<?php
namespace AccessNow\SimpleLMS;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

// This class reads and writes the plugin's own {prefix}slms_* tables, so direct
// queries are required; the data is per-user and changes on every action, so it is
// not cached. Table names are built from $wpdb->prefix and fixed strings, and every
// value goes through $wpdb->prepare() or $wpdb->insert/update/delete.
// phpcs:disable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching

class Gamification {

	const POINTS_LESSON_COMPLETE = 10;
	const POINTS_QUIZ_PASS       = 25;
	const POINTS_COURSE_COMPLETE = 100;

	public static function init() {
		add_action( 'accessnow_slms_lesson_completed', array( __CLASS__, 'on_lesson_completed' ), 10, 4 );
		add_action( 'accessnow_slms_quiz_submitted', array( __CLASS__, 'on_quiz_submitted' ), 10, 5 );
		add_action( 'accessnow_slms_quiz_regraded', array( __CLASS__, 'on_quiz_regraded' ), 10, 3 );
		add_action( 'accessnow_slms_course_completed', array( __CLASS__, 'on_course_completed' ), 10, 3 );
	}

	/**
	 * Points for a completed lesson.
	 *
	 * @param int $user_id       User ID.
	 * @param int $lesson_id     Lesson ID.
	 * @param int $course_id     Course ID.
	 * @param int $enrollment_id Enrolment ID.
	 */
	public static function on_lesson_completed( $user_id, $lesson_id, $course_id, $enrollment_id ) {
		self::award_points( $user_id, Settings::get( 'points_lesson_complete', self::POINTS_LESSON_COMPLETE ), 'lesson_complete', $lesson_id, $enrollment_id );
	}

	/**
	 * Points for a passed quiz.
	 *
	 * @param int   $user_id        User ID.
	 * @param int   $quiz_id        Quiz ID.
	 * @param array $result         Graded result.
	 * @param int   $attempt_number Attempt number.
	 * @param int   $enrollment_id  Enrolment ID.
	 */
	public static function on_quiz_submitted( $user_id, $quiz_id, $result, $attempt_number, $enrollment_id ) {
		if ( ! empty( $result['passed'] ) ) {
			self::award_points( $user_id, Settings::get( 'points_quiz_pass', self::POINTS_QUIZ_PASS ), 'quiz_pass', $quiz_id, $enrollment_id );
		}
	}

	/**
	 * A quiz attempt marked or regraded as a pass after it was submitted earns the pass points then.
	 * award_points() keeps one award per quiz and enrolment, so a regrade never pays twice.
	 *
	 * @param int    $attempt_id Attempt ID.
	 * @param object $old        Attempt row before the change.
	 * @param array  $result     New result (passed, pending, percentage).
	 */
	public static function on_quiz_regraded( $attempt_id, $old, $result ) {
		if ( ! empty( $result['passed'] ) && empty( $old->passed ) ) {
			self::award_points( (int) $old->user_id, Settings::get( 'points_quiz_pass', self::POINTS_QUIZ_PASS ), 'quiz_pass', (int) $old->quiz_id, (int) $old->enrollment_id );
		}
	}

	/**
	 * Points for a completed course.
	 *
	 * @param int $user_id       User ID.
	 * @param int $course_id     Course ID.
	 * @param int $enrollment_id Enrolment ID.
	 */
	public static function on_course_completed( $user_id, $course_id, $enrollment_id ) {
		self::award_points( $user_id, Settings::get( 'points_course_complete', self::POINTS_COURSE_COMPLETE ), 'course_complete', $course_id, $enrollment_id );
	}

	public static function award_points( $user_id, $points, $action, $reference_id = 0, $enrollment_id = 0 ) {
		global $wpdb;

