from pydantic import BaseModel, EmailStr, Field, ConfigDict
from typing import Optional, List, Any
from datetime import datetime
from bson import ObjectId

class PyObjectId(ObjectId):
    @classmethod
    def __get_validators__(cls):
        yield cls.validate

    @classmethod
    def validate(cls, v, handler=None):
        if isinstance(v, ObjectId):
            return v
        if isinstance(v, str):
            if ObjectId.is_valid(v):
                return ObjectId(v)
        raise ValueError("Invalid ObjectId")

    @classmethod
    def __get_pydantic_json_schema__(cls, field_schema):
        field_schema.update(type="string")

class UserCreate(BaseModel):
    firstName: str
    lastName: str
    email: EmailStr
    password: str
    academicStage: Optional[str] = None
    researchArea: Optional[str] = None

class UserLogin(BaseModel):
    email: EmailStr
    password: str

class User(BaseModel):
    model_config = ConfigDict(
        populate_by_name=True,
        arbitrary_types_allowed=True,
        json_encoders={ObjectId: str}
    )
    
    id: PyObjectId = Field(default_factory=PyObjectId, alias="_id")
    firstName: str
    lastName: str
    email: EmailStr
    hashed_password: str
    academicStage: Optional[str] = None
    researchArea: Optional[str] = None
    avatarId: Optional[str] = None
    created_at: datetime = Field(default_factory=datetime.utcnow)
    last_login: Optional[datetime] = None
    is_active: bool = True

class UserUpdate(BaseModel):
    avatarId: Optional[str] = None
    firstName: Optional[str] = None
    lastName: Optional[str] = None
    email: Optional[EmailStr] = None
    academicStage: Optional[str] = None
    researchArea: Optional[str] = None


class UserResponse(BaseModel):
    id: str
    firstName: str
    lastName: str
    email: str
    academicStage: Optional[str] = None
    researchArea: Optional[str] = None
    avatarId: Optional[str] = None
    created_at: datetime
    last_login: Optional[datetime] = None

class ChatSession(BaseModel):
    model_config = ConfigDict(
        populate_by_name=True,
        arbitrary_types_allowed=True,
        json_encoders={ObjectId: str}
    )
    
    id: PyObjectId = Field(default_factory=PyObjectId, alias="_id")
    user_id: PyObjectId
    title: str
    messages: List[dict] = []
    created_at: datetime = Field(default_factory=datetime.utcnow)
    updated_at: datetime = Field(default_factory=datetime.utcnow)
    is_active: bool = True

class ChatSessionResponse(BaseModel):
    id: str
    title: str
    created_at: datetime
    updated_at: datetime
    message_count: int

class Token(BaseModel):
    access_token: str
    token_type: str
    user: UserResponse