"""API v3 文件下载服务。

下载用户提供的图片/视频/音频到本地存储。
"""

import base64
import logging
import os
import re
import uuid
from datetime import datetime
from urllib.parse import urlparse

import httpx

from app.config import settings

logger = logging.getLogger("videogen")


def _get_date_str() -> str:
    """获取当前日期字符串。"""
    return datetime.now().strftime("%Y%m%d")


def _get_uploads_dir() -> str:
    """获取上传文件存储目录。"""
    upload_dir = os.path.join(os.path.dirname(settings.STORAGE_LOCAL_PATH), "uploads", "api")
    os.makedirs(upload_dir, exist_ok=True)
    return upload_dir


async def download_file_from_url(url: str, sub_dir: str = "") -> str:
    """从 URL 下载文件到本地。

    Args:
        url: 文件 URL
        sub_dir: 子目录（如 images/videos/audios）

    Returns:
        相对路径: /uploads/api/{sub_dir}/{date}/{filename}
    """
    upload_dir = _get_uploads_dir()
    date_str = _get_date_str()

    # 创建目标目录
    dest_dir = os.path.join(upload_dir, sub_dir, date_str)
    os.makedirs(dest_dir, exist_ok=True)

    # 从 URL 提取扩展名
    parsed = urlparse(url)
    path = parsed.path
    ext = os.path.splitext(path)[1].lower()
    if not ext or len(ext) > 10:
        ext = ".bin"  # 默认扩展名

    # 生成唯一文件名
    filename = f"{uuid.uuid4().hex}{ext}"
    dest_path = os.path.join(dest_dir, filename)

    # 下载文件
    async with httpx.AsyncClient(timeout=300, follow_redirects=True) as client:
        async with client.stream("GET", url) as response:
            response.raise_for_status()
            with open(dest_path, "wb") as f:
                async for chunk in response.aiter_bytes(chunk_size=8192):
                    f.write(chunk)

    # 返回相对路径
    rel_path = f"/uploads/api/{sub_dir}/{date_str}/{filename}"
    logger.info("Downloaded file: %s -> %s", url[:80], rel_path)
    return rel_path


def save_base64_file(data: str, sub_dir: str = "") -> str:
    """保存 Base64 编码的文件到本地。

    Args:
        data: Base64 编码的数据（可包含 data:...;base64, 前缀）
        sub_dir: 子目录

    Returns:
        相对路径: /uploads/api/{sub_dir}/{date}/{filename}
    """
    upload_dir = _get_uploads_dir()
    date_str = _get_date_str()

    # 创建目标目录
    dest_dir = os.path.join(upload_dir, sub_dir, date_str)
    os.makedirs(dest_dir, exist_ok=True)

    # 解析 Base64 数据
    if "," in data:
        header, b64_data = data.split(",", 1)
        # 从 header 提取 MIME 类型
        mime_match = re.search(r"data:([^;]+)", header)
        mime_type = mime_match.group(1) if mime_match else "application/octet-stream"
        # 根据 MIME 类型确定扩展名
        ext_map = {
            "image/jpeg": ".jpg",
            "image/png": ".png",
            "image/webp": ".webp",
            "image/gif": ".gif",
            "video/mp4": ".mp4",
            "video/webm": ".webm",
            "audio/mpeg": ".mp3",
            "audio/wav": ".wav",
            "audio/ogg": ".ogg",
        }
        ext = ext_map.get(mime_type, ".bin")
    else:
        b64_data = data
        ext = ".bin"

    # 解码并保存
    try:
        file_data = base64.b64decode(b64_data)
    except Exception as exc:
        raise ValueError(f"Base64 解码失败: {exc}")

    filename = f"{uuid.uuid4().hex}{ext}"
    dest_path = os.path.join(dest_dir, filename)

    with open(dest_path, "wb") as f:
        f.write(file_data)

    rel_path = f"/uploads/api/{sub_dir}/{date_str}/{filename}"
    logger.info("Saved base64 file: %s (%d bytes)", rel_path, len(file_data))
    return rel_path


async def process_media_url(url: str, media_type: str) -> str:
    """处理媒体 URL：下载到本地或保存 Base64。

    Args:
        url: URL 或 Base64 数据
        media_type: image / video / audio

    Returns:
        相对路径: /uploads/api/{type}/{date}/{filename}
    """
    sub_dir = {"image": "images", "video": "videos", "audio": "audios"}.get(media_type, "files")

    # 判断是 Base64 还是 URL
    if url.startswith("data:"):
        return save_base64_file(url, sub_dir)
    else:
        return await download_file_from_url(url, sub_dir)