"""
Updated:
- Add line-type 'note' with syntax '='
- Add line-type 'list' with syntax '&'
- Change syntax of line-type 'title' to '+' instead of '-'
- Remove unnecessary spaces in input file

To be updated:
- Learn answers
- Remove unnecessary line breaks in input file
- Answer judged correct if contains keyword
- Title and subtitle also printed if answer in the section is incorrect
- Consider to use json input file
- Graphic user interface
- Another program to help create related input file
- Optimize
"""

try:

    import re
    import difflib

    def check_string(line):
        string = r"[\w\d\s\?\.\"\(\)\[\]\{\}\-!,;'/]*"
        return bool(
            re.match(
                f"([+~=] {string}\Z)|(! version: \d+\.?\d*\s?\Z)|(# {string}: {string}\Z)|(& ({string}: )+{string}\Z)",
                line,
            )
        )

    def compare_string(answer, response):
        diff = list(difflib.ndiff(answer, response))
        diff_count = 0
        for line in diff:
            if line[0] != " ":
                diff_count += 1
        return round(1 - (diff_count / len(diff)), 4) * 100

    file_name = input("Enter file name (with postfix) >> ")
    if file_name == "":
        file_name = "test_2.0.rvwt"
    with open(file_name) as f:
        data = f.readlines()
    count_prompts = 0
    count_correct = 0
    correct_param = 70
    incorrect = []

    if len(data) == 0:
        raise Exception("Error: file empty")

    if data.pop(0).split(".")[0].replace("\n", "") != "! version: 2":
        raise Exception("Error: file version not provided or does not match")

    for line_index in range(len(data)):
        if not check_string(data[line_index]):
            raise Exception(
                f"Error: invalid syntax at line {line_index+2} of file '{file_name}'"
            )

    for line_index in range(len(data)):
        line = data[line_index]
        if line[0] == "+":
            line = line[2:].replace("\n", "")
            print("\n\n- " + line + " -\n")
        elif line[0] == "~":
            line = line[2:].replace("\n", "")
            print("\n" + line + "\n")
        elif line[0] == "=":
            line = line[2:].replace("\n", "")
            print(line)
        elif line[0] == "#":
            count_prompts += 1
            line = line[2:].split(":")
            prompt = line[0]
            answer = line[1][1:-1]
            if prompt != "":
                prompt += " "
            response = input(prompt + ">> ")
            if response.lower() == answer.lower():
                print("Correct")
                count_correct += 1
            elif compare_string(response.lower(), answer.lower()) >= correct_param:
                print(
                    f"Probably correct: answer is '{answer}', similarity {round(compare_string(response.lower(), answer.lower()), 4)}%"
                )
                judge = input("Is your answer correct? [[y]/n] ").lower()
                if judge == "n":
                    incorrect.append((prompt, answer))
                else:
                    count_correct += 1
                    if judge != "y":
                        print("Warning: invalid input, answer judged as correct")
            else:
                print(
                    f"Probably incorrect: answer is '{answer}', similarity {round(compare_string(response.lower(), answer.lower()), 4)}%"
                )
                judge = input("Is your answer correct? [y/[n]] ").lower()
                if judge == "y":
                    count_correct += 1
                else:
                    incorrect.append((prompt, answer))
                    if judge != "n":
                        print("Warning: invalid input, answer judged as incorrect")
        elif line[0] == "&":
            line = line[2:].split(":")
            prompt = line.pop(0)
            answers = list(map(lambda x: x[1:].lower().replace("\n", ""), line))
            items = len(answers)
            count_prompts += items
            correct_answers = 1
            answers_max = items
            print(prompt)
            while answers_max >= correct_answers: 
                response = input(f"{correct_answers}/{answers_max} >> ")
                if response == "":
                    break
                elif response.lower() in answers:
                    print("Correct")
                    answers.pop(answers.index(response.lower()))
                    correct_answers += 1
                else:
                    max_similarity = 0
                    max_index = 0
                    for answer in answers:
                        if compare_string(response.lower(), answer) > max_similarity: 
                            max_similarity = compare_string(response.lower(), answer)
                            max_index = answers.index(answer)
                    if max_similarity >= correct_param:
                        print(
                            f"Probably correct: closest answer is '{answers[max_index]}', similarity {round(compare_string(response.lower(), answers[max_index]), 4)}%"
                        )
                        judge = input("Is your answer correct? [[y]/n] ").lower()
                        if judge == "n":
                            answers_max -= 1
                        else:
                            answers.pop(max_index)
                            correct_answers += 1
                            if judge != "y":
                                print("Warning: invalid input, answer judged as correct")
                    else:
                        print("Probably incorrect")
                        answers_max -= 1
            if len(answers) != 0:
                print("You didn't get the following answers correct: ", end="")
            for answer in answers:
                incorrect.append((prompt, answer))
                print("'" + answer+ "' ", end="")
            count_correct += correct_answers - 1
            if len(answers) != 0:
                print()
        else:
            continue

    if count_prompts <= 1:
        print(f"\n\nOut of {count_prompts} question, ", end="")
    else:
        print(f"\n\nOut of {count_prompts} questions, ", end="")
    if count_correct <= 1:
        print(f"{count_correct} was answered correctly, ", end="")
    else:
        print(f"{count_correct} were answered correctly, ", end="")
    print(f"which is {round(count_correct / count_prompts * 100, 2)}%. ")

    if count_prompts == count_correct:
        print("Congratulations for finishing perfectly! ")
    else:
        if count_prompts - count_correct <= 1:
            print(f"The question with incorrect response is listed below: \n")
        else:
            print(f"The questions with incorrect responses are listed below: \n")
        for line in incorrect:
            (prompt, answer) = line
            print(prompt + "-> " + answer)


except Exception as e:
    print("\nException: " + str(e))
except KeyboardInterrupt:
    print("\nProcess quitted")