"""Tests for agent/context_compressor.py — compression logic, thresholds, truncation fallback."""

import pytest
from unittest.mock import patch, MagicMock

from agent.context_compressor import ContextCompressor, SUMMARY_PREFIX


@pytest.fixture()
def compressor():
    """Create a ContextCompressor with mocked dependencies."""
    with patch("agent.context_compressor.get_model_context_length", return_value=100000):
        c = ContextCompressor(
            model="test/model",
            threshold_percent=0.85,
            protect_first_n=2,
            protect_last_n=2,
            quiet_mode=True,
        )
        return c


class TestShouldCompress:
    def test_below_threshold(self, compressor):
        compressor.last_prompt_tokens = 50000
        assert compressor.should_compress() is False

    def test_above_threshold(self, compressor):
        compressor.last_prompt_tokens = 90000
        assert compressor.should_compress() is True

    def test_exact_threshold(self, compressor):
        compressor.last_prompt_tokens = 85000
        assert compressor.should_compress() is True

    def test_explicit_tokens(self, compressor):
        assert compressor.should_compress(prompt_tokens=90000) is True
        assert compressor.should_compress(prompt_tokens=50000) is False


class TestShouldCompressPreflight:
    def test_short_messages(self, compressor):
        msgs = [{"role": "user", "content": "short"}]
        assert compressor.should_compress_preflight(msgs) is False

    def test_long_messages(self, compressor):
        # Each message ~100k chars / 4 = 25k tokens, need >85k threshold
        msgs = [{"role": "user", "content": "x" * 400000}]
        assert compressor.should_compress_preflight(msgs) is True


class TestUpdateFromResponse:
    def test_updates_fields(self, compressor):
        compressor.update_from_response({
            "prompt_tokens": 5000,
            "completion_tokens": 1000,
            "total_tokens": 6000,
        })
        assert compressor.last_prompt_tokens == 5000
        assert compressor.last_completion_tokens == 1000
        assert compressor.last_total_tokens == 6000

    def test_missing_fields_default_zero(self, compressor):
        compressor.update_from_response({})
        assert compressor.last_prompt_tokens == 0


class TestGetStatus:
    def test_returns_expected_keys(self, compressor):
        status = compressor.get_status()
        assert "last_prompt_tokens" in status
        assert "threshold_tokens" in status
        assert "context_length" in status
        assert "usage_percent" in status
        assert "compression_count" in status

    def test_usage_percent_calculation(self, compressor):
        compressor.last_prompt_tokens = 50000
        status = compressor.get_status()
        assert status["usage_percent"] == 50.0


class TestCompress:
    def _make_messages(self, n):
        return [{"role": "user" if i % 2 == 0 else "assistant", "content": f"msg {i}"} for i in range(n)]

    def test_too_few_messages_returns_unchanged(self, compressor):
        msgs = self._make_messages(4)  # protect_first=2 + protect_last=2 + 1 = 5 needed
        result = compressor.compress(msgs)
        assert result == msgs

    def test_truncation_fallback_no_client(self, compressor):
        # compressor has client=None, so should use truncation fallback
        msgs = [{"role": "system", "content": "System prompt"}] + self._make_messages(10)
        result = compressor.compress(msgs)
        assert len(result) < len(msgs)
        # Should keep system message and last N
        assert result[0]["role"] == "system"
        assert compressor.compression_count == 1

    def test_compression_increments_count(self, compressor):
        msgs = self._make_messages(10)
        compressor.compress(msgs)
        assert compressor.compression_count == 1
        compressor.compress(msgs)
        assert compressor.compression_count == 2

    def test_protects_first_and_last(self, compressor):
        msgs = self._make_messages(10)
        result = compressor.compress(msgs)
        # First 2 messages should be preserved (protect_first_n=2)
        # Last 2 messages should be preserved (protect_last_n=2)
        assert result[-1]["content"] == msgs[-1]["content"]
        assert result[-2]["content"] == msgs[-2]["content"]


class TestGenerateSummaryNoneContent:
    """Regression: content=None (from tool-call-only assistant messages) must not crash."""

