"""线程安全对话历史"""
import json
import threading
from .types import Message


class History:
    def __init__(self, max_size=999999):
        self._msgs = []
        self._lock = threading.RLock()
        self._max = max_size

    def add_user(self, text):
        with self._lock:
            self._msgs.append(Message("user", text))
            self._trim()

    def add_assistant(self, text, tool_calls=None):
        with self._lock:
            m = Message("assistant", text)
            if tool_calls:
                m.tool_calls = tool_calls
            self._msgs.append(m)
            self._trim()

    def add_tool(self, call_id, name, result):
        with self._lock:
            self._msgs.append(Message("tool", result, tool_call_id=call_id, name=name))
            self._trim()

    def add_cancel(self, name, args):
        with self._lock:
            self._msgs.append(Message("user", f"工具 {name} 已取消。参数: {args}"))
            self._trim()

    def _trim(self):
        if len(self._msgs) > self._max:
            self._msgs = self._msgs[-self._max:]

    def render(self, system_prompt="", current=None, fc=False):
        """渲染为消息列表。fc=True 用 role:tool，否则工具结果用 role:user"""
        with self._lock:
            result = []
            if system_prompt:
                result.append({"role": "system", "content": system_prompt})
            for m in self._msgs:
                if m.role == "tool" and not fc:
                    result.append({"role": "user", "content": m.content})
                else:
                    entry = {"role": m.role, "content": m.content}
                    if fc and m.role == "tool" and m.tool_call_id:
                        entry["tool_call_id"] = m.tool_call_id
                        if m.name:
                            entry["name"] = m.name
                    if fc and m.role == "assistant" and m.tool_calls:
                        # content 为空时设为 None（OpenAI 规范：有 tool_calls 时 content 可为 null）
                        if not entry.get("content"):
                            entry["content"] = None
                        # arguments 必须是 JSON 字符串（OpenAI 规范）
                        entry["tool_calls"] = [
                            {"id": tc.id, "type": "function",
                             "function": {
                                 "name": tc.name,
                                 "arguments": json.dumps(tc.arguments, ensure_ascii=False) if tc.arguments
                                              else json.dumps({"args": tc.args}, ensure_ascii=False)
                             }}
                            for tc in m.tool_calls
                        ]
                    result.append(entry)
            if current:
                result.append({"role": "user", "content": current})
            return result

    def snapshot(self):
        with self._lock:
            return list(self._msgs)

    def clear(self):
        with self._lock:
            self._msgs.clear()

    def __len__(self):
        with self._lock:
            return len(self._msgs)