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

/*	Trying to duplicate the behavior:

<cfexecute name="c:\program files\HTMLDOC\htmldoc.exe"
           arguments="-f #variables.ContentPath##variables.FileName#.pdf
            --compression=9 --jpeg --webpage #variables.ContentPath##variables.FileName#.html">
</cfexecute>

*/

int main(void) {

	//get a pointer to the Query String passed in by IIS
	char *data1 = getenv("QUERY_STRING");		//character pointer to point to query data
	char *old_string = data1;					//second pointer to first char in data string
	
	//allocate a clean string of equal size that will hold the URL-Decoded version
	char *data = calloc(strlen(data1), sizeof(char));
	char *new_string = data;					//put the pointer at the beginning
	
	//allocate a char buffer for hex decoding
	char val[2];
	char c;
	
	//we need to manually URL-Decode the input string
	int i;
	for (i=0; *old_string != '\0'; old_string++) { 
		//starting with a pointer at the beginning of the string
		//look at each character until we encouter the NULL at the end of the data string
		//increment the pointer by 1 memory unit each iteration
		if( *old_string == '%'){ 
			//if we encounter a % sign, the next 2 chars represent
			//the hexidecimal value for a character
			
			//get the next 2 chars and store them in val[0]val[1]
			old_string++; 
			val[0]=*old_string; 
			old_string++; 
			val[1]=*old_string; 
	
			//now convert to decimal
			//convert to lower case and check A-F use the corresponding value
			switch( tolower(val[1]) ){ 
				case 'a': 
				i=10; 
				break;

				case 'b': 
				i=11; 
				break; 

				case 'c': 
				i=12; 
				break; 

				case 'd': 
				i=13; 
				break; 

				case 'e': 
				i=14; 
				break; 

				case 'f': 
				i=15; 
				break; 

				//if it is not A-F, it is a number 0-9 so just use the numeric
				//representation
				default: 
				i=atoi( &val[1] ); 
				break; 
			} 

			c=val[0];
			
			//now convert to ASCII
			i+=16*(atoi( &c )); 

			//now that we have the ASCII URL-Decoded value
			//copy it into the new string
			*new_string=i; 
			new_string++; 
		} else if( *old_string == '+'){ 
			//plus'es become spaces
			*new_string=' '; 
			new_string++; 
		} else { 
			//anything else is non-special and gets copied as is.
			*new_string = *old_string; 
			new_string++; 
		} 
	} 

	//Print HTTP header (required by RFC 2616, Hypertext Transfer Protocol - HTTP/1.1)
	printf("%s%c%c\n","Content-Type:text/html;charset=iso-8859-1",13,10);

	

	if(data == NULL) {
		//no query string found
		printf("No query string.");
		return(-1);	//nothing to do
	} else {
		int i = 0;
		int nEq = 0;
		int nAmp = 0;
		
		int e1Pos;
		int ampPos;
		
		char * e1;
		char * e2;
		
		//SPLIT THE QUERY STRING:
		//	make sure there are exactly 2 ='s and 1 & char
		while (i < strlen(data)) {
			char c = data[i];
			if (c == '=') {
			
				if (nEq == 0) {
					e1Pos = i;
				}
				
				nEq++;
			}
			
			if (c == '&') {
				nAmp++;
				ampPos = i;
			}
			
			i++;
		}
		
		if (nAmp != 1 || nEq != 2) {
			printf("Invalid number of query arguments.\n");
			return(-1);
		}
		
		//note the locations of both = signs in the data string
		e1 = strchr(data, '=');
		e2 = strrchr(data, '=');
		
		//the length of arg1 is the number of chars between the first = sign
		//and the & sign, - 1 because we start counting at 0.
		int arg1Length = ampPos - e1Pos - 1;
	
		//allocate a string to hold the content path
		char *contentPath = calloc(arg1Length + 1, sizeof(char));
		
		//the filename is the remainder of the string starting with this pointer
		char *fileName = e2 + 1;
		
		//copy the first arg from the data string into the new contentPath variable
		strncpy(contentPath, e1+1, arg1Length);
	
		//query string successfully parsed. Launch a process to generate the PDF
		int statusCode;

		//build input filename = #contentpath##filename#.html
		
			//since we don't know the max length of contentPath + fileName + .html at compile time
			//we need to count the length of the string and dynamically allocate a char array buffer
			//to hold this
			//adding 6 extra places - 1 for the ., 4 for "html" and one for the null char at the end of the string
			int strLen = strlen(contentPath) + strlen(fileName) + 6;

		//dynamically allocate clean (byte-zero'ed) strLen x size of character bytes of memory
			char * outPath = calloc(strLen + 1, sizeof(char));
			char * inPath = calloc(strLen + 1, sizeof(char));
	
			//copy the char arrays into the new memory buffers
			sprintf(outPath,"%s%s.pdf", contentPath, fileName);
			sprintf(inPath, "%s%s.html", contentPath, fileName);

			//build a command string and ask the OS to launch a shell & run it
			char * cmd = calloc(80 + strlen(outPath) + strlen(inPath), sizeof(char));
			sprintf(cmd, "c:\\progra~1\\HTMLDOC\\htmldoc.exe -f %s --compression=9 --jpeg --webpage %s", outPath, inPath);
			
			printf("Running: %s<br>\n", cmd);
			
			//tells the operating system to execute command cmd and prints the return status to the browser
			printf("Process returned status: %i", system(cmd));
			
			//free dynamic memory
			free(contentPath);
			free(outPath);
			free(inPath);
			free(cmd);
			free(data);
			
			//exit with no error
			exit(0);
		
	}
}