<?php

namespace RoosterLMS\Display;

use RoosterLMS\Community\CommunitySettings;
use RoosterLMS\Community\ReviewState;
use RoosterLMS\Content\Course;
use RoosterLMS\CourseInfo\ComingSoonFlag;
use RoosterLMS\CourseInfo\CoursePointKind;
use RoosterLMS\CourseInfo\CourseTextKind;
use RoosterLMS\CourseInfo\FileAccess;
use RoosterLMS\CourseInfo\Lookup;
use RoosterLMS\Data\Db;
use RoosterLMS\Data\SqlPart;
use RoosterLMS\Data\Transaction;
use RoosterLMS\Domain\Services;
use RoosterLMS\I18n\Names;
use RoosterLMS\I18n\TextObject;
use RoosterLMS\Media\MediaOwner;
use RoosterLMS\Media\MediaRole;

defined( 'ABSPATH' ) || exit;

final class CoursePage {

	private static array $memo = array();

	public array $texts = array();

	public array $points = array();

	public int $faq_links = 0;

	public bool $has_intro = false;

	public array $files = array();

	public int $rating_count = 0;

	public int $learners = 0;

	public int $principal = 0;

	public ?float $rating_avg = null;

	public array $distribution = array(
		1 => 0,
		2 => 0,
		3 => 0,
		4 => 0,
		5 => 0,
	);

	public ?Lookup $level = null;

	public ?Lookup $badge = null;

	private array $texts_in = array();

	private array $points_in = array();

	private function __construct( public readonly Course $course ) {}

	public static function for( int $course_id ): ?self {
		if ( $course_id <= 0 ) {
			return null;
		}
		if ( isset( self::$memo[ $course_id ] ) ) {
			return false === self::$memo[ $course_id ] ? null : self::$memo[ $course_id ];
		}
		$course = Services::course_repo()->get( $course_id );
		if ( null === $course ) {
			self::$memo[ $course_id ] = false;
			return null;
		}
		$page                     = new self( $course );
		self::$memo[ $course_id ] = $page;
		$page->load();
		return $page;
	}

	public static function forget(): void {
		self::$memo = array();
	}

	private function load(): void {
		global $wpdb;
		$id    = $this->course->id;
		$parts = array(
			SqlPart::of( "SELECT 't' AS src, kind AS k, 0 AS n, 0 AS pos, html AS txt, '' AS aux FROM %i WHERE course_id = %d", Db::table( 'course_texts' ), $id ),
			SqlPart::of( "SELECT 'p', kind, id, position, text, '' FROM %i WHERE course_id = %d", Db::table( 'course_points' ), $id ),
			SqlPart::of( "SELECT 'f', 0, COUNT(*), 0, '', '' FROM %i WHERE target_type = 1 AND target_id = %d", Db::table( 'faq_links' ), $id ),
			SqlPart::of( "SELECT 'm', 0, COUNT(*), 0, '', '' FROM %i WHERE owner_type = %d AND owner_id = %d AND role = %d", Db::table( 'media' ), MediaOwner::COURSE->value, $id, MediaRole::INTRO->value ),
			SqlPart::of( "SELECT 'c', access, COUNT(*), 0, '', '' FROM %i WHERE course_id = %d GROUP BY access", Db::table( 'course_files' ), $id ),
			SqlPart::of( "SELECT 's', rating_count, learners, 0, COALESCE( CAST( rating_avg AS CHAR ), '' ), '' FROM %i WHERE course_id = %d", Db::table( 'course_stats' ), $id ),
			SqlPart::of( "SELECT 'i', user_id, 0, position, '', '' FROM %i WHERE course_id = %d AND role = %d ORDER BY position, user_id LIMIT 1", Db::table( 'course_staff' ), $id, \RoosterLMS\Content\StaffRole::PRINCIPAL->value ),
			SqlPart::of( "SELECT 'r', rating, COUNT(*), 0, '', '' FROM %i WHERE course_id = %d AND state = %d GROUP BY rating", Db::table( 'course_reviews' ), $id, ReviewState::APPROVED->value ),
		);
		if ( $this->course->level_id > 0 ) {
			$parts[] = SqlPart::of( "SELECT 'l', id, state, builtin, label, slug FROM %i WHERE id = %d", Db::table( 'course_levels' ), $this->course->level_id );
		}
		if ( $this->course->badge_id > 0 ) {
			$parts[] = SqlPart::of( "SELECT 'b', id, state, builtin, label, CONCAT_WS( CHAR(31), slug, color, icon ) FROM %i WHERE id = %d", Db::table( 'course_badges' ), $this->course->badge_id );
		}
		$rows = Db::rows( SqlPart::of( '( ' )->add( SqlPart::join( ' ) UNION ALL ( ', $parts ) )->add( ' ) ORDER BY src, k, pos, n' ) );
		foreach ( $rows as $row ) {
			$k = (int) $row['k'];
			switch ( (string) $row['src'] ) {
				case 't':
					$this->texts[ $k ] = (string) $row['txt'];
					break;
				case 'p':
					$this->points[ $k ][] = array(
						'id'   => (int) $row['n'],
						'text' => (string) $row['txt'],
					);
					break;
				case 'f':
					$this->faq_links = (int) $row['n'];
					break;
				case 'm':
					$this->has_intro = (int) $row['n'] > 0;
					break;
				case 'c':
					$this->files[ $k ] = (int) $row['n'];
					break;
				case 'i':
					$this->principal = $k;
					break;
				case 's':
					$this->rating_count = $k;
					$this->learners     = (int) $row['n'];
					$this->rating_avg   = '' === (string) $row['txt'] || 0 === $k ? null : (float) $row['txt'];
					break;
				case 'r':
					if ( isset( $this->distribution[ $k ] ) ) {
						$this->distribution[ $k ] = (int) $row['n'];
					}
					break;
				case 'l':
				case 'b':
					$aux    = explode( "\x1f", (string) $row['aux'] );
					$lookup = Lookup::from_row(
						array(
							'id'       => $k,
							'slug'     => $aux[0],
							'label'    => (string) $row['txt'],
							'position' => 0,
							'state'    => (int) $row['n'],
							'builtin'  => (int) $row['pos'],
							'color'    => $aux[1] ?? '',
							'icon'     => $aux[2] ?? '',
						)
					);
					if ( 'l' === $row['src'] ) {
						$this->level = $lookup;
					} else {
						$this->badge = $lookup;
					}
					break;
			}
		}
	}

