# book example
# book = {
#    'name': 'Programming with Python 3',
#    'pages': 157,
#    'read': True
# }

bookshelf = [False] * 10 # = [False, False, False, False, False, False, False, False, False, False]

# (0) this function will return False, if there is a book at specified "position" in bookshelf. If there is none, return True (True → there is no book, the space is free)
# position = index (0 - 9)
# this function is not graded, but is used in other functions
def isFree(position):
    return not bool(bookshelf[position])

# (1) this function will add a book with "name", number of pages "pages" and wether the book was read "read"
# if there already is a book at given "position", this function does nothing
# use the function "isFree"
def addBook(position, name, pages, read = False):
    if isFree(position):
        bookshelf[position] = {
            "name": name,
            "pages": pages,
            "read": read
        }
        
# (2) returns False or index of the book with a given "name"
def findBook(name):
    for book in bookshelf:
        if book:
            if book["name"] == name:
                return bookshelf.index(book)
    
# (3) this function uses the "findBook" function and if there is a book with a given "name" in the "bookshelf", it changes its "read" value to True
def readBook(name):
    if findBook(name):
        bookshelf[findBook(name)]["read"] = True
    
# (4) this function removes all books that were read from the "bookshelf" (read == True) (replaces them with False)
def removeReadBooks():
    for book in bookshelf:
        if book:
            if book["read"]:
                bookshelf[bookshelf.index(book)] = False

# (5) returns a list with names of books in the "bookshelf"
def namesOfBooks():
    names = []
    for book in bookshelf:
        if book:
            names.append(book["name"])
    return names

# BONUS: returns the average number of pages of books in the "bookshelf"
def averageNumberOfPages():
    sum = 0
    count = 0
    for book in bookshelf:
        if book:
            sum += book["pages"]
            count += 1
    return sum/float(count)
    

# testing

# 1
addBook(0, 'A Byte of python', 120, read = True)
addBook(1, 'Automate the boring stuff with Python', 420)
addBook(2, 'Python for Informatics', 500, read = True)
addBook(3, 'Learning Geospatial Analysis with Python', 155)
addBook(4, 'Python Geospatial Development', 211)
addBook(5, 'Python for Data Analysis', 362, read = True)
addBook(5, 'Programming Java', 874)

print isFree(5) # False
print isFree(6) # True


# 2
print findBook('A Byte of python') # 0
print findBook('Python Geospatial Development') # 4
print findBook('Programming Java') # False

# 3
readBook('A Byte of python')
readBook('Automate the boring stuff with Python')
readBook('Programming Java')


# 4
removeReadBooks()
print isFree(1) # True
print isFree(3) # False


# 5
print namesOfBooks() # ['Learning Geospatial Analysis with Python', 'Python Geospatial Development']


# BONUS
print averageNumberOfPages() # 183


# HINT
print bookshelf
# [False, False, False, {'pages': 155, 'name': 'Learning Geospatial Analysis with Python', 'read': False}, {'pages': 211, 'name': 'Python Geospatial Development', 'read': False}, False, False, False, False, False]