main.py

from fastapi import FastAPI, HTTPException, status
from pydantic import BaseModel, Field
from typing import Optional
from datetime import date

user_db = {
  "metin": { "username": "metin", "date_joined": "01-02-2025",  "location": "New York", "age" : 22 },
  "omer": { "username": "omer", "date_joined": "15-06-2023",  "location": "Istanbul", "age" : 29 },
  "ebubekir": { "username": "ebubekir", "date_joined": "22-11-2024",  "location": "Baku", "age" : 40 },
  "osman": { "username": "osman", "date_joined": "10-09-2022",  "location": "London", "age" : 32 },
  "ali": { "username": "ali", "date_joined": "30-04-2021",  "location": "Paris", "age" : 19 },
  "talha": { "username": "talha", "date_joined": "11-11-2021",  "location": "Kahire", "age" : 25 },
  "zubeyr": { "username": "zubeyr", "date_joined": "21-07-2021",  "location": "Ottawa", "age" : 36 },
}

class User(BaseModel):
    username: str = Field(min_length=3, max_length=20)
    date_joined: date
    location: Optional[str] = None
    age: int = Field(None, gt=0, lt=100)
    

class UpdateUser(BaseModel):
    date_joined: Optional[date] = None
    age: int = Field(None, gt=5, lt=200)


def ensure_username_in_db(username: str):
    if username not in user_db:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail=f"Username not found. {username}")

app = FastAPI()

@app.get("/users")
async def get_users_limit(limit: int = 20):
    users = list(user_db.values())
    return users[:limit]


@app.get("/users/{username}")
async def get_user(username: str):
    ensure_username_in_db(username)
    return user_db[username]


@app.post('/users')
async def create_user(user: User):
    username = user.username
    if username in user_db:
        raise HTTPException(status_code=status.HTTP_409_CONFLICT, detail=f"Username already exists. {username}")
    user_db[username] = user.dict()
    return {'message' : f'User created successfully: {username}'}


@app.delete('/users/{username}')
async def delete_user(username: str):
    ensure_username_in_db(username)
    del user_db[username]
    return {'message' : f'User deleted successfully: {username}'}


@app.put('/users')
async def update_user(user: User):
    username = user.username
    ensure_username_in_db(username)
    user_db[username] = user.dict()
    return {'message' : f'User updated successfully: {username}'}


@app.patch('/users')
async def update_user_partial(user: User):
    username = user.username
    ensure_username_in_db(username)
    user_db[username].update(user.dict(exclude_unset=True))
    return {'message' : f'User updated successfully: {username}'}