/* CGI for processing El Nino quiz form and returning results */
/* CGI stuff at top from a web tutorial, the rest by me */
/* Adrian Taylor 1997 */

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

char x2c(char *what);
void unescape_url(char url[]);
char **getcgivars(void);
void printAggregates(int marksGot);
void printTopOfPage(void);
void printBottomOfPage(void);
int markEachQuestion(void);
void printCorrectAnswer(int theQuestion);
int isItCorrect(int questionNumber,char *theAnswer);
int contains(char *outerString,char *innerString);

/*************/
void main (void)
{
	int marksGot;

	printTopOfPage();
	marksGot=markEachQuestion();
	printAggregates(marksGot);
	printBottomOfPage();
}

/*****************************************/
/*** CGI code copied from a web tutorial */
/*****************************************/

char x2c(char *what)
{
	/* This takes a hex number and returns its real character */
	char digit;
	
	digit = (what[0]>='A' ? ((what[0] & 0xDF )-'A')+10 : (what[0]-'0'));
	digit *=16;
	digit += (what[1]>='A'?((what[1] & 0xDF )-'A')+10: (what[1]-'0'));
	
	return (digit);
}

void unescape_url(char url[])
{
	/* This removes the escape sequences from an URL */
	int i,j;
	
	for (i=0,j=0;url[j];++i,++j)
	{
		if ((url[i] = url[j]) == '%')
		{
			url[i]=x2c(&url[j+1]);
			j+=2;
		}
	}
	url[i]='\0';
}

char **getcgivars(void)
{
	/* Returns a list of strings: name1, value1, name2, value2 etc. */
	
	int i;
	char *request_method;
	int content_length;
	char *cgiinput;
	char **cgivars;
	char **pairlist;
	int paircount;
	char *nvpair;
	char *eqpos;
	
	request_method=getenv("REQUEST_METHOD");

	if(!getenv("REQUEST_METHOD") || (!strcmp(request_method, "GET")&& !getenv("QUERY_STRING")) || !getenv("CONTENT_TYPE") || !getenv("CONTENT_LENGTH"))
	{
		printf("getcgivars(): Required environment variables have not been set!\n");
		exit(1);
	}
	
	if (!strcmp(request_method,"GET"))
	{
		/* We are using get method */
		cgiinput=strdup(getenv("QUERY_STRING"));
	}
	else if (!strcmp(request_method,"POST"))
	{
		/* We are using post method */

		if(strcmp(getenv("CONTENT_TYPE"),"application/x-www-form-urlencoded"))
		{
			printf("getcgivars(): Unsupported Content-Type.\n");
			printf("Ctype is %s\n",getenv("CONTENT_TYPE"));
			exit(1);
		}
		if (!(content_length=atoi(getenv("CONTENT_LENGTH"))))
		{
			printf("getcgivars(): No content-length was sent with the POST request.\n");
			exit(1);
		}
		if (!(cgiinput=(char *)malloc(content_length+1)))
		{
			printf("getcgivars(): Could not malloc for CGI Input.\n");
			exit(1);
		}
		if (!fread(cgiinput,content_length,1,stdin))
		{
			printf("getcgivars(): Couldn't read CGI input from stdin.\n");
			exit(1);
		}
		cgiinput[content_length]='\0';
	}
	else
	{
		printf("getcgivars(): unsupported REQUEST_METHOD\n");
		exit(1);
	}
	
	/* Change all plusses back to spaces */
	
	for (i=0;cgiinput[i];i++)
		if (cgiinput[i]=='+')
			cgiinput[i]=' ';
			
	/* Now split on & to extract the name-value pairs into pairlist */
	
	pairlist=(char**)malloc(256*sizeof(char**));
	paircount=0;
	nvpair=strtok(cgiinput,"&");
	while (nvpair)
	{
		pairlist[paircount++]=strdup(nvpair);
		if (!(paircount%256))
			pairlist=(char**) realloc(pairlist,(paircount+256)*sizeof(char**));
		nvpair=strtok(NULL,"&");
	}
	pairlist[paircount]=0;
	
	/* Then from the list of pairs extract the names and values */
	cgivars=(char**)malloc((paircount*2+1)*sizeof(char**));
	for (i=0;i<paircount;i++)
	{
		if (eqpos=strchr(pairlist[i],'='))
		{
			*eqpos='\0';
			unescape_url(cgivars[i*2+1]=strdup(eqpos+1));
		}
		else
		{
			unescape_url(cgivars[i*2+1]=strdup(""));
		}
		unescape_url(cgivars[i*2]=strdup(pairlist[i]));
	}
	
