"""Unit tests for conversation truncation logic."""

from pathlib import Path

import pytest

from app.agent.context import SessionContext
from app.models.config import AgentConfig, AppConfig, LLMConfig


@pytest.fixture
def config() -> AppConfig:
    return AppConfig(
        llm=LLMConfig(model="test-model", endpoint="http://localhost:11434"),
        agent=AgentConfig(
            max_conversation_tokens=200,
            truncation_keep_recent=3,
            truncation_threshold=0.85,
            workspace_root=Path("/tmp/test"),
        ),
    )


@pytest.fixture
def ctx(config: AppConfig) -> SessionContext:
    return SessionContext(config)


class TestTruncation:
    def test_no_truncation_under_threshold(self, ctx: SessionContext) -> None:
        """No messages dropped when under threshold."""
        ctx.add_message("user", "Hello")
        ctx.add_message("assistant", "Hi there!")

        dropped = ctx.truncate_history()
        assert dropped == 0
        assert ctx.message_count == 2

    def test_drops_oldest_messages(self, ctx: SessionContext) -> None:
        """Drops middle messages when over budget."""
        # Fill with enough content to exceed the small 200-token budget
        ctx.add_message("user", "First message " * 20)
        for i in range(8):
            ctx.add_message("assistant", f"Response {i} " * 15)
            ctx.add_message("user", f"Follow-up {i} " * 15)

        # Force the token counter to report over budget
        from app.utils.token_counter import TokenUsage
        ctx.token_counter.count_usage(TokenUsage(total_tokens=200))

        original_count = len(ctx.get_history())
        dropped = ctx.truncate_history()

        assert dropped > 0
        assert len(ctx.get_history()) < original_count

    def test_preserves_recent_messages(self, ctx: SessionContext) -> None:
        """The most recent N messages are always preserved."""
        ctx.add_message("user", "First message " * 20)
        for i in range(10):
            ctx.add_message("assistant", f"Response {i} " * 10)
            ctx.add_message("user", f"Follow-up {i} " * 10)

        from app.utils.token_counter import TokenUsage
        ctx.token_counter.count_usage(TokenUsage(total_tokens=200))

        history_before = ctx.get_history()
        recent_before = history_before[-3:]  # keep_recent=3

        ctx.truncate_history()

        history_after = ctx.get_history()
        recent_after = history_after[-3:]

        # Recent messages should be preserved
        for before, after in zip(recent_before, recent_after):
            assert before.content == after.content

    def test_preserves_first_user_message(self, ctx: SessionContext) -> None:
        """First user message is always kept."""
        first_content = "This is the very first user message"
        ctx.add_message("user", first_content)
        for i in range(10):
            ctx.add_message("assistant", f"Response {i} " * 10)
            ctx.add_message("user", f"Follow-up {i} " * 10)

        from app.utils.token_counter import TokenUsage
        ctx.token_counter.count_usage(TokenUsage(total_tokens=200))

        ctx.truncate_history()

        history = ctx.get_history()
        assert history[0].role == "user"
        assert history[0].content == first_content

    def test_orphaned_tool_messages_cleaned(self, ctx: SessionContext) -> None:
        """Tool messages without matching tool_call are cleaned up."""
        from app.models.tool_call import ToolCall, ToolCallFunction

        ctx.add_message("user", "Do something " * 20)
        # Assistant with tool call
        ctx.add_message(
            "assistant",
            None,
            tool_calls=[ToolCall(id="tc_1", type="function", function=ToolCallFunction(name="read_file", arguments='{"path": "x"}'))],
        )
        # Tool result for tc_1
        ctx.add_message("tool", "file contents " * 20, tool_call_id="tc_1", name="read_file")
        # More padding to push over budget
        for i in range(8):
            ctx.add_message("assistant", f"Analysis {i} " * 15)
            ctx.add_message("user", f"Next {i} " * 15)

        from app.utils.token_counter import TokenUsage
        ctx.token_counter.count_usage(TokenUsage(total_tokens=200))

        ctx.truncate_history()

        history = ctx.get_history()
        # If the assistant message with tc_1 was dropped, the orphaned tool message should also be gone
        has_tc1_assistant = any(
            m.role == "assistant" and m.tool_calls and any(tc.id == "tc_1" for tc in m.tool_calls)
            for m in history
        )
        has_tc1_tool = any(m.role == "tool" and m.tool_call_id == "tc_1" for m in history)

        # Either both exist or neither exists
        assert has_tc1_assistant == has_tc1_tool