Registration section resync (#12)

* Changes to be committed:
new file:   sample_bin/registration_section_resync.php

WIP: Registration re-sync tool for issue Submitty/Submitty#2960: "Registration Section data not always synced between master DB and course DB"

* Changes to be committed:
modified:   sample_bin/registration_section_resync.php

WIP

* Changes to be committed:
modified:   sample_bin/registration_section_resync.php

WIP

* Changes to be committed:
modified:   sample_bin/registration_section_resync.php

Ready for PR

Author: pbailie

sample_bin/registration_section_resync.php

@@ -0,0 +1,161 @@
+#!/usr/bin/env php
+<?php
+
+/**
+ * Sysadmin tool to correct out of sync database issue with registration
+ * sections.  Github issue #2690.
+ *
+ * Run this script to resync registration sections for all courses registered
+ * in every term specified on cli.
+ *
+ * e.g. ./registration_section_resync.php u18 f18
+ *
+ * resync regustration sections for all courses registered in the u18 and f18
+ * terms.
+ *
+ * @author Peter Bailie (systems programmer, RPI dept. of computer science)
+ */
+
+error_reporting(E_ERROR);
+ini_set('display_errors', 'stderr');
+define ('DB_CONFIG_PATH', '/usr/local/submitty/config/database.json');
+
+//Run script
+new registration_section_resync();
+exit(0);
+
+class registration_section_resync {
+
+	private static $db_conn = array('master' => null, 'course' => null);
+	private static $db_host;
+	private static $db_user;
+	private static $db_password;
+	private static $academic_terms;
+
+	public function __construct() {
+		$this->init();
+		$this->process();
+		printf("Re-sync process finished.%s", PHP_EOL);
+	}
+
+	public function __destruct() {
+		$this->close_db_conn('course');
+		$this->close_db_conn('master');
+	}
+
+	/** Setup properties and open master DB connection */
+	private function init() {
+		//This script should be run as root.
+		if (posix_getuid() !== 0) {
+			exit(sprintf("This script must be run as root.%s", PHP_EOL));
+		}
+
+		//This script cannot be run as a webpage.
+		if (PHP_SAPI !== 'cli') {
+			exit(sprintf("This script must be run from the command line.%s", PHP_EOL));
+		}
+
+		//Get all academic terms to be processed (as cli arguments).
+		if ($_SERVER['argc'] < 2) {
+			exit(sprintf("Please specify at least one academic term code as a command line argument.%s", PHP_EOL));
+		}
+		self::$academic_terms = array_splice($_SERVER['argv'], 1);
+
+		//Get DB connection config from Submitty
+		$json_data = file_get_contents(DB_CONFIG_PATH);
+		if ($json_data === false) {
+			exit(sprintf("Could not read database configuration at %s%s", DB_CONFIG_PATH, PHP_EOL));
+		}
+
+		$json_data = json_decode($json_data, true);
+		self::$db_host     = $json_data['database_host'];
+		self::$db_user     = $json_data['database_user'];
+		self::$db_password = $json_data['database_password'];
+
+		//Connect to master DB.
+		self::$db_conn['master'] = pg_connect(sprintf("dbname=submitty host=%s user=%s password=%s sslmode=prefer", self::$db_host, self::$db_user, self::$db_password));
+		if (pg_connection_status(self::$db_conn['master']) !== PGSQL_CONNECTION_OK) {
+			exit(sprintf("ERROR: Could not establish connection to Submitty Master DB%sCheck configuration at %s%s", PHP_EOL, DB_CONFIG_PATH, PHP_EOL));
+		}
+	}
+
+	/** Loop through academic terms and then loop through each course to sync registration sections */
+	private function process() {
+		//Loop through academic terms
+		foreach (self::$academic_terms as $term) {
+			//Get courses list for $term
+			$res = pg_query_params(self::$db_conn['master'], "SELECT course FROM courses WHERE semester = $1", array($term));
