// License: AGPLv3 or later. https://www.gnu.org/licenses/licenses.html

#include <fstream>
#include <iostream>
#include <sstream>
# include "general_functions.h"
# include "abc.h"

using namespace std;

const int MAX_ATTEMPTS_ALLOWED = 3;

input_files_name  perform_checks_on_args(
    int argc, char *argv[])
{
    if (argc != 5) 
    {
        cerr << "Expected 5 arguments, received " << argc
            << " argument(s). Please provide exactly 5 arguments and "
            "in correct order i.e.:\n"
            "1. Program name/path (received automatically)\n"
            "2. Students File such as Students.txt\n"
            "3. Subjects File such as Subjects.txt\n"
            "4. Teachers File such as Teachers.txt\n"
            "5. Output-file such as Results.txt\n"
            "\n"
            "Run program similar to this:\n"
            "$ ./ABC Students.txt Subjects.txt Teachers.txt "
            "Results.txt\n";
        exit(1);
    }
    else
    {
        input_files_name args;
        args.students = argv[1];
        args.subjects = argv[2];
        args.teachers = argv[3];
        args.results = argv[4];
        return args;
    }
}

input_files_textlines read_input_files(
        input_files_name file_names)
{
    input_files_textlines files_textlines;
    files_textlines.students = get_textfile_lines(
        file_names.students);
    files_textlines.subjects = get_textfile_lines(
        file_names.subjects);
    files_textlines.teachers = get_textfile_lines(
        file_names.teachers);
    
    print_three_newlines();
    
    return files_textlines;
}

vector<student> generate_students_struct(
        vector<string> students_lines)
{
    cout << "Processing students file text:" << endl;
    
    vector<student> students;
	int line_number = 0;
    for (auto student_line:students_lines)
    {
		line_number++;
		
		// Ignoring empty line. Giving no warning/error for it either.
		if (student_line.size() == 0)
			continue;
		
		try
		{
			student a_student;
			string ability_string;
			string consistency_string;
			string subject_sring;
			
			istringstream line(student_line);
			getline(line, a_student.name, ',');
			getline(line, a_student.code, ',');
			getline(line, ability_string, ',');
			a_student.ability = stoi(ability_string);
			getline(line, consistency_string, ',');
			a_student.consistency = stoi(consistency_string);
			getline(line, a_student.program, ':');
			while(getline(line, subject_sring, ','))
			{
				int subject_code = stoi(subject_sring);
				if (subject_code > 0)
					a_student.subjects.push_back(subject_code);
				else
					throw "Anything that you can";
			}
			
			if (a_student.name.size() == 0
				or a_student.code.size() != 6
				or is_string_some_positive_number(
					a_student.code) == false
				or a_student.ability < 0
				or a_student.ability > 100
				or a_student.consistency < 0
				or a_student.consistency > 15
				or a_student.program.size() == 0
				or a_student.subjects.size() == 0)
			{
				throw "All the things that you can";
			}
			
			students.push_back(a_student);
            
            cout << "Student Name: " << a_student.name << '\n'
                << "Code: " << a_student.code << '\n'
                << "Ability: " << a_student.ability << '\n'
                << "Consistency: " << a_student.consistency << '\n'
                << "Program Name: " << a_student.program << '\n'
                << "Subjects code: ";
            for (auto subject_code: a_student.subjects)
            {
                cout << subject_code << "  ";
            }
            cout << '\n' << endl;
            
