import json
import os
import secrets
from fastapi import FastAPI, HTTPException, Header
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel
from argon2 import PasswordHasher
from argon2.exceptions import VerifyMismatchError

app = FastAPI()

app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_methods=["*"],
    allow_headers=["*"],
)

DB_FILE = "database.json"
OBJ_FILE = "objects.json"
ph = PasswordHasher()
SESSIONS = {}

class User(BaseModel):
    username: str
    password: str

class ChangePasswordModel(BaseModel):
    new_password: str

class NoteObject(BaseModel):
    title: str  # Добавили название
    text: str

def read_json(filename):
    if not os.path.exists(filename): return []
    with open(filename, "r") as f:
        try: return json.load(f)
        except json.JSONDecodeError: return []

def write_json(filename, data):
    with open(filename, "w") as f: json.dump(data, f, indent=4)

def get_user_from_token(token: str):
    if not token or token not in SESSIONS:
        raise HTTPException(status_code=401, detail="Токен невалидный")
    return SESSIONS[token]

@app.post("/register")
def register(user: User):
    db = read_json(DB_FILE)
    if any(u["username"] == user.username for u in db):
        raise HTTPException(status_code=400, detail="Такой юзер уже есть")
    db.append({"username": user.username, "password": ph.hash(user.password)})
    write_json(DB_FILE, db)
    return {"message": "Регистрация успешна"}

@app.post("/login")
def login(user: User):
    db = read_json(DB_FILE)
    for u in db:
        if u["username"] == user.username:
            try:
                ph.verify(u["password"], user.password)
                session_token = secrets.token_hex(32)
                SESSIONS[session_token] = user.username
                return {"message": "Успешный вход", "token": session_token, "username": user.username}
            except VerifyMismatchError:
                raise HTTPException(status_code=401, detail="Неверный пароль")
    raise HTTPException(status_code=401, detail="Юзер не найден")

@app.get("/profile")
def get_profile(x_token: str = Header(None)):
    username = get_user_from_token(x_token)
    db = read_json(DB_FILE)
    for u in db:
        if u["username"] == username:
            return {"username": u["username"], "hash": u["password"]}
    raise HTTPException(status_code=404, detail="User not found")

# Эндпоинт для смены пароля (любой юзер меняет свой, root в админке меняет тоже свой, т.к. сессия его)
@app.post("/change-password")
def change_password(data: ChangePasswordModel, x_token: str = Header(None)):
    username = get_user_from_token(x_token)
    db = read_json(DB_FILE)
    for u in db:
        if u["username"] == username:
            u["password"] = ph.hash(data.new_password)
            write_json(DB_FILE, db)
            return {"message": "Пароль успешно изменен"}
    raise HTTPException(status_code=404, detail="User not found")

@app.post("/objects")
def create_object(obj: NoteObject, x_token: str = Header(None)):
    username = get_user_from_token(x_token)
    objects = read_json(OBJ_FILE)
    objects.append({"username": username, "title": obj.title, "text": obj.text})
    write_json(OBJ_FILE, objects)
    return {"message": "Объект создан"}

@app.get("/objects")
def get_objects(x_token: str = Header(None)):
    username = get_user_from_token(x_token)
    objects = read_json(OBJ_FILE)
    return [o for o in objects if o["username"] == username]

@app.get("/admin/objects")
def admin_get_objects(x_token: str = Header(None)):
    username = get_user_from_token(x_token)
    if username != "root": raise HTTPException(status_code=403)
    return read_json(OBJ_FILE)

@app.get("/admin/users")
def admin_get_users(x_token: str = Header(None)):
    username = get_user_from_token(x_token)
    if username != "root": raise HTTPException(status_code=403)
    return read_json(DB_FILE)