// hanzifuncs.js    -*- mode:C; coding: utf-8 -*-
// version 0.3.1
// Copyright (C) 2003 by Forrest Cahoon (hanziquiz@abstractfactory.org)
//
// This program 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 2 of the License, or
// (at your option) any later version.
//
// This program 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, write to the Free Software
// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

////////////////////////////////////////////////////////////////////////

var Qcat; // questions are of type Category[Qcat]
var Acat; // answer choices are of type Category[Acat]
var Qnum; // Question[Qnum] is displayed, then Qnum is incremented
var Numchoices = 5; // Number of choices displayed for each question

var Question = new Array(); // an array of objects with this structure:
    // Question[].deck_idx : index of Deck array for this question's Deck
    // Question[].card : Card which is the correct answer
    // Question[].choice[] : Array of Numchoices guesses

var Recent_answers = new Object(); // Store correct answers here while
    // constructing the questions to avoid presenting them as choices in
    // subsequent questions.  Structure:
    // Recent_answers.deck : Array containing an array of recent answers
    //                       for each deck (indexed by Deck array index)
    // Recent_answers.max_length : Array containing the max number of
    //                             recent answers to store for each deck
    // Recent_answers.insert_point : Array containing, for each deck i,
    //                               the index of Recent_answers.deck[i] to
    //                               which the next answer should be written.
 


var Display = new Object(); // Contains the textNodes whose values
			    // we want to update:
    // Display.question is the question textNode
    // Display.choice[] is an array of the textNodes for the choices

var Starttime; // start time for timing stats
var Rightcount = 0, Wrongcount = 0; // right and wrong counts for stats
var Wronglist = new Array(); // list of incorrectly guessed cards to
			     // display at the end of the quiz

////////////////////////////////////////////////////////////////////////

function setup()
{
   var i;

  // Initialize Recent_answers
   Recent_answers.max_length = new Object();
   Recent_answers.insert_point = new Object();
   Recent_answers.deck = new Array();
   for (i=0; i<Deck.length; i++) {
      Recent_answers.deck[i] = new Array();
      if (Deck[i].length < 2*Numchoices) {
         alert("Sorry, not enough questions have been provided\n" +
               "deck " + (i+1) + " to run this program");
         window.location = "about:blank"; // change to error page
      }
      Recent_answers.max_length[i] = 
         Math.min(Math.round(Deck[i].length/2), Deck[i].length - 2*Numchoices);

      Recent_answers.insert_point[i] = 0;
   }

   // Build the selection lists for questions and answers

   var Qsel_list = document.getElementById("Qsel");
   var Asel_list = document.getElementById("Asel");

   var q_selected, a_selected;
   for (i=0; i<Category.length; i++) {
      q_selected = (i == Qsel_default_index);
      Qsel_list.options[i] = new Option(Category[i], "",
                                        q_selected, q_selected);
      
      a_selected = (i == Asel_default_index);
      Asel_list.options[i] = new Option(Category[i], "",
                                        a_selected, a_selected);
   }
}

////////////////////////////////////////////////////////////////////////

function begin_quiz()
{
   Qcat = document.getElementById("Qsel").selectedIndex;
   Acat = document.getElementById("Asel").selectedIndex;

   if (Qcat == Acat) {
      alert ("The question and answer categories can't be the same!");
      window.location = "hanziquiz.html";
      return;
   }

   // Build the question <table>
   var table = document.getElementById("question");
   var tbody = document.createElement("tbody") // IE requires this.
   var tr = document.createElement("tr");
   var td = document.createElement("td");
   td.className = Category[Qcat].replace(/\W/,"") + "_question";
   Display.question = document.createTextNode("");
   td.appendChild(Display.question);
   tr.appendChild(td);
   tbody.appendChild(tr);

