import os
import uuid
from pathlib import Path
from typing import Optional
from fastapi import APIRouter, UploadFile, File, HTTPException, status, Depends
from fastapi.responses import FileResponse
from app.dependencies import get_current_user, get_optional_current_user
from app.models.user import User

router = APIRouter(prefix="/api/uploads", tags=["uploads"])

# Storage directory for uploaded images
# Use relative path from project root to work in both dev and production
STORAGE_DIR = Path(__file__).resolve().parent.parent.parent / "storage" / "images"
STORAGE_DIR.mkdir(parents=True, exist_ok=True)

# Allowed image types
ALLOWED_EXTENSIONS = {".jpg", ".jpeg", ".png", ".gif", ".webp", ".bmp"}
ALLOWED_MIME_TYPES = {
    "image/jpeg",
    "image/png",
    "image/gif",
    "image/webp",
    "image/bmp"
}

# Maximum file size: 8MB
MAX_FILE_SIZE = 8 * 1024 * 1024


@router.post("/image")
async def upload_image(
    file: UploadFile = File(...),
    current_user: User = Depends(get_current_user)
):
    """
    Upload an image file.
    Returns the file path that can be used to retrieve the image.
    """
    # Validate file type by MIME type
    if file.content_type not in ALLOWED_MIME_TYPES:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail=f"Invalid file type. Allowed types: {', '.join(ALLOWED_MIME_TYPES)}"
        )

    # Read file content
    content = await file.read()

    # Validate file size
    if len(content) > MAX_FILE_SIZE:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail=f"File too large. Maximum size is 8MB."
        )

    # Get file extension
    original_extension = Path(file.filename).suffix.lower()
    if original_extension not in ALLOWED_EXTENSIONS:
        # Fallback to MIME type mapping
        mime_to_ext = {
            "image/jpeg": ".jpg",
            "image/png": ".png",
            "image/gif": ".gif",
            "image/webp": ".webp",
            "image/bmp": ".bmp"
        }
        original_extension = mime_to_ext.get(file.content_type, ".jpg")

    # Generate random filename
    random_filename = f"{uuid.uuid4()}{original_extension}"
    file_path = STORAGE_DIR / random_filename

    # Save file
    try:
        with open(file_path, "wb") as f:
            f.write(content)
    except Exception as e:
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=f"Failed to save file: {str(e)}"
        )

    # Return the relative path
    return {
        "filename": random_filename,
        "path": f"/api/uploads/image/{random_filename}",
        "size": len(content)
    }


@router.get("/image/{filename}")
async def get_image(
    filename: str,
    current_user: Optional[User] = Depends(get_optional_current_user)
):
    """
    Retrieve an uploaded image.
    Public endpoint - requires either authenticated user or valid share token.
    """
    # Validate filename to prevent directory traversal
    if ".." in filename or "/" in filename or "\\" in filename:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Invalid filename"
        )

    file_path = STORAGE_DIR / filename

    # Check if file exists
    if not file_path.exists() or not file_path.is_file():
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Image not found"
        )

    # Determine media type based on extension
    extension = file_path.suffix.lower()
    media_type_map = {
        ".jpg": "image/jpeg",
        ".jpeg": "image/jpeg",
        ".png": "image/png",
        ".gif": "image/gif",
        ".webp": "image/webp",
        ".bmp": "image/bmp"
    }
    media_type = media_type_map.get(extension, "application/octet-stream")

    return FileResponse(file_path, media_type=media_type)


@router.delete("/image/{filename}")
async def delete_image(
    filename: str,
    current_user: User = Depends(get_current_user)
):
    """
    Delete an uploaded image.
    Requires authentication.
    """
    # Validate filename to prevent directory traversal
    if ".." in filename or "/" in filename or "\\" in filename:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Invalid filename"
        )

    file_path = STORAGE_DIR / filename

    # Check if file exists
    if not file_path.exists() or not file_path.is_file():
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Image not found"
        )

    # Delete file
    try:
        os.remove(file_path)
    except Exception as e:
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=f"Failed to delete file: {str(e)}"
        )

    return {"message": "Image deleted successfully"}