		}
		catch(...)
		{
			cerr << "Non-Fatal Error Occured while processing student"
                << " file lines into student structs. However as per "
				<< "specifiction, skipping proccesing anymore "
				<< "students.\n"
				<< "Line number: " << line_number << " is not in "
				<< "proper format.\n"
				<< "Actual Line:\n"
				<< student_line << "\n"
				<< "Expected line format:\n"
				<< "Name,Student code,Ability,Consistency,Program "
				<< "name:Subject list\n"
				<< "Where,\n"
				<< "1. Name is an non-empty string.\n"
				<< "2. Student code is 6 *digit* string.\n"
				<< "3. Ability is an integer in range 0 to 100.\n"
				<< "4. Consistency is an integer in range 0 to 15.\n"
				<< "5. Program name is an non-empty string.\n"
				<< "6. Subject list is the list of comma-seprated "
				<< "positive integers representing subject codes.\n";
				break;
		}
    }
    
    print_three_newlines();
    
    return students;
}

vector<subject> generate_subjects_struct(
        vector<string> subjects_lines)
{
    cout << "Processing subjects file text:" << endl;
    
    vector<subject> subjects;
	int line_number = 0;
    for (auto subject_line: subjects_lines)
    {
		line_number++;
		
		// Ignoring empty line. Giving no warning/error for it either.
		if (subject_line.size() == 0)
			continue;
		
		try
		{
			subject a_subject;
			string difficulty_string;
			string variability_string;
			
			istringstream line(subject_line);
			getline(line, a_subject.name, ',');
			getline(line, difficulty_string, ',');
			a_subject.difficulty = stoi(difficulty_string);
			getline(line, variability_string);
			a_subject.variability = stoi(variability_string);
			
			if (a_subject.name.size() == 0
				or a_subject.difficulty < -15
				or a_subject.difficulty > 15
				or a_subject.variability < -3
				or a_subject.variability > 3)
			{
				throw "Buzzwords";
			}
			
			subjects.push_back(a_subject);
            
            cout << "Subject Name: " << a_subject.name << '\n'
                << "Difficulty: " << a_subject.difficulty << '\n'
                << "Variability: " << a_subject.variability << '\n'
                << endl;
            
		}
		catch (...)
		{
			cerr << "Fatal error occured while processing subjects "
				<< "file lines into subject structs. Line: "
				<< line_number << " is not in proper format.\n"
				<< "Actual line:\n"
				<< subject_line << "\n"
				<< "Expected line format: \n"
				<< "Name,Difficulty,Variability\n"
				<< "Where,\n"
				<< "1. Name is a non-empty string.\n"
				<< "2. Diffuculty is interger in range -15 to 15.\n"
				<< "3. Variability is integer in range -3 to 3.\n";
			exit(3);
		}
    }
    
    print_three_newlines();
    
    return subjects;
}

vector<teacher> generate_teachers_struct(
        vector<string> teachers_lines)
{
    cout << "Processing teachers file text:" << endl;
    
    vector<teacher> teachers;
    int line_number = 0;
    for (auto teacher_line: teachers_lines)
    {
		line_number++;
		
		// Ignoring empty line. Giving no warning/error for it either.
		if (teacher_line.size() == 0)
			continue;
		
        try
        {
            teacher a_teacher;
            istringstream line(teacher_line);
            string toughness_string;
            string variability_string;
            string subject_string;
            
            getline(line, a_teacher.name, ',');
            getline(line, toughness_string, ',');
            a_teacher.toughness = stoi(toughness_string);
            getline(line, variability_string, ':');
            a_teacher.variability = stoi(variability_string);
            while(getline(line, subject_string, ','))
            {
				int subject_code = stoi(subject_string);
				if (subject_code > 0)
					a_teacher.subjects.push_back(subject_code);
				else
					throw "Cheesy praises at teacher";
            }
            
            if (a_teacher.name.size() == 0
                or a_teacher.toughness < -15
                or a_teacher.toughness > 15
                or a_teacher.variability < -3
                or a_teacher.variability > 3
                or a_teacher.subjects.size() == 0)
            {
                throw "some swag";
            }
            
            cout << "Teacher Name: " << a_teacher.name << '\n'
                << "Toughness: " << a_teacher.toughness << '\n'
                << "Variability: " << a_teacher.variability << '\n'
                << endl;
            
