// File: ex6-2.cpp - overloaded functions

#include <cctype>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
using namespace std;

#ifdef __GNUG__
#include <unistd.h>
#else
#include <io.h>		// for access() function
#endif

// Overloaded function prototypes

void copyFile(const char* fn1, const char* fn2);
void copyFile(const char* fn1, const char* fn2, const char* option);
void copyFile(const char* fn1, const char* fn2, const char* fromto, int lineno);
void copyFile(const char* fn1, const char* fn2, const char* from, int line1,
			  const char* to, int line2);
void errorMessage(char* msg);
void errorMessage(char* msg, FILE* fp1);
void errorMessage(char* msg, FILE* fp1, FILE* fp2);

void displayCmdSyntax() {
    fprintf(stderr,"Usage:\n");
    fprintf(stderr,"\tcopyFile <file1> <file2>\n");
    fprintf(stderr,"\tcopyFile <file1> <file2> -append\n");
    fprintf(stderr,"\tcopyFile <file1> <file2> -upper\n");
    fprintf(stderr,"\tcopyFile <file1> <file2> -lower\n");
    fprintf(stderr,"\tcopyFile <file1> <file2> -noreplace\n");
    fprintf(stderr,"\tcopyFile <file1> <file2> -from <line#> -to <line#>\n");
    fprintf(stderr,"\tcopyFile <file1> <file2> -from <line#>\n");
    fprintf(stderr,"\tcopyFile <file1> <file2> -to <line#>\n");
}

int main(int argc, char* argv[])
{
	if (argc<3 || *argv[1] == '?') {
		displayCmdSyntax();
		exit(0);
	}
	
	switch (argc) {
    case 3: 	copyFile(argv[1],argv[2]);
    				break;
    case 4: 	copyFile(argv[1],argv[2],argv[3]);
    				break;
	case 5: 	copyFile(argv[1],argv[2],argv[3],atoi(argv[4]));
		break;
	case 7: 	copyFile(argv[1],argv[2],argv[3],atoi(argv[4]),
					argv[5],atoi(argv[6]));
		break;
	default:	errorMessage("Error: Invalid syntax\n");
	}
	printf("Ok\n");
	return 0;
}

// copies file fn1 to file fn2
void copyFile(const char* fn1, const char* fn2)
{
	char 	buffer[256];
	FILE	* fp1, * fp2;
	
	fp1 = fopen(fn1,"r");
	if (!fp1) errorMessage("Unable to open input file\n");
	fp2 = fopen(fn2,"w");
	if (!fp2) errorMessage("Unable to open output file\n",fp1);
	while (fgets(buffer,sizeof(buffer),fp1)) fputs(buffer,fp2);
	fclose(fp1);
	fclose(fp2);
}

// copies file fn1 to file fn2 using append, upper, lower or noreplace
void copyFile(const char* fn1, const char* fn2, const char* option) {
	char	buffer[256];
	FILE	* fp1, * fp2;
	int		status;			// of fputs()
	
	// check for valid option
	if (strcmp(option,"-upper")==0 ||
		strcmp(option,"-lower")==0 ||
		strcmp(option,"-append")==0 ||
		strcmp(option,"-noreplace")==0) /* keep going */ ;
	else errorMessage("Invalid option");
	
	fp1 = fopen(fn1,"r");
	if (!fp1) errorMessage("Unable to open input file\n");
	// append option
	if (strcmp(option,"-append")==0) {
		fp2 = fopen(fn2,"a");
		if (!fp2) errorMessage("Unable to open output file\n",fp1);
		else {
			while (fgets(buffer,sizeof(buffer),fp1)) {
				status = fputs(buffer,fp2);
				if (status == EOF)
					errorMessage("Unable to write to output file\n",fp1,fp2);
			}
		}
	}
	// upper & lower case options
	if (strcmp(option,"-upper")==0 || strcmp(option,"-lower")==0) {
		char ch;
		fp2 = fopen(fn2,"w");
		if (!fp2) errorMessage("Unable to open output file\n",fp1);
		else {
			while ((ch = getc(fp1)) != EOF) {
				if (strcmp(option,"-upper")==0) putc(toupper(ch),fp2);
				else putc(tolower(ch),fp2);
			}
		}
	}
	
