import os
from typing import List, Optional
from pydantic import BaseModel, Field, validator

class TaskCard(BaseModel):
    """Pydantic model representing a structured task card.

    Attributes
    ----------
    title: str
        Short title of the task (max 10 words).
    subject: str
        Subject or topic of the task.
    deadline: Optional[str]
        Deadline string if mentioned, otherwise None.
    deliverable: str
        What needs to be submitted.
    requirements: List[str]
        List of concrete requirements extracted from the raw text.
    difficulty: str
        Difficulty level: "легко", "средне" or "сложно".
    grading_criteria: Optional[str]
        Grading criteria if present.
    tags: List[str]
        Tags describing the task.
    """

    title: str = Field(..., description="Short title of the task (max 10 words)")
    subject: str = Field(..., description="Subject or topic of the task")
    deadline: Optional[str] = Field(None, description="Deadline if mentioned")
    deliverable: str = Field(..., description="What needs to be submitted")
    requirements: List[str] = Field(default_factory=list, description="Concrete requirements")
    difficulty: str = Field(..., description="Difficulty level: легко, средне, сложно")
    grading_criteria: Optional[str] = Field(None, description="Grading criteria if present")
    tags: List[str] = Field(default_factory=list, description="Tags describing the task")

    @validator("title")
    def title_word_limit(cls, v: str) -> str:
        if len(v.split()) > 10:
            raise ValueError("Title must be at most 10 words")
        return v

    def to_markdown(self) -> str:
        """Return a nicely formatted Markdown representation of the card."""
        md = [f"## {self.title}"]
        md.append(f"**Предмет:** {self.subject}")
        if self.deadline:
            md.append(f"**Дедлайн:** {self.deadline}")
        md.append(f"**Сдать:** {self.deliverable}")
        if self.requirements:
            md.append("**Требования:**")
            for req in self.requirements:
                md.append(f"- {req}")
        md.append(f"**Сложность:** {self.difficulty}")
        if self.grading_criteria:
            md.append(f"**Критерии оценки:** {self.grading_criteria}")
        if self.tags:
            md.append("**Теги:** " + ", ".join(self.tags))
        return "\n".join(md)

# End of models.py