            teachers.push_back(a_teacher);
        }
        catch (...)
        {
			cerr << "Fatal error occured while processing teachers "
				<< "file lines into teacher structs. Line: "
				<< line_number << " is not in proper format.\n"
				<< "Actual line:\n"
				<< teacher_line << "\n"
				<< "Expected line format: \n"
				<< "Name,Toughness,Variability:Subjects List\n"
				<< "Where,\n"
				<< "1. Name is a non-empty string.\n"
				<< "2. Toughness is interger in range -15 to 15.\n"
				<< "3. Variability is integer in range -3 to 3.\n"
				<< "4. Subects list is comma-seprated list of positive"
				<< "integers representing subjects codes.\n";
            exit(4);
        }
    }
    
    print_three_newlines();
    
    return teachers;
}

void add_teachers_vector_index_number_to_subjects_struct(
    vector<teacher> &teachers,
    vector<subject> &subjects)
{
    for (int i=0; i < teachers.size(); i++)
    {
        for (auto subject_code: teachers[i].subjects)
        {
            if (subject_code <= subjects.size())
            {
                /* -1 and +1 since indexes starts from 0.
                */
                subjects[subject_code-1].teachers.push_back(i+1);
            }
            else
            {
                cerr << "Fatal error. Subject code " << subject_code
                    << " of teacher: " << i+1 << " i.e. "
                    << teachers[i].name << " is more than total "
                    << "number of subjects i.e. " << subjects.size()
                    << '\n';
                exit(5);
            }
        }
    }
}

void process_students_and_generate_results(
        vector<student> &students,
        vector<subject> &subjects,
        vector<teacher> &teachers)
{
    cout << "Processing students results:" << endl;
    
    int student_number = 0;
    for (auto &a_student: students)
    {
        student_number++;
        int attempts = 0;
        
        cout << "Processing student " << student_number << " i.e. "
            << a_student.name << ":" << endl;
        
        for (int i=0; i < a_student.subjects.size(); i++)
        {
            attempts++;
            result a_result;
            
            a_result.subject_code = a_student.subjects[i];
            if (a_result.subject_code > subjects.size())
            {
                cerr << "Fatal error. Subject code "
                    << a_result.subject_code << " of student: "
                    << student_number << " i.e. " << a_student.name
                    << " is more than total number of subjects i.e. "
                    << subjects.size() << '\n';
                exit(5);
            }
			// -1 since index starts at 0
            auto &a_subject = subjects[a_result.subject_code-1];
			a_result.subject_name = a_subject.name;
            
            a_result.teacher_code = pick_teacher_randomly(
                a_subject.teachers);
			// -1 since index starts at 0
            auto &a_teacher = teachers[a_result.teacher_code-1];
			a_result.teacher_name = a_teacher.name;
            
            int attempts_based_marks_modifier = (attempts-1)*5;
            a_result.mean = (
                a_student.ability
                - a_subject.difficulty
                - a_teacher.toughness
                + attempts_based_marks_modifier);
            
            a_result.standard_deviation = (
                a_student.consistency
                - a_subject.variability
                - a_teacher.variability);
            a_result.standard_deviation = absolute_number(
                a_result.standard_deviation);
            
            int minimum_possible_marks = (
                a_result.mean - a_result.standard_deviation);
            minimum_possible_marks = bigger_number(
                minimum_possible_marks, 0);
            minimum_possible_marks = smaller_number(
                minimum_possible_marks, 100);
            
            int maximum_possible_marks = (
                a_result.mean + a_result.standard_deviation);
            maximum_possible_marks = smaller_number(
                maximum_possible_marks, 100);
            maximum_possible_marks = bigger_number(
                maximum_possible_marks, 0);
            
            int marks = random_int(
                minimum_possible_marks,
                maximum_possible_marks);
            a_result.marks = marks;
			a_result.grade = return_grade_for_float((float)marks);
            a_student.results.push_back(a_result);
            
            cout << a_result.subject_name << " ("
                << a_result.subject_code << ") by "
                << a_result.teacher_name << " ("
                << a_result.teacher_code << ") Attempt: "
                << attempts << " Mean: "
                << a_result.mean << " Standard Deviation: "
                << a_result.standard_deviation << " Maximum: "
                << maximum_possible_marks << " Minimum: "
                << minimum_possible_marks << " Marks: "
                << a_result.marks << " Grade: " << a_result.grade
                << endl;
            
