import unittest

from core.context import prepare_messages_for_llm, prepare_messages_with_stats


class ContextCompactionTests(unittest.TestCase):
    def test_preserves_system_and_recent_messages(self) -> None:
        messages = [
            {"role": "system", "content": "rules"},
            {"role": "user", "content": "old"},
            {"role": "tool", "tool_call_id": "old-tool", "name": "shell", "content": "A" * 200},
            {"role": "user", "content": "latest"},
            {"role": "tool", "tool_call_id": "new-tool", "name": "shell", "content": "B" * 200},
        ]

        prepared = prepare_messages_for_llm(
            messages,
            keep_recent=2,
            old_tool_chars=40,
        )

        self.assertEqual(prepared[0], messages[0])
        self.assertEqual(prepared[-2], messages[-2])
        self.assertEqual(prepared[-1], messages[-1])

    def test_compacts_old_tool_content_without_breaking_protocol_fields(self) -> None:
        messages = [
            {"role": "system", "content": "rules"},
            {"role": "assistant", "tool_calls": [{"id": "tc1"}], "content": None},
            {"role": "tool", "tool_call_id": "tc1", "name": "run_python", "content": "A" * 200},
            {"role": "user", "content": "continue"},
        ]

        prepared = prepare_messages_for_llm(
            messages,
            keep_recent=1,
            old_tool_chars=40,
        )
        tool_msg = prepared[2]

        self.assertEqual(tool_msg["role"], "tool")
        self.assertEqual(tool_msg["tool_call_id"], "tc1")
        self.assertEqual(tool_msg["name"], "run_python")
        self.assertIn("[compacted old tool result", tool_msg["content"])
        self.assertLess(len(tool_msg["content"]), 120)

    def test_short_old_tool_content_is_left_unchanged(self) -> None:
        messages = [
            {"role": "system", "content": "rules"},
            {"role": "tool", "tool_call_id": "tc1", "name": "grep", "content": "short"},
            {"role": "user", "content": "next"},
        ]

        prepared = prepare_messages_for_llm(
            messages,
            keep_recent=1,
            old_tool_chars=40,
        )

        self.assertEqual(prepared[1]["content"], "short")

    def test_compacts_old_load_skill_result_to_marker(self) -> None:
        messages = [
            {"role": "system", "content": "rules"},
            {
                "role": "tool",
                "tool_call_id": "tc1",
                "name": "load_skill",
                "content": "[skill=proposal, dir=/sandbox/skills/proposal]\n" + "A" * 5000,
            },
            {"role": "user", "content": "next"},
        ]

        prepared = prepare_messages_for_llm(messages, keep_recent=1)

        self.assertIn("loaded skill: proposal", prepared[1]["content"])
        self.assertIn("dir=/sandbox/skills/proposal", prepared[1]["content"])
        self.assertNotIn("A" * 100, prepared[1]["content"])

    def test_prepare_messages_reports_compaction_stats(self) -> None:
        messages = [
            {"role": "system", "content": "rules"},
            {"role": "tool", "tool_call_id": "tc1", "name": "shell", "content": "A" * 200},
            {"role": "user", "content": "next"},
        ]

        prepared, stats = prepare_messages_with_stats(
            messages,
            keep_recent=1,
            old_tool_chars=40,
        )

        self.assertLess(stats["sent_chars"], stats["original_chars"])
        self.assertEqual(stats["compacted_tool_messages"], 1)
        self.assertGreater(stats["saved_chars"], 0)
        self.assertEqual(len(prepared), len(messages))


if __name__ == "__main__":
    unittest.main()