"""上下文组装（架构 §7.2 步骤③）的纯逻辑测试：画像注入与历史截尾。"""

from __future__ import annotations

from packages.agent.context import (
    PROFILE_SUMMARY_MAX_CHARS,
    build_context_messages,
    build_profile_message,
)
from packages.llm.types import Message


class TestBuildContextMessages:
    def test_profile_first_then_history(self) -> None:
        history = [
            Message(role="user", content="第一句"),
            Message(role="assistant", content="第一答"),
        ]
        messages = build_context_messages(
            profile_summary='{"dimensions":[]}', history=history, history_turns=10
        )
        assert len(messages) == 3
        assert messages[0].role == "system"
        assert '{"dimensions":[]}' in messages[0].content
        assert [m.role for m in messages[1:]] == ["user", "assistant"]
        assert [m.content for m in messages[1:]] == ["第一句", "第一答"]

    def test_no_profile_degrades_to_history_only(self) -> None:
        """无画像用户（FR-AGT-10 降级）：不注入画像消息，历史照常携带。"""
        history = [Message(role="user", content="hi")]
        messages = build_context_messages(profile_summary=None, history=history, history_turns=10)
        assert len(messages) == 1
        assert messages[0].role == "user"

    def test_empty_profile_string_treated_as_absent(self) -> None:
        messages = build_context_messages(profile_summary="", history=[], history_turns=10)
        assert messages == []

    def test_history_tail_kept_by_turns(self) -> None:
        """一轮 = user+assistant 两条；N=2 时只留最近 4 条，截头不截尾。"""
        history: list[Message] = []
        for i in range(5):
            history.append(Message(role="user", content=f"u{i}"))
            history.append(Message(role="assistant", content=f"a{i}"))
        messages = build_context_messages(profile_summary=None, history=history, history_turns=2)
        assert [m.content for m in messages] == ["u3", "a3", "u4", "a4"]

    def test_zero_turns_drops_history(self) -> None:
        history = [Message(role="user", content="u0")]
        messages = build_context_messages(profile_summary=None, history=history, history_turns=0)
        assert messages == []

    def test_history_message_content_capped(self) -> None:
        history = [Message(role="user", content="x" * 5000)]
        messages = build_context_messages(profile_summary=None, history=history, history_turns=10)
        assert len(messages[0].content) == 2000


class TestBuildProfileMessage:
    def test_wraps_summary_as_system_message(self) -> None:
        message = build_profile_message("{}")
        assert message.role == "system"
        assert message.content.endswith("{}")

    def test_budget_constant_within_token_budget(self) -> None:
        """画像摘要预算 ≤ 500 token（README 预算表），按 ~1.6 字符/token 折算。"""
        assert PROFILE_SUMMARY_MAX_CHARS <= 500 * 1.6