageTemp = computeAverage(temperature1, temperature2, temperature3)

    # likewise for the standard deviation
    stddevTemp = standardDeviation(temperature1, temperature2, temperature3, averageTemp)

    print "Average temperature = ", averageTemp, "+/-", stddevTemp


def intro_to_lists():
    squareList = []
    myList = [1, 2, 3, 4, 5, 6] # Like we can set the value of a number,
                                # we can set the value of a list using
                                # [] and , to separate values
    # Print out myList
    for item in myList:
        print item
    # this would display the numbers 1, 2, 3, 4, 5, and 6

    # populate squareList
    for item in myList:
        # Append the square of each value in myList
        # to the end of squareList
        squareList.append(item ** 2)

    # Print out squareList
    for item in squareList:
        print item
    # this would display 1, 4, 9, 16, 25, and 36

    # modify something in squareList
    squareList[5] = 27.39
    # print again
    for item in squareList:
        print item
    # this would now print 1, 4, 9, 16, 27.39, and 36


def list_based_weather_station():

    def computeAverage(nums):
        sum = 0
        # add up all the elements in the list
        for index in xrange(len(nums)):
            sum = sum + nums[index]
        # divide the sum by the number of elements
        return sum / len(nums)

    def standardDeviation(nums, avg):
        sum = 0
        for index in xrange(len(nums)):
            sqDist = (nums[index] - avg) ** 2
            sum = sum + sqDist
        return (sum / len(nums)) ** 0.5

    temperatures = []
    choice = ""     # read in as many temperatures as the user wants!

    choice = "Y"
    while choice == "Y":
        temp = float(raw_input("Please input a temperature: "))
        # add the newest read in value to the list of temperatures
        temperatures.append(temp)
        choice = raw_input("Would you like to enter another value? [Y/N] ")
    # At this point we have a list of temperatures,
    # we don't know how long it is, but we'd like to
    # find it average and standard deviation, just like before

    # We can pass a list to a function like any other data
    averageTemp = computeAverage(temperatures)
    stddevTemp = standardDeviation(temperatures, averageTemp)

    print "Average temperature =", averageTemp, "+/-", stddevTemp


def fibonacci():

    def computeFibonacci(n):
        if n == 0:      # if we are asking for the first Fibonacci number
            return 0    # 0 is the first Fibonacci number
        elif n == 1:
            return 1    # 1 is the second Fibonacci number
        # If we are not asking for the first or second
        # Fibonacci number, then we need to compute it
        return computeFibonacci(n - 1) + computeFibonacci(n - 2)   # /Neo: Woah!

    fibNumber = int(raw_input("Which Fibonacci number would you like to compute? "))
    answer = computeFibonacci(fibNumber)
    print "Fibonacci number", fibNumber, "is", answer



def main():
    parser = argparse.ArgumentParser(
        description='Run Ars Technica programming examples',
        epilog=__doc__,
        formatter_class=argparse.RawDescriptionHelpFormatter )
    group = parser.add_mutually_exclusive_group(required=True)
    group.add_argument('-l', '--list', action='store_true', help='list examples')
    group.add_argument('example', nargs='?', metavar='EXAMPLE_NAME', help='run one example')
    group.add_argument('-a', '--all', action='store_true', help='run all examples')
    parser.add_argument('-p', '--print', action='store_true', dest='print_source', help='print source')
    args = parser.parse_args()

    examples = {}
    for member in inspect.getmembers(sys.modules[__name__]):
        if not member[0].startswith('__') and member[0] != 'main' and callable(member[1]):
            examples[member[0]] = member[1]

    if args.list:
        sys.stderr.write('Valid examples:\n{}\n'.format('\n'.join(examples.keys())))
    elif args.all:
        for example in examples:
            if args.print_source:
                print inspect.getsource(examples[example])
            else:
                examples[example]()
                print
    else:
        if args.example in examples:
            if args.print_source:
                print inspect.getsource(examples[args.example])
            else:
                examples[args.example]()
        else:
            sys.stderr.write('Valid examples:\n{}\n'.format('\n'.join(examples.keys())))
            sys.exit(1)


if __name__ == '__main__':
    try:
        main()
    except KeyboardInterrupt:
        sys.exit(1)