/*
	* Vector-based Course Tool
	* Author: Cody Cook
	* Date: 2023/08/10
	* Southern New Hampshire University
	* CS-300-J7303 DSA: Analysis and Design 23EW6
*/

#include <iostream>
#include <fstream>
#include <vector>
#include <sstream>

using namespace std;

// build a Course struct
struct Course {
	string courseNumber;
	string title;
	vector<string> prerequisites;
};

// global variables
vector<Course> courses;

// functions

// function to display a course
void displayCourse(const Course& c) {

	// if courseNumber is empty, let's just skip it
	if (c.courseNumber.empty()) {
		return;
	}

	// display the course number and course title
	cout << "Course Number: " << c.courseNumber << endl;
	cout << "Course Title: " << c.title << endl;

	// display prereqs
	cout << "Course Prerequisites: ";

	// if there are no prerequisites, print "None"
	if (c.prerequisites.size() == 0) {
		cout << "None";
	}
	else {
		for (const auto& prereq : c.prerequisites) {
			// if this is the last prerequisite, don't print the comma
			if (prereq != c.prerequisites.back()) {
				cout << prereq << ", ";
			}
			else {
				cout << prereq;
			}
		}
	}
	cout << endl << endl;
}

// Function to get course info from the user
Course getCourse() {
	string getCourseNumber;

	// Default "empty" course to return in case of an error or if not found
	Course emptyCourse;

	if (courses.size() == 0) {
		cout << "\nCourses are not currently loaded. Please load courses.\n\n";
		return emptyCourse;
	}
	else {

		cout << "Enter course number: ";
		cin >> getCourseNumber;
		cout << endl;

		for (unsigned int i = 0; i < courses.size(); i++) {
			if (courses[i].courseNumber == getCourseNumber) {
				return courses[i];
			}
		}

		// if we didn't return already, then
		// the course wasn't found
		cout << "Course not found.";
		cout << "\n\n";
	}
	return emptyCourse;
}

// Selection sort function for the vector sorting
void selectionSortCourses(vector<Course>& courses) {
	// Get the total number of courses
	int n = courses.size();

	// Traverse through all courses in the vector
	for (int i = 0; i < n - 1; i++) {
		// Assume the current index holds the smallest courseNumber
		int min_idx = i;

		// Traverse the vector from the element next to i up to the end
		for (int j = i + 1; j < n; j++) {
			// If a smaller courseNumber is found, update min_idx
			if (courses[j].courseNumber < courses[min_idx].courseNumber) {
				min_idx = j;
			}
		}
		// Swap the found minimum course with the course at current index 'i'
		swap(courses[i], courses[min_idx]);
	}
}

// Function to load courses from a CSV file
void loadCourses() {
	string filePath;
	string line;

	// empty courses for a fresh import
	courses.clear();

	// prompt user for the path
	cout << "\nEnter the Courses csv file (Default: courses.csv): ";

	// clear the newline left in the buffer from previous inputs
	// we will get the whole link for an absolute path; relative works, too.
	cin.ignore();
	getline(cin, filePath);
	cout << endl;

	if (filePath.front() == '\"' && filePath.back() == '\"') {
		filePath = filePath.substr(1, filePath.length() - 2);
	}

	// open the file for reading
	ifstream file(filePath);

	// if we didn't open the file
	if (!file.is_open()) {
		cout << "Error opening file: " << filePath << endl << endl;
		// error
		return;
	}

	// while we go through each line
	while (getline(file, line)) {
		stringstream ss(line);
		Course c;
		getline(ss, c.courseNumber, ',');
		getline(ss, c.title, ',');
		string prereq;
		while (getline(ss, prereq, ',')) {
			c.prerequisites.push_back(prereq);
		}
		courses.push_back(c);
	}

	// sort the courses
	selectionSortCourses(courses);
}


void menu() {
	int menuOption = 0;

	while (menuOption != 9) {
		// display the menu options
		cout << "1. Load Data Structure\n";
		cout << "2. Print Course List\n";
		cout << "3. Print Course\n";
		cout << "9. Exit\n\n";

		// ask the user to select an option
		cout << "What would you like to do? ";
		cin >> menuOption;

		// check if cin failed
		if (cin.fail()) {

			// clear the error state
			cin.clear();

			// remove the erroneous input from the stream
			cin.ignore(INT_MAX, '\n');
			cout << "Please enter a valid number." << endl << endl;

			// skip the rest of the loop iteration
			continue;
		}

		// process the user's input
		switch (menuOption) {
		case 1:
			// load data structure
			loadCourses();
			break;
		case 2:
			
			// print course list
			if (courses.size() == 0) {
				cout << "\nCourses are not currently loaded. Please load courses.\n\n";
			}
			else {
				for (unsigned int i = 0; i < courses.size(); i++) {
					// show each course
					displayCourse(courses[i]);
				}
			}
			break;
		case 3:
		{
			// get the course
			Course c = getCourse();

			// show the course details
			displayCourse(c);
		}
		break;
		case 9:
			// we're just going to edit next loop
			break;
		default:
			// no valid options
			cout << "Invalid option. Please try again." << endl;
			break;
		}
	}
}

int main() {
	// greet the user
	cout << "Welcome to the course planner.\n\n";

	// display the menu
	menu();

	// salutate the user
	cout << "Thank you for using the course planner!\n\n";

	// exit the program
	return 0;
}