"""Tests for /compress here [N] — boundary-aware partial compression.

Verifies the CLI handler (_manual_compress) splits the history, compresses
only the head, and re-appends the verbatim tail. Inspired by Claude Code's
Rewind "Summarize up to here" action (v2.1.139, May 2026).
"""

from unittest.mock import MagicMock, patch

from tests.cli.test_cli_init import _make_cli


def _make_history() -> list[dict[str, str]]:
    # 8 messages = 4 exchanges.
    h: list[dict[str, str]] = []
    for i in range(4):
        h.append({"role": "user", "content": f"u{i}"})
        h.append({"role": "assistant", "content": f"a{i}"})
    return h


def _wire_agent(shell, compressed_head):
    shell.agent = MagicMock()
    shell.agent.compression_enabled = True
    shell.agent._cached_system_prompt = ""
    shell.agent.session_id = None
    shell.agent.tools = None
    shell.agent._compress_context.return_value = (compressed_head, "")


def test_compress_here_compresses_head_only(capsys):
    """/compress here 2 passes only the head to _compress_context."""
    shell = _make_cli()
    history = _make_history()
    shell.conversation_history = history
    # Pretend compression collapses the head into a single summary message.
    summary = [{"role": "user", "content": "[summary of earlier turns]"}]
    _wire_agent(shell, summary)

    with patch("agent.model_metadata.estimate_request_tokens_rough", return_value=100):
        shell._manual_compress("/compress here 2")

    # _compress_context should have been called with the HEAD only
    # (everything before the last 2 user-starts = first 4 messages).
    shell.agent._compress_context.assert_called_once()
    call = shell.agent._compress_context.call_args
    passed_head = call.args[0]
    assert passed_head == history[:4]
    # focus_topic must be None in partial mode (modes are exclusive).
    assert call.kwargs.get("focus_topic") is None


def test_compress_here_reappends_verbatim_tail(capsys):
    """The most recent exchanges are preserved verbatim after the summary."""
    shell = _make_cli()
    history = _make_history()
    shell.conversation_history = history
    # Head compresses to an assistant-role summary so the seam
    # (assistant -> user tail) is already valid — tail rides along whole.
    summary = [{"role": "assistant", "content": "[summary]"}]
    _wire_agent(shell, summary)

    with patch("agent.model_metadata.estimate_request_tokens_rough", return_value=100):
        shell._manual_compress("/compress here 2")

    # Result = compressed head + verbatim tail (last 2 exchanges).
    assert shell.conversation_history == summary + history[4:]
    # Tail boundary keeps role alternation valid (tail starts on user).
    assert history[4]["role"] == "user"
    # No consecutive same-role user/assistant messages anywhere.
    roles = [m["role"] for m in shell.conversation_history
             if m["role"] in ("user", "assistant")]
    assert all(roles[i] != roles[i + 1] for i in range(len(roles) - 1))


def test_compress_here_banner_mentions_summarizing_up_to_here(capsys):
    shell = _make_cli()
    history = _make_history()
    shell.conversation_history = history
    _wire_agent(shell, [{"role": "user", "content": "[summary]"}])

    with patch("agent.model_metadata.estimate_request_tokens_rough", return_value=100):
        shell._manual_compress("/compress here")

    out = capsys.readouterr().out
    assert "Summarizing up to here" in out
    assert "verbatim" in out


def test_bare_compress_still_full(capsys):
    """/compress with no args compresses the whole history (full mode)."""
    shell = _make_cli()
    history = _make_history()
    shell.conversation_history = history
    _wire_agent(shell, list(history))

    with patch("agent.model_metadata.estimate_request_tokens_rough", return_value=100):
        shell._manual_compress("/compress")

    call = shell.agent._compress_context.call_args
    # Full mode passes the entire history as the head.
    assert call.args[0] == history
    out = capsys.readouterr().out
    assert "Summarizing up to here" not in out


def test_focus_still_works(capsys):
    """/compress <focus> keeps the existing focus behavior."""
    shell = _make_cli()
    history = _make_history()
    shell.conversation_history = history
    _wire_agent(shell, list(history))

    with patch("agent.model_metadata.estimate_request_tokens_rough", return_value=100):
        shell._manual_compress("/compress database schema")

    call = shell.agent._compress_context.call_args
    assert call.args[0] == history
    assert call.kwargs.get("focus_topic") == "database schema"