<?php namespace BookStack\Entities;

use BookStack\Uploads\Image;
use Exception;
use Illuminate\Database\Eloquent\Relations\BelongsTo;
use Illuminate\Database\Eloquent\Relations\BelongsToMany;
use Illuminate\Database\Eloquent\Relations\HasMany;
use Illuminate\Support\Collection;

/**
 * Class Book
 * @property string $description
 * @property int $image_id
 * @property Image|null $cover
 * @package BookStack\Entities
 */
class Book extends Entity implements HasCoverImage
{
    public $searchFactor = 2;

    protected $fillable = ['name', 'description'];
    protected $hidden = ['restricted', 'pivot', 'image_id'];

    /**
     * Get the url for this book.
     * @param string|bool $path
     * @return string
     */
    public function getUrl($path = false)
    {
        if ($path !== false) {
            return url('/books/' . urlencode($this->slug) . '/' . trim($path, '/'));
        }
        return url('/books/' . urlencode($this->slug));
    }

    /**
     * Returns book cover image, if book cover not exists return default cover image.
     * @param int $width - Width of the image
     * @param int $height - Height of the image
     * @return string
     */
    public function getBookCover($width = 440, $height = 250)
    {
        $default = 'data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==';
        if (!$this->image_id) {
            return $default;
        }

        try {
            $cover = $this->cover ? url($this->cover->getThumb($width, $height, false)) : $default;
        } catch (Exception $err) {
            $cover = $default;
        }
        return $cover;
    }

    /**
     * Get the cover image of the book
     */
    public function cover(): BelongsTo
    {
        return $this->belongsTo(Image::class, 'image_id');
    }

    /**
     * Get the type of the image model that is used when storing a cover image.
     */
    public function coverImageTypeKey(): string
    {
        return 'cover_book';
    }

    /**
     * Get all pages within this book.
     * @return HasMany
     */
    public function pages()
    {
        return $this->hasMany(Page::class);
    }

    /**
     * Get the direct child pages of this book.
     * @return HasMany
     */
    public function directPages()
    {
        return $this->pages()->where('chapter_id', '=', '0');
    }

    /**
     * Get all chapters within this book.
     * @return HasMany
     */
    public function chapters()
    {
        return $this->hasMany(Chapter::class);
    }

    /**
     * Get the shelves this book is contained within.
     * @return BelongsToMany
     */
    public function shelves()
    {
        return $this->belongsToMany(Bookshelf::class, 'bookshelves_books', 'book_id', 'bookshelf_id');
    }

    /**
     * Get the direct child items within this book.
     * @return Collection
     */
    public function getDirectChildren(): Collection
    {
        $pages = $this->directPages()->visible()->get();
        $chapters = $this->chapters()->visible()->get();
        return $pages->concat($chapters)->sortBy('priority')->sortByDesc('draft');
    }

    /**
     * Get an excerpt of this book's description to the specified length or less.
     * @param int $length
     * @return string
     */
    public function getExcerpt(int $length = 100)
    {
        $description = $this->description;
        return mb_strlen($description) > $length ? mb_substr($description, 0, $length-3) . '...' : $description;
    }
}