    def test_none_content_does_not_crash(self):
        mock_response = MagicMock()
        mock_response.choices = [MagicMock()]
        mock_response.choices[0].message.content = "[CONTEXT SUMMARY]: tool calls happened"

        with patch("agent.context_compressor.get_model_context_length", return_value=100000):
            c = ContextCompressor(model="test", quiet_mode=True)

        messages = [
            {"role": "user", "content": "do something"},
            {"role": "assistant", "content": None, "tool_calls": [
                {"function": {"name": "search"}}
            ]},
            {"role": "tool", "content": "result"},
            {"role": "assistant", "content": None},
            {"role": "user", "content": "thanks"},
        ]

        with patch("agent.context_compressor.call_llm", return_value=mock_response):
            summary = c._generate_summary(messages)
        assert isinstance(summary, str)
        assert summary.startswith(SUMMARY_PREFIX)

    def test_none_content_in_system_message_compress(self):
        """System message with content=None should not crash during compress."""
        with patch("agent.context_compressor.get_model_context_length", return_value=100000):
            c = ContextCompressor(model="test", quiet_mode=True, protect_first_n=2, protect_last_n=2)

        msgs = [{"role": "system", "content": None}] + [
            {"role": "user" if i % 2 == 0 else "assistant", "content": f"msg {i}"}
            for i in range(10)
        ]
        result = c.compress(msgs)
        assert len(result) < len(msgs)


class TestNonStringContent:
    """Regression: content as dict (e.g., llama.cpp tool calls) must not crash."""

    def test_dict_content_coerced_to_string(self):
        mock_response = MagicMock()
        mock_response.choices = [MagicMock()]
        mock_response.choices[0].message.content = {"text": "some summary"}

        with patch("agent.context_compressor.get_model_context_length", return_value=100000):
            c = ContextCompressor(model="test", quiet_mode=True)

        messages = [
            {"role": "user", "content": "do something"},
            {"role": "assistant", "content": "ok"},
        ]

        with patch("agent.context_compressor.call_llm", return_value=mock_response):
            summary = c._generate_summary(messages)
        assert isinstance(summary, str)
        assert summary.startswith(SUMMARY_PREFIX)

    def test_none_content_coerced_to_empty(self):
        mock_response = MagicMock()
        mock_response.choices = [MagicMock()]
        mock_response.choices[0].message.content = None

        with patch("agent.context_compressor.get_model_context_length", return_value=100000):
            c = ContextCompressor(model="test", quiet_mode=True)

        messages = [
            {"role": "user", "content": "do something"},
            {"role": "assistant", "content": "ok"},
        ]

        with patch("agent.context_compressor.call_llm", return_value=mock_response):
            summary = c._generate_summary(messages)
        # None content → empty string → standardized compaction handoff prefix added
        assert summary is not None
        assert summary == SUMMARY_PREFIX


class TestSummaryPrefixNormalization:
    def test_legacy_prefix_is_replaced(self):
        summary = ContextCompressor._with_summary_prefix("[CONTEXT SUMMARY]: did work")
        assert summary == f"{SUMMARY_PREFIX}\ndid work"

    def test_existing_new_prefix_is_not_duplicated(self):
        summary = ContextCompressor._with_summary_prefix(f"{SUMMARY_PREFIX}\ndid work")
        assert summary == f"{SUMMARY_PREFIX}\ndid work"


class TestCompressWithClient:
    def test_summarization_path(self):
        mock_client = MagicMock()
        mock_response = MagicMock()
        mock_response.choices = [MagicMock()]
        mock_response.choices[0].message.content = "[CONTEXT SUMMARY]: stuff happened"
        mock_client.chat.completions.create.return_value = mock_response

        with patch("agent.context_compressor.get_model_context_length", return_value=100000):
            c = ContextCompressor(model="test", quiet_mode=True)

        msgs = [{"role": "user" if i % 2 == 0 else "assistant", "content": f"msg {i}"} for i in range(10)]
        with patch("agent.context_compressor.call_llm", return_value=mock_response):
            result = c.compress(msgs)

        # Should have summary message in the middle
        contents = [m.get("content", "") for m in result]
        assert any(c.startswith(SUMMARY_PREFIX) for c in contents)
        assert len(result) < len(msgs)

    def test_summarization_does_not_split_tool_call_pairs(self):
        mock_client = MagicMock()
        mock_response = MagicMock()
        mock_response.choices = [MagicMock()]
        mock_response.choices[0].message.content = "[CONTEXT SUMMARY]: compressed middle"
        mock_client.chat.completions.create.return_value = mock_response

        with patch("agent.context_compressor.get_model_context_length", return_value=100000):
            c = ContextCompressor(
                model="test",
                quiet_mode=True,
                protect_first_n=3,
                protect_last_n=4,
            )

        msgs = [
            {"role": "user", "content": "Could you address the reviewer comments in PR#71"},
            {
                "role": "assistant",
                "content": "",
                "tool_calls": [
                    {"id": "call_a", "type": "function", "function": {"name": "skill_view", "arguments": "{}"}},
                    {"id": "call_b", "type": "function", "function": {"name": "skill_view", "arguments": "{}"}},
                ],
            },
            {"role": "tool", "tool_call_id": "call_a", "content": "output a"},
            {"role": "tool", "tool_call_id": "call_b", "content": "output b"},
            {"role": "user", "content": "later 1"},
            {"role": "assistant", "content": "later 2"},
            {"role": "tool", "tool_call_id": "call_x", "content": "later output"},
            {"role": "assistant", "content": "later 3"},
            {"role": "user", "content": "later 4"},
        ]

