<?php if (!defined('PmWiki')) exit();

# generate exercises based on wiki content and its structure
# 
# still to implement (cf http://fabien.benetou.fr/Cookbook/Cognition#DailyExercisesFeed )
#	is word X from page A, B, C or D?
#	does page A contains word X, Y or Z?
#	what is the correct order for pages A, B and C on descending criteria i A>B>C? A>C>B? B>C>A? B>A>C? C>B>A? C>A>B?
#		e.g. size, frequency update, last edition, ... 
#	which of those page corresponds the updates visualization V, A, B or C? 
#	keyword or URL in pages
# implemented
#	is page A linked to page B? (type=pagelink)
# consider a difficulty parameter
#	should be linked to the counter
#	e.g. increasing the number of possibilities (at least 1 out of 5 pages instead of at least 1 out of 3)


$RecipeInfo['Exercises']['Version'] = '2011-12-08';

SDV($HandleActions['Exercises'], 'Exercises');
SDV($HandleAuth['Exercises'],'read');

function Exercises($pagename, $auth){
	$type = $_GET["type"];
	$counter = (int) $_GET["counter"];
	$difficulty = (int) $_GET["difficulty"];
	list($group,$page) = explode(".",$pagename);

	$availableexercisetypes = array("pagelink", "expressioninpage", "pagehasexpression");
	if ($type=="random")
		$type= $availableexercisetypes[rand(0,count($availableexercisetypes)-1)];

	switch ($type){
		case "pagelink":
			// the pattern should be improve, e.g. remove PmWiki. , RecentChanges, GroupFooter, GroupHeader, Template, ...
			if ($group == "AllPages"){
				// equivalent to getting ALL pages
				$pages = ListPages();
			} else {
				$pages = ListPages("/$group\./e");

			}

			//randomly pick a page in the possible pages
			$sourcepage = $pages[rand(0,count($pages)-1)];

			$content = ReadPage($sourcepage,READPAGE_CURRENT);
			//$text = $content["text"];
			// to use later on for expression exercises
			$links = $content["targets"];
			$links_array = explode(",",$links);

			//$answers = array();
			//consider pilling up potential in $answers[]

			//randomly pick a page amongst the linked pages
			$answers[] = $links_array[rand(0,count($links_array)-1)];

			unset($pages[array_search($answers[0],$links_array)]);
			unset($pages[array_search($answers[0],$pages)]);

			//randomly pick n-1 others pages which may not be amongst the list of linked page
			// n should be based on $difficulty, e.g. n=2+$difficulty or n=2^$difficulty
			$n=3;
			for ($i=1;$i<$n;$i++) {
				$answers[] = $pages[rand(0,count($pages)-1)];
				unset($pages[array_search($answers[$i],$pages)]);
			}

			//display
			$result .="Is page [[$sourcepage]] linked to ";

			$counterparam = "";
			if ( $counter > 0) {
				$counterparam = "counter=$counter&";
			}

			// there should now be at least 1 needle in the haystack, the first one
			// note that there might be more but this is not a problem as long as the question is stated clearly.
			shuffle($answers);

			for ($i=0;$i<count($answers);$i++) {
				if ($answers[$i] != "") {
					if ( $i == count($answers) -1 )
						$result .= " or ";
					//display the groupname everytime only if using AllPages
					if ($group != "AllPages") {
						list($currentgroup,$currentpage) = explode(".",$answers[$i]);
						$result .="[[$pagename?action=ExercisesCheck&".$counterparam
							."type=$type&source=$sourcepage&answer=".$answers[$i]."|".$currentpage."]], ";
					} else {
						$result .="[[$pagename?action=ExercisesCheck&".$counterparam
							."type=$type&source=$sourcepage&answer=".$answers[$i]."|".$answers[$i]."]], ";
					}
				}
			}
			$result .="? ";
			$result .="\n\nClick on the answer.";
			break;
		case "pagehasexpression":
			// explode content by line "%0a" or word " "
			$result .= "Does the page 'PAGE' has expression 'EXPRESSIONA', 'EXPRESSIONB' or 'EXPRESSIONC?";
			break;
		case "expressioninpage":
			// explode content by line "%0a" or word " "
			$result .= "Does the expression 'EXPRESSION' come from PAGEA, PAGEB or PAGEC?";
			break;
		default:
			$result .= "Exercise type unknown.";
	}

	$result .= "\n\nGenerated by [[http://fabien.benetou.fr/MemoryRecalls/ImprovingPIM#PIMBasedExercises|PIM Based Exercises]]. ";
        unset($availableexercisetypes[array_search($type,$availableexercisetypes)]);
	if (count($availableexercisetypes) > 0) {
		$result .= " Try other types of exercises:";
		foreach ($availableexercisetypes as $e) {
			$result	.= " [[$pagename?action=Exercises&type=$e|$e]],";
		}
		$result .= " or a [[$pagename?action=Exercises&type=random|random]] one.";
		if ( $counter > 0) {
			$result .= " (note that it resets the counter)";
		}
	}
	$renderedresult = MarkupToHTML($pagename, $result);
	print $renderedresult;
	
	//$text = RetrieveAuthSection($pagename,$auth);
	//$content = MarkupToHTML($pagename, $text);
	//print $content;
}

SDV($HandleActions['ExercisesCheck'], 'ExercisesCheck');
SDV($HandleAuth['ExercisesCheck'],'read');

function ExercisesCheck($pagename, $auth){
	$type = $_GET["type"];
	$sourcepage = $_GET["source"];
	$answer = $_GET["answer"];
	$counter = (int) $_GET["counter"];

	list($group,$page) = explode(".",$pagename);
	if ($group == "AllPages"){
		// equivalent to getting ALL pages
	        $pages = ListPages();
	} else {
	        $pages = ListPages("/$group\./e");
	}

	switch ($type) {
		case "pagelink":
			$content = ReadPage($sourcepage,READPAGE_CURRENT);
			$links = $content["targets"];
			$links_array = explode(",",$links);
			$formattedlinks = implode(", ",$links_array);

			if ( in_array($answer,$links_array) ) {
				$result .="Excellent! [[$sourcepage]] is indeed linked to [[$answer]]. ";
				$result .="Note that $formattedlinks also are. ";
				if ( $counter > 0) {
					$counter++;
					$result .="\n\nSee if you can [[$pagename?action=Exercises&counter=$counter|solve yet another one]]. ";
				} else {
					$result .="\n\nSee if you can [[$pagename?action=Exercises&counter=1|solve yet another one]]. ";
				}
			} else {
				$result .="No, [[$sourcepage]] is not linked to [[$answer]] ";
				$result .="but $formattedlinks are. ";
				$result .="\n\nTry to redeem yourself by [[$pagename?action=Exercises|trying another time]]. ";
			}
			break;
		default:
			$result .= "Exercise type unknown.";
	}
	$result .= "\n\nGenerated by [[http://fabien.benetou.fr/MemoryRecalls/ImprovingPIM#PIMBasedExercises|PIM Based Exercises]]";
	$renderedresult = MarkupToHTML($pagename, $result);
	print $renderedresult;
}

?>