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

void query_files (FILE *new_stock_file, FILE *query_file);
void amend_details (char type, int *qty, int *buy, int *sell, int value);

int main ()
{
	FILE 	*stock_file			= NULL,
			*amend_file			= NULL,
			*query_file 		= NULL,
			*new_stock_file		= NULL;

	int 	code 	  		= -1,
			qty	 	 		= 0,
			buy 	  		= 0,
			sell 	 	 	= 0,
			amend	  		= 0,
			value	  		= 0,
			pre_amend		= 0;

	char	type			= NULL,
			pre_type		= NULL;

	/*Open files ready for processing*/
	if ( (stock_file = fopen("stock.dat","rt")) == NULL  ||       	/*Read*/
		  (amend_file = fopen("amend.dat","rt")) == NULL  ||       	/*Read*/
		  (new_stock_file = fopen("new_stock.dat","wt")) == NULL ) 	/*Write*/
	{	printf("Error in Opening Files for Amendment Processing.\n");
		exit(1);
	}

	/*Get amendment file details*/
	fscanf(amend_file,"%d,%c,%d",&amend,&type,&value);

	/*Store values needed for writing to new stock file*/
	pre_amend = amend;
	pre_type = type;

	/*Process files until amendment code is equal to 9999 */
	while(amend != 9999)
	{	/*Get next line from stock file while the product code is less than */
		/*that of the amend files product code.                             */
		while ( code < amend )
		{	fscanf(stock_file,"%d,%d,%d,%d",&code,&qty,&buy,&sell);
			/*If no amendments to current product, add product to new file */
			if (code != amend && code >= 0)
				fprintf(new_stock_file,"%d,%d,%d,%d\n",code,qty,buy,sell);
		}

		/* Amend stock file values */
		amend_details(type,&qty,&buy,&sell,value);

		/*Get next amendment file details*/
		fscanf(amend_file,"%d,%c,%d",&amend,&type,&value);

		/*If there are no more amendments for the current product then write */
      	/*the new values to the new stock file                               */
		if (amend != pre_amend)
		{	if (pre_type != 'D')  /*Do not write a product marked for deletion*/
				  fprintf(new_stock_file,"%d,%d,%d,%d\n",code,qty,buy,sell);
			pre_type = type;
			pre_amend = amend;
		}
	}

	/*Add the remainder of stock file to new file*/
	while ( code != 9999 )
	{	fscanf(stock_file,"%d,%d,%d,%d",&code,&qty,&buy,&sell);
		if (code == 9999)
			fprintf(new_stock_file,"9999\n");
		else
			fprintf(new_stock_file,"%d,%d,%d,%d\n",code,qty,buy,sell);
	}

	/* Close files after processing */
	fclose(stock_file);
	fclose(amend_file);
	fclose(new_stock_file);

	/*Open files ready for processing */
	if ( (query_file = fopen("query.dat","wt")) == NULL  ||        /*Write*/
		  (new_stock_file = fopen("new_stock.dat","rt")) == NULL )  /*Read*/
	{	printf("Error in Opening Files for Query Processing.\n");
		exit(1);
	}

	/* Query file - Check if any stock item is outside the given range */
	query_files(new_stock_file, query_file);

	/* Close files after processing */
	fclose(query_file);
	fclose(new_stock_file);
	return EXIT_SUCCESS;
}

void amend_details (char type, int *qty, int *buy, int *sell, int value)
{	switch (type)
	{	case 'I':
			/* Process Amendment - Issue from stock.*/
			*qty -= value;
			break;
		case 'R':
			/* Process Amendment - Receipt into stock.*/
			*qty += value;
			break;
		case 'B':
			/* Process Amendment - Buying price.*/
			*buy += value;
			break;
		case 'S':
			/* Process Amendment - Sale price.*/
			*sell += value;
			break;
		case 'D':
			/* Do not write current entry to new stock file */
			/* Process Amendment - Delete stock item.*/
			break;
		default:
			printf("Undefinded Amendment!! Program Terminated.\n");
			exit(EXIT_FAILURE);
	}
}

void query_files (FILE *new_stock_file, FILE *query_file)
{	int 	code 					= -1,
			qty					= 0,
			buy 					= 0,
			sell 					= 0;

	fscanf(new_stock_file,"%d,%d,%d,%d",&code,&qty,&buy,&sell);

	while (code != 9999)
	{	if (qty < 1000 || qty > 9999)
			  fprintf(query_file,"%d,%d,%d,%d\n",code,qty,buy,sell);
		fscanf(new_stock_file,"%d,%d,%d,%d",&code,&qty,&buy,&sell);
	}
}