/* -*- Mode: C; indent-tabs-mode: t; c-basic-offset: 4; tab-width: 4 -*- */
/*
 * readability.c
 * Copyright (C) 2012 drdev <drdev@localhost.com>
 * 
 * readability is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * readability is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License along
 * with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 //This program calculates the Flesch Reading Ease and the
 //Flesch Kincaid Grade Level of a text file

#include <stdio.h>
#include <stddef.h>
#define debug 0

const char delimiters[] = " .,;:!-";
char *token;
int vowel_flag,old_vowel_flag;
int i;
int sentence_count,word_count,syllable_count;
char str[2048];
char fn1[64];
char fn2[64];
FILE *indata;
FILE *outdata;

/* Prototypes */
char * strtok (char *newstring, const char *delimiters);
char *strcpy(char *dest, const char *src);
char *fgets(char *s, int n, FILE *f);
size_t strlen(const char *s);
void parse(char *string);
void sentences(char *string);
void syllables(char *string);
float Flesch_Kincaid_Ease(void);
float Flesch_Kincaid_Grade(void);
void exit(int status);
/* end of prototypes */

void parse(char *string)
{
char *token1;
	
//First call to strtok
token1 = strtok (string, delimiters);

while (token1 != NULL)
{
	
for(i=0;i<=strlen(token1);i++)
{
if(token1[i] > 47) //filter LF, CR, etc.
{
if(debug){printf("%c",token1[i]);fprintf(outdata,"%c",token1[i]);}
}

}

syllables(token1);

//increment word count
//Check for stray non-alphanumerics

if((((token1[strlen(token1)-1] >47)&&(token1[strlen(token1)-1] <58))||((token1[strlen(token1)-1] >64)&&(token1[strlen(token1)-1] <91))||((token1[strlen(token1)-1] >96)&&(token1[strlen(token1)-1] <123))))
{
word_count++;
if(debug){printf("*"); fprintf(outdata,"*");}//word separator

}

token1 = strtok (NULL, delimiters);
}

}

void sentences(char *string)
{
for(i=0;i<strlen(string);i++)
{
if((string[i]== '.')||(string[i]== '!')||(string[i]== '?')) sentence_count++;
}
}

void syllables(char *word)
//Returns number of syllables in a word using vowel count.
//Subtracts any silent endings and double vowels.
//With a few exceptions, we get the number of syllables.
{
old_vowel_flag = 0;
for(i=0;i<=strlen(word);i++)
{
vowel_flag = 0;
if((word[i]=='a')||(word[i]=='A')) vowel_flag=1;
if((word[i]=='e')||(word[i]=='E')) vowel_flag=1;
if((word[i]=='i')||(word[i]=='I')) vowel_flag=1;
if((word[i]=='o')||(word[i]=='O')) vowel_flag=1;
if((word[i]=='u')||(word[i]=='U')) vowel_flag=1;
if((word[i]=='y')||(word[i]=='Y')) vowel_flag=1;
if((vowel_flag==1)&&(old_vowel_flag != 1))
{
syllable_count++;
}
old_vowel_flag = vowel_flag;
}
//taking care of e, es and ed at word end
if((strlen(word)>2)&&(word[strlen(word)-1]=='e')) syllable_count--;
if((strlen(word)>2)&&(word[strlen(word)-2]=='e')&&(word[strlen(word)-1]=='s')) syllable_count--;
if((strlen(word)>2)&&(word[strlen(word)-2]=='e')&&(word[strlen(word)-1]=='d')) syllable_count--;

if(debug){printf("[%d]",syllable_count);fprintf(outdata,"[%d]",syllable_count);}
}

float Flesch_Kincaid_Ease(void)
{
return (205.835 - (1.015*((float)word_count/(float)sentence_count)))-(84.6*((float)syllable_count/(float)word_count));
}

float Flesch_Kincaid_Grade(void)
{
return (0.39*((float)word_count/(float)sentence_count))+(11.8*((float)syllable_count/(float)word_count))-15.59;
}

int main(int argc, char *argv[])
{

if (argc<2)
{
printf("Usage: readability input.txt output.txt\n");
exit(1);
}

strcpy(fn1,argv[1]);
printf("\nInput file selected = %s\n",fn1);

if ((indata = fopen(fn1,"rb"))==NULL)
	{printf ("\nInput file cannot be opened.\n");
	exit (1);}

if (argc<3)
{
strcpy(fn2,"output.txt");
}
else
{
strcpy(fn2,argv[2]);
}

printf("Output file selected = %s\n",fn2);

if ((outdata = fopen(fn2,"w"))==NULL)
	{printf ("\nOutput file cannot be opened.\n");
	exit (1);}
	
fprintf(outdata,"\nInput file selected = %s\n",fn1);

sentence_count=0;
word_count=0;
syllable_count=0;

while (fgets(str, 2048, indata) != NULL)
{

sentences(str);
	
}

//Back to file start
fseek(indata, 0, SEEK_SET);

while (fgets(str, 2048, indata) != NULL)
{

parse(str);
	
}

printf("Word count = %d\n",word_count);
fprintf(outdata,"Word count = %d\n",word_count);
printf("Sentence count = %d\n",sentence_count);
fprintf(outdata,"Sentence count = %d\n",sentence_count);
printf("Syllable count = %d\n",syllable_count);
fprintf(outdata,"Syllable count = %d\n",syllable_count);
printf("Flesch Reading Ease = %f\n",Flesch_Kincaid_Ease());
printf("(90->100 = 11 year olds, 60->70 = 13-15 year olds, and 0->30 = college graduate.)\n");
fprintf(outdata,"Flesch Reading Ease = %f\n",Flesch_Kincaid_Ease());
fprintf(outdata,"(90->100 = 11 year olds, 60->70 = 13-15 year olds, and 0->30 = college graduate.)\n");
printf("Flesch-Kincaid Grade Level = %f\n",Flesch_Kincaid_Grade());
fprintf(outdata,"Flesch-Kincaid Grade Level = %f\n",Flesch_Kincaid_Grade());


fclose(indata);
fclose(outdata);

	return (0);
}