"""Tests for rag_retriever — pure-Python, no network calls."""

from __future__ import annotations

from tai.collectors import CollectedItem, CollectionReport
from tai.rag_retriever import Chunk, EmbeddedChunk, _cosine_similarity, chunk_report, retrieve
from tai.ssh_client import SSHCommandResult


def _report(*items: tuple[str, str, int]) -> CollectionReport:
    """Build a CollectionReport from (name, stdout, exit_code) tuples."""
    return CollectionReport(
        host="test-host",
        items=[
            CollectedItem(
                name=name,
                result=SSHCommandResult(
                    command=f"cmd-{name}",
                    exit_code=code,
                    stdout=stdout,
                    stderr="",
                ),
            )
            for name, stdout, code in items
        ],
    )


# ---------------------------------------------------------------------------
# chunk_report
# ---------------------------------------------------------------------------


def test_chunk_report_creates_one_chunk_per_item() -> None:
    report = _report(("kernel", "Linux test 6.1", 0), ("journal", "Started nginx.", 0))
    chunks = chunk_report(report)
    assert len(chunks) == 2
    assert chunks[0].name == "kernel"
    assert chunks[1].name == "journal"


def test_chunk_report_includes_stdout_in_content() -> None:
    report = _report(("kernel", "Linux test 6.1", 0))
    chunks = chunk_report(report)
    assert "Linux test 6.1" in chunks[0].content


def test_chunk_report_includes_exit_code_in_content() -> None:
    report = _report(("fail", "error output", 1))
    chunks = chunk_report(report)
    assert "Exit code: 1" in chunks[0].content


def test_chunk_report_skips_ssh_unreachable_items() -> None:
    """Items with exit 255 and no output represent SSH failures and are dropped."""
    report = CollectionReport(
        host="test-host",
        items=[
            CollectedItem(
                name="unreachable",
                result=SSHCommandResult(
                    command="some-cmd", exit_code=255, stdout="", stderr=""
                ),
            ),
            CollectedItem(
                name="ok",
                result=SSHCommandResult(
                    command="uname -a", exit_code=0, stdout="Linux", stderr=""
                ),
            ),
        ],
    )
    chunks = chunk_report(report)
    assert len(chunks) == 1
    assert chunks[0].name == "ok"


def test_chunk_report_keeps_exit_255_with_output() -> None:
    """Exit 255 with stderr present is a real failure — keep it."""
    report = CollectionReport(
        host="test-host",
        items=[
            CollectedItem(
                name="partial",
                result=SSHCommandResult(
                    command="some-cmd",
                    exit_code=255,
                    stdout="",
                    stderr="Permission denied",
                ),
            ),
        ],
    )
    chunks = chunk_report(report)
    assert len(chunks) == 1
    assert "Permission denied" in chunks[0].content


def test_chunk_report_notes_no_output() -> None:
    report = CollectionReport(
        host="test-host",
        items=[
            CollectedItem(
                name="silent",
                result=SSHCommandResult(command="cmd", exit_code=0, stdout="", stderr=""),
            ),
        ],
    )
    chunks = chunk_report(report)
    assert "(no output)" in chunks[0].content


# ---------------------------------------------------------------------------
# _cosine_similarity
# ---------------------------------------------------------------------------


def test_cosine_similarity_identical_vectors() -> None:
    v = [1.0, 0.0, 0.0]
    assert abs(_cosine_similarity(v, v) - 1.0) < 1e-9


def test_cosine_similarity_orthogonal_vectors() -> None:
    a = [1.0, 0.0]
    b = [0.0, 1.0]
    assert abs(_cosine_similarity(a, b)) < 1e-9


def test_cosine_similarity_opposite_vectors() -> None:
    a = [1.0, 0.0]
    b = [-1.0, 0.0]
    assert abs(_cosine_similarity(a, b) - (-1.0)) < 1e-9


def test_cosine_similarity_zero_vector_returns_zero() -> None:
    assert _cosine_similarity([0.0, 0.0], [1.0, 0.0]) == 0.0


# ---------------------------------------------------------------------------
# retrieve
# ---------------------------------------------------------------------------


def _embedded(name: str, vec: list[float]) -> EmbeddedChunk:
    return EmbeddedChunk(chunk=Chunk(name=name, content=f"content of {name}"), embedding=vec)


def test_retrieve_returns_top_k_by_similarity() -> None:
    chunks = [
        _embedded("close", [1.0, 0.0]),   # most similar
        _embedded("mid",   [0.7, 0.7]),
        _embedded("far",   [0.0, 1.0]),   # orthogonal to query
    ]
    query = [1.0, 0.0]
    result = retrieve(query, chunks, top_k=2)
    assert len(result) == 2
    assert result[0].name == "close"
    assert result[1].name == "mid"


def test_retrieve_respects_top_k_larger_than_pool() -> None:
    chunks = [_embedded("only", [1.0, 0.0])]
    result = retrieve([1.0, 0.0], chunks, top_k=10)
    assert len(result) == 1


def test_retrieve_empty_pool_returns_empty() -> None:
    assert retrieve([1.0, 0.0], [], top_k=5) == []


def test_retrieve_top_k_zero_returns_empty() -> None:
    chunks = [_embedded("x", [1.0, 0.0])]
    assert retrieve([1.0, 0.0], chunks, top_k=0) == []