from typing import Literal

from pydantic import BaseModel, field_validator


class ChatMessage(BaseModel):
    role: Literal["system", "user", "assistant"]
    content: str


class ChatRequest(BaseModel):
    messages: list[ChatMessage]
    max_tokens: int = 2048
    temperature: float = 0.0
    response_format: Literal["json", "text"] = "text"

    @field_validator("messages")
    @classmethod
    def messages_not_empty(cls, v: list) -> list:
        if not v:
            raise ValueError("messages must not be empty")
        return v


class ChatResponse(BaseModel):
    content: str
    provider: str
    model: str
    input_tokens: int | None = None
    output_tokens: int | None = None