		/**
		 * Points awarded for an action. Return 0 to award nothing.
		 *
		 * Each action is awarded once per enrolment and reference (lesson, quiz or course).
		 *
		 * @since 1.0.0
		 *
		 * @param int    $points        Points from the settings.
		 * @param string $action        'lesson_complete', 'quiz_pass' or 'course_complete'.
		 * @param int    $user_id       User ID.
		 * @param int    $reference_id  Lesson, quiz or course ID.
		 * @param int    $enrollment_id Enrolment ID.
		 */
		$points = (int) apply_filters( 'accessnow_slms_points', (int) $points, $action, (int) $user_id, (int) $reference_id, (int) $enrollment_id );
		if ( 0 === $points ) {
			return false;
		}

		// Atomic duplicate prevention via UNIQUE KEY idx_points_dedup
		$result = $wpdb->query(
			$wpdb->prepare(
				"INSERT IGNORE INTO {$wpdb->prefix}slms_points (user_id, points, action, reference_id, enrollment_id, earned_at)
             VALUES (%d, %d, %s, %d, %d, %s)",
				$user_id,
				$points,
				sanitize_text_field( $action ),
				$reference_id,
				$enrollment_id,
				current_time( 'mysql', true )
			)
		);

		if ( ! $result ) {
			return false; // Duplicate — already awarded
		}

		self::check_badges( $user_id );

		return true;
	}

	public static function get_total_points( $user_id ) {
		global $wpdb;
		return (int) $wpdb->get_var(
			$wpdb->prepare(
				"SELECT COALESCE(SUM(points), 0) FROM {$wpdb->prefix}slms_points WHERE user_id = %d",
				$user_id
			)
		);
	}

	public static function get_points_history( $user_id, $limit = 20 ) {
		global $wpdb;
		return $wpdb->get_results(
			$wpdb->prepare(
				"SELECT * FROM {$wpdb->prefix}slms_points WHERE user_id = %d ORDER BY earned_at DESC LIMIT %d",
				$user_id,
				$limit
			)
		);
	}

	public static function award_badge( $user_id, $badge_type, $badge_label ) {
		global $wpdb;
		$table = $wpdb->prefix . 'slms_badges';

		$existing = $wpdb->get_var(
			$wpdb->prepare(
				"SELECT id FROM {$wpdb->prefix}slms_badges WHERE user_id = %d AND badge_type = %s",
				$user_id,
				$badge_type
			)
		);

		if ( $existing ) {
			return false;
		}

		$wpdb->insert(
			$table,
			array(
				'user_id'     => $user_id,
				'badge_type'  => sanitize_text_field( $badge_type ),
				'badge_label' => sanitize_text_field( $badge_label ),
				'earned_at'   => current_time( 'mysql', true ),
			),
			array( '%d', '%s', '%s', '%s' )
		);

		return true;
	}

	public static function get_user_badges( $user_id ) {
		global $wpdb;
		return $wpdb->get_results(
			$wpdb->prepare(
				"SELECT * FROM {$wpdb->prefix}slms_badges WHERE user_id = %d ORDER BY earned_at DESC",
				$user_id
			)
		);
	}

	public static function check_badges( $user_id ) {
		global $wpdb;

		// First Course Completed
		$completed_courses = $wpdb->get_var(
			$wpdb->prepare(
				"SELECT COUNT(*) FROM {$wpdb->prefix}slms_enrollments WHERE user_id = %d AND status = 'completed'",
				$user_id
			)
		);

		if ( $completed_courses >= 1 ) {
			self::award_badge( $user_id, 'first_course', __( 'First Course Completed', 'accessnow-lms' ) );
		}
		if ( $completed_courses >= 5 ) {
			self::award_badge( $user_id, 'five_courses', __( '5 Courses Completed', 'accessnow-lms' ) );
		}

		// Perfect Quiz Score
		$perfect_scores = $wpdb->get_var(
			$wpdb->prepare(
				"SELECT COUNT(*) FROM {$wpdb->prefix}slms_quiz_attempts WHERE user_id = %d AND score = 100.00",
				$user_id
			)
		);
		if ( $perfect_scores >= 1 ) {
			self::award_badge( $user_id, 'perfect_quiz', __( 'Perfect Quiz Score', 'accessnow-lms' ) );
		}
	}
}