+			if ($res === false) {
+				exit(sprintf("Error reading course list for %s.%s", $term, PHP_EOL));
+			}
+
+			$courses = pg_fetch_all_columns($res, 0);
+			if (empty($courses)) {
+				fprintf(STDERR, "No courses registered for %s.%s", $term, PHP_EOL);
+				continue;
+			}
+
+			//Now loop through all courses
+			foreach($courses as $course) {
+				//We need to compare registration sections in both master and course DBs
+				//Connect to course DB
+				$db_name = sprintf("submitty_%s_%s", $term, $course);
+				self::$db_conn['course'] = pg_connect(sprintf("dbname=%s host=%s user=%s password=%s sslmode=prefer", $db_name, self::$db_host, self::$db_user, self::$db_password));
+				if (pg_connection_status(self::$db_conn['course']) !== PGSQL_CONNECTION_OK) {
+					fprintf(STDERR, "ERROR: Could not establish connection to Submitty Course DB %s.%sSkipping %s %s.%s", $db_name, PHP_EOL, $term, $course, PHP_EOL);
+					continue;
+				}
+
+				//First retrieve registration sections in master DB
+				$res = pg_query_params(self::$db_conn['master'], "SELECT registration_section_id FROM courses_registration_sections WHERE semester=$1 AND course=$2", array($term, $course));
+				if ($res === false) {
+					fprintf(STDERR, "Error reading registration sections from master DB: %s %s.%sSkipping %s %s.%s", $term, $course, PHP_EOL, $term, $course, PHP_EOL);
+					$this->close_db_conn('course');
+					continue;
+				}
+				$master_registration_sections = pg_fetch_all_columns($res, 0);
+
+				//Next retrieve registration sections in course DB
+				$res = pg_query(self::$db_conn['course'], "SELECT sections_registration_id FROM sections_registration");
+				if ($res === false) {
+					fprintf(STDERR, "Error reading registration sections from course DB: %s.%sSkipping %s %s.%s", $dbname, PHP_EOL, $term, $course, PHP_EOL);
+					$this->close_db_conn('course');
+					continue;
+				}
+				$course_registration_sections = pg_fetch_all_columns($res, 0);
+
+				//Get the differences of both lists (a registration section in either list, but not the other).
+				$sync_list = array_diff($course_registration_sections, $master_registration_sections);
+				$sync_list = array_merge($sync_list, array_diff($master_registration_sections, $course_registration_sections));
+				if (empty($sync_list)) {
+					printf("No sync required for %s %s.%s", $term, $course, PHP_EOL);
+					$this->close_db_conn('course');
+					continue;
+				}
+
+				//INSERT $sync_list to master DB, ON CONFLICT DO NOTHING (prevents potential PK violations).  We're using DB schema trigger to complete resync.
+				foreach($sync_list as $section) {
+					$res = pg_query_params(self::$db_conn['master'], "INSERT INTO courses_registration_sections (semester, course, registration_section_id) VALUES ($1, $2, $3) ON CONFLICT ON CONSTRAINT courses_registration_sections_pkey DO UPDATE SET semester=$1, course=$2, registration_section_id=$3", array($term, $course, $section));
+					if ($res === false) {
+						fprintf(STDERR, "Error during re-sync procedure: %s %s section %s.%s.This section could not be synced.%s", $term, $course, $section, PHP_EOL, PHP_EOL);
+						$this->close_db_conn('course');
+						continue;
+					}
+				}
+				printf("Sync complete for %s %s.%s", $term, $course, PHP_EOL);
+				$this->close_db_conn('course');
+			}
+		}
+	}
+
+	/**
+	 *  Close a given DB connection.
+	 *
+	 *  @param string DB connection to close.
+	 */
+	private function close_db_conn($conn) {
+		if (pg_connection_status(self::$db_conn[$conn]) === PGSQL_CONNECTION_OK) {
+			pg_close(self::$db_conn[$conn]);
+		}
+	}
+}