Adds line removing

Allows you to remove a specific ID in the book DB
this will also update the subsequent lines to be in numerical order

src/csv.c

@@ -31,14 +31,34 @@ int get_next_id()
 	return atoi(id) + 1;
 }
 
-long find_id(int id_to_find)
+void update_line(char** line, int new_id)
 {
-	FILE* csv;
+	int i;
 	char* buffer;
-	size_t line_size = MAX_BUFFER_SIZE - 1;
-	int i, file_exists;
-	long file_pos;
+	for (i = 0; i < MAX_BUFFER_SIZE; i++) {
+		if ((*line)[i] == ',')
+			break;
+	}
 	
+	if (i == MAX_BUFFER_SIZE - 1) {
+		fprintf(stderr, "There was an error in %s file!\n", FILE_NAME);
+		exit(EXIT_FAILURE);
+	}
+
+	buffer = malloc(sizeof(char) * MAX_BUFFER_SIZE);
+	strncpy(buffer, (*line) + i, MAX_BUFFER_SIZE);
+
+	snprintf(*line, MAX_BUFFER_SIZE, "%d%s", new_id, buffer);
+	free(buffer);
+}
+
+void remove_line_from_file(int id_to_remove)
+{
+	int file_exists, line_count;
+	FILE* csv;
+	FILE* new_csv;
+	char* line;
+	size_t line_size = MAX_BUFFER_SIZE;
 
 	file_exists = access(FILE_NAME, F_OK);
 	if (0 != file_exists) {
@@ -52,16 +72,25 @@ long find_id(int id_to_find)
 		exit(EXIT_FAILURE);
 	}
 
-	for(i = 0; i < id_to_find + 1; i++)
-		getline(&buffer, &line_size, csv);
+	new_csv = fopen("temp.csv", "w");
 
-	file_pos = ftell(csv);
+	line_count = 0;
+	while(getline(&line, &line_size, csv) != -1) {
+		if (id_to_remove > line_count) {
+			fprintf(new_csv, "%s", line);
+		} else if (id_to_remove < line_count) {
+			update_line(&line, line_count - 1);
+			fprintf(new_csv, "%s", line);
+		}
+		line_count++;
+	}
+	fclose(new_csv);
 	fclose(csv);
 
-	return file_pos;
+	remove(FILE_NAME);
+	rename("temp.csv", FILE_NAME); // new csv is now the original file, without that line
 }
 
-
 void write_to_file(book_t* book)
 {
 	FILE* file;

src/csv.h

@@ -19,11 +19,20 @@ int get_next_id();
 void write_to_file(book_t* book);
 
 /**
- * long find_id
- * int id_to_find - The ID we're looking for
+ * void remove_line_from_file
+ * int id_to_remove - The book ID that we don't want anymore
  *
- * Returns the position of a FILE to the line with the ID we're looking for
+ * Removes a book from the CSV file
  */
-long find_id(int id_to_find);
+void remove_line_from_file(int id_to_remove);
+
+/**
+ * void update_line
+ * char** line - Pointer to the book entry string
+ * int new_id - The new ID that should be placed into this book entry
+ *
+ * Takes a book entry and changes the ID to the given one
+ */
+void update_line(char** line, int new_id);
 
 #endif

src/main.c

@@ -58,6 +58,7 @@ void do_ISBN_get(char* argv[])
 
 void process_args(char* argv[])
 {
+	int id;
 	if (0 == strcmp(argv[1], "--help")) {
 		printf("%s - An ISBN lookup tool.\n", argv[0]);
 		printf("Author: Nathan Singer\n");
@@ -68,8 +69,19 @@ void process_args(char* argv[])
 		puts("[isbn] -- Attempts to download a book from the given ISBN-10 or ISBN-13 input.");
 		puts("remove [id] -- Removes a book with the given ID from the book database.");
 	} else if (0 == strcmp(argv[1], "remove")) {
-		// remove a book here
-		return;
+		if (NULL == argv[2]) {
+			printf("Not enough arguments! Try typing %s --help\n", argv[0]);
+			exit(EXIT_FAILURE);
+		}
+
+		id = atoi(argv[2]);
+
+		if (0 == id) {
+			printf("Invalid book ID given!\n");
+			exit(EXIT_FAILURE);
+		}
+
+		remove_line_from_file(id);
 	} else {
 		// lets assume its an ISBN and let the other functions fail if its not
 		do_ISBN_get(argv);
@@ -80,8 +92,6 @@ void process_args(char* argv[])
 
 int main(int argc, char* argv[])
 {
-	return 0;
-	
 	if (1 == argc) {
 		printf("Not enough arguments! Try typing %s --help\n", argv[0]);
 		return EXIT_FAILURE;