<?php
namespace AccessNow\SimpleLMS;

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

class Course_Cloner {

	public static function init() {
		add_filter( 'post_row_actions', array( __CLASS__, 'add_clone_action' ), 10, 2 );
		add_action( 'admin_action_accessnow_slms_clone_course', array( __CLASS__, 'handle_clone' ) );
	}

	public static function add_clone_action( $actions, $post ) {
		if ( 'slms_course' !== $post->post_type || ! current_user_can( 'manage_options' ) ) {
			return $actions;
		}

		$url = wp_nonce_url(
			admin_url( 'admin.php?action=accessnow_slms_clone_course&course_id=' . $post->ID ),
			'accessnow_slms_clone_' . $post->ID
		);

		$actions['slms_clone'] = sprintf(
			'<a href="%s">%s</a>',
			esc_url( $url ),
			esc_html__( 'Clone', 'accessnow-lms' )
		);

		return $actions;
	}

	public static function handle_clone() {
		$course_id = absint( $_GET['course_id'] ?? 0 );

		if ( ! $course_id || ! current_user_can( 'manage_options' ) ) {
			wp_die( esc_html__( 'Unauthorized.', 'accessnow-lms' ) );
		}

		check_admin_referer( 'accessnow_slms_clone_' . $course_id );

		$new_course_id = self::clone_course( $course_id );

		if ( is_wp_error( $new_course_id ) ) {
			wp_die( esc_html( $new_course_id->get_error_message() ) );
		}

		wp_safe_redirect( get_edit_post_link( $new_course_id, 'raw' ) );
		exit;
	}

	private static function clone_course( $course_id ) {
		$data = Export_Import::gather_course_data( $course_id );
		if ( ! $data || empty( $data['course'] ) ) {
			return new \WP_Error( 'slms_clone_failed', __( 'Could not read course data.', 'accessnow-lms' ) );
		}

		// Generate unique title with (Copy) suffix
		$data['course']['title'] = self::generate_copy_title( $data['course']['title'] );

		// Create course as draft
		$new_course_id = wp_insert_post(
			wp_slash( array(
				'post_type'    => 'slms_course',
				'post_title'   => sanitize_text_field( $data['course']['title'] ),
				'post_content' => wp_kses_post( $data['course']['content'] ),
				'post_status'  => 'draft',
			) ),
			true
		);

		if ( is_wp_error( $new_course_id ) ) {
			return $new_course_id;
		}

		// Course meta
		if ( ! empty( $data['course']['meta'] ) ) {
			foreach ( $data['course']['meta'] as $key => $value ) {
				update_post_meta( $new_course_id, $key, wp_slash( $value ) );
			}
		}

		// Course thumbnail
		$thumb_id = get_post_thumbnail_id( $course_id );
		if ( $thumb_id ) {
			$new_thumb = self::clone_attachment( $thumb_id );
			if ( $new_thumb ) {
				set_post_thumbnail( $new_course_id, $new_thumb );
			}
		}

		// Units
		if ( ! empty( $data['units'] ) ) {
			foreach ( $data['units'] as $unit_data ) {
				$unit_id = wp_insert_post(
					wp_slash( array(
						'post_type'   => 'slms_unit',
						'post_title'  => sanitize_text_field( $unit_data['title'] ),
						'post_status' => $unit_data['status'] ?? 'publish',
					) ),
					true
				);

				if ( is_wp_error( $unit_id ) ) {
					continue;
				}

				update_post_meta( $unit_id, '_slms_parent_course', $new_course_id );
				if ( isset( $unit_data['meta']['_slms_sort_order'] ) ) {
					update_post_meta( $unit_id, '_slms_sort_order', absint( $unit_data['meta']['_slms_sort_order'] ) );
				}
				// Keys added through accessnow_slms_export_meta_keys (sort order and header are handled here).
				self::copy_meta( $unit_id, $unit_data, array_diff( Export_Import::meta_keys( 'slms_unit' ), array( '_slms_sort_order', Lesson_Header::META ) ) );
				if ( ! empty( $unit_data['meta'][ Lesson_Header::META ] ) ) {
					update_post_meta( $unit_id, Lesson_Header::META, Lesson_Header::sanitize_style( $unit_data['meta'][ Lesson_Header::META ] ) );
				}
				self::clone_thumbnail( $unit_id, $unit_data );

				// Lessons
				if ( ! empty( $unit_data['lessons'] ) ) {
					foreach ( $unit_data['lessons'] as $lesson_data ) {
						$lesson_id = wp_insert_post(
							wp_slash( array(
								'post_type'    => 'slms_lesson',
								'post_title'   => sanitize_text_field( $lesson_data['title'] ),
								'post_content' => wp_kses_post( $lesson_data['content'] ),
								'post_status'  => $lesson_data['status'] ?? 'publish',
							) ),
							true
						);

						if ( is_wp_error( $lesson_id ) ) {
							continue;
						}

						update_post_meta( $lesson_id, '_slms_parent_unit', $unit_id );
						self::copy_meta( $lesson_id, $lesson_data, Export_Import::meta_keys( 'slms_lesson' ) );
						self::clone_thumbnail( $lesson_id, $lesson_data );