	public function texts_in( string $lang = '' ): array {
		$lang = '' !== $lang ? $lang : Names::display_language();
		if ( ! isset( $this->texts_in[ $lang ] ) ) {
			$defaults = array();
			foreach ( $this->texts as $kind => $html ) {
				$case = CourseTextKind::tryFrom( $kind );
				if ( null !== $case && '' !== $html ) {
					$defaults[ $case->field() ] = $html;
				}
			}
			$this->texts_in[ $lang ] = array() === $defaults ? array() : Services::strings()->translate_fields( TextObject::COURSE, $this->course->id, $defaults, $lang );
		}
		return $this->texts_in[ $lang ];
	}

	public function text( CourseTextKind $kind, string $lang = '' ): string {
		return $this->texts_in( $lang )[ $kind->field() ] ?? '';
	}

	public function points_of( CoursePointKind $kind, string $lang = '' ): array {
		$lang = '' !== $lang ? $lang : Names::display_language();
		if ( ! isset( $this->points_in[ $lang ] ) ) {
			$defaults = array();
			foreach ( $this->points as $list ) {
				foreach ( $list as $point ) {
					$defaults[ $point['id'] ] = $point['text'];
				}
			}
			$texts = array() === $defaults ? array() : Services::strings()->translate_many( TextObject::COURSE_POINT, $defaults, $lang, 'text' );
			$out   = array();
			foreach ( $this->points as $k => $list ) {
				$case = CoursePointKind::tryFrom( (int) $k );
				if ( null !== $case ) {
					$out[ $case->slug() ] = array_map( static fn( array $p ): string => (string) ( $texts[ $p['id'] ] ?? $p['text'] ), $list );
				}
			}
			$this->points_in[ $lang ] = $out;
		}
		return $this->points_in[ $lang ][ $kind->slug() ] ?? array();
	}

	public function level_label( string $lang = '' ): string {
		return null === $this->level ? '' : Services::course_levels()->labels( array( $this->level ), $lang )[ $this->level->id ] ?? '';
	}

	public function badge_now( string $lang = '' ): ?array {
		if ( null === $this->badge || ! $this->course->badge_active( Transaction::now() ) ) {
			return null;
		}
		return array(
			'label' => (string) ( Services::course_badges()->labels( array( $this->badge ), $lang )[ $this->badge->id ] ?? $this->badge->slug ),
			'slug'  => $this->badge->slug,
			'color' => $this->badge->color,
			'icon'  => $this->badge->icon,
		);
	}

	public function approved(): int {
		return (int) array_sum( $this->distribution );
	}

	public function reviews_on(): bool {
		return match ( $this->course->reviews_mode ) {
			1 => false,
			2 => true,
			default => (bool) CommunitySettings::get( 'reviews_enabled' ),
		};
	}

	public function coming_soon(): bool {
		return $this->course->is_coming_soon( Transaction::now() );
	}

	public function hides_details( int $user_id ): bool {
		if ( ! $this->coming_soon() || 0 !== ( $this->course->coming_soon_flags & ComingSoonFlag::SHOW_DETAILS->value ) ) {
			return false;
		}
		return ! Services::course_details()->can_edit( $this->course->id, $user_id );
	}

	public function public_files(): int {
		return (int) ( $this->files[ FileAccess::EVERYONE->value ] ?? 0 );
	}

	public function enrolled_files(): int {
		return (int) ( $this->files[ FileAccess::ENROLLED->value ] ?? 0 );
	}
}