<?php

namespace RoosterLMS\Blocks;

use RoosterLMS\Assessment\AttemptStatus;
use RoosterLMS\Content\Item;
use RoosterLMS\Content\ObjectType;
use RoosterLMS\Content\Outline;
use RoosterLMS\Data\Db;
use RoosterLMS\Domain\Services;
use RoosterLMS\Enrolment\Enrolment;
use RoosterLMS\I18n\Language;
use RoosterLMS\I18n\Providers;
use RoosterLMS\I18n\Switcher;
use RoosterLMS\I18n\TextObject;
use RoosterLMS\Progress\ProgressSnapshot;
use RoosterLMS\Progress\ProgressStatus;
use RoosterLMS\Routing\Urls;

defined( 'ABSPATH' ) || exit;

final class Learner {

	private static ?\WeakMap $statuses = null;

	public static function outline( int $course_id ): Outline {
		$outline  = Services::curriculum_repo()->outline( $course_id );
		$unit_ids = array_values( array_unique( array_map( static fn( Item $item ): int => $item->unit_id, $outline->items ) ) );
		if ( array() !== $unit_ids ) {
			Services::unit_repo()->get_many( $unit_ids );
			Services::posts()->for_objects( ObjectType::UNIT, $unit_ids, Switcher::current() );
		}
		return $outline;
	}

	public static function enrolment( int $user_id, int $course_id ): ?Enrolment {
		if ( $user_id <= 0 || $course_id <= 0 ) {
			return null;
		}
		return Services::enrolment_repo()->for_user( $user_id, array( $course_id ) )[ $course_id ] ?? null;
	}

	public static function is_enrolled( int $user_id, int $course_id ): bool {
		$enrolment = self::enrolment( $user_id, $course_id );
		return null !== $enrolment && $enrolment->is_active();
	}

	public static function snapshot( int $user_id, int $course_id ): ?ProgressSnapshot {
		if ( $user_id <= 0 || $course_id <= 0 ) {
			return null;
		}
		return Services::progress_repo()->for_user( $user_id, array( $course_id ) )[ $course_id ] ?? null;
	}

	public static function item_statuses( int $user_id, int $course_id ): array {
		$snapshot = self::snapshot( $user_id, $course_id );
		if ( null === $snapshot ) {
			return array();
		}
		if ( null === self::$statuses ) {
			self::$statuses = new \WeakMap();
		}
		if ( ! isset( self::$statuses[ $snapshot ] ) ) {
			self::$statuses[ $snapshot ] = Services::progress_repo()->item_statuses( $user_id, $course_id, $snapshot->cycle );
		}
		return self::$statuses[ $snapshot ];
	}

	public static function may_have_feedback( int $user_id, int $course_id ): bool {
		if ( $user_id <= 0 || ! \RoosterLMS\Feedback\FeedbackRepository::any() ) {
			return false;
		}
		$snapshot = self::snapshot( $user_id, $course_id );
		if ( null === $snapshot ) {
			return false;
		}
		foreach ( self::item_statuses( $user_id, $course_id ) as $status ) {
			if ( ProgressStatus::COMPLETED === $status ) {
				return true;
			}
		}
		foreach ( Services::progress_repo()->item_flags( $user_id, $course_id, $snapshot->cycle ) as $flags ) {
			if ( 0 !== ( $flags & \RoosterLMS\Progress\ProgressRepository::AWAITING_RESULTS ) ) {
				return true;
			}
		}
		return false;
	}

	public static function withheld_releases( int $user_id, array $course_ids, int $cycle = 0 ): array {
		$course_ids = array_values( array_unique( array_filter( array_map( 'intval', $course_ids ), static fn( int $id ): bool => $id > 0 ) ) );
		if ( $user_id <= 0 || array() === $course_ids ) {
			return array();
		}
		$by   = $cycle > 0 ? 'item_id' : 'course_id';
		$sql  = 'SELECT ' . $by . ' AS k, MIN(release_at) AS release_at FROM %i WHERE user_id = %d AND course_id IN (' . implode( ',', array_fill( 0, count( $course_ids ), '%d' ) ) . ') AND status IN (%d, %d) AND release_at IS NOT NULL AND released_at IS NULL'
			. ( $cycle > 0 ? ' AND cycle = %d' : '' ) . ' GROUP BY ' . $by;
		$args = array_merge( array( Db::table( 'attempts' ), $user_id ), $course_ids, array( AttemptStatus::GRADED->value, AttemptStatus::NEEDS_REVIEW->value ) );
		if ( $cycle > 0 ) {
			$args[] = $cycle;
		}
		$out = array();
		foreach ( Db::rows( $sql, $args ) as $row ) { // phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared -- the query is built above from constant SQL (one of two column names) and placeholders; every value is a replacement.
			$out[ (int) $row['k'] ] = (string) $row['release_at'];
		}
		return $out;
	}

	public static function neighbours( int $user_id, int $item_id ): ?array {
		$item = $item_id > 0 ? ( Services::curriculum_repo()->items( array( $item_id ) )[ $item_id ] ?? null ) : null;
		if ( null === $item ) {
			return null;
		}
		$course_id = $item->course_id;
		$lang      = Switcher::current();
		$outline   = self::outline( $course_id );
		$unit_ids  = array_values( array_unique( array_map( static fn( Item $entry ): int => $entry->unit_id, $outline->items ) ) );
		$posts     = array() === $unit_ids ? array() : Services::posts()->for_objects( ObjectType::UNIT, $unit_ids, $lang );
		$listed    = array_values( array_filter( $outline->items, static fn( Item $entry ): bool => ( $posts[ $entry->unit_id ] ?? 0 ) > 0 ) );
		$index     = null;
		foreach ( $listed as $i => $entry ) {
			if ( $entry->id === $item_id ) {
				$index = $i;
				break;
			}
		}
		if ( null === $index ) {
			return null;
		}
		$section = '';
		foreach ( $outline->sections as $candidate ) {
			if ( $candidate->id === $item->section_id ) {
				$section = Services::strings()->translate_many( TextObject::SECTION, array( $candidate->id => $candidate->title ), $lang )[ $candidate->id ] ?? $candidate->title;
				break;
			}
		}
		$neighbour = static function ( ?Item $entry ) use ( $user_id, $course_id, $posts, $lang ): ?array {
			if ( null === $entry ) {
				return null;
			}
			$decision = Services::gate()->can_open_item( $user_id, $entry->id );
			$title    = wp_strip_all_tags( Services::posts()->title( (int) $posts[ $entry->unit_id ] ) );
			$reason   = '';
			if ( ! $decision->allowed ) {
				$reason = Locks::item_reason( $decision->reason, $entry, $user_id );
				$reason = '' !== $reason ? $reason : __( 'Locked', 'rooster-lms' );
			}
			return array(
				'item_id' => $entry->id,
				'title'   => '' !== trim( $title ) ? $title : __( '(no title)', 'rooster-lms' ),
				'url'     => $decision->allowed ? Urls::item_url( $course_id, $entry->id, $lang ) : '',
				'open'    => $decision->allowed,
				'reason'  => $reason,
			);
		};
		return array(
			'previous' => $neighbour( $listed[ $index - 1 ] ?? null ),
			'next'     => $neighbour( $listed[ $index + 1 ] ?? null ),
			'section'  => $section,
			'index'    => $index + 1,
			'total'    => count( $listed ),
		);
	}
}