'''
🗄️ PostgreSQL Database Integration

Database Tables:
users - Stores user_id, api_key, and creation timestamp
files - Stores file metadata with foreign key to users
Automatic cascading delete when user is removed
Indexed columns for fast lookups

Stored Information:
API keys and user IDs
File metadata (name, size, path, upload date)
User-file relationships

📁 File Organization
Directory Structure:
uploads/
├── user-id-1/
│   ├── file-id-1_document.pdf
│   └── file-id-2_image.jpg
└── user-id-2/
    └── file-id-3_data.csv
Each user gets their own subdirectory for better organization and isolation.

⚙️ Setup Instructions

Install dependencies:
bashpip install fastapi uvicorn python-multipart asyncpg

Set up PostgreSQL database:
bash# Create database
createdb fileserver

# Set DATABASE_URL environment variable
export DATABASE_URL="postgresql://username:password@localhost:5432/fileserver"

Run the server:
bashpython script_name.py

The database tables will be created automatically on startup!
🔑 Key Features

✅ All data persists in PostgreSQL
✅ Files organized in user-specific subdirectories
✅ Automatic database initialization
✅ Connection pooling for better performance
✅ Proper foreign key relationships with cascade delete
✅ Timestamps for all uploads

The DATABASE_URL can be configured via environment variable for different environments (development, production, etc.).
'''
import random
import string
import sys
from fastapi import FastAPI, File, UploadFile, HTTPException, Header, Depends
from fastapi.responses import FileResponse, HTMLResponse
from fastapi.security import APIKeyHeader
from pathlib import Path
import shutil
import os
from typing import List, Optional
import uuid
import secrets
from datetime import datetime
import asyncpg
from contextlib import asynccontextmanager
import app_config

ERROR_STATUS_NO_DB_URL = 10
STYLE_MACRO = "#$STYLE$#"
SCRIPT_MACRO = "#$SCRIPT$#"

# Database configuration
app_config.init_config()
DATABASE_URL = app_config.DB_URL

# Global database pool
db_pool: asyncpg.Pool | None = None

@asynccontextmanager
async def lifespan(app: FastAPI):
    """Checking DB URL"""
    global DATABASE_URL
    if not DATABASE_URL:
        DATABASE_URL = os.getenv("DATABASE_URL", "")
    if not DATABASE_URL:
        print('DB URL does not set. DB URL is a mandatory variable.\nPlease provide it in config file or as a environment variable and restart the server')
        sys.exit(ERROR_STATUS_NO_DB_URL)

    """Manage application lifespan - startup and shutdown"""
    global db_pool

    # Startup: Create database pool and initialize tables
    db_pool = await asyncpg.create_pool(DATABASE_URL, min_size=2, max_size=10)
    await init_database()
    print("✅ Database connected and initialized")

    yield

    # Shutdown: Close database pool
    await db_pool.close()
    print("👋 Database connection closed")


app = FastAPI(
    title="Das File Server",
    description="Upload, save, and download files with API key authentication",
    lifespan=lifespan,
    openapi_url="/api/v1/openapi.json" if app_config.IS_DOCS_AVAILABLE else None
)

# Configure upload directory
UPLOAD_DIR = Path(app_config.UPLOAD_DIR)
UPLOAD_DIR.mkdir(exist_ok=True)

# API Key header
api_key_header = APIKeyHeader(name="X-API-Key", auto_error=False)


async def init_database():
    """Initialize database tables"""
    async with db_pool.acquire() as conn:
        # Create users table
        await conn.execute("""
            CREATE TABLE IF NOT EXISTS users (
                user_id UUID PRIMARY KEY,
                api_key VARCHAR(255) UNIQUE NOT NULL,
                alias VARCHAR(32) UNIQUE NOT NULL,
                created_at TIMESTAMP DEFAULT NOW()
            )
        """)

        # Create files table
        await conn.execute("""
            CREATE TABLE IF NOT EXISTS files (
                file_id UUID PRIMARY KEY,
                user_id UUID NOT NULL REFERENCES users(user_id) ON DELETE CASCADE,
                original_name VARCHAR(500) NOT NULL,
                stored_name VARCHAR(500) NOT NULL,
                file_path TEXT NOT NULL,
                size BIGINT NOT NULL,
                uploaded_at TIMESTAMP DEFAULT NOW(),
                CONSTRAINT fk_user FOREIGN KEY (user_id) REFERENCES users(user_id)
            )
        """)

