from __future__ import annotations

import os
import re
import shutil
import tempfile
import uuid
from dataclasses import dataclass
from datetime import datetime
from pathlib import Path

from fastapi import HTTPException, UploadFile

from app.config import settings
from app.enums.admin_upload import (
    ADMIN_UPLOAD_AUDIO_EXTENSIONS,
    ADMIN_UPLOAD_AUDIO_MAX_BYTES,
    ADMIN_UPLOAD_FILE_MAX_BYTES,
    ADMIN_UPLOAD_FILE_NAME_MAX_LEN,
    ADMIN_UPLOAD_IMAGE_EXTENSIONS,
    ADMIN_UPLOAD_IMAGE_MAX_BYTES,
    ADMIN_UPLOAD_PDF_EXTENSIONS,
    ADMIN_UPLOAD_PDF_MAX_BYTES,
    ADMIN_UPLOAD_VIDEO_EXTENSIONS,
    ADMIN_UPLOAD_VIDEO_MAX_BYTES,
    AdminUploadResourceTypeEnum,
    AdminUploadSceneEnum,
)

CHUNK_SIZE = 1024 * 1024


@dataclass(slots=True)
class StoredAdminUploadFile:
    storage_path: str
    file_url: str
    file_name: str
    original_file_name: str | None
    file_size_bytes: int


def _upload_root() -> Path:
    return Path(settings.UPLOAD_LOCAL_PATH).resolve()


def _safe_original_name(filename: str | None) -> str | None:
    if not filename:
        return None
    name = Path(filename).name.strip()
    name = re.sub(r"[\\/\r\n\t]+", "_", name)
    return name[:ADMIN_UPLOAD_FILE_NAME_MAX_LEN] or None


def _ext(filename: str | None) -> str:
    return Path(filename or "").suffix.lower()


def _allowed_extensions(resource_type: AdminUploadResourceTypeEnum) -> set[str] | None:
    if resource_type == AdminUploadResourceTypeEnum.IMAGE:
        return ADMIN_UPLOAD_IMAGE_EXTENSIONS
    if resource_type == AdminUploadResourceTypeEnum.VIDEO:
        return ADMIN_UPLOAD_VIDEO_EXTENSIONS
    if resource_type == AdminUploadResourceTypeEnum.AUDIO:
        return ADMIN_UPLOAD_AUDIO_EXTENSIONS
    if resource_type == AdminUploadResourceTypeEnum.PDF:
        return ADMIN_UPLOAD_PDF_EXTENSIONS
    return None


def _max_bytes(resource_type: AdminUploadResourceTypeEnum) -> int:
    if resource_type == AdminUploadResourceTypeEnum.IMAGE:
        return ADMIN_UPLOAD_IMAGE_MAX_BYTES
    if resource_type == AdminUploadResourceTypeEnum.VIDEO:
        return ADMIN_UPLOAD_VIDEO_MAX_BYTES
    if resource_type == AdminUploadResourceTypeEnum.AUDIO:
        return ADMIN_UPLOAD_AUDIO_MAX_BYTES
    if resource_type == AdminUploadResourceTypeEnum.PDF:
        return ADMIN_UPLOAD_PDF_MAX_BYTES
    return ADMIN_UPLOAD_FILE_MAX_BYTES


def validate_file_name(filename: str | None, resource_type: AdminUploadResourceTypeEnum) -> str:
    safe_name = _safe_original_name(filename)
    if not safe_name:
        raise HTTPException(status_code=400, detail="请选择文件")
    allowed = _allowed_extensions(resource_type)
    ext = _ext(safe_name)
    if allowed is not None and ext not in allowed:
        if resource_type == AdminUploadResourceTypeEnum.IMAGE:
            raise HTTPException(status_code=400, detail="仅支持 jpg/jpeg/png/webp/gif 图片")
        if resource_type == AdminUploadResourceTypeEnum.VIDEO:
            raise HTTPException(status_code=400, detail="仅支持 mp4/mov/m4v/webm 视频")
        if resource_type == AdminUploadResourceTypeEnum.AUDIO:
            raise HTTPException(status_code=400, detail="仅支持 mp3/wav/m4a/aac 音频")
        if resource_type == AdminUploadResourceTypeEnum.PDF:
            raise HTTPException(status_code=400, detail="仅支持 PDF 文件")
    return safe_name


