<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Builder;
use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\SoftDeletes;
use Illuminate\Support\Str;

class Article extends Model
{
    use HasFactory, SoftDeletes;

    // ==================== Constants ====================

    const STATUS_DRAFT = 'draft';

    const STATUS_PUBLISHED = 'published';

    const STATUS_ARCHIVED = 'archived';

    const ACCESS_LEVEL_PUBLIC = 'public';

    const ACCESS_LEVEL_MEMBERS = 'members';

    const ACCESS_LEVEL_BOARD = 'board';

    const ACCESS_LEVEL_ADMIN = 'admin';

    const CONTENT_TYPE_BLOG = 'blog';

    const CONTENT_TYPE_NOTICE = 'notice';

    const CONTENT_TYPE_DOCUMENT = 'document';

    const CONTENT_TYPE_RELATED_NEWS = 'related_news';

    // ==================== Configuration ====================

    protected $fillable = [
        'title',
        'slug',
        'summary',
        'content',
        'content_type',
        'status',
        'access_level',
        'featured_image_path',
        'featured_image_alt',
        'author_name',
        'author_user_id',
        'meta_description',
        'meta_keywords',
        'is_pinned',
        'display_order',
        'published_at',
        'expires_at',
        'archived_at',
        'view_count',
        'created_by_user_id',
        'last_updated_by_user_id',
    ];

    protected $casts = [
        'is_pinned' => 'boolean',
        'display_order' => 'integer',
        'view_count' => 'integer',
        'meta_keywords' => 'array',
        'published_at' => 'datetime',
        'expires_at' => 'datetime',
        'archived_at' => 'datetime',
    ];

    // ==================== Boot ====================

    protected static function boot()
    {
        parent::boot();

        static::creating(function (Article $article) {
            if (empty($article->slug)) {
                $article->slug = static::generateUniqueSlug($article->title);
            }
        });
    }

    public static function generateUniqueSlug(string $title): string
    {
        $slug = Str::slug($title);

        // For Chinese titles, slug may be empty
        if (empty($slug)) {
            $slug = Str::slug(Str::ascii($title));
        }
        if (empty($slug)) {
            $slug = 'article-'.time();
        }

        $originalSlug = $slug;
        $count = 1;
        while (static::withTrashed()->where('slug', $slug)->exists()) {
            $slug = $originalSlug.'-'.$count++;
        }

        return $slug;
    }

    // ==================== Relationships ====================

    public function categories()
    {
        return $this->belongsToMany(ArticleCategory::class, 'article_category', 'article_id', 'category_id');
    }

    public function tags()
    {
        return $this->belongsToMany(ArticleTag::class, 'article_tag', 'article_id', 'tag_id');
    }

    public function attachments()
    {
        return $this->hasMany(ArticleAttachment::class);
    }

    public function creator()
    {
        return $this->belongsTo(User::class, 'created_by_user_id');
    }

    public function lastUpdatedBy()
    {
        return $this->belongsTo(User::class, 'last_updated_by_user_id');
    }

    public function authorUser()
    {
        return $this->belongsTo(User::class, 'author_user_id');
    }

    // ==================== Status Check Methods ====================

    public function isDraft(): bool
    {
        return $this->status === self::STATUS_DRAFT;
    }

    public function isPublished(): bool
    {
        return $this->status === self::STATUS_PUBLISHED;
    }

    public function isArchived(): bool
    {
        return $this->status === self::STATUS_ARCHIVED;
    }

    public function isPinned(): bool
    {
        return $this->is_pinned;
    }

    public function isExpired(): bool
    {
        if (! $this->expires_at) {
            return false;
        }

        return $this->expires_at->isPast();
    }

    public function isScheduled(): bool
    {
        if (! $this->published_at) {
            return false;
        }

        return $this->published_at->isFuture();
    }

    public function isActive(): bool
    {
        return $this->isPublished()
            && ! $this->isExpired()
            && (! $this->published_at || $this->published_at->isPast());
    }

    // ==================== Access Control Methods ====================

    public function canBeViewedBy(?User $user): bool
    {
        if ($this->isDraft()) {
            if (! $user) {
                return false;
            }

            return $user->id === $this->created_by_user_id
                || $user->hasRole('admin')
                || $user->can('manage_all_articles');
        }

        if ($this->isArchived()) {
            if (! $user) {
                return false;
            }

            return $user->hasRole('admin') || $user->can('manage_all_articles');
        }

        if ($this->isExpired()) {
            if (! $user) {
                return false;
            }

            return $user->hasRole('admin') || $user->can('manage_all_articles');
        }

        if ($this->isScheduled()) {
            if (! $user) {
                return false;
            }

            return $user->id === $this->created_by_user_id
                || $user->hasRole('admin')
                || $user->can('manage_all_articles');
        }

        if ($this->access_level === self::ACCESS_LEVEL_PUBLIC) {
            return true;
        }

        if (! $user) {
            return false;
        }

        if ($user->hasRole('admin')) {
            return true;
        }

        if ($this->access_level === self::ACCESS_LEVEL_MEMBERS) {
            return $user->member && $user->member->hasPaidMembership();
        }