        # Create index for faster lookups
        await conn.execute("""
            CREATE INDEX IF NOT EXISTS idx_files_user_id ON files(user_id)
        """)
        await conn.execute("""
            CREATE INDEX IF NOT EXISTS idx_users_api_key ON users(api_key)
        """)


async def get_user_id(api_key: Optional[str] = Depends(api_key_header)) -> str:
    """Validate API key and return user ID"""
    if not api_key:
        raise HTTPException(status_code=401, detail="Missing API key")

    async with db_pool.acquire() as conn:
        user = await conn.fetchrow(
            "SELECT user_id FROM users WHERE api_key = $1",
            api_key
        )

        if not user:
            raise HTTPException(status_code=401, detail="Invalid API key")

        return str(user['user_id'])


def get_user_directory(user_id: str) -> Path:
    """Get or create user's subdirectory"""
    user_dir = UPLOAD_DIR / user_id
    user_dir.mkdir(exist_ok=True)
    return user_dir


def get_file_content(file_name):
    try:
        with open(file_name, 'r') as file:
            file_content = file.read()
        return file_content
    except FileNotFoundError:
        print(f"Error: The file '{file_name}' was not found.")
    except Exception as e:
        print(f"An error occurred: {e}")


@app.get("/", response_class=HTMLResponse)
async def home():
    """Serve the web interface"""
    css = get_file_content(app_config.CSS_FILE)
    js = get_file_content(app_config.JS_FILE)
    return (get_file_content(app_config.HTML_FILE)
            .replace(STYLE_MACRO, css)
            .replace(SCRIPT_MACRO, js))


@app.post("/new-key")
@app.get("/new-key")
async def generate_key():
    """Generate a new API key for a user"""
    api_key = secrets.token_urlsafe(32)
    try:
        return {
            "api_key": api_key,
            "message": "New API key generated successfully."
        }
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"Failed to generate API key: {str(e)}")


@app.post("/new-alias")
@app.get("/new-alias")
async def generate_alias():
    """Generate a new alias"""
    return {
        "alias": await get_alias(),
        "message": "New Alias generated successfully."
    }

async def get_all_aliases():
    async with db_pool.acquire() as conn:
        aliases = await conn.fetch("""
            SELECT alias FROM users
        """)
        return aliases

async def get_alias():
    """Getting the alias"""
    existing_aliases = await get_all_aliases()
    alias = existing_aliases[0] if existing_aliases else ""
    while alias in existing_aliases or alias == "":
        num_letters = app_config.ALIAS_NUM_LETTERS
        num_digits = app_config.ALIAS_NUM_DIGITS
        letters = [random.choice(string.ascii_letters) for _ in range(num_letters)]
        digits = [random.choice(string.digits) for _ in range(num_digits)]
        res_list = letters + digits
        #random.shuffle(res_list)
        alias = ''.join(res_list)
    return alias


@app.post("/add-user")
async def add_new_user():
    """Add new user with new API key"""
    # Generate secure random API key
    api_key = secrets.token_urlsafe(32)
    user_id = uuid.uuid4()
    user_alias = get_alias()

    async with db_pool.acquire() as conn:
        try:
            # Store API key in database
            await conn.execute(
                "INSERT INTO users (user_id, api_key) VALUES ($1, $2, $3)",
                user_id, api_key, user_alias
            )

            # Create user's directory
            get_user_directory(str(user_id))

            return {
                "api_key": api_key,
                "user_id": str(user_id),
                "message": "API key generated successfully. Keep it secure!"
            }
        except Exception as e:
            raise HTTPException(status_code=500, detail=f"Failed to generate API key: {str(e)}")


@app.post("/upload")
async def upload_files(
        files: List[UploadFile] = File(...),
        user_id: str = Depends(get_user_id)
):
    """Upload one or multiple files (requires API key)"""
    uploaded_files = []
    user_dir = get_user_directory(user_id)

    async with db_pool.acquire() as conn:
        for file in files:
            # Generate unique ID for file
            file_id = uuid.uuid4()
            stored_name = f"{file_id}_{file.filename}"
            file_path = user_dir / stored_name

            # Save file
            try:
                with open(file_path, "wb") as buffer:
                    shutil.copyfileobj(file.file, buffer)

                file_size = os.path.getsize(file_path)