   Display.choice = new Array();
   for (i=0 ; i<Numchoices ; i++) {
      tr = document.createElement("tr");
      td = document.createElement("td");
      var button = document.createElement("button");
      button.className = Category[Acat].replace(/\W/,"") + "_choice";
      Display.choice[i] = document.createTextNode("");
      button.appendChild(Display.choice[i]);
      button.name = i; // Set the name attribute to the array index so
		       // the event handler can determine which button
		       // was clicked.
      button.onclick = process_answer;
      td.appendChild(button);
      tr.appendChild(td);
      tbody.appendChild(tr);
   }
   table.appendChild(tbody);

   buildQuestion();
   Qnum = 0;
   Starttime = new Date().getTime();

   display_question();

   document.getElementById("setup").style.display="none";
   document.getElementById("question").style.visibility="visible";
}

///////////////////////////////////////////////////////////////////

function buildQuestion()
{
   var num = 0;
   for (var i=0 ; i<Deck.length ; i++) {
      for (var j=0 ; j<Deck[i].length ; j++) {
	 Question[num] = new Object();
	 Question[num].deck_idx = i;
	 Question[num].card = Deck[i][j];
	 num++;
      }
   }
   shuffle(Question);
   for (i=0 ; i<Question.length ; i++) {
      buildChoice(Question[i]);
   }
}

///////////////////////////////////////////////////////////////////

function in_recent_answers(answer, deck_idx) 
{
   for (var i=0 ; i<Recent_answers.deck[deck_idx].length ; i++) {
      if (answer == Recent_answers.deck[deck_idx][i]) return true;
   }
   return false;
}

///////////////////////////////////////////////////////////////////

function add_to_recent_answers(answer, deck_idx)
{
   Recent_answers.deck[deck_idx][Recent_answers.insert_point[deck_idx]] = 
      answer;
   Recent_answers.insert_point[deck_idx]++;
   if (Recent_answers.insert_point[deck_idx] >= 
              Recent_answers.max_length[deck_idx]) {
      Recent_answers.insert_point[deck_idx] = 0;
   }
}

///////////////////////////////////////////////////////////////////

function buildChoice(Q)
{
   var allowed_choices = new Array();
   var i, j, k, test_card;

   j = 0;
   for (i=0; i<Deck[Q.deck_idx].length; i++) {
      test_card = Deck[Q.deck_idx][i];
      if (!in_recent_answers(test_card, Q.deck_idx) &&
          Q.card[Qcat] != test_card[Qcat] &&
	  Q.card[Acat] != test_card[Acat]) {
	 allowed_choices[j] = test_card;
	 j++;
      }
   }

   Q.choice = new Array();
   Q.choice[0] = Q.card;
   for (i=1 ; i<Numchoices ; i++) {
      var good_choice = false;
      while (!good_choice) {
	 Q.choice[i] = allowed_choices[Math.floor(Math.random() *
						  allowed_choices.length)];
	 good_choice = true;
	 for (j = 1; j<i ; j++) {
	    if (Q.choice[i][Acat] == Q.choice[j][Acat]) {
	       good_choice = false;
	       break;
	    }
	 }
      }
      // remove the choice we just used from allowed_choices
      k=0;
      while (allowed_choices[k] != Q.choice[i] &&
             k < allowed_choices.length) k++;

      // Argh!  This should be a one-liner:
      //
      // if (k < allowed_choices.length) allowed_choices.splice(k,1);
      //
      // But NoooOOoo! Mac IE doesn't implement the splice method of
      // Array and *just*goes*into*outer*space* when you try to use it.
      //
      // We implement our own.  Thanks, Microsoft!

      while (k < allowed_choices.length - 2) {
         allowed_choices[k] = allowed_choices[k+1];
         k++;
      }
      allowed_choices.length = k+1;
   }
   shuffle(Q.choice);
   add_to_recent_answers(Q.card, Q.deck_idx);
}

///////////////////////////////////////////////////////////////////

function shuffle(arr)
{
   for (var i=arr.length-1 ; i>0 ; i--) {
      var j = Math.floor(Math.random() * (i + 0.999));
      var tmp = arr[i];
      arr[i] = arr[j];
      arr[j] = tmp;
   }
}

