<?php

namespace RoosterLMS\Notify;

use RoosterLMS\Content\CourseRepository;
use RoosterLMS\Content\ObjectType;
use RoosterLMS\Data\Db;
use RoosterLMS\Data\SqlPart;
use RoosterLMS\Domain\Services;
use RoosterLMS\I18n\Fold;
use RoosterLMS\Routing\Urls;

defined( 'ABSPATH' ) || exit;

final class Syllabus {

	public function for_member( int $org_id, int $user_id, string $lang, ?array $only_course_ids = null ): array {
		global $wpdb;
		$sql = SqlPart::of( 'SELECT DISTINCT course_id FROM %i WHERE user_id = %d AND revoked_at IS NULL', Db::table( 'grants' ), $user_id );
		if ( $org_id > 0 ) {
			$sql = $sql->add( SqlPart::of( ' AND org_id = %d', $org_id ) );
		}
		$courses = array_map( 'intval', Db::col( $sql ) );
		if ( null !== $only_course_ids ) {
			$courses = array_values( array_intersect( $courses, CourseRepository::ids( $only_course_ids ) ) );
		}
		return $this->for_courses( $user_id, $courses, $lang );
	}

	public function for_courses( int $user_id, array $course_ids, string $lang, bool $with_items = true ): array {
		$course_ids = array_keys( Services::course_repo()->get_many( CourseRepository::ids( $course_ids ) ) );
		if ( array() === $course_ids ) {
			return array();
		}
		$titles = Services::posts()->titles( ObjectType::COURSE, $course_ids, $lang );
		$keys   = $this->sort_keys( $course_ids, $titles );
		usort( $course_ids, static fn( int $a, int $b ): int => $keys[ $a ] <=> $keys[ $b ] );
		$hidden = $with_items ? Services::programme_gate()->hidden_items_many( $user_id, $course_ids ) : array();
		$out    = array();
		foreach ( $course_ids as $course_id ) {
			$out[] = array(
				'course_id' => $course_id,
				'title'     => $titles[ $course_id ]['title'] ?? '',
				'url'       => Urls::course_url( $course_id, $lang ),
				'items'     => $with_items ? $this->items( $course_id, $hidden[ $course_id ] ?? array(), $lang ) : array(),
			);
		}
		return $out;
	}

	private function items( int $course_id, array $hidden, string $lang ): array {
		$items = array();
		foreach ( Services::curriculum_repo()->outline( $course_id )->items as $item ) {
			if ( ! in_array( $item->id, $hidden, true ) ) {
				$items[] = $item;
			}
		}
		if ( array() === $items ) {
			return array();
		}
		$units   = Services::unit_repo()->get_many( array_map( static fn( $i ): int => $i->unit_id, $items ) );
		$content = true;
		foreach ( $items as $item ) {
			$unit    = $units[ $item->unit_id ] ?? null;
			$content = $content && null !== $unit && $unit->type->is_content_controlled();
		}
		if ( $content ) {
			return array();
		}
		$titles = Services::posts()->titles( ObjectType::UNIT, array_map( static fn( $i ): int => $i->unit_id, $items ), $lang );
		$out    = array();
		foreach ( $items as $item ) {
			$out[] = array(
				'title' => $titles[ $item->unit_id ]['title'] ?? '',
				'url'   => Urls::item_url( $course_id, $item->id, $lang ),
			);
		}
		return $out;
	}

	private function sort_keys( array $course_ids, array $titles ): array {
		$filings = Services::category_repo()->filings( ObjectType::COURSE, $course_ids );
		$first   = array();
		foreach ( $filings as $course_id => $categories ) {
			if ( array() !== $categories ) {
				$first[ $course_id ] = (int) $categories[0];
			}
		}
		$ranks     = array();
		$positions = array();
		if ( array() !== $first ) {
			foreach ( Services::category_repo()->get_many( array_values( array_unique( $first ) ) ) as $id => $category ) {
				$ranks[ $id ] = $category->tree_rank;
			}
			foreach ( Db::rows(

					'SELECT category_id, object_id, position FROM %i WHERE object_type = %d AND object_id IN (' . implode( ',', array_fill( 0, count( $first ), '%d' ) ) . ')',
					array_merge( array( Db::table( 'category_objects' ), ObjectType::COURSE->value ), array_keys( $first ) )

			) as $row ) {
				if ( ( $first[ (int) $row['object_id'] ] ?? 0 ) === (int) $row['category_id'] ) {
					$positions[ (int) $row['object_id'] ] = (int) $row['position'];
				}
			}
		}
		$keys = array();
		foreach ( $course_ids as $course_id ) {
			$category           = $first[ $course_id ] ?? 0;
			$position           = $positions[ $course_id ] ?? 0;
			$keys[ $course_id ] = array(
				$category > 0 ? ( $ranks[ $category ] ?? PHP_INT_MAX - 1 ) : PHP_INT_MAX,
				$position > 0 ? $position : PHP_INT_MAX,
				Fold::fold( $titles[ $course_id ]['title'] ?? '' ),
				$course_id,
			);
		}
		return $keys;
	}
}