#!/usr/bin/nawk -f
#Q&D to print off a set of arithmetic flash cards
# print pdf: double sided, Landscape & Flip on Short Side
# type must be sub, add, mul or div

BEGIN{
  test=0;
  type="sub"; #must be set to sub, add, mul or div
  if (type!="sub"&&type!="add"&&type!="mul"&&type!="div"){
    print "\nError: type must be sub, add, mul or div\n";
    exit;
  }#end if 
  a="\x27";q="\x22";
  Dir="/tmp/FLASHCARDS";
  s="mkdir "Dir;
  if(test==1)print s;else system(s);
  if (type=="sub"){
    for (i=1;i<=20;i++)
      for(j=1;j<=10;j++){
        if (i>=j){           #don't subtract bigger from smaller
          Q[++cnt]=" "i" - "j" = ";
          A[cnt]=i-j;
        }#end if
    }#end for i j
  }#if sub
  if (type=="add"){
    for (i=1;i<=10;i++)
      for(j=1;j<=10;j++){
        Q[++cnt]=" "i" + "j" = ";
        A[cnt]=i+j;
    }#end for i j
  }#if add
  if (type=="mul"){
  for (i=2;i<=12;i++)
    for(j=2;j<=12;j++){
      Q[++cnt]=" "i" x "j" = ";
      A[cnt]=i*j;
    }#end for i j
  }#if mul
  if (type=="div"){
  for (i=2;i<=12;i++)
    for(j=2;j<=12;j++){
      k=i*j;
      if (k>=j){           #don't divide bigger by smaller
        Q[++cnt]=" "k" / "j" = ";
        A[cnt]=k/j;
      }#end if
    }#end for i j
  }#if div
  fmtQ="convert -size 230x142 xc:white -gravity center -bordercolor gray -border 1 -font Courier-Bold -pointsize 36 -draw \x22text 0,0 \x27 %s \x27\x22 %s/question_%02d.jpg";
  fmtA="convert -size 232x144 xc:white -gravity center  -font Courier-Bold -pointsize 36 -draw \x22text 0,0 \x27 %s \x27\x22 +flop %s/answer_%02d.jpg";
#cnt=31;

  if(type=="sub"||type=="add")a=0;
  if(type=="mul"||type=="div")a=2;
  i=cnt;while (i>=a){
    n=0;
    for (j=1;j<=3;j++){
      for (k=1;k<=4;k++){
        i--;
        s=sprintf(fmtQ,Q[i],Dir,++n);
        if(test==1)print s;else system(s);
        s=sprintf(fmtA,A[i],Dir,n);
        if(test==1)print s;else system(s);
      }#end for k
    }#end for j

    for (j=1;j<=3;j++){
      for (k=1;k<=4;k++){
        s="montage /tmp/FLASHCARDS/question_??.jpg -mode Concatenate -tile 3x4 /tmp/FLASHCARDS/question.jpg";
        if(test==1)print s;else system(s);
        s="montage /tmp/FLASHCARDS/answer_??.jpg -mode Concatenate -tile 3x4 /tmp/FLASHCARDS/answer0.jpg";
        if(test==1)print s;else system(s);
#note: page is "flopped" mirror imaged for back side of question page
        s= "convert /tmp/FLASHCARDS/answer0.jpg +flop /tmp/FLASHCARDS/answer.jpg";
        if(test==1)print s;else system(s);
      }#end for k
    }#end for j
    s=sprintf("convert %s/question.jpg %s/answer.jpg -resize 3300x550 %s/flashcard_%s_%02d.pdf",Dir,Dir,Dir,type,++p);
    if(test==1)print s;else system(s);
  }#end while i=cnt
}#end BEGIN