from fastapi import FastAPI, HTTPException
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel
from typing import List, Optional
from datetime import datetime
import uvicorn

app = FastAPI(
    title="Users Service",
    description="User management microservice",
    version="0.1.0"
)

# CORS middleware
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# In-memory storage for now (will be replaced with MongoDB later)
users_db = {}
user_id_counter = 1

# Pydantic models
class UserCreate(BaseModel):
    username: str
    email: str
    full_name: Optional[str] = None

class UserUpdate(BaseModel):
    username: Optional[str] = None
    email: Optional[str] = None
    full_name: Optional[str] = None

class User(BaseModel):
    id: int
    username: str
    email: str
    full_name: Optional[str] = None
    created_at: datetime
    updated_at: datetime

# Health check
@app.get("/health")
async def health_check():
    return {
        "status": "healthy",
        "service": "users",
        "timestamp": datetime.now().isoformat()
    }

# CRUD Operations
@app.get("/users", response_model=List[User])
async def get_users():
    return list(users_db.values())

@app.get("/users/{user_id}", response_model=User)
async def get_user(user_id: int):
    if user_id not in users_db:
        raise HTTPException(status_code=404, detail="User not found")
    return users_db[user_id]

@app.post("/users", response_model=User, status_code=201)
async def create_user(user: UserCreate):
    global user_id_counter
    
    # Check if username already exists
    for existing_user in users_db.values():
        if existing_user["username"] == user.username:
            raise HTTPException(status_code=400, detail="Username already exists")
    
    new_user = {
        "id": user_id_counter,
        "username": user.username,
        "email": user.email,
        "full_name": user.full_name,
        "created_at": datetime.now(),
        "updated_at": datetime.now()
    }
    
    users_db[user_id_counter] = new_user
    user_id_counter += 1
    
    return new_user

@app.put("/users/{user_id}", response_model=User)
async def update_user(user_id: int, user_update: UserUpdate):
    if user_id not in users_db:
        raise HTTPException(status_code=404, detail="User not found")
    
    user = users_db[user_id]
    
    if user_update.username is not None:
        # Check if new username already exists
        for uid, existing_user in users_db.items():
            if uid != user_id and existing_user["username"] == user_update.username:
                raise HTTPException(status_code=400, detail="Username already exists")
        user["username"] = user_update.username
    
    if user_update.email is not None:
        user["email"] = user_update.email
    
    if user_update.full_name is not None:
        user["full_name"] = user_update.full_name
    
    user["updated_at"] = datetime.now()
    
    return user

@app.delete("/users/{user_id}")
async def delete_user(user_id: int):
    if user_id not in users_db:
        raise HTTPException(status_code=404, detail="User not found")
    
    del users_db[user_id]
    return {"message": "User deleted successfully"}

if __name__ == "__main__":
    uvicorn.run(
        "main:app",
        host="0.0.0.0",
        port=8000,
        reload=True
    )