"""
Session state management.
"""
from dataclasses import dataclass, field
from datetime import datetime
from typing import Literal


@dataclass
class Message:
    """Single message in conversation history."""
    role: Literal["user", "assistant", "system"]
    content: str
    timestamp: datetime = field(default_factory=datetime.now)

    def __str__(self) -> str:
        return f"[{self.role}] {self.content[:50]}..."


@dataclass
class SessionState:
    """
    Persistent state for a CLI session.

    Tracks conversation history and context.
    """
    working_dir: str
    messages: list[Message] = field(default_factory=list)
    started_at: datetime = field(default_factory=datetime.now)

    # Token tracking (for future context management)
    estimated_tokens: int = 0
    max_tokens: int = 128000

    def add_message(self, role: Literal["user", "assistant", "system"], content: str) -> None:
        """Add a message to history."""
        self.messages.append(Message(role=role, content=content))
        # Rough token estimate (4 chars per token)
        self.estimated_tokens += len(content) // 4

    def get_history(self, limit: int | None = None) -> list[Message]:
        """Get recent message history."""
        if limit:
            return self.messages[-limit:]
        return self.messages

    def clear_history(self) -> None:
        """Clear message history."""
        self.messages.clear()
        self.estimated_tokens = 0

    @property
    def message_count(self) -> int:
        """Number of messages in history."""
        return len(self.messages)

    @property
    def is_near_limit(self) -> bool:
        """Check if approaching token limit."""
        return self.estimated_tokens > (self.max_tokens * 0.8)