            // Supplementary provided.
            if (marks >= 45 and marks < 50)
            {
                int supplementary_marks_modifier = 5;
                a_result.mean += supplementary_marks_modifier;
                marks = random_int(
                    minimum_possible_marks,
                    maximum_possible_marks)
                    + supplementary_marks_modifier;
                a_result.marks = marks;
                
				if (marks >= 50)
                {
					a_result.grade = "SP";
                }
				else
					a_result.grade = "F";
                
                a_student.results.push_back(a_result);
                
                cout << "Supplementary Marks: " << a_result.marks
                    << " Grade: " << a_result.grade << endl;
            }
            
            // Fail.
            if (a_result.grade == "F")
            {
                /* Max attempts allowed reached. Excluded from college.
                 * No more subjects are taught.
                 */
                if (attempts >= MAX_ATTEMPTS_ALLOWED)
                {
                    a_student.overall_marks += marks;
                    cout << endl; //cosmetic hotfix
					a_student.overall_grade_or_status = "F";
                    a_student.subjects_studied += 1;
                    break;
                }
                // Repeat same subject
                else
                {
                 i--;
                }
            }
            // Study next subject with attempt reset to 0.
            else
            {   
                a_student.overall_marks += marks;
                attempts = 0;
                a_student.subjects_studied += 1;
            }
            
            // line between every subject attempt
            cout << endl;
        }
        
		a_student.percentage = ((float)
			((a_student.overall_marks*100)/\
			a_student.subjects_studied)/100.0);
			
		if (a_student.overall_grade_or_status == "?")
		{
			a_student.overall_grade_or_status =\
				return_grade_for_float(a_student.percentage);
		}
		
		cout << "Overall Percentage: " << a_student.percentage
            << " Overall Grade: " << a_student.overall_grade_or_status
            << '\n' << endl;
    }
}

void write_results_to_output_file(
    vector<student> &students, std::string results_file_name)
{
	ofstream results_file(results_file_name);
    
    if (!results_file.good())
    {
        cerr << "Fatal Error: Could not write results to output-file:"
            << results_file_name << "\n"
            << "Possibly do not have write acces to directory\n";
            exit(6);
    }
    
	for (auto a_student: students)
	{
		results_file << a_student.code << "-" << a_student.name << ","\
			<< a_student.program << "-" << a_student.percentage << "-"\
			<< a_student.overall_grade_or_status << ":";
			for (auto a_result:a_student.results)
			{
				results_file << a_result.subject_code << "-"\
					<< a_result.subject_name << ","\
					<< a_result.teacher_code << "-"\
					<< a_result.teacher_name << ","\
					<< a_result.mean << "+-"\
					<< a_result.standard_deviation << "=>"\
					<< a_result.marks << "-" << a_result.grade << ";";
			}
		results_file << "\n";
	}
	results_file.close();
}

int pick_teacher_randomly(vector<int> teachers_codes)
{
    int selected_teacher_index = random_int(
        0, (teachers_codes.size()-1));
    return teachers_codes[selected_teacher_index];
}

string return_grade_for_float(float percentage)
{
	if (percentage >= 85.0)
		return "HD";
	else if (percentage >= 75.0)
		return "D";
	else if (percentage >= 65.0)
		return "C";
	else if (percentage >= 50.0)
		return "P";
	else
		return "F";
}