        with patch("agent.context_compressor.call_llm", return_value=mock_response):
            result = c.compress(msgs)

        answered_ids = {
            msg.get("tool_call_id")
            for msg in result
            if msg.get("role") == "tool" and msg.get("tool_call_id")
        }
        for msg in result:
            if msg.get("role") == "assistant" and msg.get("tool_calls"):
                for tc in msg["tool_calls"]:
                    assert tc["id"] in answered_ids

    def test_summary_role_avoids_consecutive_user_messages(self):
        """Summary role should alternate with the last head message to avoid consecutive same-role messages."""
        mock_client = MagicMock()
        mock_response = MagicMock()
        mock_response.choices = [MagicMock()]
        mock_response.choices[0].message.content = "[CONTEXT SUMMARY]: stuff happened"
        mock_client.chat.completions.create.return_value = mock_response

        with patch("agent.context_compressor.get_model_context_length", return_value=100000):
            c = ContextCompressor(model="test", quiet_mode=True, protect_first_n=2, protect_last_n=2)

        # Last head message (index 1) is "assistant" → summary should be "user"
        msgs = [
            {"role": "user", "content": "msg 0"},
            {"role": "assistant", "content": "msg 1"},
            {"role": "user", "content": "msg 2"},
            {"role": "assistant", "content": "msg 3"},
            {"role": "user", "content": "msg 4"},
            {"role": "assistant", "content": "msg 5"},
        ]
        with patch("agent.context_compressor.call_llm", return_value=mock_response):
            result = c.compress(msgs)
        summary_msg = [
            m for m in result if (m.get("content") or "").startswith(SUMMARY_PREFIX)
        ]
        assert len(summary_msg) == 1
        assert summary_msg[0]["role"] == "user"

    def test_summary_role_avoids_consecutive_user_when_head_ends_with_user(self):
        """When last head message is 'user', summary must be 'assistant' to avoid two consecutive user messages."""
        mock_client = MagicMock()
        mock_response = MagicMock()
        mock_response.choices = [MagicMock()]
        mock_response.choices[0].message.content = "[CONTEXT SUMMARY]: stuff happened"
        mock_client.chat.completions.create.return_value = mock_response

        with patch("agent.context_compressor.get_model_context_length", return_value=100000):
            c = ContextCompressor(model="test", quiet_mode=True, protect_first_n=3, protect_last_n=2)

        # Last head message (index 2) is "user" → summary should be "assistant"
        msgs = [
            {"role": "system", "content": "system prompt"},
            {"role": "user", "content": "msg 1"},
            {"role": "user", "content": "msg 2"},  # last head — user
            {"role": "assistant", "content": "msg 3"},
            {"role": "user", "content": "msg 4"},
            {"role": "assistant", "content": "msg 5"},
            {"role": "user", "content": "msg 6"},
            {"role": "assistant", "content": "msg 7"},
        ]
        with patch("agent.context_compressor.call_llm", return_value=mock_response):
            result = c.compress(msgs)
        summary_msg = [
            m for m in result if (m.get("content") or "").startswith(SUMMARY_PREFIX)
        ]
        assert len(summary_msg) == 1
        assert summary_msg[0]["role"] == "assistant"

    def test_summarization_does_not_start_tail_with_tool_outputs(self):
        mock_response = MagicMock()
        mock_response.choices = [MagicMock()]
        mock_response.choices[0].message.content = "[CONTEXT SUMMARY]: compressed middle"

        with patch("agent.context_compressor.get_model_context_length", return_value=100000):
            c = ContextCompressor(
                model="test",
                quiet_mode=True,
                protect_first_n=2,
                protect_last_n=3,
            )

        msgs = [
            {"role": "user", "content": "earlier 1"},
            {"role": "assistant", "content": "earlier 2"},
            {"role": "user", "content": "earlier 3"},
            {
                "role": "assistant",
                "content": "",
                "tool_calls": [
                    {"id": "call_c", "type": "function", "function": {"name": "search_files", "arguments": "{}"}},
                ],
            },
            {"role": "tool", "tool_call_id": "call_c", "content": "output c"},
            {"role": "user", "content": "latest user"},
        ]

        with patch("agent.context_compressor.call_llm", return_value=mock_response):
            result = c.compress(msgs)

        called_ids = {
            tc["id"]
            for msg in result
            if msg.get("role") == "assistant" and msg.get("tool_calls")
            for tc in msg["tool_calls"]
        }
        for msg in result:
            if msg.get("role") == "tool" and msg.get("tool_call_id"):
                assert msg["tool_call_id"] in called_ids