	/* That was nasty. Now free anything that needs to be freed */
	free(cgiinput);
	for (i=0;pairlist[i];i++)
		free(pairlist[i]);
	free(pairlist);
	
	return cgivars;
}

/***********************************************************************/
/* End of hideous unix CGI argument passing module bunged in at top*/
/***********************************************************************/
void printAggregates(int marksGot)
{
	/* This prints total scores and percentages */
	/* It also then prints a comment on the result */
	printf("<hr><h1>Total scores</h1>\n\nYou got %d",marksGot);
	printf(" right, which is %3.1f percent.<p>",
		marksGot*10.0);
	switch (marksGot)
	{
		case 0:
			printf("That's just silly, really, isn't it?");
			break;
		case 1:
		case 2:
		case 3:
			printf("It could be worse.");
			break;
		case 4:
			printf("Well, it's a pass.");
			break;
		case 5:
			printf("Half way!");
			break;
		case 6:
			printf("If only I could get that in exams...");
			break;
		case 7:
			printf("A first! Wow!");
			break;
		case 8:
			printf("You've been revising.");
			break;
		case 9:
			printf("Swot.");
			break;
		case 10:
			printf("That'll be &pound;1000 for tuition, please, Doctor.");
			break;
	}
	printf("<p>");
}

void printTopOfPage(void)
{
	/* Prints the top of the returned page, before any processing occurs */
	printf("Content-type: text/html\n\n");
	/* That line is necessary to indicate that we are returning
		HTML */
	printf("<html><head><title>Marks for El Ni&ntilde;o Quiz</title>");
	printf("</head>\n<body bgcolor=\"#FFFFFF\">\n");
	printf("<h1>Marks for quiz</h1>\n\n");
}

void printBottomOfPage(void)
{
	printf("<hr>Thank you for taking the quiz.\n\n<p><a href=\"http://www.bits.bris.ac.uk/ade/cm1/Welcome.htm\">Return to main page (on BITS)</a>.</body></html>");
}

int markEachQuestion(void)
{
	/* Goes through and marks each individual question */
	char **cgivars;
	char *theAnswer;
	int currentQuestion,cgiVarQuestion,foundCurrentQuestionResponse;
	int sumOfMarksSoFar=0,gotItRight,i,j;
	
	cgivars=getcgivars();
	/* Puts the input variables into a string array of form name1,value1,name2,value2 */
	
	for (currentQuestion=1;currentQuestion<11;currentQuestion++)
	{
		foundCurrentQuestionResponse=0;
		gotItRight=0;
		printf("\n\n<h2>Question %d</h2>",currentQuestion);
		for (i=0;cgivars[i];i+=2)
		{
			if (sscanf(cgivars[i],"%d",&cgiVarQuestion))
			{
				if (cgiVarQuestion==currentQuestion)
				{
					theAnswer=cgivars[i+1];
					
					/* We now have the answer they gave to question currentQuestion */
					
					foundCurrentQuestionResponse++;

					for (j=0;j<strlen(theAnswer);j++)
						theAnswer[j]=tolower(theAnswer[j]);

					gotItRight = isItCorrect(currentQuestion,theAnswer);
					
					/* It has now been marked */
					
					sumOfMarksSoFar+=gotItRight;
					if (gotItRight)
					{
						printf("<img src=\"http://www.bits.bris.ac.uk/ade/cm1/quiz/right.gif\" alt=\"icon(430bytes)\" align=left height=48 width=57>\n");	
						printf("\nCorrect!<p>\n");
					}
					else
					{
						printf("<img src=\"http://www.bits.bris.ac.uk/ade/cm1/quiz/wrong.gif\" alt=\"icon(418bytes)\" align=left height=38 width=57>\n");	
						printf("\nWrong!<p>\nThe correct answer is: ");
						printCorrectAnswer(currentQuestion);
						printf(". ");
					}
					printf("You said %s.",theAnswer);
					printf(" Marks so far: %d.<p>",sumOfMarksSoFar);
					printf("<br clear=left>\n");
				}
			}
		}
		if (foundCurrentQuestionResponse!=1)
			printf("Whoops: question %d has %d responses.<p>",currentQuestion,foundCurrentQuestionResponse);
	}
	
	return sumOfMarksSoFar;
}

void printCorrectAnswer(int theQuestion)
{
	switch (theQuestion)
	{
		case 1:
			printf("Fred Bloggs");
			break;
		case 2:
			printf("sort of icky");
			break;
		case 3:
			printf("acme widgets");
			break;
		case 4:
			printf("Fred");		
			break;
		case 5:
			printf("Fred's");
			break;
		case 6:
			printf("None at all");
			break;
		case 7:
			printf("Wavy");
			break;
		case 8:
			printf("2004");
			break;
		case 9:
			printf("it goes all shiny");
			break;
		case 10:
			printf("Beeblebroxes");
			break;
	}
}

int isItCorrect(int questionNumber,char *theAnswer)
{
	switch (questionNumber)
	{
		case 1:
			return (contains(theAnswer,"bloggs"));
		case 2:
			return (contains(theAnswer,"sort of icky"));
		case 3:
			return (contains(theAnswer,"acme widgets"));
		case 4:
			return (contains(theAnswer,"fred"));
		case 5:
			return (contains(theAnswer,"fred"));
		case 6:
			return (contains(theAnswer,"none"));
		case 7:
			return (contains(theAnswer,"wavy"));
		case 8:
			return (contains(theAnswer,"04")||contains(theAnswer,"2004"));
		case 9:
			return (contains(theAnswer,"shiny")||contains(theAnswer,"glossy"));
		case 10:
			return (contains(theAnswer,"beeblebroxes"));
	}
}

int contains(char *outerString,char *innerString)
{
	if (strstr(outerString,innerString))
		return 1;
	else
		return 0;
}