import json
import pprint

def readfile(filename):
    """
    Returns the content of a file
    """
    handle = open(filename, 'r')
    data = handle.read()
    handle.close()
    return data


def printheader(text):
    """
    Format a header depending on the given text
    """
    # 79 times '-'
    print("-" * 79)

    print(text)

    # same as above
    print("-" * 79)


def jsonfiletodict(filename):
    """
    Returns a dictionary of a JSON file
    """
    plaintext = readfile(filename)
    return json.loads(plaintext)


def createcourseslist(data):
    """
    Returns a list (courses, important)
    """
    course_id = 1
    courses = []
    for course in data:
        if not (course["title"], 0) in courses:
            courses.append((course["title"], False))
            course_id += 1
    return courses


def viewcourseslist(courses):
    """
    Prints courses list
    """
    printheader("Courses list")
    for i in range(len(courses)):
        (name, important) = courses[i]
        print(i + 1, ": ", name, end="")
        if important:
            print("    [Important]")
        else:
            print("    [Not important]")


def tagasimportant(courses):
    """
    Tags a title as important
    """
    course_id = int(getinput("Please enter a course id: "))
    (name, important) = courses[course_id - 1]
    courses[course_id - 1] = (name, True)


def untagasimportant(courses):
    """
    Untags a title as important
    """
    course_id = int(getinput("Please enter a course id: "))
    (name, important) = courses[course_id - 1]
    courses[course_id - 1] = (name, False)


def exportcourses(data, filename):
    """
    Exports the data into a file
    """
    filename = getinput("Please enter a filename: ")
    handle = open(filename, 'w')
    handle.write(data)
    handle.close()
    print("File exported with success !")


def savequery(search, courses, filename):
    """
    Save courses
    """
    handle = open(filename, 'w')
    handle.write(search + ":\n")
    for course in courses:
        handle.write("    " + course + '\n')
    handle.close()


def querybycategory(data):
    category = getinput("Please enter a category: ")
    filename = getinput("Please enter a filename: ")
    courses = []
    for course in data:
        if course["category"] == category and course["title"] != "":
            courses.append(course["title"])
    savequery(category, courses, filename)
    return courses


def querybysubject(data):
    subject = getinput("Please enter a subject: ")
    filename = getinput("Please enter a filename: ")
    courses = []
    for i in range(len(data)):
        course = data[i]
        if course["subject"] == subject and course["title"] != "":
            courses.append(course["title"])
    savequery(subject, courses, filename)
    return courses


def savequerydate(date_min, date_max, courses, filename):
    handle = open(filename, 'w')
    handle.write("Courses between " + str(date_min) + " and " + str(date_max) + '\n')
    for (course, year) in courses:
        handle.write(str(year) + ": " + course + '\n')
    handle.close()


def querybydate(data):
    date_min = int(getinput("Please enter the first year: "))
    date_max = int(getinput("Please enter the second year: "))
    filename = getinput("Please enter a filename: ")
    courses = []
    for course in data:
        year = int(course["date"])
        if year >= date_min and year <= date_max and course["title"] != "":
            courses.append((course["title"], course["date"]))
    savequerydate(date_min, date_max, courses, filename)
    return courses


def getinput(text):
    print(text, end="")
    return input()


def changecourse(data):
    """
    Changes subject and category of a course
    """
    title = getinput("Please enter a title: ")
    new_subject = getinput("Please enter a new subject for the course: ")
    new_category = getinput("Please enter a new category for the course: ")
    i = 0
    while i < len(data):
        course = data[i]
        if course["title"] == title:
            break
        i += 1

    data[i]["category"] = new_category
    data[i]["new_subject"] = new_subject
    return data


def printchoices():
    print("Please enter a number to select an option.")
    print("1: View courses list")
    print("2: Tag a course as important")
    print("3: Untag a course as important")
    print("4: Query courses by a category")
    print("5: Query courses by a subject")
    print("6: Query courses by a date range")
    print("7: Change a course")
    print("8: Export courses")
    print("9: Leave the app")


def main():
    data = jsonfiletodict("metadata.json")
    courses = createcourseslist(data)
    while True:
        printheader("Welcome on the app !")
        printchoices()
        choice = int(input())
        if choice == 1:
            viewcourseslist(courses)
        elif choice == 2:
            tagasimportant(courses)
        elif choice == 3:
            untagasimportant(courses)
        elif choice == 4:
            querybycategory(data)
        elif choice == 5:
            querybysubject(data)
        elif choice == 6:
            querybydate(data)
        elif choice == 7:
            data = changecourse(data)
        elif choice == 8:
            exportcourses(data)
        elif choice == 9:
            break


if __name__ == "__main__":
    main()