<?php

namespace App\Services;

use App\Library\Contracts\TemplateSubjectInterface;
use App\Model\Email;
use App\Model\Template;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;
use Illuminate\Support\Facades\Schema;
use InvalidArgumentException;

class TemplateService
{
    private Model $subject;

    private function __construct(TemplateSubjectInterface $subject)
    {
        if (!$subject instanceof Model) {
            throw new InvalidArgumentException('TemplateService subjects must be Eloquent models');
        }

        $relation = $subject->template();

        if (!$relation instanceof BelongsTo) {
            throw new InvalidArgumentException('TemplateService requires a belongsTo template() relation');
        }

        if ($relation->getForeignKeyName() !== 'template_id') {
            throw new InvalidArgumentException('TemplateService requires template() to use template_id as the foreign key');
        }

        $this->subject = $subject;
    }

    public static function for(TemplateSubjectInterface $subject): self
    {
        return new self($subject);
    }

    public function setTemplate(Template $template, string $name): Template
    {
        $this->propagateNameToSubject($name);

        $copy = $template->copyAsPrivate([
            'name' => $name,
            'customer_id' => $this->subject->getAttribute('customer_id'),
        ]);

        return $this->replaceWithTemplate($copy);
    }

    public function replaceWithTemplate(Template $template): Template
    {
        $currentTemplate = $this->subject->template;

        $this->subject->template()->associate($template);
        $this->subject->save();
        $this->subject->refresh();

        if ($currentTemplate && !$currentTemplate->is($template)) {
            $currentTemplate->deleteAndCleanup();
        }

        return $this->subject->template;
    }

    public function setCustomHtml(string $html, string $name): Template
    {
        $this->propagateNameToSubject($name);

        $template = Template::makeUploaded(name: $name, html: $html);
        $template->save();

        return $this->replaceWithTemplate($template);
    }

    /**
     * Write $name to the subject's `name` column if it has one. Email uses `subject`
     * for its label, so we skip it; MailListTemplate has no name column either.
     */
    private function propagateNameToSubject(string $name): void
    {
        static $cache = [];
        $class = get_class($this->subject);
        $cache[$class] ??= Schema::hasColumn($this->subject->getTable(), 'name');
        if ($cache[$class]) {
            $this->subject->setAttribute('name', $name);
        }
    }

    public function removeTemplate(): void
    {
        $currentTemplate = $this->subject->template;

        if (!$currentTemplate) {
            return;
        }

        $this->subject->template()->dissociate();
        $this->subject->save();
        $this->subject->unsetRelation('template');

        $currentTemplate->deleteAndCleanup();
        $this->subject->refresh();
    }

    public function deleteSubjectAndTemplate(): void
    {
        $currentTemplate = $this->subject->template;

        if ($currentTemplate) {
            $currentTemplate->deleteAndCleanup();
        }

        if ($this->subject->getKey() && $this->subject->newQuery()->whereKey($this->subject->getKey())->exists()) {
            $this->subject->delete();
        }
    }
}