"""Agent 会话管理

负责会话状态的定义、序列化和持久化。
"""

from __future__ import annotations

import json
from dataclasses import asdict, dataclass, field
from enum import StrEnum
from pathlib import Path
from typing import Any

from .. import get_logger

log = get_logger("agent.session")

# ------------------------------------------------------------------
# 状态枚举
# ------------------------------------------------------------------


class AgentState(StrEnum):
    IDLE = "idle"
    EXTRACTING = "extracting"
    AWAITING_SUPPLEMENT = "awaiting_supplement"
    READY = "ready"
    SUBMITTING = "submitting"
    DONE = "done"
    ERROR = "error"


# ------------------------------------------------------------------
# Agent 会话数据模型
# ------------------------------------------------------------------


@dataclass
class AgentSession:
    """Agent 会话状态"""

    session_id: str
    state: AgentState = AgentState.IDLE
    rounds: int = 0
    max_rounds: int = 5
    invoice_type: str = "travel"  # "travel" 或 "normal"
    extracted_info: dict[str, Any] = field(default_factory=dict)
    validation_reports: list[dict[str, Any]] = field(default_factory=list)
    user_supplements: list[str] = field(default_factory=list)
    error_message: str = ""

    def to_dict(self) -> dict[str, Any]:
        return asdict(self)

    @classmethod
    def from_dict(cls, data: dict[str, Any]) -> AgentSession:
        # 兼容旧版本：state 可能是字符串
        if "state" in data and isinstance(data["state"], str):
            data["state"] = AgentState(data["state"])
        return cls(**data)

    def is_terminal(self) -> bool:
        """判断会话是否处于终态（已提交或已完成）"""
        return self.state in (AgentState.DONE, AgentState.SUBMITTING, AgentState.READY)


# ------------------------------------------------------------------
# 持久化
# ------------------------------------------------------------------

AGENT_STATE_FILE = "agent_state.json"


def save_agent_state(session_dir: Path, session: AgentSession) -> None:
    """将 Agent 会话状态持久化到 session 目录。"""
    state_path = session_dir / AGENT_STATE_FILE
    tmp_path = session_dir / (AGENT_STATE_FILE + ".tmp")
    with open(tmp_path, "w", encoding="utf-8") as f:
        json.dump(session.to_dict(), f, ensure_ascii=False, indent=2)
    tmp_path.replace(state_path)


def load_agent_state(session_dir: Path) -> AgentSession | None:
    """从 session 目录加载 Agent 会话状态。"""
    state_path = session_dir / AGENT_STATE_FILE
    if not state_path.exists():
        return None
    try:
        with open(state_path, encoding="utf-8") as f:
            return AgentSession.from_dict(json.load(f))
    except Exception as e:
        log.warning("加载 Agent 状态失败: %s", e)
        return None


def create_agent_session(session_id: str, invoice_type: str = "travel") -> AgentSession:
    """创建新的 Agent 会话。"""
    return AgentSession(
        session_id=session_id,
        invoice_type=invoice_type,
    )