        if ($this->access_level === self::ACCESS_LEVEL_BOARD) {
            return $user->hasRole(['admin', 'finance_chair', 'finance_board_member']);
        }

        if ($this->access_level === self::ACCESS_LEVEL_ADMIN) {
            return $user->hasRole('admin');
        }

        return false;
    }

    public function canBeEditedBy(User $user): bool
    {
        if ($user->hasRole('admin') || $user->can('manage_all_articles')) {
            return true;
        }

        if (! $user->can('edit_articles')) {
            return false;
        }

        return $user->id === $this->created_by_user_id;
    }

    // ==================== Query Scopes ====================

    public function scopePublished(Builder $query): Builder
    {
        return $query->where('status', self::STATUS_PUBLISHED);
    }

    public function scopeDraft(Builder $query): Builder
    {
        return $query->where('status', self::STATUS_DRAFT);
    }

    public function scopeArchived(Builder $query): Builder
    {
        return $query->where('status', self::STATUS_ARCHIVED);
    }

    public function scopeActive(Builder $query): Builder
    {
        return $query->where('status', self::STATUS_PUBLISHED)
            ->where(function ($q) {
                $q->whereNull('published_at')
                    ->orWhere('published_at', '<=', now());
            })
            ->where(function ($q) {
                $q->whereNull('expires_at')
                    ->orWhere('expires_at', '>', now());
            });
    }

    public function scopeByContentType(Builder $query, string $contentType): Builder
    {
        return $query->where('content_type', $contentType);
    }

    public function scopePinned(Builder $query): Builder
    {
        return $query->where('is_pinned', true);
    }

    public function scopeForAccessLevel(Builder $query, ?User $user = null): Builder
    {
        if ($user && $user->hasRole('admin')) {
            return $query;
        }

        $accessLevels = [self::ACCESS_LEVEL_PUBLIC];

        if ($user) {
            if ($user->member && $user->member->hasPaidMembership()) {
                $accessLevels[] = self::ACCESS_LEVEL_MEMBERS;
            }

            if ($user->hasRole(['finance_chair', 'finance_board_member'])) {
                $accessLevels[] = self::ACCESS_LEVEL_BOARD;
            }
        }

        return $query->whereIn('access_level', $accessLevels);
    }

    // ==================== Helper Methods ====================

    public function publish(?User $user = null): void
    {
        $updates = [
            'status' => self::STATUS_PUBLISHED,
        ];

        if (! $this->published_at) {
            $updates['published_at'] = now();
        }

        if ($user) {
            $updates['last_updated_by_user_id'] = $user->id;
        }

        $this->update($updates);
    }

    public function archive(?User $user = null): void
    {
        $updates = [
            'status' => self::STATUS_ARCHIVED,
            'archived_at' => now(),
        ];

        if ($user) {
            $updates['last_updated_by_user_id'] = $user->id;
        }

        $this->update($updates);
    }

    public function pin(?int $order = null, ?User $user = null): void
    {
        $updates = [
            'is_pinned' => true,
            'display_order' => $order ?? 0,
        ];

        if ($user) {
            $updates['last_updated_by_user_id'] = $user->id;
        }

        $this->update($updates);
    }

    public function unpin(?User $user = null): void
    {
        $updates = [
            'is_pinned' => false,
            'display_order' => 0,
        ];

        if ($user) {
            $updates['last_updated_by_user_id'] = $user->id;
        }

        $this->update($updates);
    }

    public function incrementViewCount(): void
    {
        $this->increment('view_count');
    }

    public function getAccessLevelLabel(): string
    {
        return match ($this->access_level) {
            self::ACCESS_LEVEL_PUBLIC => '公開',
            self::ACCESS_LEVEL_MEMBERS => '會員',
            self::ACCESS_LEVEL_BOARD => '理事會',
            self::ACCESS_LEVEL_ADMIN => '管理員',
            default => '未知',
        };
    }

    public function getStatusLabel(): string
    {
        return match ($this->status) {
            self::STATUS_DRAFT => '草稿',
            self::STATUS_PUBLISHED => '已發布',
            self::STATUS_ARCHIVED => '已歸檔',
            default => '未知',
        };
    }

    public function getStatusBadgeColor(): string
    {
        return match ($this->status) {
            self::STATUS_DRAFT => 'gray',
            self::STATUS_PUBLISHED => 'green',
            self::STATUS_ARCHIVED => 'yellow',
            default => 'gray',
        };
    }

    public function getContentTypeLabel(): string
    {
        return match ($this->content_type) {
            self::CONTENT_TYPE_BLOG => '部落格',
            self::CONTENT_TYPE_NOTICE => '公告',
            self::CONTENT_TYPE_DOCUMENT => '文件',
            self::CONTENT_TYPE_RELATED_NEWS => '相關新聞',
            default => '未知',
        };
    }

    public function getExcerpt(int $length = 150): string
    {
        $plainText = strip_tags($this->summary ?: $this->content);

        return Str::limit($plainText, $length);
    }

    public function getFeaturedImageUrlAttribute(): ?string
    {
        if (! $this->featured_image_path) {
            return null;
        }

        // Return relative path for Next.js frontend (images served from public/)
        return '/'.$this->featured_image_path;
    }
}