def _kind_dir(resource_type: AdminUploadResourceTypeEnum) -> str:
    if resource_type == AdminUploadResourceTypeEnum.IMAGE:
        return "images"
    if resource_type == AdminUploadResourceTypeEnum.VIDEO:
        return "videos"
    if resource_type == AdminUploadResourceTypeEnum.AUDIO:
        return "audios"
    return "files"


def _scene_base_dir(scene: AdminUploadSceneEnum, resource_type: AdminUploadResourceTypeEnum) -> Path:
    if scene == AdminUploadSceneEnum.HOME_MATERIAL_REFERENCE:
        if resource_type not in {AdminUploadResourceTypeEnum.IMAGE, AdminUploadResourceTypeEnum.VIDEO, AdminUploadResourceTypeEnum.AUDIO}:
            raise HTTPException(status_code=400, detail="首页素材附件仅支持图片、视频、音频")
        return Path("home_materials") / "references" / _kind_dir(resource_type)
    if scene == AdminUploadSceneEnum.SYSTEM_LOGO:
        if resource_type != AdminUploadResourceTypeEnum.IMAGE:
            raise HTTPException(status_code=400, detail="系统Logo仅支持图片")
        return Path("admin_uploads") / "system_logo" / "images"
    if scene == AdminUploadSceneEnum.SYSTEM_PDF:
        if resource_type != AdminUploadResourceTypeEnum.PDF:
            raise HTTPException(status_code=400, detail="系统PDF仅支持PDF文件")
        return Path("admin_uploads") / "system_pdf" / "files"
    if scene == AdminUploadSceneEnum.OPEN_TYPE_THUMB:
        if resource_type != AdminUploadResourceTypeEnum.IMAGE:
            raise HTTPException(status_code=400, detail="开户方式缩略图仅支持图片")
        return Path("admin_uploads") / "open_type_thumb" / "images"
    return Path("admin_uploads") / "common" / _kind_dir(resource_type)


def build_target(scene: AdminUploadSceneEnum, resource_type: AdminUploadResourceTypeEnum, admin_id: str, original_filename: str | None) -> tuple[Path, str, str]:
    safe_original = validate_file_name(original_filename, resource_type)
    now = datetime.now()
    date_dir = now.strftime("%Y/%m/%d")
    timestamp = now.strftime("%Y%m%d_%H%M%S")
    suffix = uuid.uuid4().hex[:8]
    ext = _ext(safe_original)
    prefix = {
        AdminUploadResourceTypeEnum.IMAGE: "admin_img",
        AdminUploadResourceTypeEnum.VIDEO: "admin_video",
        AdminUploadResourceTypeEnum.AUDIO: "admin_audio",
        AdminUploadResourceTypeEnum.PDF: "admin_pdf",
    }.get(resource_type, "admin_file")
    file_name = f"{prefix}_{admin_id}_{timestamp}_{suffix}{ext}"
    rel_dir = _scene_base_dir(scene, resource_type) / date_dir
    storage_path = _upload_root() / rel_dir / file_name
    file_url = f"/uploads/{(rel_dir / file_name).as_posix()}"
    return storage_path, file_url, file_name


async def save_upload_file(file: UploadFile, *, scene: AdminUploadSceneEnum, resource_type: AdminUploadResourceTypeEnum, admin_id: str) -> StoredAdminUploadFile:
    original_file_name = validate_file_name(file.filename, resource_type)
    max_bytes = _max_bytes(resource_type)
    fd, temp_path = tempfile.mkstemp(prefix="admin_upload_", suffix=".tmp")
    total = 0
    final_path: Path | None = None
    try:
        with os.fdopen(fd, "wb") as out:
            while True:
                chunk = await file.read(CHUNK_SIZE)
                if not chunk:
                    break
                total += len(chunk)
                if total > max_bytes:
                    raise HTTPException(status_code=400, detail=f"文件大小不能超过 {max_bytes // 1024 // 1024}MB")
                out.write(chunk)
        final_path, file_url, file_name = build_target(scene, resource_type, admin_id, original_file_name)
        final_path.parent.mkdir(parents=True, exist_ok=True)
        shutil.move(temp_path, final_path)
        temp_path = ""
        return StoredAdminUploadFile(
            storage_path=str(final_path),
            file_url=file_url,
            file_name=file_name,
            original_file_name=original_file_name,
            file_size_bytes=total,
        )
    except Exception:
        if temp_path:
            try:
                os.remove(temp_path)
            except OSError:
                pass
        if final_path and final_path.exists():
            try:
                final_path.unlink()
            except OSError:
                pass
        raise