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

#include "List.h"

#define STORAGEFILE "TextFileStorage.txt"
#define SEPARATOR "|"

// show a list of options and return the one the user chose
int user_choice;
int Menu(void) {

	printf("Menu:\n\n");
	printf("1. Add entry\n");
	printf("2. View entries\n");
	printf("3. Edit entry\n");
	printf("4. Delete entry\n");
	printf("5. Exit\n\n");

	scanf("%d\n", &user_choice);
	return user_choice;
	
	}

// add an entry to the database
void AddEntry(LIST *list, int edit) {

	int i, c, y, z, editnum, bufsize = 256;
	char numreadbuf[32] = {0};
	char *readbuf, *p, *item;

	if (edit == 0)
		printf("Add Entry:\n\n");
	else {
		printf("Edit Entry:\n\n");
		printf("Enter entry number to edit:\n");

		// read the user input as a fixed length string (for error handling)
		if (fgets(numreadbuf, sizeof(numreadbuf)-1, stdin) == NULL) {
			printf("Invalid input\n\n");
			return;
		}

		// convert the string to an integer and check it's within a valid range
		if (sscanf(numreadbuf, "%d", &editnum) != 1 || editnum < 1 || editnum > list->nItems) {
			printf("Invalid input\n\n");
			return;
		}
	}

	printf("Enter X (string):\n");

	// allocate an initial amount of memory to store X in
	readbuf = malloc(bufsize);
	if (readbuf == NULL) {
		printf("Memory allocation error\n\n");
		return;
	}

	// read a character at a time and append it to the memory
	for (i=0; ;i++) {
		
		c = getchar();
		if (c == '\r') {
			readbuf[i] = '\0';	// set end of string when carriage return reached
		}
		else if (c == '\n') {
			readbuf[i] = '\0';
			break;
		}
		else {
			readbuf[i] = c;
		}

		// length of input exceeds the size of memory allocated so allocate more
		if (i == bufsize-1) {
			p = realloc(readbuf, bufsize += 256);
			if (p == NULL) {
				free(readbuf);
				printf("Memory reallocation error\n\n");
				return;
			}
			readbuf = p;
		}

	}

	printf("Enter Y (integer < 20):\n");

	// read the user input as a fixed length string (for error handling)
	if (fgets(numreadbuf, sizeof(numreadbuf)-1, stdin) == NULL) {
		printf("Invalid input\n\n");
		free(readbuf);
		return;
	}

	// convert the string to an integer and check it's within a valid range
	if (sscanf(numreadbuf, "%d", &y) != 1 || y >= 20) {
		printf("Invalid input\n\n");
		free(readbuf);
		return;
	}

	printf("Enter Z (integer < 10):\n");

	// read the user input as a fixed length string (for error handling)
	if (fgets(numreadbuf, sizeof(numreadbuf)-1, stdin) == NULL) {
		printf("Invalid input\n\n");
		free(readbuf);
		return;
	}

	// convert the string to an integer and check it's within a valid range
	if (sscanf(numreadbuf, "%d", &z) != 1 || z >= 10) {
		printf("Invalid input\n\n");
		free(readbuf);
		return;
	}

	// allocate memory for item to enter list
	item = malloc(bufsize + 32);
	if (item == NULL) {
		free(readbuf);
		printf("Memory allocation error\n\n");
		return;
	}

	// build the item from existing values
	sprintf(item, "%s%s%d%s%d", readbuf, SEPARATOR, y, SEPARATOR, z);

	if (edit == 0)
		ListAddItem(list, item);					// add item to list
	else
		ListReplaceItem(list, editnum-1, item);		// edit item in list

	// show user what was entered
	printf("Entered: %s\n\n", item);

	// free memory
	free(item);
	free(readbuf);
}

void DeleteEntry(LIST *list) {

	int n;
	char numreadbuf[32] = {0};

	printf("Delete Entry:\n\n");

	printf("Enter entry number to delete:\n");

	// read the user input as a fixed length string (for error handling)
	if (fgets(numreadbuf, sizeof(numreadbuf)-1, stdin) == NULL) {
		printf("Invalid input\n\n");
		return;
	}

	// convert the string to an integer and check it's within a valid range
	if (sscanf(numreadbuf, "%d", &n) != 1 || n < 1 || n > list->nItems) {
		printf("Invalid input\n\n");
		return;
	}

	// delete the entry from the list
	ListDeleteItem(list, n-1);

	printf("Entry deleted\n\n");

}

// list each entry in the list
void ViewEntries(LIST *list) {

	int i;

	printf("View Entries:\n\n");

	// cycle through the list printing each entry
	for (i=0; i<list->nItems; i++) {

		printf("%d. %s\n", i+1, list->pItems[i]);
	}

	putchar('\n');
}

// execution starts here
int main(int argc, char *argv[]) {
	
	LIST list;
	int ret;

	// initalise the list
	ListInit(&list);

	// load list file to memory (if exists)
	if ((ret = ListLoadFile(&list, STORAGEFILE)) != 0) {
		
		printf("Error %d loading file\n", ret);
	}

	// show the menu asking for input until told to exit
	while ((ret = Menu()) != 5) {
		
		// exit command
		if (ret == 5) break;

		// handle each option
		switch (ret) {
			
		// add entry
		case 1:
			AddEntry(&list, 0);
			ListSaveFile(&list, STORAGEFILE);
			break;
		// view entries
		case 2:
			ViewEntries(&list);
			break;
		// edit entry
		case 3:
			AddEntry(&list, 1);
			ListSaveFile(&list, STORAGEFILE);
			break;
		// delete entry
		case 4:
			DeleteEntry(&list);
			ListSaveFile(&list, STORAGEFILE);
			break;
		}
	}

	// destroy the list, freeing memory
	ListCleanup(&list);

	return 0;
}