<?php

namespace RoosterLMS\CourseBuilder\Lessons;

use RoosterLMS\Assessment\QuizMode;
use RoosterLMS\Content\ItemState;
use RoosterLMS\Content\LessonKind;
use RoosterLMS\Content\ObjectState;
use RoosterLMS\Content\ObjectType;
use RoosterLMS\Content\UnitType;
use RoosterLMS\Data\Db;
use RoosterLMS\Live\Placement;
use RoosterLMS\Live\ProviderKey;
use RoosterLMS\Live\SessionState;

defined( 'ABSPATH' ) || exit;

final class MaterialSearch {

	public const PER_PAGE = 20;

	public static function search( string $q, string $kind, int $not_in_course, int $page, string $lang, int $user_id ): array {
		global $wpdb;
		$page  = max( 1, $page );
		$q     = trim( $q );
		$where = array( 'u.state <> %d', "ph.post_status NOT IN ('trash', 'auto-draft')", '(u.unit_type <> %d OR u.quiz_mode <> %d)' );
		$args  = array( ObjectState::TRASHED->value, UnitType::QUIZ->value, QuizMode::BANK->value );
		$type  = self::kind_where( $kind );
		if ( null === $type ) {
			return array(
				'items' => array(),
				'page'  => $page,
				'more'  => false,
			);
		}
		$where[] = $type[0];
		$args    = array_merge( $args, $type[1] );
		if ( '' !== $q ) {
			$like    = '%' . $wpdb->esc_like( $q ) . '%';
			$where[] = '(ph.post_title LIKE %s OR EXISTS (SELECT 1 FROM %i o2 JOIN %i p2 ON p2.ID = o2.post_id WHERE o2.object_type = %d AND o2.object_id = u.id AND p2.post_title LIKE %s))';
			$args    = array_merge( $args, array( $like, Db::table( 'object_posts' ), $wpdb->posts, ObjectType::UNIT->value, $like ) );
		}
		if ( $not_in_course > 0 ) {
			$where[] = 'NOT EXISTS (SELECT 1 FROM %i ni WHERE ni.course_id = %d AND ni.unit_id = u.id AND ni.state = %d)';
			$args    = array_merge( $args, array( Db::table( 'items' ), $not_in_course, ItemState::ACTIVE->value ) );
		}
		$having = '';
		if ( 'stream' === $kind ) {
			$having = ' HAVING provider = ' . (int) ProviderKey::STREAM->value;
		} elseif ( 'live' === $kind ) {
			$having = ' HAVING provider IS NULL OR provider <> ' . (int) ProviderKey::STREAM->value;
		}
		$sql  = 'SELECT u.id, u.unit_type, u.lesson_kind, u.home_post_id, ph.post_status, ph.post_title AS home_title, MAX(pc.post_title) AS shown_title, MAX(ls.provider) AS provider,'
			. ' (SELECT COUNT(DISTINCT ic.course_id) FROM %i ic WHERE ic.unit_id = u.id AND ic.state = %d) AS courses'
			. ' FROM %i u JOIN %i ph ON ph.ID = u.home_post_id'
			. ' LEFT JOIN %i oc ON oc.object_type = %d AND oc.object_id = u.id AND oc.lang = %s'
			. ' LEFT JOIN %i pc ON pc.ID = oc.post_id AND pc.post_status NOT IN (\'trash\', \'auto-draft\')'
			. ' LEFT JOIN %i ls ON ls.unit_id = u.id AND ls.placement = %d AND ls.state <> %d'
			. ' WHERE ' . implode( ' AND ', $where )
			. ' GROUP BY u.id' . $having
			. ( '' !== $q ? ' ORDER BY COALESCE(MAX(pc.post_title), ph.post_title), u.id' : ' ORDER BY ph.post_modified_gmt DESC, u.id DESC' )
			. ' LIMIT %d OFFSET %d';
		$head = array(
			Db::table( 'items' ),
			ItemState::ACTIVE->value,
			Db::table( 'units' ),
			$wpdb->posts,
			Db::table( 'object_posts' ),
			ObjectType::UNIT->value,
			$lang,
			$wpdb->posts,
			Db::table( 'live_sessions' ),
			Placement::LESSON->value,
			SessionState::TRASHED->value,
		);
		$rows = Db::rows( $sql, array_merge( $head, $args, array( self::PER_PAGE + 1, ( $page - 1 ) * self::PER_PAGE ) ) ); // phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared -- the query is built above from constant SQL and placeholders (the HAVING numbers are enum constants); every value is a replacement.
		$more = count( $rows ) > self::PER_PAGE;
		$rows = array_slice( $rows, 0, self::PER_PAGE );
		$all = self::edits_all( $user_id );
		$ids = array_values( array_filter( array_map( static fn( array $r ): int => (int) $r['home_post_id'], $rows ) ) );
		if ( ! $all && array() !== $ids ) {
			_prime_post_caches( $ids, false, false );
		}
		$out = array();
		foreach ( $rows as $r ) {
			$post_id = (int) $r['home_post_id'];
			if ( $post_id <= 0 || ( ! $all && ! self::can( $user_id, 'edit_post', $post_id ) ) ) {
				continue;
			}
			$title = trim( html_entity_decode( wp_strip_all_tags( (string) ( null !== $r['shown_title'] && '' !== trim( (string) $r['shown_title'] ) ? $r['shown_title'] : $r['home_title'] ) ), ENT_QUOTES | ENT_HTML5, 'UTF-8' ) );
			$out[] = array(
				'unit_id' => (int) $r['id'],
				'post_id' => $post_id,
				'title'   => '' !== $title ? $title : __( '(no title)', 'rooster-lms' ),
				'kind'    => self::kind_of_row( $r ),
				'status'  => (string) $r['post_status'],
				'courses' => (int) $r['courses'],
			);
		}
		return array(
			'items' => $out,
			'page'  => $page,
			'more'  => $more,
		);
	}

	private static function can( int $user_id, string $cap, ...$args ): bool {
		return get_current_user_id() === $user_id ? current_user_can( $cap, ...$args ) : user_can( $user_id, $cap, ...$args ); // phpcs:ignore WordPress.WP.Capabilities.Undetermined -- edit_post or a post type's edit_others capability.
	}

	private static function edits_all( int $user_id ): bool {
		foreach ( array( \RoosterLMS\Content\PostTypes::LESSON, \RoosterLMS\Content\PostTypes::QUIZ ) as $type ) {
			$object = get_post_type_object( $type );
			if ( null === $object || ! self::can( $user_id, (string) $object->cap->edit_others_posts ) ) {
				return false;
			}
		}
		return true;
	}

	private static function kind_where( string $kind ): ?array {
		if ( '' === $kind ) {
			return array( '1 = 1', array() );
		}
		$lesson = LessonKind::from_slug( $kind );
		if ( null !== $lesson ) {
			return array( 'u.unit_type = %d AND u.lesson_kind = %d', array( UnitType::LESSON->value, $lesson->value ) );
		}
		$type = match ( $kind ) {
			'quiz' => UnitType::QUIZ,
			'assignment' => UnitType::ASSIGNMENT,
			'live', 'stream' => UnitType::LIVE,
			'scorm' => UnitType::PACKAGE,
			'external' => UnitType::EXTERNAL,
			default => null,
		};
		return null === $type ? null : array( 'u.unit_type = %d', array( $type->value ) );
	}

	private static function kind_of_row( array $r ): string {
		return Kinds::of_row( (int) $r['unit_type'], null === $r['lesson_kind'] ? null : (int) $r['lesson_kind'], null === $r['provider'] ? null : (int) $r['provider'] );
	}
}