///////////////////////////////////////////////////////////////////

function time_stat_string()
{
   var count = Qnum + 1;
   var usecs = (new Date().getTime()) - Starttime;
   return count + ' questions answered in ' +
      Math.round(usecs/100)/10 + ' seconds (' +
      Math.round(usecs/(100*Rightcount))/10 +
      ' secs/right answer)';
}

///////////////////////////////////////////////////////////////////

function display_question()
{
   var Q = Question[Qnum];

   Display.question.nodeValue = Q.card[Qcat];
   for (var i=0 ; i<Numchoices ; i++) {
      Display.choice[i].nodeValue = Q.choice[i][Acat];
   }

}

///////////////////////////////////////////////////////////////////

function process_answer(e)
{
   if (!e) e = window.event; // IE event model

   var ansnum;
   if (e.target) {
      ansnum = e.target.name; // W3C event model
   } else {
      ansnum = e.srcElement.name; // IE event model
   }
   // We know choice[ansnum] was chosen, because that's how we set the
   // name attribute of the choice buttons.
   var Q = Question[Qnum];
   var right_or_wrong = document.getElementById("right_or_wrong");
   var correct_answer = document.getElementById("correct_answer");
   var right_count = document.getElementById("right_count");
   var wrong_count = document.getElementById("wrong_count");
   var time_stats = document.getElementById("time_stats");
   if (Display.choice[ansnum].nodeValue == Q.card[Acat]) {
      Rightcount++;
      right_or_wrong.style.color = "blue";
      right_or_wrong.firstChild.nodeValue = "Right";
      right_count.firstChild.nodeValue = Rightcount;
   } else {
      Wrongcount++;
      right_or_wrong.style.color = "red";
      right_or_wrong.firstChild.nodeValue = "Wrong";
      wrong_count.style.color = "red";
      wrong_count.firstChild.nodeValue = Wrongcount;
      Wronglist[Wronglist.length] = Q.card;
   }
   correct_answer.firstChild.nodeValue =
      "The correct " + Category[Acat]  + " for " +
      Q.card[Qcat] + " is " + Q.card[Acat];
   time_stats.firstChild.nodeValue = time_stat_string();
   document.getElementById("score").style.visibility = "visible";
   if (Qnum < Question.length - 1) {
      Qnum++;
      display_question();
   } else {
      display_end_quiz();
   }
}

///////////////////////////////////////////////////////////////////

function display_end_quiz()
{
   document.getElementById("question").style.display = "none";
   var endtable = document.getElementById("end_quiz");

   var tbody, tr, td, textnode, button;
   var cellwidth =  (100.0/Category.length) + "%";

   tbody = document.createElement("tbody");
   tr = document.createElement("tr");
   td = document.createElement("td");
   td.colSpan = Category.length;

   if (Wronglist.length) {
      textnode =
	 document.createTextNode("You missed:");
   } else {
      textnode =
	 document.createTextNode("Congratulations on your perfect score!");
   }
   td.appendChild(textnode);
   tr.appendChild(td);
   tbody.appendChild(tr);

   for (var i=0 ; i<Wronglist.length ; i++) {
      tr = document.createElement("tr");
      if (i % 2 == 0) tr.style.backgroundColor = "#cccc99"
      for (var j=0 ; j<Category.length ; j++) {
	 td = document.createElement("td");
	 td.style.width = cellwidth;
	 textnode = document.createTextNode(Wronglist[i][j]);
	 td.appendChild(textnode);
	 tr.appendChild(td);
      }
      tbody.appendChild(tr);
   }

   tr = document.createElement("tr");
   td = document.createElement("td");
   td.colSpan = Category.length;
   button = document.createElement("button");
   button.onclick = function () { window.location = "hanziquiz.html"; };
   textnode = document.createTextNode("Try Again!");
   button.appendChild(textnode);
   td.appendChild(button);
   tr.appendChild(td);
   tbody.appendChild(tr);

   endtable.appendChild(tbody);

   endtable.style.visibility = "visible";
}

///////////////////////////////////////////////////////////////////