#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#ifdef _WIN32
	#define STG_IGNORECASE_CMP _stricmp
	#define PAUSE system("pause");
	#define DRAINO fflush(stdin);fflush(stdout)

#else
	#define STG_IGNORECASE_CMP strcasecmp
	#define PAUSE printf("\nPress the ANY KEY to continue... \n"); getchar();
	#define DRAINO pacMan()
#endif

struct student
{
	char firstName[15];
	char lastName[15];
	float percentGrade;
	char letterGrade;
};
typedef struct student STUDENT;

float calcPercent(void);
float calcLabs(void);
float calcExams(void);
float calcFinal(void);
char calcLetter(float);

void enterStudent(STUDENT[], int*);
void sortName(STUDENT[]);
void sortGPA(STUDENT[]);
void writeFile(STUDENT[], int*, char[]);
void writeScreen(STUDENT[], int*);

void loadClass(STUDENT[], int*, char[]);
void writeClass(STUDENT[], int, char[]);

void pacMan(void)
{
	char eatMe = '0';
	while (eatMe != '\n')
	{
		eatMe = getchar();
	}
}

#define NUMBER_OF_STUDENTS 30
#define MAXLABS 8
#define LABWEIGHT 0.4f
#define MAXEXAMS 3
#define EXAMWEIGHT 0.4f
#define FINALWEIGHT 0.2f

main(int argc, char * argv [])
{
	int choice;
	STUDENT students[NUMBER_OF_STUDENTS];
	int studentCount = 0;
	char dataFile[25];
	char reportFile[25];
	if (argc != 2)
	{
		printf("\nError, please enter program name and class to be graded on the command line. \n\n");
		PAUSE
		exit(0);
	}
	sprintf(dataFile, "%s.dat", argv[1]);
	sprintf(reportFile, "%s.txt", argv[1]);
	printf("\n%s", argv[1]);
	loadClass(students, &studentCount, dataFile);
	do
	{
		printf("\nGRADE REPORT MENU\n");
		printf("\n1. Enter Student Info and Grades");
		printf("\n2. View Sorted Report by Name on Screen");
		printf("\n3. View Sorted Report by GPA on Screen");
		printf("\n4. Send Sorted Report by Name to File");
		printf("\n5. Send Sorted Report by GPA to File");
		printf("\n0. Exit Program");
		printf("\n   Enter Your Selection: ");
		scanf("%d", &choice);
		DRAINO;
		switch (choice)
		{
		case 1: enterStudent(students, &studentCount);
			break;
		case 2: sortName(students);
			writeScreen(students, &studentCount);
			break;
		case 3: sortGPA(students);
			writeScreen(students, &studentCount);
			break;
		case 4: sortName(students);
			writeFile(students, &studentCount, reportFile);
			break;
		case 5: sortGPA(students);
			writeFile(students, &studentCount, reportFile);
		case 0: break;
		}
	} while (choice);
	writeClass(students, &studentCount, dataFile);
	return(0);
}
void loadClass(STUDENT students[], int* ptr_studentCount, char dataFile[])
{
	FILE* fdat;
	fdat = fopen(dataFile, "rb");
	if (fdat != NULL)
	{
		int i = 0;

		fread(&students[i], sizeof(STUDENT), 1, fdat);
		while (!feof(fdat))
		{
			i++;
			fread(&students[i], sizeof(STUDENT), 1, fdat);
		}
		ptr_studentCount = i;

		for (i = 0; i < ptr_studentCount; i++)
		{
			printf("\n %s %s %.2f %c", students[i].firstName, students[i].lastName, students[i].percentGrade, students[i].letterGrade);
		}
		printf("\nClass loaded. Ready for input. ");
		PAUSE
	}
}
void writeClass(STUDENT students[], int studentCount, char dataFile[])
{
	FILE* fdat;
	int i = 0;
	fdat = fopen(dataFile, "a+b");

	if (fdat == NULL)
	{
		printf("\nError, file not loaded!\n\n");
		PAUSE
		exit(0);
	}

	for (i = 0; i < studentCount; i++)
	{
		fwrite(&students[i], sizeof(STUDENT), 1, fdat);
	}

	fclose(fdat);
}
void enterStudent(STUDENT students[], int* ptr_studentCount)
{
	char firstName[15];
	char lastName[15];
	float percentGrade = 0.0;
	char letterGrade;

	printf("\nEnter student first name or (0) to Exit: ");
	scanf(" %14[^\n]", firstName);
	DRAINO;
	while (STG_IGNORECASE_CMP(firstName, "0"))
	{
		if (*ptr_studentCount == NUMBER_OF_STUDENTS - 1)
		{
			printf("\nThis is the last student you can enter. Class is full.");
		}
		if (*ptr_studentCount == NUMBER_OF_STUDENTS)
		{
			printf("\nMaximum number of students reached. No further grades can be processed. ");
			exit(0);
		}
		printf("\nEnter student last name: ");
		scanf(" %14[^\n]", lastName);
		DRAINO;
		percentGrade = calcPercent();
		letterGrade = calcLetter(percentGrade);

		strcpy(students[*ptr_studentCount].firstName, firstName);
		strcpy(students[*ptr_studentCount].lastName, lastName);
		students[*ptr_studentCount].percentGrade = percentGrade;
		students[*ptr_studentCount].letterGrade = letterGrade;

