// do some exercises on procedures: add static methods that work
// on an array of books that are read from a file


import java.io.*;

public class SearchLib2 {


    // lib[] is the array of Books stored in our library
    // being an attribute of SearchLib, it is visible to all methods
    private static Book lib[];


    // the main method reads the books from file book.txt, stores
    // them in lib[] and tests some of our methods here
    public static void main(String a[]) {

       int i;

       // STEP 1: first pass: just count the number of lines in the file

       int count = 0;
       try {
           BufferedReader file = new BufferedReader(new FileReader("book.txt"));
           while(file.readLine() != null) {
               count++;
           }
           file.close();
       } catch (Exception e) {
           System.err.println("there's an error reading the file");
           System.exit(1);
       }

       if (count == 0) {
           System.err.println("can't find any books");
           System.exit(1);
       }

       if (count % 3 != 0) { 
            System.err.println("oops: got " + count + " lines -> not divisible by 3");
            System.exit(1);
       }

       // STEP 2: create an array of Books with enough space for all the books in my file
       //         there's three lines for each book: title, author, year 
       lib = new Book[count / 3];


       // STEP 3: read all the books into lib[]

       try {  

           // open the text file book.txt
           // (create a BufferedReader object)
           BufferedReader file = new BufferedReader(new FileReader("book.txt"));

           // read three Book records (each having three lines)
          for (i = 0; i < lib.length; i++) {

              String title  = file.readLine();  // first line -> title
              String author = file.readLine();  // second line -> author
              String year   = file.readLine();  // third line -> year

                                                // watch out: you need to transform the String year
                                                // into an int, so the constructor is happy
              lib[i] = new Book(title, author, Integer.parseInt(year));
          }
          file.close();

          // close the file
    
       } catch (Exception e) {
           System.out.println("something is wrong");
           System.exit(1);
       }  
       // ---------------------------------------------------------------- 


        // just to check, I want to print out the three titles
        System.out.println("");
        System.out.println("here come all the titles:");
        for (i = 0; i < lib.length; i++) {
           System.out.println(lib[i].getTitle());
        }


        // look for books by Shakespeare
        System.out.println("");
        System.out.println("here come all of Shakespear's books:");
        String titles[] = search("W. Shakespear");
        for (i = 0; i < titles.length; i++) {
           System.out.println(titles[i]);
        }

        // find the oldest book
        System.out.println("");
        System.out.println("the oldest book is: " + findOldest());
        

        // lend out / give back a few books
        lib[0].lendTo("Lecha");
        lib[5].lendTo("Foruzan");
        lib[3].lendTo("Bersam");
        lib[3].giveBack();
        lib[3].lendTo("Khuseyn");
 
        // now see a list of all the books that are lent out and by whom
        System.out.println("");
        System.out.println("Current list of lent out books:");
        printUsers();


   }





   // add a method that prints to the terminal the titles
   // of all books that are lend out including the names
   // of the people that lend them

   public static void printUsers() {
        int i;
        for (i = 0; i < lib.length; i++) {
            if (lib[i].isAvailable() == false) {
                System.out.println(lib[i].getTitle() + "    " + lib[i].getUser());
            }
        }      

   }


   
   // add a method that returns the title of the oldest book in lib[]
   // method name: findOldest
   // arguments: none
   // return type: you find out
   public static String findOldest() {
        int oldest_so_far = 0;
        int i;
        for (i = 0; i < lib.length; i++) {

	      if (lib[i].getYear() < lib[oldest_so_far].getYear()) {
                   oldest_so_far = i;
              }
        }
        return lib[oldest_so_far].getTitle(); 
  }

  
  // write a method that given two books returns the title of the older Book,
  // or the first Book if both have the same age
  // the method should be called getOlder
  public static String getOlder(Book a, Book b) {
        if (a.getYear() < b.getYear()){
             return a.getTitle();
        } else if (a.getYear() == b.getYear()){
             return a.getTitle();
        } else {
             return b.getTitle();
        }
  }


   // a method that returns the number of books in my library
   public static int getNumber() {
       return lib.length;
   }

  
   // NEW: add a method that is given an author and return all title of the books by the
   // given author as an array of Strings
   public static String[] search(String aut) {

        int i;

        // we need to store all results before returning them, but we don't know in advance
        // how many results we will get. So the (cheap and dirty) trick is to look for that
        // author twice: first we just count the results, so we know how large the result
        // array should be; then we make a second pass where we store the results.

        // in real life of course you would use dynamic arrays (see java.utils)

        int count = 0;
        for (i = 0; i < lib.length; i++) {
            if (aut.equals(lib[i].getAuthor())) {
                count++;
            }
        }      

        String results[] = new String[count];

        int r = 0;
        for (i = 0; i < lib.length; i++) {
            if (aut.equals(lib[i].getAuthor())) {
                // we have found that book number i is by author aut
                String title = lib[i].getTitle();
                results[r] = title;
                r++;
            }
        }      
        return results;

 }
 


}