"""Code for examples from lecture 35"""

# Basic coroutine: match a pattern

def match(pattern):
    print("Looking for %s" % pattern)
    try:
        while True:
            line = (yield)
            if pattern in line:
                print(line)
    except GeneratorExit as e:
        print("Done.")


def read(text, next_coroutine):
    for word in text.split():
        next_coroutine.send(word)
    next_coroutine.close()

# Example

text = "Commending spending is offending to people pending lending!"
matcher = match("ending")
matcher.__next__()
read(text, matcher)

# More advanced -- counting the most frequent letter

def count_letters(next_coroutine):
    try:
        while True:
            line = (yield)
            counts = {}
            for letter in line:
                if letter != " ":
                    if letter in counts:
                        counts[letter] += 1
                    else:
                        counts[letter] = 1
            next_coroutine.send(counts)
    except GeneratorExit as e:
        next_coroutine.close()
        
def sum_dictionaries():
    aggregated = {}
    try:
        while True:
            dictionary = (yield)
            for key in dictionary.keys():
                if key not in aggregated:
                    aggregated[key] = dictionary[key]
                else:
                    aggregated[key] += dictionary[key]
    except GeneratorExit as e:
        max_key = None
        max_value = -1
        for key in aggregated.keys():
            if aggregated[key] > max_value:
                max_key = key
                max_value = aggregated[key]
        print("Most frequent key: "+str(max_key))

s = sum_dictionaries()
s.__next__()
c = count_letters(s)
c.__next__()
r = read(text, c)

# Multitasking

def read_to_many(text, coroutines):
    for word in text.split():
        for coroutine in coroutines:
            coroutine.send(word)
    for coroutine in coroutines:
        coroutine.close()

def match_filter(pattern, next_coroutine):
    print('Looking for ' + pattern)
    try:
        while True:
            s = (yield)
            if pattern in s:
                next_coroutine.send(s)
    except GeneratorExit:
        next_coroutine.close()

def print_consumer():
    print('Preparing to print')
    try:
        while True:
            line = (yield)
            print(line)
    except GeneratorExit:
        print("Done.")

# Example

printer = print_consumer()
printer.__next__()
m = match_filter("mend", printer)
m.__next__()
p = match_filter("pe", printer)
p.__next__()
read_to_many(text, [m, p])