<?php

	require_once 'config.php';
	require_once 'dbh.inc.php';
	require_once 'checkLogin.php';
	
	
	// EXAMPLE INPUT...
	// array(2) { ["questionnaireID"]=> string(3) "137" ["deleteQuestionnaire"]=> string(0) "" }
	
	// WARNING: SHOULD CONFIRM THAT QUESTIONNAIRE BELONGS TO THE CORRECT USER (AUTHENTICATE THE TRANSACTION)


	if(isset($_POST['deleteQuestionnaire'])) {
		

		$questionnaireID = mysqli_real_escape_string($connection, trim($_POST['questionnaireID']));
		
		
		// Check that questionnaire ID is not empty string
		if($questionnaireID === "") {
			http_response_code(400);
			echo json_encode(array("error" => "Please specify questionnaire ID."));
			exit();
		}
		
		
		// Check that questionnaire is registered in the database
		if(mysqli_query($connection, "SELECT * FROM questionnair WHERE id = '$questionnaireID';")->num_rows !== 1) {
			http_response_code(400);
			echo json_encode(array("error" => "Given questionnaire ID ($questionnaireID) not in database."));
			exit();
		}
		
		
		// Check that no corresponding moments have been answered yet
		if(mysqli_query($connection, "SELECT * FROM student_subquestionnair WHERE id_subquestionnair IN (SELECT id FROM subquestionnair WHERE id_questionnair = '$questionnaireID');")->num_rows !== 0) {
			http_response_code(400);
			echo json_encode(array("error" => "Questionnaire already active, deletion denied."));
			exit();
		}
		
		
		/*** STEPS ***/
		
		// DELETE CATEGORIES	 	(USE QUESTIONNAIRE-QUESTION, THEN QUESTION TABLE TO GET TO CATEGORY TABLE)*
		// DELETE SUBCATEGORIES 	(USE QUESTIONNAIRE-QUESTION, THEN QUESTION TABLE TO GET TO SUBCATEGORY TABLE)*
		// DELETE REFERENCE 		(USE QUESTIONNAIRE-QUESTION, THEN QUESTION TABLE TO GET TO REFERENCE TABLE)*
		// DELETE QUESTION-TYPE 	(USE QUESTIONNAIRE-QUESTION TABLE)*
		// DELETE QUESTIONS 		(USE QUESTIONNAIRE-QUESTION TABLE)*

		// DELETE MOMENT-QUESTION RELATIONS 	(USE MOMENT TABLE TO GET TO MOMENT-QUESTION TABLE)*
		// DELETE EXPERIENCE-MOMENT RELATIONS 	(USE MOMENT TABLE TO GET TO EXPERIENCE-MOMENT TABLE)*
		// DELETE MOMENTS

		// DELETE QUESTIONNAIRE-QUESTION RELATIONS
		// DELETE EXPERIENCE-QUESTIONNAIRE RELATION
		// DELETE QUESTIONNAIRE


		// Delete categories
		$queryDeleteCategories = "DELETE FROM category WHERE id IN (SELECT DISTINCT id_category FROM question WHERE id IN (SELECT id_question FROM questionnair_question WHERE id_questionnair = '$questionnaireID'));";
		$result = mysqli_query($connection, $queryDeleteCategories) or die("Error: ".mysqli_error($connection));
		
		// Delete subcategories
		$queryDeleteSubcategories = "DELETE FROM subcategory WHERE id IN (SELECT DISTINCT id_subcategory FROM question WHERE id IN (SELECT id_question FROM questionnair_question WHERE id_questionnair = '$questionnaireID'));";
		$result = mysqli_query($connection, $queryDeleteSubcategories) or die("Error: ".mysqli_error($connection));
	
		// Delete reference
		$queryDeleteReference = "DELETE FROM reference WHERE id IN (SELECT DISTINCT id_referencia FROM question WHERE id IN (SELECT id_question FROM questionnair_question WHERE id_questionnair = '$questionnaireID'));";
		$result = mysqli_query($connection, $queryDeleteReference) or die("Error: ".mysqli_error($connection));

		// Delete question types
		$queryDeleteQuestionTypes = "DELETE FROM question_type WHERE id_question IN (SELECT id_question FROM questionnair_question WHERE id_questionnair = '$questionnaireID');";
		$result = mysqli_query($connection, $queryDeleteQuestionTypes) or die("Error: ".mysqli_error($connection));

		// Delete questions
		$queryDeleteQuestions = "DELETE FROM question WHERE id IN (SELECT id_question FROM questionnair_question WHERE id_questionnair = '$questionnaireID');";
		$result = mysqli_query($connection, $queryDeleteQuestions) or die("Error: ".mysqli_error($connection));
		
		// Delete moment-question relations
		$queryUnhookQuestionFromMoment = "DELETE FROM subquestionnair_question WHERE id_subquestionnair IN (SELECT id FROM subquestionnair WHERE id_questionnair = '$questionnaireID');";
		$result = mysqli_query($connection, $queryUnhookQuestionFromMoment) or die("Error: ".mysqli_error($connection));

		// Delete experience-moment relations
		$queryUnhookMomentFromExperience = "DELETE FROM experience_subquestionnair WHERE id_subquestionnair IN (SELECT id FROM subquestionnair WHERE id_questionnair = '$questionnaireID');";
		$result = mysqli_query($connection, $queryUnhookMomentFromExperience) or die("Error: ".mysqli_error($connection));

		// Delete moments
		$queryDeleteMoments = "DELETE FROM subquestionnair WHERE id_questionnair = '$questionnaireID';";
		$result = mysqli_query($connection, $queryDeleteMoments) or die("Error: ".mysqli_error($connection));

		// Delete questionnaire-question relations
		$queryUnhookQuestionFromQuestionnaire = "DELETE FROM questionnair_question WHERE id_questionnair = '$questionnaireID';";
		$result = mysqli_query($connection, $queryUnhookQuestionFromQuestionnaire) or die("Error: ".mysqli_error($connection));

		// Delete experience-questionnaire relations
		$queryUnhookQuestionnaireFromExperience = "DELETE FROM experience_questionnair WHERE id_questionnair = '$questionnaireID';";
		$result = mysqli_query($connection, $queryUnhookQuestionnaireFromExperience) or die("Error: ".mysqli_error($connection));	

		// Delete questionnaire
		$queryDeleteQuestionnaire = "DELETE FROM questionnair WHERE id = '$questionnaireID';";
		$result = mysqli_query($connection, $queryDeleteQuestionnaire) or die("Error: ".mysqli_error($connection));
		
		
	}