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

//Name: Isaac Di Francesco
//ID: 260868693

int main(int argc, char *argv[]) {
	//check if at least one argument was passed for CMD
	if (argc == 1) {
		puts("You did not provide any arguments. Please enter: ./database CMD OPT1 OPT2 OPT3 OPT4");
		return -1;
	}

	//input variables
	char *CMD = argv[1];
	char *OPT1 = argv[2];
	char *OPT2 = argv[3];
	char *OPT3 = argv[4];
	char *OPT4 = argv[5];
	int ID, AGE;
	float GPA;

	int charCount = 0, lineCount = 1, fieldCount = 0; //counters for loop

	//check CMD input
	if (strcmp(CMD, "SHOW") == 0) {
		FILE *dataFile;
		dataFile = fopen("database.csv", "r");

		//variables for each line
		char *line = NULL;
		size_t length = 0;
		char field1[100], field2[100], field3[100], field4[100];

		//iterate through CSV file and get each line
		while (getline(&line, &length, dataFile) != -1) {
			//reset the field arrays
			memset(field1, 0, sizeof field1);
			memset(field2, 0, sizeof field2);
			memset(field3, 0, sizeof field3);
			memset(field4, 0, sizeof field4);

			//update parameters
			fieldCount = 0;
			charCount = 0;

			//get first field
			while (line[charCount] != ',') {
				//check for space
				if (line[charCount] != ' ') {
					field1[fieldCount] = line[charCount];
					fieldCount++;
				}
				charCount++;
			}

			// update parameters
			charCount++;
			fieldCount = 0;

			// get second field
			while (line[charCount] != ',') {
				//check for space
				if (line[charCount] != ' ') {
					field2[fieldCount] = line[charCount];
					fieldCount++;
				}
				charCount++;
			}

			// update parameters
			charCount++;
			fieldCount = 0;

			// get third field
			while (line[charCount] != ',') {
				//check for space
				if (line[charCount] != ' ') {
					field3[fieldCount] = line[charCount];
					fieldCount++;
				}
				charCount++;
			}

			// update parameters
			charCount++;
			fieldCount = 0;

			// get fourth field
			while (line[charCount] != '\n') {
				//check for space
				if (line[charCount] != ' ') {
					field4[fieldCount] = line[charCount];
					fieldCount++;
				}
				charCount++;
			}

			//format fields to proper data type
			sscanf(field1, "%d", &ID);
			sscanf(field3, "%d", &AGE);
			sscanf(field4, "%f", &GPA);

			//display record
			printf("Record %d: ID=%-3d NAME=%-5s AGE=%-3d GPA=%-3.1f \n", lineCount, ID, field2, AGE, GPA);

			lineCount++;
	    }

			//free memory location for line & close file
			free(line);
			fclose(dataFile);
	} else if (strcmp(CMD, "DELETE") == 0) {
		//check if OPT1 has been passed
		if (argc <= 2) {
			printf("Name of record to delete is missing\n");
			return -1;
		}

		// open database file
		FILE *dataFile;
		FILE *tempFile;
		dataFile = fopen("database.csv", "r");
		tempFile = fopen("database.tmp", "w");

		//variables for each line
		char *line = NULL;
		size_t length = 0;
		char fieldCheck[100];
		int i = 0, j = 0;
		int notFound = 1;

		//iterate through database file
		while (getline(&line, &length, dataFile) != -1) {
			i = 0;
			j = 0;
			while (line[i] != ',') {
				//check for space
				if (line[i] != ' ') {
					fieldCheck[j] = line[i];
					j++;
				}
				i++;
			}

			//end string for further iterations of loop
			fieldCheck[j] = '\0';

			// check if ID field from current line matches OPT1 and ID hasn't already been found
			if (strcmp(fieldCheck, OPT1) == 0 && notFound) {
				// exclude line from copy
				notFound = 0;
			} else {
				// copy line to temp file
				fputs(line, tempFile);
			}
		}
		if (notFound) {
			printf("Sorry, that user was not found. Nothing was deleted.\n");
			system("rm database.tmp");
		} else {
			system("mv database.tmp database.csv");
		}
		//free memory location of line & close files
		free(line);
		fclose(dataFile);
		fclose(tempFile);
	} else if (strcmp(CMD, "ADD") == 0) {
		// check if OPT variables have been passed
    if (argc < 6) {
      printf("Missing ID, Name, AGE, and GPA arguments\n");
      return -1;
    }

    FILE *dataFile;
    dataFile = fopen("database.csv", "a");

		//add line to datafile
    fputs(OPT1, dataFile);
    fputs(",", dataFile);
    fputs(OPT2, dataFile);
    fputs(",", dataFile);
    fputs(OPT3, dataFile);
    fputs(",", dataFile);
    fputs(OPT4, dataFile);
    fputs("\n", dataFile);

		//close datafile
		fclose(dataFile);
  } else {
	  printf("The command you requested is invalid. Please select from one of these: SHOW, DELETE, ADD\n");\
	  return -1;
  }

   return 0;
}