		(*ptr_studentCount)++;

		printf("\nEnter another student first name or (0) to Exit to previous menu: ");
		scanf(" %14[^\n]", firstName);
		DRAINO;
	}
	return;
}
void sortName(STUDENT students[])
{
	STUDENT temp;
	int i;
	int x;

	for (x = 0; x < NUMBER_OF_STUDENTS; x++)
	{
		for (i = 0; i < NUMBER_OF_STUDENTS - 1 - x; i++)
		{
			if (STG_IGNORECASE_CMP(students[i].lastName, students[i + 1].lastName) > 0)
			{
				temp = students[i];
				students[i] = students[i + 1];
				students[i + 1] = temp;
			}
		}
	}
}
void sortGPA(STUDENT students[])
{
	STUDENT temp;
	int i;
	int x;

	for (x = 0; x < NUMBER_OF_STUDENTS; x++)
	{
		for (i = 0; i < NUMBER_OF_STUDENTS - 1 - x; i++)
		{
			if (students[i].percentGrade < students[i + 1].percentGrade)
			{
				temp = students[i];
				students[i] = students[i + 1];
				students[i + 1] = temp;
			}
		}
	}
}
void writeFile(STUDENT students[], int* ptr_studentCount, char reportFile[])
{
	int i = 0;
	FILE* rpt;
	rpt = fopen(reportFile, "w");
	if (rpt == NULL)
	{
		printf("\nThere was an error opening the report file. Ending program. ");
		DRAINO;
		PAUSE
		exit(0);
	}
	fprintf(rpt, "%s", reportFile);
	fprintf(rpt, "\nGRADE REPORT \n\n");
	fprintf(rpt, "FIRST NAME     LAST NAME     PERCENT GRADE     LETTER GRADE\n");
	for (i = 0;i < (*ptr_studentCount);i++)
	{
		fprintf(rpt, "\n%-14s %-13s %.2f %13c", students[i].firstName, students[i].lastName, students[i].percentGrade, students[i].letterGrade);
	}
	fprintf(rpt, "\n\nYou have recorded grades for %d students. \n", *ptr_studentCount);
	fclose(rpt);
	printf("\nGrades sent to report file.\n");
}
void writeScreen(STUDENT students[], int* ptr_studentCount)
{
	int i = 0;
	printf("\n\nGRADE REPORT \n\n");
	printf("FIRST NAME     LAST NAME     PERCENT GRADE     LETTER GRADE\n");
	for (i = 0;i < (*ptr_studentCount);i++)
	{
		printf("\n%-14s %-13s %.2f %13c", students[i].firstName, students[i].lastName, students[i].percentGrade, students[i].letterGrade);
	}
	printf("\n\nYou have recorded grades for %d students. \n", *ptr_studentCount);
}
float calcPercent(void)
{
	return (calcLabs() + calcExams() + calcFinal());
}

float calcLabs(void)
{
	int i = 0;
	float entry = 0;
	float labs = 0;
	float average = 0;
	float weighted = 0;
	for (i = 0; i < MAXLABS; i++)
	{
		printf("\nEnter the score for Lab# %d: ", i + 1);
		scanf("%f", &entry);
		DRAINO;
		labs = entry + labs;
		average = labs / MAXLABS;
	}
	return average * LABWEIGHT;
}

float calcExams(void)
{
	int i = 0;
	float entry = 0;
	float exams = 0;
	float average = 0;
	float weighted = 0;
	for (i = 0; i < MAXEXAMS; i++)
	{
		printf("\nEnter the score for Exam# %d: ", i + 1);
		scanf("%f", &entry);
		DRAINO;
		exams = entry + exams;
		average = exams / MAXEXAMS;
	}
	return average * EXAMWEIGHT;
}

float calcFinal(void)
{
	float final = 0;
	float weighted = 0;
	printf("\nEnter the score for the Final Exam: ");
	scanf("%f", &final);
	DRAINO;
	return final * FINALWEIGHT;
}

char calcLetter(float percentGrade)
{
	if ((percentGrade >= 94) && (percentGrade <= 100))
		return('A');
	else if ((percentGrade >= 85) && (percentGrade <= 93))
		return('B');
	else if ((percentGrade >= 75) && (percentGrade <= 84))
		return('C');
	else if ((percentGrade >= 65) && (percentGrade <= 74))
		return('D');
	else if ((percentGrade >= 0) && (percentGrade <= 64))
		return('F');
	else
		return('*');
}