<?php
namespace Digiter\BuilderStudio;
defined('ABSPATH') || exit;

/** Linked visual styles, site-scoped, with optimistic concurrency protection. */
final class GlobalStyles {
    private const OPTION='digibl_global_styles';
    public function __construct(){add_action('rest_api_init',[$this,'routes']);}
    public static function state(): array {
        $state=get_option(self::OPTION,[]);
        return is_array($state)&&isset($state['revision'],$state['items'])?$state:['revision'=>'','items'=>[]];
    }
    public static function keys(): array {
        $keys=[];foreach(StylePresets::groups() as $group){$keys=array_merge($keys,$group['keys']);}return array_values(array_unique($keys));
    }
    public static function resolve(array $style): array {
        $id=$style['globalStyle']??'';
        if(!$id){return $style;}
        $item=self::state()['items'][$id]??null;
        if(!$item){return $style;}
        $overrides=array_fill_keys($style['globalOverrides']??[],true);
        foreach($item['style'] as $key=>$value){if(!isset($overrides[$key])){$style[$key]=$value;}}
        return $style;
    }
    private static function response(array $state): \WP_REST_Response {
        $response=new \WP_REST_Response(['revision'=>$state['revision'],'items'=>array_values($state['items']),'canRestore'=>isset($state['previous'])]);
        $response->header('Cache-Control','no-store, private');return $response;
    }
    public function routes(): void {
        register_rest_route('digiter-builder/v1','/global-styles',[
            ['methods'=>'GET','permission_callback'=>static fn()=>PostTypes::can_edit(),'callback'=>static fn()=>self::response(self::state())],
            ['methods'=>'POST','permission_callback'=>static fn()=>current_user_can('manage_options'),'callback'=>[$this,'save']],
        ]);
        register_rest_route('digiter-builder/v1','/global-styles/(?P<id>[a-f0-9-]{36})',[
            'methods'=>'DELETE','permission_callback'=>static fn()=>current_user_can('manage_options'),'callback'=>[$this,'remove'],
        ]);
        register_rest_route('digiter-builder/v1','/global-styles/restore',[
            'methods'=>'POST','permission_callback'=>static fn()=>current_user_can('manage_options'),'callback'=>function($request){
                $state=self::state();$revision=$request->get_param('revision');
                if(!is_string($revision)||!isset($state['previous']['items'])){return self::error('No previous global styles are available.');}
                return self::commit(['items'=>$state['previous']['items']],$revision);
            },
        ]);
    }
    private static function error(string $message,int $status=400): \WP_Error {return new \WP_Error('digibl_global_style',$message,['status'=>$status]);}
    private static function commit(array $state,string $revision) {
        global $wpdb;
        wp_cache_delete(self::OPTION,'options');$stored=get_option(self::OPTION,false);$current=self::state();
        if(!hash_equals((string)$current['revision'],$revision)){return self::error('Global styles changed in another session. Reload before saving.',409);}
        $state['revision']=wp_generate_uuid4();
        $state['previous']=['items'=>$current['items']];
        if($stored===false){$success=add_option(self::OPTION,$state,'',false);}
        else{$success=1===$wpdb->update($wpdb->options,['option_value'=>maybe_serialize($state)],['option_name'=>self::OPTION,'option_value'=>maybe_serialize($stored)],['%s'],['%s','%s']);}
        wp_cache_delete(self::OPTION,'options');
        if(!$success){return self::error('Global styles could not be saved or changed concurrently. Reload and retry.',409);}
        do_action('digibl_global_styles_changed',$state);
        return self::response($state);
    }
    public function save($request) {
        $name=$request->get_param('name');$style=$request->get_param('style');$revision=$request->get_param('revision');$id=$request->get_param('id');
        if(!is_string($name)||!($name=Document::text($name,100))||!is_array($style)||!is_string($revision)){return self::error('A name, visual style and revision are required.');}
        if(strlen((string)wp_json_encode($style))>60000){return self::error('This global style is too large.',413);}
        $visual=StylePresets::visual($style);if(!$visual){return self::error('Choose at least one visual style property.');}
        $doc=Document::blank();$doc['nodes']=[['id'=>'style','type'=>'heading','props'=>[],'style'=>$visual,'children'=>[]]];
        $clean=Document::clean($doc);if(is_wp_error($clean)){return $clean;}
        $state=self::state();
        if($id!==null){if(!is_string($id)||!isset($state['items'][$id])){return self::error('This global style is unavailable.',404);}}
        else{if(count($state['items'])>=50){return self::error('Use at most 50 linked global styles.',409);}$id=wp_generate_uuid4();}
        $state['items'][$id]=['id'=>$id,'name'=>$name,'style'=>array_intersect_key(StylePresets::visual($clean['nodes'][0]['style']),$visual),'updated'=>gmdate('c')];
        return self::commit($state,$revision);
    }
    public function remove($request) {
        $revision=$request->get_param('revision');$id=(string)$request->get_url_params()['id'];$state=self::state();
        if(!is_string($revision)){return self::error('A revision is required.');}
        if(!isset($state['items'][$id])){return self::error('This global style is unavailable.',404);}
        unset($state['items'][$id]);return self::commit($state,$revision);
    }
}