<?php

declare(strict_types=1);

namespace App\Blog\Services;

use App\Models\Post;
use Illuminate\Support\Facades\Http;
use Illuminate\Support\Str;

/**
 * AI 封面生成：复用「AI 设置」的 LLM 配置调 OpenAI 兼容 /image_generation 接口
 * （如 MiniMax image-01），图片存入 media cover 集合（singleFile，重复生成自动替换）。
 */
class CoverGenerator
{
    public function __construct(private LlmClient $llm) {}

    public function isConfigured(): bool
    {
        return $this->llm->isConfigured();
    }

    public function model(?string $override = null): string
    {
        return $override ?: (string) blog_setting('llm_image_model', 'image-01');
    }

    public function generateFor(Post $post, ?string $model = null, ?string $style = null): void
    {
        if (! $this->llm->isConfigured()) {
            throw new \RuntimeException('LLM 未配置：请先在后台「AI 设置」配置 Base URL / API Key');
        }

        // 站点无常驻 queue worker：同步产出 card 转换，避免缩略图永远卡在队列里。
        config(['media-library.queue_conversions_by_default' => false]);

        $response = $this->requestImage($this->buildPrompt($post, $style), $model);

        // 标题触发内容审核（input new_sensitive）：退化为不含标题的通用提示词重试一次。
        if (str_contains((string) $response->body(), 'sensitive')
            && ! is_string($response->json('data.image_urls.0'))) {
            $response = $this->requestImage($this->neutralPrompt($style), $model);
        }

        if ($response->failed()) {
            throw new \RuntimeException('HTTP '.$response->status().'：'.Str::limit($response->body(), 200));
        }

        $url = $response->json('data.image_urls.0');
        if (! is_string($url) || $url === '') {
            $reason = $response->json('base_resp.status_msg') ?: $response->body();

            throw new \RuntimeException('接口未返回图片：'.Str::limit((string) $reason, 200));
        }

        $image = Http::timeout(60)->get($url)->throw();
        $ext = match (strtolower(explode(';', (string) $image->header('Content-Type'))[0])) {
            'image/png' => 'png',
            'image/webp' => 'webp',
            default => 'jpg',
        };

        $tmp = tempnam(sys_get_temp_dir(), 'cover_');
        file_put_contents($tmp, $image->body());

        try {
            $post->addMedia($tmp)
                ->usingFileName('cover-'.$post->id.'.'.$ext)
                ->toMediaCollection('cover');
        } finally {
            @unlink($tmp);
        }
    }

    public function buildPrompt(Post $post, ?string $style = null): string
    {
        $style = trim((string) ($style
            ?: blog_setting('cover_prompt_style', '扁平插画风格，色调柔和，构图简洁')));
        $excerpt = Str::limit(trim(strip_tags((string) $post->excerpt)), 60, '');

        $parts = ["为博客文章《{$post->title}》生成一张封面配图"];
        if ($excerpt !== '') {
            $parts[] = "内容大意：{$excerpt}";
        }
        $parts[] = $style;
        $parts[] = '画面中不要出现任何文字';

        return implode('。', $parts);
    }

    /**
     * 不含标题/摘要的通用封面提示词（标题触发审核时的兜底）。
     */
    public function neutralPrompt(?string $style = null): string
    {
        $style = trim((string) ($style
            ?: blog_setting('cover_prompt_style', '扁平插画风格，色调柔和，构图简洁')));

        return "博客文章封面配图。{$style}。画面中不要出现任何文字";
    }

    private function requestImage(string $prompt, ?string $model = null): \Illuminate\Http\Client\Response
    {
        return Http::timeout(120)
            ->withToken($this->llm->apiKey())
            ->post($this->llm->baseUrl().'/image_generation', [
                'model' => $this->model($model),
                'prompt' => $prompt,
                'aspect_ratio' => '16:9',
                'response_format' => 'url',
                'n' => 1,
                'prompt_optimizer' => true,
            ]);
    }
}