	// noreplace option
	if (strcmp(option,"-noreplace")==0) {		
		// check for the existance of file fn2
		// Note: The access() function is non-ANSI, but available on Borland/UNIX compilers
		// MS compilers use _access		
		if (access(fn2,0)==0) errorMessage("Noreplace error for output file\n",fp1);
		else copyFile(fn1,fn2);
	}
	fclose(fp1);
	fclose(fp2);
}

// copy part of fn1 to fn2 (from linto or to lineno)
void copyFile(const char* fn1, const char* fn2, const char* fromto, int lineno)
{
	char	buffer[256], *fgets_status, err_msg[80];
	FILE	* fp1, * fp2;
	int 	i;
	fp1 = fopen(fn1,"r");
	if (!fp1)  errorMessage("Unable to open input file\n");
	fp2 = fopen(fn2,"w");
	if (!fp2)  errorMessage("Unable to open output file\n");
	
	// copy "from" lineno to the end of file
	if (strcmp(fromto,"-from")==0) {
		// read records up to "from"
		for (i = 1; i<lineno;i++) {
			fgets_status = fgets(buffer,sizeof(buffer),fp1);
			if (!fgets_status) {		// make sure the records are read up to "from"
				sprintf(err_msg,"Unable to read past record %d\n",i);
				errorMessage(err_msg,fp1,fp2);
			}
		}
		// read the rest of the file & write it out
		while (fgets(buffer,sizeof(buffer),fp1)) fputs(buffer,fp2);
	}
	else if (strcmp(fromto,"-to")==0) {
		// read records up to "to" & write them out
		for (i = 0; i<lineno;i++) {
			fgets_status = fgets(buffer,sizeof(buffer),fp1);
			if (!fgets_status) {		// make sure the records are read up to "from"
				sprintf(err_msg,"Unable to read past record %d\n",i);
				errorMessage(err_msg,fp1,fp2);
			}
			fputs(buffer,fp2);
		}
	}
	else errorMessage("Invalid syntax",fp1,fp2);
	fclose(fp1);
	fclose(fp2);
}

void copyFile(const char* fn1, const char* fn2, const char* from, int line1,
			  const char* to, int line2)
{
	char	buffer[256], err_msg[80], *fgets_status;
	FILE	* fp1, * fp2;
	int 	i;
	// check the syntax
	if (strcmp(from,"-from")||strcmp(to,"-to"))
		errorMessage("Invalid from/to syntax\n");
	if (line1>line2) errorMessage("Invalid 'from' > 'to'\n");
	
	fp1 = fopen(fn1,"r");
	if (!fp1)  errorMessage("Unable to open input file\n");
	fp2 = fopen(fn2,"w");
	if (!fp2)  errorMessage("Unable to open output file\n");
	
	// read records up to "from" line1
	for (i = 1; i<line1;i++) {
		fgets_status = fgets(buffer,sizeof(buffer),fp1);
		if (!fgets_status) {		// make sure the records are read up to "from"
			sprintf(err_msg,"Unable to read past record %d\n",i);
			errorMessage(err_msg,fp1,fp2);
		}
	}
	for (i = line1; i<=line2;i++) {
		fgets_status = fgets(buffer,sizeof(buffer),fp1);
		if (!fgets_status) {		// make sure the records are read up to "to"
			sprintf(err_msg,"Unable to read past record %d\n",i);
			errorMessage(err_msg,fp1,fp2);
		}
		fputs(buffer,fp2);
	}
	fclose(fp1);
	fclose(fp2);
}

void errorMessage(char* msg) {
	fprintf(stderr,msg);
	exit (-1);
}
void errorMessage(char* msg, FILE* fp1) {
	fprintf(stderr,msg);
	fclose(fp1);
	exit (-1);
}
void errorMessage(char* msg, FILE* fp1, FILE* fp2) {
	fprintf(stderr,msg);
	fclose(fp1);
	fclose(fp2);
	exit (-1);
}