<?php
namespace AccessNow\SimpleLMS;

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

class Enrollment_Admin {

	/** Most matches the user search returns. */
	const SEARCH_LIMIT = 10;

	public static function init() {
		// The page itself is added by Admin's menu; this is the search behind its student picker.
		add_action( 'wp_ajax_accessnow_slms_user_search', array( __CLASS__, 'ajax_user_search' ) );
	}

	/**
	 * Find users by name, username or email for the "Enroll students" picker.
	 */
	public static function ajax_user_search() {
		check_ajax_referer( 'accessnow_slms_admin', 'nonce' );
		if ( ! current_user_can( 'manage_slms_enrollments' ) ) {
			wp_send_json_error( __( 'Unauthorized.', 'accessnow-lms' ) );
		}
		$term = trim( sanitize_text_field( wp_unslash( $_GET['term'] ?? '' ) ) );
		if ( mb_strlen( $term ) < 2 ) {
			wp_send_json_success( array() );
		}
		$query = new \WP_User_Query(
			array(
				'search'         => '*' . $term . '*',
				'search_columns' => array( 'user_login', 'user_email', 'display_name' ),
				'number'         => self::SEARCH_LIMIT,
				'orderby'        => 'display_name',
				'fields'         => array( 'ID', 'display_name', 'user_login', 'user_email' ),
			)
		);
		$results = array();
		foreach ( $query->get_results() as $user ) {
			$results[] = array(
				'id'    => (int) $user->ID,
				'label' => self::user_label( $user ),
			);
		}
		wp_send_json_success( $results );
	}

	/**
	 * "Display Name (login, email)" for a user in the picker.
	 *
	 * @param object $user User (ID, display_name, user_login, user_email).
	 * @return string
	 */
	private static function user_label( $user ) {
		/* translators: 1: display name, 2: username, 3: email address. */
		return sprintf( __( '%1$s (%2$s, %3$s)', 'accessnow-lms' ), $user->display_name, $user->user_login, $user->user_email );
	}

	/**
	 * Users named in the enrolment form: the picker's IDs, plus anything typed in the box
	 * (user IDs, usernames or emails separated by commas or new lines, which also works without
	 * JavaScript).
	 *
	 * @param array  $ids  Picked user IDs.
	 * @param string $text Typed text.
	 * @return array { users: int[], unknown: string[] }
	 */
	public static function resolve_users( array $ids, $text ) {
		$users   = array();
		$unknown = array();
		foreach ( $ids as $id ) {
			if ( get_userdata( absint( $id ) ) ) {
				$users[] = absint( $id );
			}
		}
		foreach ( preg_split( '/[,\n]+/', (string) $text ) as $token ) {
			$token = trim( $token );
			if ( '' === $token ) {
				continue;
			}
			if ( ctype_digit( $token ) ) {
				$user = get_userdata( (int) $token );
			} elseif ( is_email( $token ) ) {
				$user = get_user_by( 'email', $token );
			} else {
				$user = get_user_by( 'login', $token );
			}
			if ( $user ) {
				$users[] = (int) $user->ID;
			} else {
				$unknown[] = $token;
			}
		}
		return array(
			'users'   => array_values( array_unique( $users ) ),
			'unknown' => $unknown,
		);
	}

	/**
	 * Enrol each named user in each chosen course and print the outcome.
	 */
	private static function handle_enroll_form() {
		$picked  = isset( $_POST['enroll_user_ids'] ) ? array_map( 'absint', (array) wp_unslash( $_POST['enroll_user_ids'] ) ) : array(); // phpcs:ignore WordPress.Security.NonceVerification.Missing -- verified by the caller.
		$typed   = isset( $_POST['enroll_users'] ) ? sanitize_textarea_field( wp_unslash( $_POST['enroll_users'] ) ) : ''; // phpcs:ignore WordPress.Security.NonceVerification.Missing -- verified by the caller.
		$courses = isset( $_POST['enroll_course_ids'] ) ? array_map( 'absint', (array) wp_unslash( $_POST['enroll_course_ids'] ) ) : array(); // phpcs:ignore WordPress.Security.NonceVerification.Missing -- verified by the caller.
		$notify  = ! empty( $_POST['notify_student'] ); // phpcs:ignore WordPress.Security.NonceVerification.Missing -- verified by the caller.
		$until   = isset( $_POST['enroll_access_until'] ) ? sanitize_text_field( wp_unslash( $_POST['enroll_access_until'] ) ) : ''; // phpcs:ignore WordPress.Security.NonceVerification.Missing -- verified by the caller.
		$expires = '' === $until ? null : Enrollment::expiry_from_date( $until );
		if ( '' !== $until && null === $expires ) {
			echo '<div class="notice notice-error"><p>' . esc_html__( 'The access end date is not a valid date.', 'accessnow-lms' ) . '</p></div>';
			return;
		}
		$courses = array_values(
			array_unique(
				array_filter(
					$courses,
					function ( $id ) {
						return 'slms_course' === get_post_type( $id );
					}
				)
			)
		);
		$found   = self::resolve_users( $picked, $typed );

