from __future__ import annotations

import os
from dataclasses import dataclass
from datetime import datetime

from app.config import settings
from app.models.chat_generation_task import ChatGenerationTask
from app.services.image_gen import download_image
from app.services.provider_limit import provider_limit
from app.services.resource_accounting_service import safe_file_size
from app.services.video_gen import download_video


@dataclass(slots=True)
class DownloadedGenerationResult:
    url: str
    storage_path: str | None
    file_size_bytes: int
    resource_type: str
    storage_type: str = "local"


async def download_generation_result(record: ChatGenerationTask) -> DownloadedGenerationResult:
    if not record.remote_result_url:
        raise ValueError("缺少远程结果URL")

    date_dir = datetime.now().strftime("%Y/%m/%d")
    if record.gen_type == "image":
        dest_dir = os.path.join(settings.STORAGE_IMAGE_LOCAL_PATH, date_dir)
        os.makedirs(dest_dir, exist_ok=True)
        dest = os.path.join(dest_dir, f"{record.id}.png")
        async with provider_limit("result_download", settings.RESULT_DOWNLOAD_MAX_CONCURRENCY):
            await download_image(record.remote_result_url, dest)
        return DownloadedGenerationResult(
            url=f"/generate/images/{date_dir}/{record.id}.png",
            storage_path=dest,
            file_size_bytes=safe_file_size(dest),
            resource_type="image",
        )

    dest_dir = os.path.join(settings.STORAGE_LOCAL_PATH, date_dir)
    os.makedirs(dest_dir, exist_ok=True)
    dest = os.path.join(dest_dir, f"{record.id}.mp4")
    async with provider_limit("result_download", settings.RESULT_DOWNLOAD_MAX_CONCURRENCY):
        await download_video(record.remote_result_url, dest)
    return DownloadedGenerationResult(
        url=f"/generate/videos/{date_dir}/{record.id}.mp4",
        storage_path=dest,
        file_size_bytes=safe_file_size(dest),
        resource_type="video",
    )