from datetime import date, datetime
from typing import Optional

from pydantic import BaseModel, ConfigDict, field_validator


def _validate_half_hours(value: float) -> float:
    if value <= 0:
        raise ValueError("hours must be greater than 0")
    scaled = value * 2
    if abs(scaled - round(scaled)) > 1e-6:
        raise ValueError("hours must be in 0.5 increments")
    return value


class ProjectBase(BaseModel):
    name: str
    description: Optional[str] = None


class ProjectCreate(ProjectBase):
    pass


class ProjectUpdate(BaseModel):
    name: Optional[str] = None
    description: Optional[str] = None


class ProjectRead(ProjectBase):
    id: int
    created_at: datetime

    model_config = ConfigDict(from_attributes=True)


class WorkLogBase(BaseModel):
    project_id: int
    date: date
    hours: float
    description: str

    _validate_hours = field_validator("hours")(_validate_half_hours)


class WorkLogCreate(WorkLogBase):
    pass


class WorkLogUpdate(BaseModel):
    project_id: Optional[int] = None
    date: Optional[date] = None
    hours: Optional[float] = None
    description: Optional[str] = None

    @field_validator("hours")
    @classmethod
    def validate_hours(cls, value: Optional[float]) -> Optional[float]:
        if value is None:
            return value
        return _validate_half_hours(value)


class WorkLogRead(WorkLogBase):
    id: int
    created_at: datetime

    model_config = ConfigDict(from_attributes=True)