		if ( $found['unknown'] ) {
			printf(
				'<div class="notice notice-error"><p>%s</p></div>',
				/* translators: %s: comma-separated list of what was typed. */
				esc_html( sprintf( __( 'No user found for: %s', 'accessnow-lms' ), implode( ', ', $found['unknown'] ) ) )
			);
		}
		if ( ! $found['users'] || ! $courses ) {
			echo '<div class="notice notice-error"><p>' . esc_html__( 'Choose at least one student and one course.', 'accessnow-lms' ) . '</p></div>';
			return;
		}

		$new     = 0;
		$already = 0;
		foreach ( $found['users'] as $user_id ) {
			foreach ( $courses as $course_id ) {
				if ( Enrollment::get_active_enrollment( $user_id, $course_id ) ) {
					++$already;
					continue;
				}
				$enrollment_id = Enrollment::enroll( $user_id, $course_id, get_current_user_id() );
				if ( $enrollment_id ) {
					++$new;
					if ( $expires ) {
						Enrollment::set_expiry( $enrollment_id, $expires );
					}
					// Self-enrolment sends its email on its own; for an administrator it is this checkbox.
					if ( $notify ) {
						Notifications::send_enrollment_email( $user_id, $course_id );
					}
				}
			}
		}
		$message = sprintf(
			/* translators: %s: number of new enrolments. */
			_n( '%s new enrollment.', '%s new enrollments.', $new, 'accessnow-lms' ),
			number_format_i18n( $new )
		);
		if ( $already ) {
			$message .= ' ' . sprintf(
				/* translators: %s: number of enrolments that already existed. */
				_n( '%s was already enrolled.', '%s were already enrolled.', $already, 'accessnow-lms' ),
				number_format_i18n( $already )
			);
		}
		printf( '<div class="notice notice-success"><p>%s</p></div>', esc_html( $message ) );
	}

	public static function render_page() {
		if ( ! current_user_can( 'manage_slms_enrollments' ) ) {
			wp_die( esc_html__( 'You do not have permission to manage enrollments.', 'accessnow-lms' ) );
		}

		// Handle add enrollment
		if ( isset( $_POST['accessnow_slms_enroll_nonce'] ) && wp_verify_nonce( sanitize_text_field( wp_unslash( $_POST['accessnow_slms_enroll_nonce'] ) ), 'accessnow_slms_admin_enroll' ) ) {
			self::handle_enroll_form();
		}

		// Handle bulk actions
		if ( isset( $_POST['slms_bulk_action'] ) && isset( $_POST['enrollment_ids'] ) ) {
			check_admin_referer( 'accessnow_slms_bulk_enrollments' );
			$action = sanitize_text_field( wp_unslash( $_POST['slms_bulk_action'] ) );
			$ids    = array_map( 'absint', (array) wp_unslash( $_POST['enrollment_ids'] ) );

