"""对话历史窗口配置测试（B3）：env 可调最大注入条数，0 = 不截断。

对照 FastGPT：服务端全量维护历史、客户端只发单条消息；
LangGraph 侧历史注入曾硬编码截断 50 条，超长会话两端行为不对称。
现由 Config.AGENT_HISTORY_MESSAGES 控制（默认 50 不变）。
"""

import pytest

from src.agent.collect import conversation_history
from src.core.config import Config


def _dialogue(n: int) -> dict:
    return {"dialogue": [
        {"role": "user", "content": f"第{i}条"} for i in range(n)
    ]}


def test_default_window_keeps_last_50(monkeypatch):
    """缺省 50：与工作流 chatNode history 配置一致（现状不变）。"""
    monkeypatch.setattr(Config, "AGENT_HISTORY_MESSAGES", 50)
    history = conversation_history(_dialogue(60))
    assert len(history) == 50
    assert history[0]["content"] == "第10条"


def test_large_window_supports_long_dialogues(monkeypatch):
    """调大窗口：长对话注入更多历史（B3 目标）。"""
    monkeypatch.setattr(Config, "AGENT_HISTORY_MESSAGES", 500)
    history = conversation_history(_dialogue(120))
    assert len(history) == 120


def test_zero_window_disables_truncation(monkeypatch):
    """0 = 不截断：对齐 FastGPT 全量历史语义。"""
    monkeypatch.setattr(Config, "AGENT_HISTORY_MESSAGES", 0)
    history = conversation_history(_dialogue(300))
    assert len(history) == 300
    assert history[0]["content"] == "第0条"


def test_history_does_not_mutate_state(monkeypatch):
    monkeypatch.setattr(Config, "AGENT_HISTORY_MESSAGES", 2)
    state = _dialogue(10)
    conversation_history(state)
    assert len(state["dialogue"]) == 10   # 原文不动，截断只发生在拷贝


def test_validate_rejects_negative_window(monkeypatch):
    monkeypatch.setattr(Config, "AGENT_HISTORY_MESSAGES", -1)
    with pytest.raises(ValueError, match="AGENT_HISTORY_MESSAGES"):
        Config.validate()


def test_validate_accepts_zero_and_positive(monkeypatch):
    monkeypatch.setattr(Config, "AGENT_HISTORY_MESSAGES", 0)
    monkeypatch.setattr(Config, "AGENT_BACKEND", "langgraph")
    monkeypatch.setattr(Config, "LLM_PROVIDER", "fake")
    Config.validate()
    monkeypatch.setattr(Config, "AGENT_HISTORY_MESSAGES", 10)
    Config.validate()