/* Write a program to "fold" long input lines into two or more shorter
* lines after the last non-blank character that occurs before the N-th column of input.
* Make sure your program does something intelligent with very long lines, and if
* there are no blanks or tabs before the specified column. */

/* case 1: found tab or blank at column <= N, subcases to consider:
*      1.1 found blank after last tab
*      1.2 tab after last blank, subcases:
*          1.2.1 tab before N
*          1.2.2 tab to N
*          1.2.3 tab exceeding N */

/* case 2: no blank or tab before at column <= N: break line at next blank/tab */

#include <stdio.h>
#define MAX 1000
#define N 20 // soft breakpoint
#define TAB 8

int foldline(char[], int, int, int);

int main() {
   char line[MAX + 1]; // +1 for '\0' termination

   while (foldline(line, MAX, N, TAB) > 0) {
       printf("%s", line);
   }
   return 0;
}

int foldline(char line[], int max, int bp, int tabsize) {
   /* folds a long input line and returns length of original line. bp: breakpoint */
   int chr, col, i, lastblank = -1, lasttab = -1, tmp, nextstop; // nextstop: next tab stop

   for (i = 0, col = 0; i < max && (chr = getchar()) != EOF && chr != '\n'; i++, col++) {
       line[i] = chr;
       nextstop = (col/tabsize)*tabsize + tabsize - 1;
       if ((chr == ' ' || chr == '\t') && col <= bp) { // found whitespace early enough  
           chr == ' '? (lastblank = col) : (lasttab = col);
           tmp = i; // save index for possible '\n' in line array
       }
       if (chr == '\t') col = nextstop;
       /* deal with case 1 */
       if (col >= bp && lastblank != lasttab) { // if lastblank == lasttab <=> found none
           lastblank > lasttab? (col = bp - lastblank) : (col -= nextstop);    
           line[tmp] = '\n';
           lastblank = -1;
           lasttab = -1;
       /* deal with case 2 */
       } else if (col > bp && (chr == ' ' || chr == '\t')) {
           line[i] = '\n';
           col = 0;
       }
   }
   if (chr == '\n') line[i++] = '\n';
   line[i] = '\0';
   return i;
}

/* Write a program to check a C program for rudimentary syntax errors like unmatched
* parentheses, brackets and braces. Don't forget about quotes, both single and double,
* escape sequences, and comments. (This program is hard if you do it in full generality.) */

#include <stdio.h>
#include <stdbool.h>
#define ON true
#define OFF false
#define MAX 5000 // max number of parens/braces/brackets in source file

int main(int numargs, char *argv[]) {
   /* check (), [] or {} depending on command line argument
    * example program call: krex1_24 ( < sourcefile.c */
   char input = *argv[1], open, close;
   
   if (input == '(' || input == ')') {
       open = '(';
       close = ')';
   } else if (input == '[' || input == ']') {
       open = '[';
       close = ']';  
   } else if (input == '{' || input == '}') {
       open = '{';
       close = '}';
   } else {
       printf("invalid input\n");
       return 0;
   }
 
   /* process input */
   char last = getchar(), c, olist[MAX], clist[MAX];
   int oindex = 0, cindex = 0, atline = 1, lastlast = '\0', i;
   bool coma = OFF, comb = OFF, dquote = OFF, squote = OFF, rightbefore = false;

   while (last != EOF && oindex < MAX && cindex < MAX) {
       if (last == '\n') {
           atline++;
       }
       c = getchar();

       /* check for comments or quotes */
       if (last == '/' && c == '*' && dquote == OFF && squote == OFF && comb == OFF) {
           coma = ON;
       } else if (coma == ON && last == '*' && c == '/') {
           coma = OFF;
       } else if (last == '/' && c == '/' && dquote == OFF && squote == OFF && coma == OFF) {
           comb = ON;
       } else if (comb == ON && c == '\n') {
           comb = OFF;
           if (last == open || last == close) {
               last = '\0'; // prevent counting ( for //comment(\n
           }
       } else if (c == '"' && dquote == OFF && squote == OFF && coma == OFF && comb == OFF) {
           dquote = ON;
           if (last == open || last == close) {
               rightbefore = true; // prevent not counting ( for ("quote"        
           }
       } else if (c == '"' && dquote == ON && (last != '\\' || lastlast == '\\')) {
           dquote = OFF;
           if (last == open || last == close) {
               last = '\0'; // prevent counting ( for "quote("
           }
       } else if (c == '\'' && dquote == OFF && squote == OFF && coma == OFF && comb == OFF) {
           squote = ON;
           if (last == open || last == close) {
               rightbefore = true; // prevent not counting ( for ('quote'        
           }
       } else if (c == '\'' && squote == ON && (last != '\\' || lastlast == '\\')) {
           squote = OFF;
           if (last == open || last == close) {
               last = '\0'; // prevent counting ( for 'quote('
           }
       }

       /* update paren/brace/bracket status, discard matching pairs */
       if ((coma == OFF && comb == OFF && dquote == OFF && squote == OFF) || rightbefore) {
           if (last == open) {
               olist[oindex] = atline;
               oindex++;
           } else if (last == close) {
               if (oindex == 0) {
                   clist[cindex] = atline;
                   cindex++;
               } else {
                   oindex--;
               }
           }
       }
       
       /* update temp vars */
       rightbefore = false;
       lastlast = last;
       last = c;
   }
   
   /* output */
   if (oindex == MAX || cindex == MAX) {
       printf("maximum number of parens/brackets/braces exceeded\n");
   } else if (oindex == 0 && cindex == 0) {
       printf("found no unmatched %c%c\n", open, close);
   } else {
       for (i = 0; i < cindex; i++) {
           printf("unmatched %c at line %d\n", close, clist[i]);
       }
       for (i = 0; i < oindex; i++) {
           printf("unmatched %c at line %d\n", open, olist[i]);
       }
   }
   return 0;
}

switch (input) {
case '(':
case ')':
 open = '(';
 close = ')';
break;
case '[':
case ']':
 open = '[';
 close = ']';  
break;
case '{':
case '}':
 open = '{';
 close = '}';
break;
deault:
 printf("invalid input\n");
break;
}