                # Store metadata in database
                await conn.execute("""
                    INSERT INTO files (file_id, user_id, original_name, stored_name, file_path, size)
                    VALUES ($1, $2, $3, $4, $5, $6)
                """, file_id, uuid.UUID(user_id), file.filename, stored_name, str(file_path), file_size)

                uploaded_files.append({
                    "id": str(file_id),
                    "filename": file.filename,
                    "size": file_size
                })
            except Exception as e:
                # Clean up file if database insert fails
                if file_path.exists():
                    os.remove(file_path)
                raise HTTPException(status_code=500, detail=f"Failed to upload {file.filename}: {str(e)}")

    return {"message": "Files uploaded successfully", "files": uploaded_files}


@app.get("/files")
async def list_files(user_id: str = Depends(get_user_id)):
    """List all files for the authenticated user"""
    async with db_pool.acquire() as conn:
        files = await conn.fetch("""
            SELECT file_id, original_name, size, uploaded_at
            FROM files
            WHERE user_id = $1
            ORDER BY uploaded_at DESC
        """, uuid.UUID(user_id))

        return [
            {
                "file_id": str(file['file_id']),
                "original_name": file['original_name'],
                "size": file['size'],
                "uploaded_at": file['uploaded_at'].isoformat()
            }
            for file in files
        ]


@app.get("/download/{file_id}")
async def download_file(
        file_id: str,
        api_key: Optional[str] = None,
        x_api_key: Optional[str] = Header(None)
):
    """Download a file by ID (requires API key)"""
    # Accept API key from query param or header
    key = api_key or x_api_key

    if not key:
        raise HTTPException(status_code=401, detail="Missing API key")

    async with db_pool.acquire() as conn:
        # Verify API key and get user
        user = await conn.fetchrow(
            "SELECT user_id FROM users WHERE api_key = $1",
            key
        )

        if not user:
            raise HTTPException(status_code=401, detail="Invalid API key")

        # Get file info and verify ownership
        file_info = await conn.fetchrow("""
            SELECT file_path, original_name
            FROM files
            WHERE file_id = $1 AND user_id = $2
        """, uuid.UUID(file_id), user['user_id'])

        if not file_info:
            raise HTTPException(status_code=404, detail="File not found or access denied")

        file_path = Path(file_info['file_path'])

        if not file_path.exists():
            raise HTTPException(status_code=404, detail="File not found on disk")

        return FileResponse(
            path=file_path,
            filename=file_info['original_name'],
            media_type="application/octet-stream"
        )


@app.get("/dn/{file_id}")
async def download_link(
        file_id: str
):
    """Download a file by DIRECT LINK (without API key)"""
    async with db_pool.acquire() as conn:
        # Get file info and verify ownership
        file_info = await conn.fetchrow("""
                    SELECT file_path, original_name
                    FROM files
                    WHERE file_id = $1
                """, uuid.UUID(file_id))

        if not file_info:
            raise HTTPException(status_code=404, detail="File not found or access denied")

        file_path = Path(file_info['file_path'])

        if not file_path.exists():
            raise HTTPException(status_code=404, detail="File not found on disk")

        return FileResponse(
            path=file_path,
            filename=file_info['original_name'],
            media_type="application/octet-stream"
        )


@app.delete("/files/{file_id}")
async def delete_file(
        file_id: str,
        user_id: str = Depends(get_user_id)
):
    """Delete a file by ID (only owner can delete)"""
    async with db_pool.acquire() as conn:
        # Get file info and verify ownership
        file_info = await conn.fetchrow("""
            SELECT file_path
            FROM files
            WHERE file_id = $1 AND user_id = $2
        """, uuid.UUID(file_id), uuid.UUID(user_id))

        if not file_info:
            raise HTTPException(status_code=404, detail="File not found or access denied")

        file_path = Path(file_info['file_path'])

        # Delete file from disk
        if file_path.exists():
            os.remove(file_path)

        # Remove from database
        await conn.execute(
            "DELETE FROM files WHERE file_id = $1",
            uuid.UUID(file_id)
        )

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


@app.get("/files/{file_id}/info")
async def get_file_info(
        file_id: str,
        user_id: str = Depends(get_user_id)
):
    """Get file information by ID (only owner can view)"""
    async with db_pool.acquire() as conn:
        file_info = await conn.fetchrow("""
            SELECT file_id, original_name, stored_name, size, uploaded_at
            FROM files
            WHERE file_id = $1 AND user_id = $2
        """, uuid.UUID(file_id), uuid.UUID(user_id))

        if not file_info:
            raise HTTPException(status_code=404, detail="File not found or access denied")

        return {
            "file_id": str(file_info['file_id']),
            "original_name": file_info['original_name'],
            "stored_name": file_info['stored_name'],
            "size": file_info['size'],
            "uploaded_at": file_info['uploaded_at'].isoformat()
        }


if __name__ == "__main__":
    import uvicorn

    uvicorn.run(app, host="0.0.0.0", port=app_config.APP_PORT)