						// Lesson attachments — clone the originals (matched by file name)
						// Find the original lesson's attachment IDs from the gathered data
						if ( ! empty( $lesson_data['attachments'] ) ) {
							// Look up original attachment IDs by matching filenames
							$new_att_ids = array();
							foreach ( $lesson_data['attachments'] as $att_info ) {
								$orig_att = self::find_attachment_by_filename( $att_info['filename'] );
								if ( $orig_att ) {
									$new_att = self::clone_attachment( $orig_att );
									if ( $new_att ) {
										$new_att_ids[] = $new_att;
									}
								}
							}
							if ( ! empty( $new_att_ids ) ) {
								update_post_meta( $lesson_id, '_slms_attachments', $new_att_ids );
							}
						}

						// Quiz
						if ( ! empty( $lesson_data['quiz'] ) ) {
							$quiz_data = $lesson_data['quiz'];
							$quiz_id   = wp_insert_post(
								wp_slash( array(
									'post_type'   => 'slms_quiz',
									'post_title'  => sanitize_text_field( $quiz_data['title'] ),
									'post_status' => $quiz_data['status'] ?? 'publish',
								) ),
								true
							);

							if ( ! is_wp_error( $quiz_id ) ) {
								update_post_meta( $quiz_id, '_slms_parent_lesson', $lesson_id );
								foreach ( Export_Import::meta_keys( 'slms_quiz' ) as $mk ) {
									if ( isset( $quiz_data['meta'][ $mk ] ) ) {
										update_post_meta( $quiz_id, $mk, wp_slash( $quiz_data['meta'][ $mk ] ) );
									}
								}
							}
						}
					}
				}
			}
		}

		return $new_course_id;
	}

	/** Give a cloned unit or lesson a copy of the original's header image. */
	private static function clone_thumbnail( $post_id, $post_data ) {
		if ( empty( $post_data['thumbnail']['filename'] ) ) {
			return;
		}
		$orig = self::find_attachment_by_filename( $post_data['thumbnail']['filename'] );
		$new  = $orig ? self::clone_attachment( $orig ) : null;
		if ( $new ) {
			set_post_thumbnail( $post_id, $new );
		}
	}

	private static function clone_attachment( $attachment_id ) {
		$file_path = get_attached_file( $attachment_id );
		if ( ! $file_path || ! file_exists( $file_path ) ) {
			return null;
		}

		$orig_post = get_post( $attachment_id );
		if ( ! $orig_post ) {
			return null;
		}

		$new_id = wp_insert_attachment(
			array(
				'post_title'     => $orig_post->post_title,
				'post_mime_type' => $orig_post->post_mime_type,
				'post_status'    => 'inherit',
			),
			$file_path
		);

		if ( is_wp_error( $new_id ) || ! $new_id ) {
			return null;
		}

		// Copy attachment metadata (includes thumbnail sizes)
		$metadata = wp_get_attachment_metadata( $attachment_id );
		if ( $metadata ) {
			wp_update_attachment_metadata( $new_id, $metadata );
		}

		// Copy alt text
		$alt = get_post_meta( $attachment_id, '_wp_attachment_image_alt', true );
		if ( $alt ) {
			update_post_meta( $new_id, '_wp_attachment_image_alt', $alt );
		}

		return $new_id;
	}

	private static function find_attachment_by_filename( $filename ) {
		global $wpdb;

		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- one-off lookup while cloning.
		$result = $wpdb->get_var(
			$wpdb->prepare(
				"SELECT post_id FROM {$wpdb->postmeta}
             WHERE meta_key = '_wp_attached_file'
             AND meta_value LIKE %s
             LIMIT 1",
				'%' . $wpdb->esc_like( $filename )
			)
		);

		return $result ? (int) $result : null;
	}

	private static function generate_copy_title( $title ) {
		// If already ends with "(Copy)" or "(Copy N)", increment
		if ( preg_match( '/\(Copy(?:\s+(\d+))?\)\s*$/', $title, $m ) ) {
			$n = isset( $m[1] ) && '' !== $m[1] ? (int) $m[1] + 1 : 2;
			return preg_replace( '/\(Copy(?:\s+\d+)?\)\s*$/', "(Copy {$n})", $title );
		}

		return $title . ' (Copy)';
	}

	/**
	 * Copy the given meta keys from gathered course data to a new post, leaving out empty values.
	 *
	 * @param int      $post_id Post to write to.
	 * @param array    $data    Gathered post data (Export_Import::gather_course_data()).
	 * @param string[] $keys    Meta keys.
	 */
	private static function copy_meta( $post_id, $data, $keys ) {
		foreach ( $keys as $key ) {
			if ( isset( $data['meta'][ $key ] ) && '' !== $data['meta'][ $key ] ) {
				update_post_meta( $post_id, $key, wp_slash( $data['meta'][ $key ] ) );
			}
		}
	}
}