			if ( 'drop' === $action ) {
				foreach ( $ids as $id ) {
					Enrollment::drop( $id, get_current_user_id() );
				}
				echo '<div class="notice notice-success"><p>' . esc_html__( 'Enrollments updated.', 'accessnow-lms' ) . '</p></div>';
			} elseif ( 'set_access' === $action || 'clear_access' === $action ) {
				$until   = isset( $_POST['slms_access_until'] ) ? sanitize_text_field( wp_unslash( $_POST['slms_access_until'] ) ) : '';
				$expires = 'set_access' === $action ? Enrollment::expiry_from_date( $until ) : null;
				if ( 'set_access' === $action && null === $expires ) {
					echo '<div class="notice notice-error"><p>' . esc_html__( 'Choose the last day of access first.', 'accessnow-lms' ) . '</p></div>';
				} else {
					$changed = 0;
					foreach ( $ids as $id ) {
						$enrollment = Enrollment::get_enrollment_by_id( $id );
						// Dropped enrolments give no access, so their end date means nothing.
						if ( $enrollment && 'dropped' !== $enrollment->status && Enrollment::set_expiry( $id, $expires ) ) {
							++$changed;
						}
					}
					printf(
						'<div class="notice notice-success"><p>%s</p></div>',
						/* translators: %s: number of enrolments. */
						esc_html( sprintf( _n( 'Access end date updated for %s enrollment.', 'Access end date updated for %s enrollments.', $changed, 'accessnow-lms' ), number_format_i18n( $changed ) ) )
					);
				}
			} elseif ( 'reenroll' === $action ) {
				$reenrolled = 0;
				foreach ( $ids as $id ) {
					$enrollment = Enrollment::get_enrollment_by_id( $id );
					if ( $enrollment && in_array( $enrollment->status, array( 'completed', 'dropped' ), true ) ) {
						$new_id = Enrollment::enroll( $enrollment->user_id, $enrollment->course_id, get_current_user_id() );
						if ( $new_id ) {
							++$reenrolled;
						}
					}
				}
				if ( $reenrolled ) {
					printf(
						'<div class="notice notice-success"><p>%s</p></div>',
						/* translators: %s: number of students. */
						esc_html( sprintf( _n( '%s student re-enrolled.', '%s students re-enrolled.', $reenrolled, 'accessnow-lms' ), number_format_i18n( $reenrolled ) ) )
					);
				}
			}
		}

		// List filters from the query string: read-only, so no nonce.
		// phpcs:disable WordPress.Security.NonceVerification.Recommended
		$filter_course = isset( $_GET['course_id'] ) ? absint( $_GET['course_id'] ) : 0;
		$filter_status = isset( $_GET['status'] ) ? sanitize_key( wp_unslash( $_GET['status'] ) ) : '';
		$paged         = isset( $_GET['paged'] ) ? max( 1, absint( $_GET['paged'] ) ) : 1;
		// phpcs:enable WordPress.Security.NonceVerification.Recommended
		if ( ! in_array( $filter_status, array( '', 'active', 'completed', 'dropped' ), true ) ) {
			$filter_status = '';
		}
		$per_page = 20;

		$args = array(
			'per_page' => $per_page,
			'offset'   => ( $paged - 1 ) * $per_page,
		);
		if ( $filter_course ) {
			$args['course_id'] = $filter_course;
		}
		if ( $filter_status ) {
			$args['status'] = $filter_status;
		}

		$enrollments = Enrollment::get_all_enrollments( $args );
		$total       = Enrollment::count_enrollments( $args );
		$total_pages = ceil( $total / $per_page );

		$courses = get_posts(
			array(
				'post_type'      => 'slms_course',
				'posts_per_page' => -1,
				'orderby'        => 'title',
				'order'          => 'ASC',
			)
		);
		?>
		<div class="wrap">
			<h1><?php esc_html_e( 'Enrollments', 'accessnow-lms' ); ?></h1>

