/*
 * This is an example program to introduce some of the basic features
 * of C.
 *
 * CSCI 315
 * Fall 2013
 *
 * Xiannong Meng
 * August 2013
 */

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

/* one can define 'global' data types, variables, and constants here */

#define MAX_STRLEN 80  // maximum length of an unknown string
#define WRD_LENGTH 32  // per word 
#define MAX_COURSE 5   // number of courses per student

#define FALSE 0
#define TRUE  1

/* the following is a C structure to hold course information */
struct course_info {
  char course[WRD_LENGTH];// in the form of 'CSCI 315', 8 chars, plus '\0'
  char * title;     // variable length string
  char * prof;      // professor name, variable length
  char time[WRD_LENGTH];// in the form of 'MWF 08:00-09:00', 16 chars, plus '\0'
  char * room;      // classroom, variable length
  float credit;     // 1.0, 0.5, 0.25, etc.
  int enrollment;   // number of students allowed in class
};

void read_a_record(FILE * f, struct course_info * a_course) {

  int len;

  fgets(a_course->course, WRD_LENGTH, f);   // read course
  len = strlen(a_course->course);
  a_course->course[len-1] = 0;         // terminate the string

  a_course->title = (char*)malloc(MAX_STRLEN + 1);
  fgets(a_course->title, MAX_STRLEN, f);   // read course title
  len = strlen(a_course->title);
  a_course->title[len-1] = 0;      // terminate the string

  a_course->prof = (char*)malloc(MAX_STRLEN + 1);
  fgets(a_course->prof, MAX_STRLEN, f);    // read professor name
  len = strlen(a_course->prof);
  a_course->prof[len-1] = 0;       // terminate the string

  fgets(a_course->time, WRD_LENGTH, f);    // read time and day of the course
  len = strlen(a_course->time);
  a_course->time[len-1] = 0;       // terminate the string

  // read the room information
  a_course->room = (char*)malloc(MAX_STRLEN + 1);
  fgets(a_course->room, MAX_STRLEN, f);
  len = strlen(a_course->room);
  a_course->room[len-1] = 0;       // terminate the string

  // read course credit, note the &
  fscanf(f, "%f", &(a_course->credit));    
   
  // read course enrollment, note the &
  fscanf(f, "%d", &(a_course->enrollment));

  fgetc(f); // move over the '\n' char that's left by 'scanf()'
}

/*
 * Read course information from a file and return them as an array.
 *
 * The format of the input file is as follows
 *  count: an integer indicating how many courses in this file, followed by
 *         the 'count' number of course structures. Each has the following form
 *  course: an 8-char sequence in the form of "CSCI 315"
 *  title:  a variable length string, e.g., "Operating Systems Design"
 *  prof:   a variable length string, e.g., "Professor Meng"
 *  time:   a 16-char string in the form of 'MWF 08:00-09:00'
 *  room:   a variable length string, e.g., "Breakiron 066"
 *  credit: a floating point number for course credit, 1.0, 0.5, 0.25 etc
 *  enrollment: an integer indicating the maximum of students
 *
 * Parameters:
 *   char * fname: name of the file where the information is stored
 * Return:
 *   an array of structures, each of which holds information for one course
 */
struct course_info * read_data(char * fname) {

  FILE * f = fopen(fname, "r");    // open data file for reading
  int count;    // number of courses
  int i;        // loop index

  fscanf(f, "%d", &count);    // read the number of records
  fgetc(f);

  // we first allocate the memory for the array of courses
  struct course_info * courses = 
    (struct course_info *)malloc((count + 1)* sizeof(struct course_info));

  // we now read the courses into this array, one at a time
  for (i = 0; i < count; i ++) {
    read_a_record(f, &courses[i]);
  }

  strcpy(courses[count].course, "END"); // sentinal value for the last

  return courses;
}

/*
 * Print a single record. Assume both parameters are valid.
 *
 * Parameters:
 *   courses : an array of structures containing course information.
 *   i : the index of the array item (course) to be printed.
 */
void print_a_record(struct course_info * courses, int i) {

    printf("course %d:\n", i);
    printf("    course %s %s\n", courses[i].course, courses[i].title);
    printf("    professor %s\n", courses[i].prof);
    printf("    date and time %s\n", courses[i].time);
    printf("    loaction %s\n", courses[i].room);
    printf("    credit %3.1f\n", courses[i].credit);
    printf("    enrollment %d\n", courses[i].enrollment);
}

/*
 * Print the entire array of the course structures.
 *
 * Version 1: print an array of records (structures) with known size
 *
 * Parameters:
 *    courses :  an array of structures containing course information.
 *    count   :  the total number of records in the array
 */
void print_records(struct course_info * courses, int count) {

  int i;

  printf("--- Course information ---\n");
  for (i = 0; i < count; i ++) {
    print_a_record(courses, i);
  }
}

/*
 * Print the entire array of the course structures.
 *
 * Version 2: print an array of records (structures) without a known size
 *
 * Parameters:
 *    courses :  an array of structures containing course information.
 */
void print_records_v2(struct course_info * courses) {

  int i;  // loop index

  i = 0;
  printf("--- Course information ---\n");
  while (strncmp(courses[i].course, "END", 3) != 0) { // 'END', a sentenal value
    print_a_record(courses, i);
    i ++; // increment i
  }
}

/*
 * Search for a record that contains 'query' in any place.
 *
 * Parameters:
 *    query: the query to search for
 *    courses: the array of courses
 *    size: the number of courses in the array
 *
 *  Returns:
 *    The index of the record containing the query, if found, -1 otherwise.
 */
int found(char * query, struct course_info * courses, int size ) {

  int i = 0;
  int found = FALSE;
  
  while (i < size && found == FALSE) {
    if (strstr(courses[i].course, query) != NULL ||
	strstr(courses[i].title, query) != NULL ||
	strstr(courses[i].prof, query) != NULL ||
	strstr(courses[i].room, query) != NULL ||
	strstr(courses[i].time, query) != NULL)
      found = TRUE;
    else
      i ++;
  }
  if (found == TRUE)
    return i;
  else
    return -1;
}

/*
 * Perform search on the array of the records.
 *
 * Parameters:
 *    courses: the array of course structures
 *    count: the number of records in the array
 */
void do_search(struct course_info * courses, int count) {

  char query[MAX_STRLEN];
  int i;

  printf("Enter a search term as a single word ('END' to quit) : ");
  scanf("%s", query);
  while (strncmp(query, "END", 3) != 0) {
    i = found(query, courses, count);
    if (i != -1) {
      printf("record found with match ...\n");
      print_a_record(courses, i);
    } else
      printf("record not found ...\n");
    printf("Enter a search term as a single word ('END' to quit) : ");
    scanf("%s", query);
  }
}

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

  // declare an array of dynamic size
  struct course_info * my_courses;

  // read course information from a file
  my_courses = read_data("course-data.txt");
  
  // print what we have read
  //  print_records(my_courses, 5);   // print with a known size
  print_records_v2(my_courses);    // print without a known size

  do_search(my_courses, 5);

  return 0;
}