"""
文件管理 API

文件上传、下载和管理 API 端点

API 列表:
- POST   /files           上传文件
- GET    /files           获取文件列表
- GET    /files/{file_id} 下载文件（或获取元数据）
- DELETE /files/{file_id} 删除文件
"""

from typing import Optional

from fastapi import APIRouter, Depends, File, HTTPException, Query, UploadFile
from fastapi.responses import Response

from ....models.schemas.file import (
    FileMetadata,
    FileUploadResponse,
    FileListResponse,
    FileDeleteResponse,
)
from ....models.schemas.common import ErrorResponse
from ....services.file_service import FileService
from ...deps import get_file_service

router = APIRouter()

# 允许的音频 MIME 类型
ALLOWED_AUDIO_TYPES = {
    "audio/wav",
    "audio/wave",
    "audio/x-wav",
    "audio/mpeg",
    "audio/mp3",
    "audio/mp4",
    "audio/aac",
    "audio/ogg",
    "audio/flac",
    "audio/x-flac",
    "audio/webm",
}

# 最大文件大小 (500MB)
MAX_FILE_SIZE = 500 * 1024 * 1024


@router.post(
    "",
    response_model=FileUploadResponse,
    summary="上传文件",
    description="""
上传音频文件用于训练。

**支持的音频格式**:
- WAV
- MP3
- FLAC
- OGG
- AAC
- WebM

**文件大小限制**: 500MB

**用途类型**:
- `training`: 训练音频（默认）
- `reference`: 参考音频
- `output`: 输出文件
""",
    responses={
        200: {"model": FileUploadResponse, "description": "文件上传成功"},
        400: {"model": ErrorResponse, "description": "文件格式或大小不合法"},
    },
)
async def upload_file(
    file: UploadFile = File(..., description="要上传的音频文件"),
    purpose: str = Query(
        "training",
        description="文件用途: training, reference, output"
    ),
    service: FileService = Depends(get_file_service),
) -> FileUploadResponse:
    """
    上传文件
    """
    # 验证用途
    if purpose not in ("training", "reference", "output"):
        raise HTTPException(
            status_code=400,
            detail="无效的用途类型，有效值: training, reference, output"
        )
    
    # 验证文件类型（可选，允许不明确类型的文件）
    content_type = file.content_type
    if content_type and content_type not in ALLOWED_AUDIO_TYPES:
        # 检查文件扩展名
        filename = file.filename or ""
        ext = filename.lower().split(".")[-1] if "." in filename else ""
        allowed_exts = {"wav", "mp3", "flac", "ogg", "aac", "webm", "m4a"}
        if ext not in allowed_exts:
            raise HTTPException(
                status_code=400,
                detail=f"不支持的文件类型: {content_type}。支持的格式: WAV, MP3, FLAC, OGG, AAC, WebM"
            )
    
    # 读取文件内容
    file_data = await file.read()
    
    # 验证文件大小
    if len(file_data) > MAX_FILE_SIZE:
        raise HTTPException(
            status_code=400,
            detail=f"文件过大，最大允许 {MAX_FILE_SIZE // (1024*1024)}MB"
        )
    
    # 验证文件不为空
    if len(file_data) == 0:
        raise HTTPException(
            status_code=400,
            detail="文件为空"
        )
    
    # 上传文件
    return await service.upload_file(
        file_data=file_data,
        filename=file.filename or "audio",
        content_type=content_type,
        purpose=purpose,
    )


@router.get(
    "",
    response_model=FileListResponse,
    summary="获取文件列表",
    description="获取已上传的文件列表，支持按用途筛选和分页。",
)
async def list_files(
    purpose: Optional[str] = Query(
        None,
        description="按用途筛选: training, reference, output"
    ),
    limit: int = Query(50, ge=1, le=100, description="每页数量"),
    offset: int = Query(0, ge=0, description="偏移量"),
    service: FileService = Depends(get_file_service),
) -> FileListResponse:
    """
    获取文件列表
    """
    return await service.list_files(purpose=purpose, limit=limit, offset=offset)


@router.get(
    "/{file_id}",
    summary="下载文件或获取元数据",
    description="""
根据请求类型返回文件内容或元数据。

- 默认返回文件内容（用于下载）
- 添加 `?metadata=true` 参数只返回元数据
""",
    responses={
        200: {
            "description": "文件内容（下载时）或元数据（metadata=true 时）",
        },
        404: {"model": ErrorResponse, "description": "文件不存在"},
    },
)
async def get_file(
    file_id: str,
    metadata: bool = Query(False, description="只返回元数据"),
    service: FileService = Depends(get_file_service),
):
    """
    下载文件或获取元数据
    """
    if metadata:
        # 只返回元数据
        file_metadata = await service.get_file(file_id)
        if not file_metadata:
            raise HTTPException(status_code=404, detail="文件不存在")
        return file_metadata
    else:
        # 下载文件
        result = await service.download_file(file_id)
        if not result:
            raise HTTPException(status_code=404, detail="文件不存在")
        
        file_data, filename, content_type = result
        
        return Response(
            content=file_data,
            media_type=content_type,
            headers={
                "Content-Disposition": f'attachment; filename="{filename}"',
                "Content-Length": str(len(file_data)),
            },
        )


@router.delete(
    "/{file_id}",
    response_model=FileDeleteResponse,
    summary="删除文件",
    description="删除指定的文件。",
    responses={
        200: {"model": FileDeleteResponse, "description": "删除结果"},
        404: {"model": ErrorResponse, "description": "文件不存在"},
    },
)
async def delete_file(
    file_id: str,
    service: FileService = Depends(get_file_service),
) -> FileDeleteResponse:
    """
    删除文件
    """
    result = await service.delete_file(file_id)
    if not result.success:
        raise HTTPException(status_code=404, detail="文件不存在或已删除")
    return result