			<!-- Add Enrollment Form -->
			<div style="background:#fff;padding:15px;border:1px solid #ccd0d4;margin:15px 0;">
				<h2 style="margin-top:0;"><?php esc_html_e( 'Enroll Students', 'accessnow-lms' ); ?></h2>
				<form method="post" class="slms-enroll-form">
					<?php wp_nonce_field( 'accessnow_slms_admin_enroll', 'accessnow_slms_enroll_nonce' ); ?>
					<div class="slms-enroll-field">
						<label for="slms-enroll-users"><?php esc_html_e( 'Students', 'accessnow-lms' ); ?></label>
						<div class="slms-user-picker">
							<ul class="slms-user-chips" aria-label="<?php esc_attr_e( 'Chosen students', 'accessnow-lms' ); ?>"></ul>
							<input type="text" id="slms-enroll-users" name="enroll_users" class="regular-text" autocomplete="off"
								role="combobox" aria-autocomplete="list" aria-expanded="false" aria-controls="slms-user-results" aria-describedby="slms-enroll-users-help"
								placeholder="<?php esc_attr_e( 'Name, username or email', 'accessnow-lms' ); ?>">
							<ul id="slms-user-results" class="slms-user-results" role="listbox" hidden></ul>
						</div>
						<p class="description" id="slms-enroll-users-help"><?php esc_html_e( 'Type at least two letters and choose from the list. You can also type user IDs, usernames or emails, separated by commas.', 'accessnow-lms' ); ?></p>
						<p class="screen-reader-text" id="slms-user-status" role="status" aria-live="polite"></p>
					</div>
					<fieldset class="slms-enroll-field">
						<legend><?php esc_html_e( 'Courses', 'accessnow-lms' ); ?></legend>
						<?php foreach ( $courses as $c ) : ?>
							<label class="slms-enroll-course"><input type="checkbox" name="enroll_course_ids[]" value="<?php echo esc_attr( $c->ID ); ?>"> <?php echo esc_html( $c->post_title ); ?></label>
						<?php endforeach; ?>
						<?php if ( ! $courses ) : ?>
							<p><?php esc_html_e( 'No courses found.', 'accessnow-lms' ); ?></p>
						<?php endif; ?>
					</fieldset>
					<div class="slms-enroll-field">
						<label for="slms-enroll-access-until"><?php esc_html_e( 'Access until (optional)', 'accessnow-lms' ); ?></label>
						<input type="date" id="slms-enroll-access-until" name="enroll_access_until" aria-describedby="slms-enroll-access-until-help">
						<p class="description" id="slms-enroll-access-until-help"><?php esc_html_e( 'The last day these students can open the courses. Leave it empty for access with no end. You can change it later from the list below.', 'accessnow-lms' ); ?></p>
					</div>
					<p>
						<label>
							<input type="checkbox" name="notify_student" value="1" <?php checked( (bool) Settings::get( 'email_enrollment', 0 ) ); ?>>
							<?php esc_html_e( 'Email each student that they have been enrolled', 'accessnow-lms' ); ?>
						</label>
					</p>
					<?php submit_button( __( 'Enroll', 'accessnow-lms' ), 'primary', 'submit', false ); ?>
				</form>
			</div>

			<!-- Filters -->
			<form method="get" style="margin-bottom:10px;">
				<input type="hidden" name="page" value="slms-enrollments">
				<label for="slms-filter-course" class="screen-reader-text"><?php esc_html_e( 'Filter by course', 'accessnow-lms' ); ?></label>
				<select name="course_id" id="slms-filter-course">
					<option value=""><?php esc_html_e( 'All Courses', 'accessnow-lms' ); ?></option>
					<?php foreach ( $courses as $c ) : ?>
						<option value="<?php echo esc_attr( $c->ID ); ?>" <?php selected( $filter_course, $c->ID ); ?>><?php echo esc_html( $c->post_title ); ?></option>
					<?php endforeach; ?>
				</select>
				<label for="slms-filter-status" class="screen-reader-text"><?php esc_html_e( 'Filter by status', 'accessnow-lms' ); ?></label>
				<select name="status" id="slms-filter-status">
					<option value=""><?php esc_html_e( 'All Statuses', 'accessnow-lms' ); ?></option>
					<option value="active" <?php selected( $filter_status, 'active' ); ?>><?php esc_html_e( 'Active', 'accessnow-lms' ); ?></option>
					<option value="completed" <?php selected( $filter_status, 'completed' ); ?>><?php esc_html_e( 'Completed', 'accessnow-lms' ); ?></option>
					<option value="dropped" <?php selected( $filter_status, 'dropped' ); ?>><?php esc_html_e( 'Dropped', 'accessnow-lms' ); ?></option>
				</select>
				<?php submit_button( __( 'Filter', 'accessnow-lms' ), 'secondary', 'submit', false ); ?>
				<?php Csv_Export::button( 'enrollments', __( 'Export CSV', 'accessnow-lms' ), $filter_course, $filter_status ); ?>
			</form>

