from datetime import datetime
from pydantic import BaseModel, EmailStr, field_validator
import re


# ── Auth ─────────────────────────────────────────────────────────────────────

class UserRegister(BaseModel):
    username: str
    email: EmailStr
    password: str

    @field_validator("username")
    @classmethod
    def username_valid(cls, v: str) -> str:
        v = v.strip()
        if not re.match(r"^[A-Za-z0-9_]{3,64}$", v):
            raise ValueError(
                "Username must be 3–64 characters, letters/numbers/underscore only."
            )
        return v

    @field_validator("password")
    @classmethod
    def password_strength(cls, v: str) -> str:
        if len(v) < 8:
            raise ValueError("Password must be at least 8 characters.")
        return v


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


class UserOut(BaseModel):
    id: int
    username: str
    email: str
    created_at: datetime

    model_config = {"from_attributes": True}


class TokenPayload(BaseModel):
    sub: int   # user id
    exp: int


# ── PDFs ──────────────────────────────────────────────────────────────────────

class PDFOut(BaseModel):
    id: int
    title: str
    total_pages: int | None
    created_at: datetime

    model_config = {"from_attributes": True}


class PDFUploadResult(BaseModel):
    filename: str
    success: bool
    pdf: PDFOut | None = None
    error: str | None = None