import type {
    CreateMediaUploadIntentRequest,
    MediaAccessUrl,
    MediaAsset,
    MediaUploadIntent,
} from '@atlas/contracts';
import { api } from '@/services/api';

/** 水印图片的用途与限制（docs/api/watermarks-and-assets.md §1） */
export const WATERMARK_IMAGE_ACCEPT = '.jpg,.jpeg,.png,.webp';
export const WATERMARK_IMAGE_MAX_BYTES = 5 * 1024 * 1024;

/** 异步操作查询，契约见 docs/api/conventions.md §5（GET /api/operations/{operation_id}） */
export const mediaApi = {
    createUploadIntent: (payload: CreateMediaUploadIntentRequest) =>
        api.post<MediaUploadIntent>('/media/upload-intents', payload, {
            headers: { 'Idempotency-Key': crypto.randomUUID() },
        }),

    completeUpload: (uploadId: string, checksumSha256: string) =>
        api.post<{ asset: MediaAsset }>(
            `/media/upload-intents/${uploadId}/complete`,
            { checksum_sha256: checksumSha256 },
            { headers: { 'Idempotency-Key': crypto.randomUUID() } }
        ),

    /** 短时预览 URL：过期后重新请求，不能写回业务表或长期缓存 */
    createPreviewUrl: (assetId: string) =>
        api.post<MediaAccessUrl>(
            `/media-assets/${assetId}/access-urls`,
            { purpose: 'preview' },
            { headers: { 'Idempotency-Key': crypto.randomUUID() } }
        ),
};

/** 浏览器端计算文件的 SHA-256 十六进制摘要（complete 校验用） */
export async function sha256Hex(file: File): Promise<string> {
    const digest = await crypto.subtle.digest('SHA-256', await file.arrayBuffer());
    return Array.from(new Uint8Array(digest))
        .map((byte) => byte.toString(16).padStart(2, '0'))
        .join('');
}

/**
 * 图片水印素材三步直传（docs/api/watermarks-and-assets.md §1）：
 * 创建上传意图 → 按返回的 method/url/headers 原样 PUT 到对象存储 → 完成校验换取素材。
 * 返回已通过校验的素材，可直接用于图片水印模板的 image_asset_id。
 */
export async function uploadWatermarkImage(file: File): Promise<MediaAsset> {
    const checksumSha256 = await sha256Hex(file);
    const intent = await mediaApi.createUploadIntent({
        purpose: 'watermark_image',
        filename: file.name,
        content_type: file.type as CreateMediaUploadIntentRequest['content_type'],
        byte_size: file.size,
        checksum_sha256: checksumSha256,
    });

    // 必须以服务端返回的 method、URL 与 headers 原样上传，不能自行拼接对象路径
    const putResponse = await fetch(intent.upload.url, {
        method: intent.upload.method,
        headers: intent.upload.headers,
        body: file,
    });
    if (!putResponse.ok) {
        throw new Error(`图片上传到对象存储失败（HTTP ${putResponse.status}）`);
    }

    const completed = await mediaApi.completeUpload(intent.upload_id, checksumSha256);
    return completed.asset;
}