			<!-- Enrollments Table -->
			<form method="post">
				<?php wp_nonce_field( 'accessnow_slms_bulk_enrollments' ); ?>
				<table class="wp-list-table widefat fixed striped">
					<thead>
						<tr>
							<td class="manage-column column-cb check-column"><label for="slms-select-all" class="screen-reader-text"><?php esc_html_e( 'Select all', 'accessnow-lms' ); ?></label><input type="checkbox" id="slms-select-all"></td>
							<th><?php esc_html_e( 'Student', 'accessnow-lms' ); ?></th>
							<th><?php esc_html_e( 'Course', 'accessnow-lms' ); ?></th>
							<th><?php esc_html_e( 'Status', 'accessnow-lms' ); ?></th>
							<th><?php esc_html_e( 'Progress', 'accessnow-lms' ); ?></th>
							<th><?php esc_html_e( 'Enrolled', 'accessnow-lms' ); ?></th>
							<th><?php esc_html_e( 'Enrolled By', 'accessnow-lms' ); ?></th>
							<th><?php esc_html_e( 'Access until', 'accessnow-lms' ); ?></th>
						</tr>
					</thead>
					<tbody>
						<?php if ( empty( $enrollments ) ) : ?>
							<tr><td colspan="8"><?php esc_html_e( 'No enrollments found.', 'accessnow-lms' ); ?></td></tr>
						<?php else : ?>
							<?php
							foreach ( $enrollments as $e ) :
								$user             = get_userdata( $e->user_id );
								$course_title     = get_the_title( $e->course_id );
								$progress         = Progress::get_course_progress( $e->user_id, $e->course_id, $e->id );
								$enrolled_by      = $e->enrolled_by ? get_userdata( $e->enrolled_by ) : null;
								$enrolled_by_name = $e->enrolled_by ? ( $enrolled_by ? $enrolled_by->display_name : '#' . $e->enrolled_by ) : __( 'Self', 'accessnow-lms' );
								$access_until     = Enrollment::access_end_date( $e );
								if ( 'dropped' === $e->status ) {
									$access_label = '&mdash;';
								} elseif ( '' === $access_until ) {
									$access_label = esc_html__( 'No end date', 'accessnow-lms' );
								} elseif ( Enrollment::is_expired( $e ) ) {
									/* translators: %s: date. */
									$access_label = esc_html( sprintf( __( 'Ended %s', 'accessnow-lms' ), $access_until ) );
								} else {
									$access_label = esc_html( $access_until );
								}
								?>
								<tr>
									<th class="check-column">
										<label for="slms-enrollment-<?php echo esc_attr( $e->id ); ?>" class="screen-reader-text">
											<?php
											/* translators: 1: student name, 2: course title. */
											echo esc_html( sprintf( __( 'Select %1$s in %2$s', 'accessnow-lms' ), $user ? $user->display_name : '#' . $e->user_id, $course_title ) );
											?>
										</label>
										<input type="checkbox" id="slms-enrollment-<?php echo esc_attr( $e->id ); ?>" name="enrollment_ids[]" value="<?php echo esc_attr( $e->id ); ?>">
									</th>
									<td><?php echo esc_html( $user ? $user->display_name : '#' . $e->user_id ); ?></td>
									<td><?php echo esc_html( $course_title ); ?></td>
									<td><span class="slms-status-<?php echo esc_attr( $e->status ); ?>"><?php echo esc_html( ucfirst( $e->status ) ); ?></span></td>
									<td><?php echo esc_html( $progress . '%' ); ?></td>
									<td><?php echo esc_html( $e->enrolled_at ); ?></td>
									<td><?php echo esc_html( $enrolled_by_name ); ?></td>
									<td><?php echo $access_label; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped -- escaped above. ?></td>
								</tr>
							<?php endforeach; ?>
						<?php endif; ?>
					</tbody>
				</table>

				<div style="margin-top:10px;">
					<label for="slms-bulk-action" class="screen-reader-text"><?php esc_html_e( 'Select bulk action', 'accessnow-lms' ); ?></label>
					<select name="slms_bulk_action" id="slms-bulk-action">
						<option value=""><?php esc_html_e( 'Bulk Actions', 'accessnow-lms' ); ?></option>
						<option value="drop"><?php esc_html_e( 'Drop Selected', 'accessnow-lms' ); ?></option>
						<option value="reenroll"><?php esc_html_e( 'Re-enroll Selected', 'accessnow-lms' ); ?></option>
						<option value="set_access"><?php esc_html_e( 'Set access end date', 'accessnow-lms' ); ?></option>
						<option value="clear_access"><?php esc_html_e( 'Remove access end date', 'accessnow-lms' ); ?></option>
					</select>
					<label for="slms-bulk-access-until"><?php esc_html_e( 'Last day of access', 'accessnow-lms' ); ?></label>
					<input type="date" id="slms-bulk-access-until" name="slms_access_until">
					<?php submit_button( __( 'Apply', 'accessnow-lms' ), 'secondary', 'submit', false ); ?>
				</div>
			</form>

			<?php if ( $total_pages > 1 ) : ?>
				<div class="tablenav bottom">
					<div class="tablenav-pages">
						<?php
						echo wp_kses_post(
							paginate_links(
								array(
									'base'    => add_query_arg( 'paged', '%#%' ),
									'format'  => '',
									'total'   => $total_pages,
									'current' => $paged,
								)
							)
						);
						?>
					</div>
				</div>
			<?php endif; ?>
		</div>
		<?php
	}
}